CN110927209B - Device and method for measuring effective heat conductivity coefficient of vacuum insulation panel by using protective heat plate method - Google Patents
Device and method for measuring effective heat conductivity coefficient of vacuum insulation panel by using protective heat plate method Download PDFInfo
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- CN110927209B CN110927209B CN201911221206.6A CN201911221206A CN110927209B CN 110927209 B CN110927209 B CN 110927209B CN 201911221206 A CN201911221206 A CN 201911221206A CN 110927209 B CN110927209 B CN 110927209B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/18—Investigating or analyzing materials by the use of thermal means by investigating thermal conductivity
Abstract
The invention discloses a device and a method for measuring the effective heat conductivity coefficient of a vacuum insulation panel by a protective heat plate method, the device and the method can directly measure the integral heat conductivity coefficient of the vacuum insulation panel containing an edge effect, and solve the technical problems that the heat conductivity coefficient of the vacuum insulation panel is measured by adopting the prior art, an error exists between a measured value and an actual value, the measured value cannot represent the effective heat conductivity coefficient of the whole vacuum insulation panel and cannot reflect the heat insulation performance of the whole vacuum insulation panel, and powerful evidence is provided for evaluating the integral heat insulation performance of the vacuum insulation panel.
Description
Technical Field
The invention relates to the technical field of thermal engineering tests, in particular to a device and a method for measuring the effective heat conductivity coefficient of a vacuum insulation panel by a protective hot plate method.
Background
The Vacuum Insulation Panel (VIP) is a novel efficient heat Insulation material with very low heat conductivity coefficient developed in recent years, the heat conductivity coefficient of the novel efficient heat Insulation material is about one tenth of that of a common EPS (expanded polystyrene) plate and a fiber type heat Insulation material, and the novel efficient heat Insulation material does not contain any toxic substance and has no pollution to the environment, so the novel efficient heat Insulation material has very good development and application prospects, and is widely applied to the fields of building heat Insulation, refrigerator cold Insulation, cold chain transportation and the like.
The vacuum insulation panel is a vacuum device composed of a core material 2, an overcoat film 1 and a getter 3, see fig. 1 (a). Since the thermal conductivity of the outer coating (e.g. aluminum foil 160W/(m · K)) is much greater than that of the inner core (e.g. 0.030W/(m · K)), the most significant feature is "edge effect", see fig. 1(b), i.e. a part of the heat flux will be transmitted along the outer coating, resulting in a higher heat flux density at the edges than in the central region, and this anisotropic heat flux characteristic is a significant feature different from other conventional homogeneous thermal insulation materials, see fig. 2(a), 2 (b). The effective thermal conductivity of the vacuum insulation panel refers to the thermal conductivity including the 'edge effect', and is an important parameter for measuring the overall thermal insulation performance of the vacuum insulation panel.
The existing test method for the thermal conductivity of the heat insulation material mainly comprises a protective hot plate method and a heat flow meter method, wherein the two methods calculate the thermal conductivity of the material by measuring the heat flow of a central area of a sample, and the test principle of the protective hot plate method is as follows: the principle formula is designed according to the relationship that the heat Q of a test piece is in direct proportion to the lambda of a tested heat conduction system and the temperature difference delta T of two surfaces of a flat plate and in inverse proportion to the thickness of the test piece under the one-dimensional steady state condition, and is shown as the formula (1):
λ＝Qd/A(T1-T2) (1)
q-average heat flow of the metering part of the heating unit, wherein the value of the average heat flow is equal to the average heating power and the unit is W;
d-average thickness of the test piece, unit is m;
T1-average hot face temperature of the test piece in K;
T2-average cold face temperature of the test piece in K;
a-area of measurement (double test piece device needs to be multiplied by 2) in m2。
Because the vacuum insulation panel has an edge effect, if the existing test equipment is adopted, only the central heat conductivity coefficient can be measured, the effective heat conductivity coefficient of the whole vacuum insulation panel cannot be represented, and the heat insulation performance of the whole vacuum insulation panel cannot be reflected.
In the prior art, the method for testing the integral effective thermal conductivity of the vacuum insulation panel is very limited, and two methods are mainly used, one method is theoretical calculation, the central thermal conductivity is measured firstly, and then the integral effective thermal conductivity is calculated according to a formula (2):
in the formula:
λeff-effective thermal conductivity of the vacuum insulation panel;
λcoptrueThe central heat conductivity coefficient of the hollow heat insulation plate is measured by adopting a traditional heat conductivity instrument;
l-perimeter of vacuum insulation panel;
d-thickness of the vacuum insulation panel;
s-area of vacuum insulation panel;
The other indirect measurement method is a hot box method, the heat transfer coefficient of the vacuum insulation panel is firstly measured from the energy consumption perspective, the influence of the 'edge effect' of the vacuum insulation panel is measured, and the effective heat transfer coefficient of the vacuum insulation panel is deduced through indirect calculation. The hot box method has the defects that the temperature in the cavity is difficult to control stably in the test process, and particularly for the material with ultralow heat conductivity coefficient, such as a vacuum insulation plate, the surface temperature of a test piece and the ambient temperature of the cavity are greatly fluctuated by factors such as air convection of a cold and hot box, the accurate measurement is difficult, and a large measurement error is easily caused.
Disclosure of Invention
The invention provