CN114485244A - Thermal diode, thermal rectifying coating, phase-change heat storage and supply device and heat monitoring method - Google Patents
Thermal diode, thermal rectifying coating, phase-change heat storage and supply device and heat monitoring method Download PDFInfo
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Abstract
The invention relates to a thermal diode, a thermal rectification coating, a phase change heat storage and supply device and a heat monitoring method. Is suitable for the technical field of energy storage and waste heat recycling. The technical scheme adopted by the invention is as follows: a thermal diode, characterized by: the carbon nanotube has a mass gradient in the axial direction, and the mass of the carbon nanotube gradually increases from one end to the other end in the axial direction. A thermal rectifying layer, characterized by: with an array of thermal diode orientation arrangements. The utility model provides a phase change heat storage device based on heat rectification coating, has the shell and wears the heat exchange tube I of adorning in the shell, its characterized in that: the surface of the heat exchange tube I is covered with a heat rectification coating I, a flowing heat exchange fluid I is arranged in the heat exchange tube I, and a phase change material is filled between the heat rectification coating I and the shell; the thermal conductivity coefficient > of the thermal rectification coating I pointing to the outside of the pipe is larger than that of the thermal conductivity coefficient > of the thermal rectification coating I pointing to the inside of the pipe, and the thermal conductivity coefficient of the thermal rectification coating I pointing to the inside of the pipe is approximately equal to 0; the thermal rectification coating I adopts the thermal rectification layer.
Description
Technical Field
The invention relates to a thermal diode, a thermal rectification coating, a phase change heat storage and supply device and a heat monitoring method. Is suitable for the technical field of energy storage and waste heat recycling.
Background
The phase change heat storage system is one of important ways for improving the energy utilization rate as an effective means for solving the contradiction between the energy supply time and the space. The solid-liquid phase change has larger practical application value, and the design of the high-performance solid-liquid phase change heat accumulator is the key for improving the energy utilization efficiency and protecting the environment. The solar energy heat pump system can be used for solving the contradiction between heat energy supply and demand mismatch, has wide application prospects in the fields of solar energy utilization, electric power peak load shifting, waste heat and waste heat recycling, energy conservation of industrial and civil buildings and air conditioners and the like, and is a research hotspot in the world.
However, the common solid-liquid phase change material has low thermal conductivity and low energy storage efficiency, and is difficult to realize efficient, rapid and uniform heat transfer in a short time, so that the increase of the heat storage/release rate of the phase change heat accumulator is severely limited, and the development of the practical application of the phase change material is restricted. In view of the above, researchers have proposed various solutions for enhancing phase change heat transfer, for example, by adding a foam metal frame or nanoparticles with high thermal conductivity to a phase change material, and adding fins to increase the heat exchange area. However, the existence of the foam metal and the fins can seriously inhibit the natural convection heat exchange of the liquid phase-change material, and the addition of the nano particles can also greatly reduce the phase-change enthalpy value of the phase-change material and weaken the heat storage capacity of the phase-change material.
In addition, because the phase-change heat storage device is a thermal battery, the heat storage and heat supply process is the energy storage and release process of the thermal battery. The battery needs to monitor its real-time electric quantity, and like a thermal battery, it also needs to monitor and display its heat storage quantity and heat storage quantity in real time. However, the phase-change heat storage devices are not visible, so that the monitoring of the heat storage quantity and the energy utilization efficiency of the phase-change heat storage devices pose difficulties.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: in order to solve the existing problems, a thermal diode, a thermal rectification coating, a phase change heat storage and supply device and a heat monitoring method are provided.
The technical scheme adopted by the invention is as follows: a thermal diode, characterized by: the carbon nanotube has a mass gradient in the axial direction, and the mass of the carbon nanotube gradually increases from one end to the other end in the axial direction.
In the carbon nano tube, a heavy-mass phonon at one end is easy to be in an excited state, the density of a phonon vibration state is higher, phonon scattering is easier, and heat transfer is easy; the light-weight terminal phonon has low vibration state density and is not easy to transfer heat; heat will therefore tend to transfer from the heavy end to the light end; and is difficult to transfer from the end with light weight to the end with heavy weight.
The surface of the carbon nano tube is non-uniformly deposited with metal ions.
The metal ions adopt metal platinum Pt2+。
A thermal rectifying layer, characterized by: with an array of the described thermal diode orientation arrangement.
Synthesizing an oriented carbon nanotube array on a template by using a microwave plasma assisted chemical vapor deposition method;
metal ions are non-uniformly deposited on the surface of the carbon nano tube by an electrochemical deposition method, so that the carbon nano tube has mass gradient in the axial direction.
The template agent adopts porous metal oxide.
The utility model provides a phase change heat storage device based on heat rectification coating, has the shell and wears the heat exchange tube I of adorning in the shell, its characterized in that: the surface of the heat exchange tube I is covered with a thermal rectification coating I, a flowing heat exchange fluid I is arranged in the heat exchange tube I, and a phase change material is filled between the thermal rectification coating I and the shell;
the thermal conductivity coefficient > of the thermal rectification coating I pointing to the outside of the pipe is larger than that of the thermal conductivity coefficient > of the thermal rectification coating I pointing to the inside of the pipe, and the thermal conductivity coefficient of the thermal rectification coating I pointing to the inside of the pipe is approximately equal to 0; the thermal rectification coating I adopts the thermal rectification layer.
A heat monitoring method of the phase change heat storage device based on the thermal rectification coating is characterized in that:
obtain the inner diameter D of a heat exchange tube I in a phase change heat storage deviceiOuter diameter D of heat exchange tube IoHeat conduction coefficient k of heat exchange tube ItLength L of heat exchange tube It,1The thermal conductivity coefficient of the heat rectifying coating I outside the pointing tube is kc,pAnd a thermal conductivity k in the indicator tubec,nThickness delta of thermal rectification coating IcAnd the flow velocity u of the heat exchange fluid in the heat exchange tube IfHeat transfer coefficient k of heat transfer fluid in heat exchange tube IfHeat diffusion coefficient alpha of heat exchange fluid in heat exchange tube IfAnd the kinematic viscosity v of the heat exchange fluid in the heat exchange tube IfMass m of phase change material and melting point T of phase change materialpcm,mLatent heat of fusion Delta H of phase change material and specific heat capacity c of solid phase change materialpcm,sThermal conductivity k of liquid phase change materialpcm,lLiquid phase change material thermal diffusion coefficient alphapcm,lAnd the kinematic viscosity v of the liquid phase-change materialpcm,l;
The heat exchange tube I and the heat rectification coating I are integrally radial and point to the heat conductivity coefficient k outside the tubet+cThe calculation formula is derived according to the calculation formula of the thermal resistance, and the calculation formula is as follows:
for the heat exchange fluid I in the heat exchange tube I, the Plantt number Pr of the ratio of the momentum diffusion capacity and the heat diffusion capacity of the heat exchange fluid IfCalculated by the following definition:
for the heat exchange fluid I in the heat exchange tube I, the Reynolds number Re representing the ratio of the inertia force and the viscous force of the heat exchange fluid IfCalculated by the following definition:
obtaining the Prandtl number PrfAnd Reynolds number RefThen, the flow of the heat exchange fluid I in the heat exchange tube I in the phase change heat accumulator is usually turbulent flow, and the Nu of the turbulent flow is NufThis can be obtained by the following formula:
obtaining the Nu of NufThen, the heat transfer coefficient h of the heat transfer fluid I and the inner wall of the heat exchange tube I is calculatediCalculated with the following definitions:
for the phase change material outside the thermal rectification coating I of the heat exchange tube I, when the temperature rises and the phase change material starts to melt, the phase change material outside the tube starts to naturally convect, and the Plantt number Pr of the ratio of the momentum diffusion capability and the heat diffusion capability of the liquid phase change material is representedpcmCalculated by the following definition:
measuring the temperature T of the phase change material in real time at set time intervals DeltatpcmAnd the temperature T of the inlet of the heat exchange fluid I in the heat exchange tube I is obtained by real-time measurement at a set time interval delta Tf,iAnd the outlet temperature T of the heat exchange fluid I in the heat exchange tube If,oThe Gravadaff number Gr for measuring the strength of natural convection in the melting process of the phase-change materialpcmCalculated by the following definitional formula:
check combinationLa Xiaofu number GrpcmMaking a judgment when Gr is the Gr numberpcmAt 1.43X 104~5.76×108When the flow is in the middle, judging that the flow is in a laminar state; gr when Gravax dawnpcmAt 5.76X 108~4.65×109When the state is in the middle, the state is judged to be a transition state; gr when Gravax dawnpcmIn that>4.65×109Judging the state of the turbulent flow; calculating the Nu of the Knudsen number of the phase-change material according to different flow states of the liquid phase-change materialpcmThe calculation formula is as follows:
obtaining the Nu of phase-change materialpcmThen, the liquid phase-change material and the convection heat transfer coefficient h of the outer wall of the thermal rectification coating I of the heat exchange tube IoCalculated with the following definitions:
further calculating the total heat exchange coefficient U of the phase change heat storage device based on the thermal rectification coating in the heat storage processallThe calculation is defined as follows:
at the initial moment of heat exchange, recording the initial temperature T of the solid phase-change materialpcm,iTheoretical total heat storage amount Q of phase change heat storage device based on thermal rectification coatingpcm:
Qpcm=cpcm,sm(Tpcm,m-Tpcm,i)+mΔH
Testing is started after the high-temperature heat exchange fluid flows in, and the temperature T of the inner wall of the heat exchange tube I is measured and obtained in real time at a set time interval delta Tt,iTemperature T of outer wall of thermal rectification coating I of heat exchange tube It,oAnd calculating to obtain the thermal rectification coating of the heat exchange tube IInstantaneous heat absorption q of phase change materials outside If:
qf=π(Do+2δc)Lt,1UallΔt(Tt,i-Tt,o)
After the time t, accumulating the instantaneous heat absorption capacity at all delta t moments in the total time t, and calculating to obtain the total heat absorption capacity Q of the phase change material outside the heat rectification coating I of the heat exchange tube IfThe calculation formula is as follows:
based on the theoretical total heat storage Q of the obtained phase change materialpcmAnd the total heat absorption capacity Q of the phase change material outside the thermal rectification coating I of the heat exchange tube IfAnd calculating to obtain the total heat storage quantity eta of the phase change heat storage device based on the thermal rectification coating1The calculation formula is as follows:
amount of stored heat η1Can be calculated and displayed on a computer in real time, and the working capacity eta of the stored heat can be displayed1And when the heat storage rate reaches 100%, stopping heat storage of the phase change heat storage device based on the thermal rectification coating.
The utility model provides a phase transition heating device based on heat rectification coating, has the shell and wears the heat exchange tube II of adorning in the shell, its characterized in that: the surface of the heat exchange tube II is covered with a heat rectification coating II, a flowing heat exchange fluid II is arranged in the heat exchange tube II, and a phase change material is filled between the heat rectification coating II and the shell;
the thermal conductivity > of the thermal rectification coating II pointing to the inside of the pipe is larger than that of the thermal conductivity > of the thermal rectification coating II pointing to the outside of the pipe, and the thermal conductivity of the thermal rectification coating II pointing to the outside of the pipe is approximately equal to 0; the thermal rectification coating II adopts the thermal rectification layer.
A phase change heating device heat monitoring method based on a thermal rectification coating is characterized in that:
obtaining the inner diameter d of a heat exchange tube II in the phase change heat supply deviceiAnd the outer diameter d of the heat exchange tube IIoAnd heat conduction coefficient k of heat exchange tube II'tLength L of heat exchange tube IIt,2The thermal conductivity coefficient of the thermal rectifying coating II pointing to the outside of the tube is k'c,pAnd k 'is a heat conductivity coefficient in the directional pipe'c,nThickness delta 'of thermal rectifier coating II'cAnd the flow velocity u of heat exchange fluid II in the heat exchange tube II'fAnd heat transfer coefficient k of heat transfer fluid II in heat exchange tube II'fAnd heat diffusion coefficient alpha of heat exchange fluid II in heat exchange tube II'fAnd the kinematic viscosity v of heat exchange fluid II in the heat exchange tube II'fMass m of phase change material, melting point T of phase change materialpcm,mLatent heat of fusion Delta H of phase change material and specific heat capacity c of liquid phase change materialpcm,lThermal conductivity k of liquid phase change materialpcm,lLiquid phase change material thermal diffusion coefficient alphapcm,lAnd the kinematic viscosity v of the liquid phase-change materialpcm,l;
For the heat exchange tube II coated with the thermal rectification coating II, the whole heat exchange tube II is radial and points to the heat conduction coefficient k 'in the tube't+cThe calculation formula is derived according to the calculation formula of the thermal resistance, and the calculation formula is as follows:
for the heat exchange fluid II in the heat exchange tube II, the Plantt number Pr 'of the ratio of momentum diffusion capacity and heat diffusion capacity of the heat exchange fluid II'fCalculated by the following definition:
for the heat exchange fluid II in the heat exchange tube II, the Reynolds number Re 'of the ratio of the inertia force to the viscous force of the heat exchange fluid II is expressed'fCalculated by the following definition:
obtaining the prandtl number Pr'fAnd Reynolds number Re'fThereafter, the flow of the heat exchange fluid II within the heat exchange tube II in the phase change heat supply unit is usually turbulent and its Nu 'of Nu Seal'fThis can be obtained by the following formula:
to obtain the Nu 'Nu of Knisel number'fThen, the convective heat transfer coefficient h of the heat transfer fluid II and the inner wall of the heat exchange tube II'iCalculated with the following definitions:
for the phase change material outside the thermal rectification coating II of the heat exchange tube II, before the phase change material starts to solidify after the temperature is reduced, the phase change material outside the tube is in a natural convection state, and the Plantt number Pr 'of the ratio of momentum diffusion capacity and heat diffusion capacity of the liquid phase change material is represented'pcmCalculated by the following definition:
measuring the temperature T 'of the phase change material in real time at set time intervals delta T'pcmAnd measuring and obtaining the inlet temperature T 'of the heat exchange fluid II in the heat exchange tube II in real time at set time interval delta T'f,iAnd the outlet temperature T of the heat exchange fluid in the heat exchange tube II'f,oAnd Gr 'of Gravadaff number for measuring strength of natural convection in cooling process of phase-change material'pcmCalculated by the following definitional formula:
gr 'of groff number by using computer algorithm'pcmJudging that Gr ' is the Gr ' number of Gr 'pcmAt 1.43X 104~5.76×108When the flow is in the middle, judging that the flow is in a laminar state; gr 'when Gr is dawn'pcmAt 5.76X 108~4.65×109When the state is in the middle, the state is judged to be a transition state; gr 'when Gr is dawn'pcmIn that>4.65×109Judging the state of the turbulent flow; calculating the Nu 'of the Nu of the phase change material according to different flow states of the liquid phase change material'pcmThe calculation formula is as follows:
obtaining the Nu 'of the Nussel number of the phase-change material'pcmThen, the convection heat transfer coefficient h 'of the liquid phase change material and the outer wall of the thermal rectification coating II of the heat exchange tube II'oCalculated with the following definitions:
calculating total heat exchange coefficient U 'of phase change heat supply device based on thermal rectification coating in heat supply process'allThe calculation is defined as follows:
recording the initial temperature T 'of the liquid phase change material at the initial moment of heat exchange'pcm,iTheoretical total heat supply Q 'of the phase change heat supply device based on the thermal rectification coating'pcm:
Q′pcm=cpcm,lm(T′pcm,i-Tpcm,m)+mΔH
Testing is started after the low-temperature heat exchange fluid II flows in, and the temperature T 'of the inner wall of the heat exchange tube II is obtained through real-time measurement at set time interval delta T't,iAnd the temperature T of the outer wall of the thermal rectification coating II of the heat exchange tube II't,oCalculating to obtain the instantaneous heat supply q 'of the phase change material outside the heat rectifying coating II of the heat exchange tube II'f:
q′f=π(do+2δ′c)Lt,2U′allΔt(Tt,o-Tt,i)
After the time t, accumulating the instantaneous heat supply at all delta t moments in the total time t, and calculating to obtain the total heat supply Q 'of the phase change material outside the heat rectifying coating II of the heat exchange tube II'fThe calculation formula is as follows:
according to the theoretical total heat supply Q 'of the obtained phase change material'pcmAnd the total heat supply Q 'of the phase change material outside the heat rectifying coating II of the heat exchange tube II'fAnd calculating to obtain the total heat supply eta of the phase change heat supply device based on the thermal rectification coating2The calculation formula is as follows:
heat supply η2Can be calculated and displayed on a computer in real time when the heat supply eta2And when the heat exchange rate reaches 100%, stopping the external heat supply of the phase change heat supply device based on the thermal rectification coating.
The utility model provides a phase transition heat accumulation heating system based on heat rectification coating, has the shell and wears heat exchange tube I and heat exchange tube II of adorning in the shell, its characterized in that: the outer surface of the heat exchange tube I is covered with a heat rectification coating I, the outer surface of the heat exchange tube II is covered with a heat rectification coating II, the inlet of the heat exchange tube I corresponds to a heat exchange fluid I, the inlet of the heat exchange tube II corresponds to a heat exchange fluid II, and phase change materials are filled between the shell and the heat rectification coatings I and II.
The thermal conductivity coefficient > of the thermal rectification coating I pointing to the outside of the pipe is larger than that of the thermal conductivity coefficient > of the thermal rectification coating I pointing to the inside of the pipe, and the thermal conductivity coefficient of the thermal rectification coating I pointing to the inside of the pipe is approximately equal to 0; the thermal rectification coating I adopts the thermal rectification layer.
The thermal conductivity > of the thermal rectification coating II pointing to the inside of the pipe is larger than that of the thermal conductivity > of the thermal rectification coating II pointing to the outside of the pipe, and the thermal conductivity of the thermal rectification coating II pointing to the outside of the pipe is approximately equal to 0; the thermal rectification coating II adopts the thermal rectification layer.
The inner surface of the shell is covered with a thermal rectification coating III, the thermal conductivity > of the thermal rectification coating III pointing to the inside of the shell is larger than the thermal conductivity > of the thermal rectification coating III pointing to the outside of the shell, and the thermal conductivity of the thermal rectification coating III pointing to the outside of the shell is approximately equal to 0; the thermal rectification coating III adopts the thermal rectification layer.
The heat monitoring method of the phase change heat storage heating system based on the thermal rectification coating is characterized by comprising the following steps of:
the total heat eta of the phase-change heat storage and supply system after the time t is calculated and displayed in real time according to the following formula:
η=η1-η2
wherein the heat storage amount eta1The heat quantity eta obtained by the heat storage device is monitored by the heat quantity monitoring method2The method is obtained by adopting the heat monitoring method of the heating device.
The invention has the beneficial effects that: it is known in the art that carbon nanotubes have a unidirectional thermal conductivity, which means a high thermal conductivity along the axial direction and a low thermal conductivity along the radial direction. Different from the unidirectional heat conduction in the prior art, the thermal diode is manufactured by enabling the carbon nano tube to have mass gradient in the axial direction, wherein one end of the carbon nano tube is light, and the other end of the carbon nano tube is heavy, the carbon nano tube with the mass gradient has low heat conduction performance from the light end to the heavy end, and the carbon nano tube with the mass gradient has high heat conduction performance from the heavy end to the light end, so that the axial unidirectional heat conduction is formed.
The carbon nano tubes which are directionally arranged into an array and have mass gradient form the thermal rectification layer, and the thermal rectification layer has unidirectional heat conduction performance by utilizing the axial unidirectional heat conduction characteristic of the carbon nano tubes with mass gradient, so that the heat transfer can be enhanced in a certain direction, and the heat preservation can be realized in the opposite direction of the direction. The invention can control the heat transfer direction of the thermal rectifying layer by controlling the direction of the mass gradient of the carbon nano tube when preparing the thermal rectifying layer.
The heat rectifying coating is covered outside the heat exchange tube, the heat conductivity coefficient of the heat rectifying coating has orientation, the heat conductivity coefficient of the heat rectifying coating is in the direction pointing to the circle center and deviating from the circle center in the radial direction of the heat exchange tube, the difference of the heat conductivity coefficients is large, and the heat rectifying coating with different heat conductivity can be conveniently selected to adapt to different requirements.
The thermal rectification coating is made of carbon nano tubes with mass gradient, has thermal rectification effect, has great difference of heat conductivity coefficient along the direction of the mass gradient and against the direction of the mass gradient, and can strengthen heat transfer in a certain direction and realize heat preservation in the opposite direction of the direction if the material is applied to a phase change heat accumulator.
The heat exchange tubes I and II and the heat rectifying coatings I and II are used for realizing the coupling of heat storage and heat supply, so that heat storage or heat supply can be independently carried out, and the heat storage and heat supply processes can be simultaneously realized.
The invention realizes the heat monitoring of the heat storage and supply device by acquiring some easily-collected parameters and processing by a specific method.
Drawings
Fig. 1 is a schematic structural view of embodiment 1.
Fig. 2 is a schematic view of the internal structural composition of the phase change heat storage device in example 1.
Fig. 3 and 4 are schematic diagrams of the thermal diode in embodiment 1.
Fig. 5 is a schematic structural view of embodiment 2.
Fig. 6 is a schematic view of the internal structure of the phase-change heating apparatus in example 2.
FIG. 7 is a schematic structural view of embodiment 3.
Fig. 8 is a schematic view of the internal structure of the phase change heat storage and supply system in embodiment 3.
1. A heat exchange tube I; 2. a thermal rectification coating I; 3. a heat exchange fluid I; 4. a heat exchange pipe II; 5. a thermal rectification coating II; 6. a heat exchange fluid II; 7. a housing; 8. a thermal rectification coating III; 9. a phase change material; 10. a data acquisition instrument; 11. and (4) a computer.
Detailed Description
Example 1: as shown in fig. 1 and 2, the present embodiment is a phase change heat storage device based on a thermal rectification coating i, and the phase change heat storage device has a heat exchange tube i, the surface of the heat exchange tube i is covered with the thermal rectification coating i, the thermal rectification coating i is covered with a shell, and the shell is in a shape of a simple container with a non-visible symmetrical and regular shape inside, such as a sphere, a cuboid, a cube or a cylinder.
The thermal conductivity of the thermal rectification coating I in the embodiment has orientation, and the thermal conductivity of the thermal rectification coating I outside the directional pipe is kc,pIn the direction tube, the thermal conductivity is kc,n,kc,p>>kc,n≈0。
In this embodiment, the thermal rectification coating i is a thermal rectification layer, the thermal rectification layer has an array formed by directional arrangement of thermal diodes, and the thermal diodes have carbon nanotubes with a mass gradient in the axial direction, and the mass of the carbon nanotubes gradually increases from one end to the other end in the axial direction (see fig. 3).
The thermal rectifying layer was prepared as follows: synthesizing an oriented carbon nanotube array on a template (such as porous metal oxide) by using a microwave plasma-assisted chemical vapor deposition method; non-uniformly depositing metal ions (e.g., platinum Pt) on the surface of the carbon nanotubes by electrochemical deposition2+Etc.). As shown in FIG. 4, the left side deposits less lightly and the right side deposits more heavily.
In the carbon nano tube, a heavy-mass phonon at one end is easy to be in an excited state, the density of a phonon vibration state is higher, phonon scattering is easier, and heat transfer is easy; the light-weight terminal phonon has low vibration state density and is not easy to transfer heat; heat will therefore tend to transfer from the heavy end to the light end; and is difficult to transfer from the end with light weight to the end with heavy weight.
The heat rectifying coating I is made of carbon nano tubes with mass gradient, the difference of heat conductivity coefficients of the carbon nano tubes along the direction of the mass gradient and the direction opposite to the direction of the mass gradient is large, if the material is applied to a phase change heat accumulator, heat transfer can be enhanced in a certain direction, and heat preservation is realized in the direction opposite to the direction.
In this embodiment, a flowing heat exchange fluid I is arranged in the heat exchange tube I, and a phase change material is filled between the heat rectification coating I and the shell. The phase-change material is in a solid state at the initial moment, and the phase-change material is in a low temperature when the heat-exchange fluid I flows out of the phase-change heat storage device, and the solid-state phase-change material absorbs heat of the heat-exchange fluid I and melts to complete heat storage.
The embodiment also provides a monitoring and parameter calculating system of the phase change heat storage device, which is used for monitoring heat, and is provided with a data acquisition instrument for measuring and acquiring relevant parameters of the phase change heat storage device in real time and a computer for processing data.
The computer in this example has a memory and a processor, the memory having stored thereon a computer program executable by the processor, the computer program when executed implementing the steps of the method of:
obtain the inner diameter D of a heat exchange tube I in a phase change heat storage deviceiOuter diameter D of heat exchange tube IoAnd heat conductivity coefficient k of heat exchange tube ItLength L of heat exchange tube It,1The thermal conductivity coefficient of the heat rectifying coating I outside the pointing tube is kc,pAnd a thermal conductivity k in the indicator tubec,nThickness delta of thermal rectification coating IcAnd the flow velocity u of the heat exchange fluid in the heat exchange tube IfHeat transfer coefficient k of heat transfer fluid in heat exchange tube IfHeat diffusion coefficient alpha of heat exchange fluid in heat exchange tube IfAnd the kinematic viscosity v of the heat exchange fluid in the heat exchange tube IfMass m of phase change material and melting point T of phase change materialpcm,mLatent heat of fusion Delta H of phase change material and specific heat capacity c of solid phase change materialpcm,sThermal conductivity k of liquid phase change materialpcm,lLiquid phase change material thermal diffusion coefficient alphapcm,lThe kinematic viscosity v of the liquid phase-change materialpcm,l;
The heat exchange tube I and the heat rectification coating I are integrally radial and point to the heat conductivity coefficient k outside the tubet+cThe calculation formula is derived according to the calculation formula of the thermal resistance, and the calculation formula is as follows:
for heat exchange pipeFor the heat exchange fluid I in the I, the Plantt number Pr representing the ratio of the momentum diffusion capacity and the heat diffusion capacity of the heat exchange fluid IfCalculated by the following definition:
for the heat exchange fluid I in the heat exchange tube I, the Reynolds number Re representing the ratio of the inertia force and the viscous force of the heat exchange fluid IfCalculated by the following definition:
obtaining the Prandtl number PrfAnd Reynolds number RefThen, the flow of the heat exchange fluid I in the heat exchange tube I in the phase change heat accumulator is usually turbulent flow, and the Nu of the turbulent flow is NufThis can be obtained by the following formula:
obtaining the Nu of NufThen, the heat transfer coefficient h of the heat transfer fluid I and the inner wall of the heat exchange tube I is calculatediCalculated with the following definitions:
for the phase change material outside the thermal rectification coating I of the heat exchange tube I, when the temperature rises and the phase change material starts to melt, the phase change material outside the tube starts to naturally convect, and the Plantt number Pr of the ratio of the momentum diffusion capability and the heat diffusion capability of the liquid phase change material is representedpcmCalculated by the following definition:
measuring the temperature T of the phase change material in real time at set time intervals DeltatpcmAnd the temperature T of the inlet of the heat exchange fluid I in the heat exchange tube I is obtained by real-time measurement at a set time interval delta Tf,iAnd the outlet temperature T of the heat exchange fluid I in the heat exchange tube If,oThe Gravadaff number Gr for measuring the strength of natural convection in the melting process of the phase-change materialpcmCalculated by the following definitional equation:
gr Xiaofu number of PaglarapcmMaking a judgment when Gr is the Gr numberpcmAt 1.43X 104~5.76×108When the flow is in the middle, judging that the flow is in a laminar state; gr when Gravax dawnpcmAt 5.76X 108~4.65×109When the state is in the middle, the state is judged to be a transition state; gr when Gravax dawnpcmAt > 4.65X 109Judging the state of the turbulent flow; calculating the Nu of the Knudsen number of the phase-change material according to different flow states of the liquid phase-change materialpcmThe calculation formula is as follows:
obtaining the Nu of phase-change materialpcmThen, the convection heat transfer coefficient h of the liquid phase-change material and the outer wall of the thermal rectification coating I of the heat exchange tube IoCalculated with the following definitions:
further calculating the total heat exchange coefficient U of the phase change heat storage device based on the thermal rectification coating in the heat storage processallThe calculation is defined as follows:
at the initial moment of heat exchange, recording the initial temperature T of the solid phase-change materialpcm,iTheoretical total heat storage amount Q of phase change heat storage device based on thermal rectification coatingpcm:
Qpcm=cpcm,sm(Tpcm,m-Tpcm,i)+mΔH
Testing is started after the high-temperature heat exchange fluid flows in, and the temperature T of the inner wall of the heat exchange tube I is measured and obtained in real time at a set time interval delta Tt,iTemperature T of outer wall of thermal rectification coating I of heat exchange tube It,oCalculating to obtain the instantaneous heat absorption q of the phase change material outside the thermal rectification coating I of the heat exchange tube If:
qf=π(Do+2δc)Lt,1UallΔt(Tt,i-Tt,o)
After the time t, accumulating the instantaneous heat absorption capacity at all delta t moments in the total time t, and calculating to obtain the total heat absorption capacity Q of the phase change material outside the heat rectification coating I of the heat exchange tube IfThe calculation formula is as follows:
based on the theoretical total heat storage Q of the obtained phase change materialpcmAnd the total heat absorption capacity Q of the phase change material outside the thermal rectification coating I of the heat exchange tube IfAnd calculating to obtain the total heat storage quantity eta of the phase change heat storage device based on the thermal rectification coating1The calculation formula is as follows:
amount of stored heat η1Can be calculated and displayed on a computer in real time, and the working capacity eta of the stored heat can be displayed1And when the heat storage rate reaches 100%, stopping heat storage of the phase change heat storage device based on the thermal rectification coating.
In the embodiment, the overall heat transfer coefficient of the heat exchange tube I and the thermal rectification coating I is obtained by fitting the thermal resistances of the heat exchange tube I and the thermal rectification coating I, and key heat storage performance parameters such as the heat storage capacity of the phase change heat accumulator can be calculated within a certain precision range.
Example 2: as shown in fig. 4 and 5, the present embodiment is a phase change heat supply device based on a thermal rectification coating ii, which has a heat exchange tube ii, the surface of the heat exchange tube ii is covered with the thermal rectification coating ii, the thermal rectification coating ii is covered with a shell, and the shell is a container with a shape of a sphere, a cuboid, a cube, a cylinder, or the like, and the interior of the shell is invisible, symmetrical, and regular, and has a simple shape.
The thermal conductivity of the thermal rectifying coating II in this example is oriented, and the thermal conductivity of the thermal rectifying coating II pointing out of the pipe is k'c,pK 'to the thermal conductivity in the tube'c,n,k'c,n>>k'c,pApproximately equal to 0, the thermal rectifier coating II adopts the thermal rectifier layer in the embodiment 1.
The thermal rectification coating II is made of carbon nano tubes with mass gradient, the difference of the heat conductivity coefficients of the carbon nano tubes along the direction of the mass gradient and the direction opposite to the direction of the mass gradient is large, if the material is applied to a phase change heat accumulator, the heat transfer can be enhanced in a certain direction, and the heat preservation can be realized in the opposite direction of the direction.
In the embodiment, a flowing heat exchange fluid II is arranged in the heat exchange tube II, and a phase change material is filled between the heat rectification coating II and the shell. When the heat exchange fluid II flows into the phase-change heat supply device, the temperature is low, the phase-change material is in a liquid state at the initial moment, when the heat exchange fluid II flows out of the phase-change heat supply device, the temperature is high, the liquid phase-change material is solidified and releases heat to the heat exchange fluid II, and the heat-absorbed high-temperature heat exchange fluid II flows out of the heat exchange tube II to complete heat supply.
The embodiment also provides a monitoring and parameter calculating system of the phase-change heating device, which is provided with a data acquisition instrument for measuring and acquiring relevant parameters of the phase-change heating device in real time and a computer for processing data.
The computer in this example has a memory and a processor, the memory having stored thereon a computer program executable by the processor, the computer program when executed implementing the steps of the method of:
obtaining the inner diameter d of a heat exchange tube II in the phase change heat supply deviceiAnd the outer diameter d of the heat exchange tube IIoAnd heat conduction coefficient k of heat exchange tube II'tLength L of heat exchange tube IIt,2The thermal conductivity coefficient of the thermal rectifying coating II pointing to the outside of the tube is k'c,pAnd k 'is a heat conductivity coefficient in the directional pipe'c,nThickness delta 'of thermal rectifier coating II'cAnd the flow velocity u of the heat exchange fluid II in the heat exchange tube II'fAnd heat transfer coefficient k of heat transfer fluid II in heat exchange tube II'fAnd heat diffusion coefficient alpha of heat exchange fluid II in heat exchange tube II'fAnd the kinematic viscosity v of heat exchange fluid II in the heat exchange tube II'fMass m of phase change material and melting point T of phase change materialpcm,mLatent heat of fusion Delta H of phase change material and specific heat capacity c of liquid phase change materialpcm,lThermal conductivity k of liquid phase change materialpcm,lLiquid phase change material thermal diffusion coefficient alphapcm,lThe kinematic viscosity v of the liquid phase-change materialpcm,l;
For the heat exchange tube II coated with the thermal rectification coating II, the whole heat exchange tube II is radial and points to the heat conduction coefficient k 'in the tube't+cThe calculation formula is derived according to the calculation formula of the thermal resistance, and the calculation formula is as follows:
for the heat exchange fluid II in the heat exchange tube II, the Plantt number Pr 'of the ratio of momentum diffusion capacity and heat diffusion capacity of the heat exchange fluid II'fCalculated by the following definition:
for the heat exchange fluid II in the heat exchange tube II, the Reynolds number Re 'of the ratio of the inertia force to the viscous force of the heat exchange fluid II is expressed'fCalculated by the following definition:
obtaining the prandtl number Pr'fAnd Reynolds number Re'fThereafter, the flow of the heat exchange fluid II within the heat exchange tube II in the phase change heat supply unit is usually turbulent and its Nu 'of Nu Seal'fThis can be obtained by the following formula:
Nu′f=0.023Re′f 0.8Pr′f 0.3
to obtain the Nu 'Nu of Knisel number'fThen, the convective heat transfer coefficient h of the heat transfer fluid II and the inner wall of the heat exchange tube II'iCalculated with the following definitions:
for the phase change material outside the thermal rectification coating II of the heat exchange tube II, before the phase change material starts to solidify after the temperature is reduced, the phase change material outside the tube is in a natural convection state, and the Plantt number Pr 'of the ratio of momentum diffusion capacity and heat diffusion capacity of the liquid phase change material is represented'pcmCalculated by the following definition:
measuring the temperature T 'of the phase change material in real time at set time intervals delta T'pcmAnd measuring and obtaining the inlet temperature T 'of the heat exchange fluid II in the heat exchange tube II in real time at set time interval delta T'f,iAnd the outlet temperature T of the heat exchange fluid in the heat exchange tube II'f,oAnd Gr 'of Gravadaff number for measuring strength of natural convection in cooling process of phase-change material'pcmCalculated by the following definitional formula:
gr 'of groff number by using computer algorithm'pcmJudging that Gr ' is the Gr ' number of Gr 'pcmIn 1.43104~5.76×108When the flow is in the middle, judging that the flow is in a laminar state; gr 'when Gr is dawn'pcmAt 5.76X 108~4.65×109When the state is in the middle, the state is judged to be a transition state; gr 'when Gr is dawn'pcmIn that>4.65×109Judging the state of the turbulent flow; calculating the Nu 'of the Nu of the phase change material according to different flow states of the liquid phase change material'pcmThe calculation formula is as follows:
obtaining the Nu 'of the Nussel number of the phase-change material'pcmThen, the convection heat transfer coefficient h 'of the liquid phase change material and the outer wall of the thermal rectification coating II of the heat exchange tube II'oCalculated with the following definitions:
calculating total heat exchange coefficient U 'of phase change heat supply device based on thermal rectification coating in heat supply process'allThe calculation is defined as follows:
recording the initial temperature T 'of the liquid phase change material at the initial moment of heat exchange'pcm,iTheoretical total heat supply Q 'of the phase change heat supply device based on the thermal rectification coating'pcm:
Q′pcm=cpcm,lm(T′pcm,i-Tpcm,m)+mΔH
Testing is started after the low-temperature heat exchange fluid II flows in, and the temperature T 'of the inner wall of the heat exchange tube II is obtained through real-time measurement at set time interval delta T't,iAnd the temperature T of the outer wall of the thermal rectification coating II of the heat exchange tube II't,oCalculating to obtain the instantaneous heat supply q 'of the phase change material outside the heat rectifying coating II of the heat exchange tube II'f:
q′f=π(do+2δ′c)Lt,2U′allΔt(Tt,o-Tt,i)
After the time t, accumulating the instantaneous heat supply at all delta t moments in the total time t, and calculating to obtain the total heat supply Q 'of the phase change material outside the heat rectifying coating II of the heat exchange tube II'fThe calculation formula is as follows:
according to the theoretical total heat supply Q 'of the obtained phase change material'pcmAnd the total heat supply Q 'of the phase change material outside the heat rectifying coating II of the heat exchange tube II'fAnd calculating to obtain the total heat supply eta of the phase change heat supply device based on the thermal rectification coating2The calculation formula is as follows:
heat supply η2Can be calculated and displayed on a computer in real time when the heat supply eta2And when the heat exchange rate reaches 100%, stopping the external heat supply of the phase change heat supply device based on the thermal rectification coating.
According to the embodiment, the overall heat transfer coefficient of the heat exchange tube II and the thermal rectification coating II is obtained by fitting the thermal resistance of the heat exchange tube II and the thermal rectification coating II, and key heat supply performance parameters such as the heat supply quantity of the phase change heat supply device can be calculated within a certain precision range.
Example 3: as shown in fig. 7 and 8, the present embodiment is a phase change heat storage and supply system based on a heat rectification coating, which comprises a housing, and a heat exchange tube i and a heat exchange tube ii penetrating through the housing, wherein the heat exchange tube i is covered with the heat rectification coating i on the outer surface thereof, and a flowing heat exchange fluid i is provided in the heat exchange tube i; 4 heat exchange tubes II evenly distributed are around heat exchange tube I, and heat rectification coating II covers on II surfaces of heat exchange tube, has mobile heat transfer fluid II in the heat exchange tube II. In the embodiment, the inner surface of the shell is covered with a thermal rectification coating III, and phase-change materials are filled between the shell and the thermal rectification coating I and between the shell and the thermal rectification coating II.
The outer shell in this example is an internally invisible symmetrical, regular, simple-shaped container that is spherical, rectangular, cubic, or cylindrical.
In this embodiment, the thermal rectification coating i adopts the thermal rectification layer in embodiment 1, and the thermal conductivity coefficient in the radial direction pointing to the center of the heat exchange tube i is almost 0, and the thermal conductivity coefficient in the radial direction deviating from the center of the heat exchange tube i of the thermal rectification coating i is larger. The difference of the heat conductivity coefficients of the two different directions is large, so that the one-way heat exchange of the heat exchange fluid I can be promoted, and the heat dissipation in the opposite direction is inhibited.
In this example, the thermal rectification coating ii adopts the thermal rectification layer in example 1, the thermal conductivity in the radial direction away from the center of the heat exchange tube ii is almost 0, the thermal conductivity in the radial direction toward the center of the heat exchange tube ii is larger, and the difference between the thermal conductivities in the two different directions is large. This promotes the unidirectional heat absorption of the heat exchange fluid ii while suppressing the heat dissipation in the opposite direction.
In this embodiment, the thermal rectification coating iii adopts the thermal rectification layer in embodiment 1, and the radial heat conductivity coefficient deviating from the center of the phase change heat storage heating system housing is almost 0, and the radial heat conductivity coefficient of the thermal rectification coating iii pointing to the center of the phase change heat storage heating system housing is larger, and the difference between the two heat conductivity coefficients in different directions is huge, so that the heat dissipation of the phase change material to the outside of the phase change heat storage heating system housing is suppressed, and only the inflow of heat is allowed, but not the outflow of heat is allowed, and the heat preservation effect is better played.
The heat storage method of the present embodiment includes:
in the heat storage process, the heat exchange fluid I is high in temperature when flowing into the heat exchange tube I, and the phase change material is solid at the initial moment. Because the heat conductivity coefficient of the thermal rectification coating I in the radial direction pointing to the circle center of the heat exchange tube I is almost 0, the heat conductivity coefficient of the thermal rectification coating I in the radial direction deviating from the circle center of the heat exchange tube I is larger. Therefore, the heat of the high-temperature heat exchange fluid can be transferred to the phase-change material only in a single direction, and the heat transfer is more efficient. The heat of the high-temperature heat exchange fluid is absorbed by the solid phase-change material through the heat exchange tube I and the heat rectification coating I. The heat exchange fluid is at a low temperature when flowing out of the heat exchange tube I. The solid phase-change material absorbs the heat of the heat exchange fluid and is completely melted to complete heat storage.
The heat conductivity coefficient of the thermal rectification coating III in the radial direction away from the center of the phase change heat storage heating system shell is almost 0, the heat conductivity coefficient of the thermal rectification coating III in the radial direction pointing to the center of the phase change heat storage heating system shell is larger, and the difference of the heat conductivity coefficients in the two different directions is huge. Therefore, the heat dissipation of the phase-change material to the outside of the shell of the phase-change heat storage and supply system is inhibited, the heat is only allowed to flow into the shell of the phase-change heat storage and supply system, and the heat is not allowed to flow out of the shell of the phase-change heat storage and supply system, so that the heat preservation effect is better achieved. The temperature of the heat exchange fluid and the phase-change material in the heat storage process is transmitted to the computer in real time through the data acquisition instrument, and the whole heat storage process and state can be monitored in real time.
The heating method of the embodiment comprises the following steps:
in the heat supply process, the temperature of the heat exchange fluid II flowing into the heat exchange tube II is low, and the phase change material is in a high-temperature liquid state at the initial moment of heat supply. Because the heat conductivity coefficient of the thermal rectification coating II in the radial direction deviating from the circle center of the heat exchange tube II is almost 0, the heat conductivity coefficient of the thermal rectification coating II in the radial direction pointing to the circle center of the heat exchange tube II is larger. Therefore, the heat of the high-temperature liquid phase-change material can only be transmitted to the heat supply fluid in a single direction, and the heat transmission is more efficient. And the heat of the high-temperature liquid phase-change material is absorbed by the heat supply fluid through the heat rectification coating II and the heat exchange tube II. The liquid phase change material solidifies releasing heat. And when flowing out of the heat exchange tube II, the heat supply fluid is at high temperature and can be used for heating.
The heat conductivity coefficient of the thermal rectification coating III in the radial direction away from the center of the phase change heat storage heating system shell is almost 0, the heat conductivity coefficient of the thermal rectification coating III in the radial direction pointing to the center of the phase change heat storage heating system shell is larger, and the difference of the heat conductivity coefficients in the two different directions is huge. Therefore, the heat dissipation of the phase-change material to the outside of the shell of the phase-change heat storage and supply system is inhibited, the heat is only allowed to flow into the shell of the phase-change heat storage and supply system, and the heat is not allowed to flow out of the shell of the phase-change heat storage and supply system, so that the heat preservation effect is better achieved. The temperature of the heat supply fluid and the phase-change material in the heat supply process is transmitted to the computer in real time through the data acquisition instrument, and the whole heat supply process and state can be monitored in real time.
In this embodiment, the heat storage process and the heat supply process may be independent, that is, the heat storage working condition may be used to perform heat storage alone or the heat supply working condition may be used to perform heat supply alone. In addition, the heat storage process and the heat supply process of the phase-change heat storage and supply system can be parallel, namely, the phase-change heat storage and supply system can work under the heat storage working condition and the heat supply working condition simultaneously, so that heat storage and heat supply are carried out simultaneously.
In the method for monitoring the heat of the phase-change heat storage and supply system based on the thermal rectification coating, by analogy with the concept of the electric quantity of the battery, the total heat eta of the phase-change heat storage and supply system after the time t passes can be calculated and displayed on a computer in real time:
η=η1-η2
wherein eta is1The heat storage amount is represented and can be calculated according to the heat amount monitoring method of the heat storage device in example 1; eta2The heat supply amount is represented and can be calculated according to the heat monitoring method of the heat supply apparatus in embodiment 2.
Claims (13)
1. A thermal diode, characterized by: the carbon nanotube has a mass gradient in the axial direction, and the mass of the carbon nanotube gradually increases from one end to the other end in the axial direction.
2. The thermal diode of claim 1, wherein: the surface of the carbon nano tube is non-uniformly deposited with metal ions.
3. The thermal diode of claim 2, wherein: the metal ions adopt metal platinum Pt2+。
4. A thermal rectifying layer, characterized by: having an array of thermal diode orientation arrangements as claimed in any one of claims 1 to 3.
5. The thermal rectifying layer according to claim 4, characterized in that:
synthesizing an oriented carbon nanotube array on a template by using a microwave plasma assisted chemical vapor deposition method;
metal ions are non-uniformly deposited on the surface of the carbon nano tube by an electrochemical deposition method, so that the carbon nano tube has mass gradient in the axial direction.
6. The thermal rectifying layer according to claim 5, characterized in that: the template agent adopts porous metal oxide.
7. The utility model provides a phase change heat storage device based on heat rectification coating, has the shell and wears the heat exchange tube I of adorning in the shell, its characterized in that: the surface of the heat exchange tube I is covered with a thermal rectification coating I, a flowing heat exchange fluid I is arranged in the heat exchange tube I, and a phase change material is filled between the thermal rectification coating I and the shell;
the thermal conductivity coefficient > of the thermal rectification coating I pointing to the outside of the pipe is larger than that of the thermal conductivity coefficient > of the thermal rectification coating I pointing to the inside of the pipe, and the thermal conductivity coefficient of the thermal rectification coating I pointing to the inside of the pipe is approximately equal to 0; the thermal rectifying coating I adopts the thermal rectifying layer as claimed in claim 4, 5 or 6.
8. A method of monitoring the heat of a phase change thermal storage device based on a thermally rectifying coating as set forth in claim 7, characterized in that:
obtain the inner diameter D of a heat exchange tube I in a phase change heat storage deviceiOuter diameter D of heat exchange tube IoHeat conduction coefficient k of heat exchange tube ItLength L of heat exchange tube It,1The thermal conductivity coefficient of the heat rectifying coating I outside the pointing tube is kc,pAnd a thermal conductivity k in the indicator tubec,nThickness delta of thermal rectification coating IcAnd the flow velocity u of the heat exchange fluid in the heat exchange tube IfHeat transfer coefficient k of heat transfer fluid in heat exchange tube IfHeat diffusion coefficient alpha of heat exchange fluid in heat exchange tube IfAnd the kinematic viscosity v of the heat exchange fluid in the heat exchange tube IfMass m of phase change material and melting point T of phase change materialpcm,mLatent heat of fusion Delta H of phase change material and specific heat capacity c of solid phase change materialpcm,sThermal conductivity k of liquid phase change materialpcm,lLiquid phase change material thermal diffusion coefficient alphapcm,lAnd the kinematic viscosity v of the liquid phase-change materialpcm,l;
The heat exchange tube I and the heat rectification coating I are integrally radial and point to the heat conductivity coefficient k outside the tubet+cThe calculation formula is derived according to the calculation formula of the thermal resistance, and the calculation formula is as follows:
for the heat exchange fluid I in the heat exchange tube I, the Plantt number Pr of the ratio of the momentum diffusion capacity and the heat diffusion capacity of the heat exchange fluid IfCalculated by the following definition:
for the heat exchange fluid I in the heat exchange tube I, the Reynolds number Re representing the ratio of the inertia force and the viscous force of the heat exchange fluid IfCalculated by the following definition:
obtaining the Prandtl number PrfAnd Reynolds number RefThen, the flow of the heat exchange fluid I in the heat exchange tube I in the phase change heat accumulator is usually turbulent flow, and the Nu of the turbulent flow is NufThis can be obtained by the following formula:
obtaining the Nu of NufThen, the heat transfer coefficient h of the heat transfer fluid I and the inner wall of the heat exchange tube I is calculatediBy using, for exampleThe following definition is calculated:
for the phase change material outside the thermal rectification coating I of the heat exchange tube I, when the temperature rises and the phase change material starts to melt, the phase change material outside the tube starts to naturally convect, and the Plantt number Pr of the ratio of the momentum diffusion capability and the heat diffusion capability of the liquid phase change material is representedpcmCalculated by the following definition:
measuring the temperature T of the phase change material in real time at set time intervals DeltatpcmAnd the temperature T of the inlet of the heat exchange fluid I in the heat exchange tube I is obtained by real-time measurement at a set time interval delta Tf,iAnd the outlet temperature T of the heat exchange fluid I in the heat exchange tube If,oThe Gravadaff number Gr for measuring the strength of natural convection in the melting process of the phase-change materialpcmCalculated by the following definitional formula:
gr Xiaofu number of PaglarapcmMaking a judgment when Gr is the Gr numberpcmAt 1.43X 104~5.76×108When the flow is in the middle, judging that the flow is in a laminar state; gr number of Gr GrataffepcmAt 5.76X 108~4.65×109When the state is in the middle, the state is judged to be a transition state; gr when Gravax dawnpcmIn that>4.65×109Judging the state of the turbulent flow; calculating the Nu of the Knudsen number of the phase-change material according to different flow states of the liquid phase-change materialpcmThe calculation formula is as follows:
obtaining the Nu of phase-change materialpcmThen, the liquid phase-change material and the convection heat transfer coefficient h of the outer wall of the thermal rectification coating I of the heat exchange tube IoCalculated with the following definitions:
further calculating the total heat exchange coefficient U of the phase change heat storage device based on the thermal rectification coating in the heat storage processallThe calculation is defined as follows:
at the initial moment of heat exchange, recording the initial temperature T of the solid phase-change materialpcm,iTheoretical total heat storage amount Q of phase change heat storage device based on thermal rectification coatingpcm:
Qpcm=cpcm,sm(Tpcm,m-Tpcm,i)+mΔH
Testing is started after the high-temperature heat exchange fluid flows in, and the temperature T of the inner wall of the heat exchange tube I is measured in real time at a set time interval delta Tt,iTemperature T of outer wall of thermal rectification coating I of heat exchange tube It,oAnd calculating to obtain the instantaneous heat absorption capacity q of the phase change material outside the thermal rectification coating I of the heat exchange tube If:
qf=π(Do+2δc)Lt,1UallΔt(Tt,i-Tt,o)
After the time t, accumulating the instantaneous heat absorption capacity at all delta t moments in the total time t, and calculating to obtain the total heat absorption capacity Q of the phase change material outside the heat rectification coating I of the heat exchange tube IfThe calculation formula is as follows:
based on the theoretical total heat storage Q of the obtained phase change materialpcmAnd the total heat absorption capacity Q of the phase change material outside the thermal rectification coating I of the heat exchange tube IfAnd calculating to obtain the total heat storage quantity eta of the phase change heat storage device based on the thermal rectification coating1The calculation formula is as follows:
amount of stored heat η1Can be calculated and displayed on a computer in real time, and the working capacity eta of the stored heat can be displayed1And when the heat storage rate reaches 100%, stopping heat storage of the phase change heat storage device based on the thermal rectification coating.
9. The utility model provides a phase transition heating device based on heat rectification coating, has the shell and wears the heat exchange tube II of adorning in the shell, its characterized in that: the surface of the heat exchange tube II is covered with a heat rectification coating II, a flowing heat exchange fluid II is arranged in the heat exchange tube II, and a phase change material is filled between the heat rectification coating II and the shell;
the thermal conductivity > of the thermal rectification coating II pointing to the inside of the pipe is larger than that of the thermal conductivity > of the thermal rectification coating II pointing to the outside of the pipe, and the thermal conductivity of the thermal rectification coating II pointing to the outside of the pipe is approximately equal to 0; the thermal rectification coating II adopts the thermal rectification layer as claimed in claim 4, 5 or 6.
10. The method for monitoring the heat quantity of the phase-change heat supply device based on the thermal rectification coating as claimed in claim 9, is characterized in that:
obtaining the inner diameter d of a heat exchange tube II in the phase change heat supply deviceiAnd the outer diameter d of the heat exchange tube IIoAnd heat exchange tube II has heat conduction coefficient k'tLength L of heat exchange tube IIt,2The thermal conductivity coefficient of the thermal rectifying coating II pointing to the outside of the tube is k'c,pAnd k 'is a heat conductivity coefficient in the directional pipe'c,nThickness delta 'of thermal rectifier coating II'cAnd the flow velocity u of heat exchange fluid II in the heat exchange tube II'fHeat conductivity coefficient of heat exchange fluid II in heat exchange tube IIk'fAnd heat diffusion coefficient alpha of heat exchange fluid II in heat exchange tube II'fAnd the kinematic viscosity v of heat exchange fluid II in the heat exchange tube II'fMass m of phase change material and melting point T of phase change materialpcm,mLatent heat of fusion Delta H of phase change material and specific heat capacity c of liquid phase change materialpcm,lThermal conductivity k of liquid phase change materialpcm,lLiquid phase change material thermal diffusion coefficient alphapcm,lAnd the kinematic viscosity v of the liquid phase-change materialpcm,l;
For the heat exchange tube II coated with the thermal rectification coating II, the whole heat exchange tube II is radial and points to the heat conduction coefficient k 'in the tube't+cThe calculation formula is derived according to the calculation formula of the thermal resistance, and the calculation formula is as follows:
for the heat exchange fluid II in the heat exchange tube II, the Plantt number Pr 'of the ratio of momentum diffusion capacity and heat diffusion capacity of the heat exchange fluid II'fCalculated by the following definition:
for the heat exchange fluid II in the heat exchange tube II, the Reynolds number Re 'of the ratio of the inertia force to the viscous force of the heat exchange fluid II is expressed'fCalculated by the following definition:
obtaining the prandtl number Pr'fAnd Reynolds number Re'fThereafter, the flow of the heat exchange fluid II within the heat exchange tube II in the phase change heat supply unit is usually turbulent and its Nu 'of Nu Seal'fThis can be obtained by the following formula:
to obtain the Nu 'Nu of Knisel number'fThen, the convective heat transfer coefficient h of the heat transfer fluid II and the inner wall of the heat exchange tube II'iCalculated with the following definitions:
for the phase change material outside the thermal rectification coating II of the heat exchange tube II, before the phase change material starts to solidify after the temperature is reduced, the phase change material outside the tube is in a natural convection state, and the Plantt number Pr 'of the ratio of momentum diffusion capacity and heat diffusion capacity of the liquid phase change material is represented'pcmCalculated by the following definition:
measuring the temperature T 'of the phase change material in real time at set time intervals delta T'pcmAnd measuring and obtaining the inlet temperature T 'of the heat exchange fluid II in the heat exchange tube II in real time at set time interval delta T'f,iAnd the outlet temperature T of the heat exchange fluid in the heat exchange tube II'f,oAnd Gr 'of Gravadaff number for measuring strength of natural convection in cooling process of phase-change material'pcmCalculated by the following definitional formula:
gr 'of groff number by using computer algorithm'pcmJudging that Gr ' is the Gr ' number of Gr 'pcmAt 1.43X 104~5.76×108When the flow is in the middle, judging that the flow is in a laminar state; gr 'when Gr is dawn'pcmAt 5.76X 108~4.65×109When the state is in the middle, the state is judged to be a transition state; gr 'when Gr is dawn'pcmIn that>4.65×109Judging the state of the turbulent flow; according to different liquid phase change materialsCalculating Nu 'of Nu of phase change material by material flow state'pcmThe calculation formula is as follows:
obtaining the Nu 'of the Nussel number of the phase-change material'pcmThen, the convection heat transfer coefficient h 'of the liquid phase change material and the outer wall of the thermal rectification coating II of the heat exchange tube II'oCalculated with the following definitions:
calculating total heat exchange coefficient U 'of phase change heat supply device based on thermal rectification coating in heat supply process'allThe calculation is defined as follows:
recording the initial temperature T 'of the liquid phase change material at the initial moment of heat exchange'pcm,iTheoretical total heat supply Q 'of the phase change heat supply device based on the thermally rectifying coating'pcm:
Q′pcm=cpcm,lm(T′pcm,i-Tpcm,m)+mΔH
Testing is started after the low-temperature heat exchange fluid II flows in, and the temperature T 'of the inner wall of the heat exchange tube II is obtained through real-time measurement at set time interval delta T't,iAnd the temperature T of the outer wall of the thermal rectification coating II of the heat exchange tube II't,oCalculating to obtain the instantaneous heat supply q 'of the phase change material outside the heat rectifying coating II of the heat exchange tube II'f:
q′f=π(do+2δ′c)Lt,2U′allΔt(Tt,o-Tt,i)
After the time t, accumulating the instantaneous heat supply at all delta t moments in the total time t, and calculating to obtain the heat exchangeTotal heat supply Q 'of phase change material outside thermal rectification coating II of pipe II'fThe calculation formula is as follows:
according to the theoretical total heat supply Q 'of the obtained phase change material'pcmAnd the total heat supply Q 'of the phase change material outside the heat rectifying coating II of the heat exchange tube II'fAnd calculating to obtain the total heat supply eta of the phase change heat supply device based on the thermal rectification coating2The calculation formula is as follows:
heat supply η2Can be calculated and displayed on a computer in real time when the heat supply eta2And when the heat exchange rate reaches 100%, stopping the external heat supply of the phase change heat supply device based on the thermal rectification coating.
11. The utility model provides a phase transition heat accumulation heating system based on heat rectification coating, has the shell and wears heat exchange tube I and heat exchange tube II of adorning in the shell, its characterized in that: the outer surface of the heat exchange tube I is covered with a heat rectification coating I, the outer surface of the heat exchange tube II is covered with a heat rectification coating II, an inlet of the heat exchange tube I corresponds to the heat exchange fluid I, an inlet of the heat exchange tube II corresponds to the heat exchange fluid II, and phase change materials are filled between the shell and the heat rectification coatings I and II;
the thermal conductivity of the thermal rectification coating I pointing to the outside of the pipe > is the thermal conductivity of the thermal rectification coating I pointing to the inside of the pipe, and the thermal conductivity of the thermal rectification coating I pointing to the inside of the pipe is approximately equal to 0; the thermal rectification coating I adopts the thermal rectification layer as claimed in claim 4, 5 or 6;
the heat conductivity coefficient > of the heat rectifying coating II pointing to the inside of the pipe is larger than that of the heat rectifying coating II pointing to the outside of the pipe, and the heat conductivity coefficient of the heat rectifying coating II pointing to the outside of the pipe is approximately equal to 0; the thermal rectification coating II adopts the thermal rectification layer as claimed in claim 4, 5 or 6.
12. The phase-change heat-storage and supply system based on the thermal rectifier coating of claim 11, wherein: the inner surface of the shell is covered with a thermal rectification coating III, the thermal conductivity > of the thermal rectification coating III pointing to the inside of the shell is larger than the thermal conductivity > of the thermal rectification coating III pointing to the outside of the shell, and the thermal conductivity of the thermal rectification coating III pointing to the outside of the shell is approximately equal to 0; the thermal rectification coating III adopts the thermal rectification layer as claimed in claim 4, 5 or 6.
13. A method of monitoring heat in a phase change heat storage heating system based on a thermal rectifier coating as claimed in claim 11 or 12, wherein:
the total heat eta of the phase-change heat storage and supply system after the time t is calculated and displayed in real time according to the following formula:
η=η1-η2
wherein the heat storage amount eta1The heat storage device of claim 8, wherein the heat supply amount η is obtained by a heat monitoring method2A method of monitoring heat using a heating installation according to claim 10.
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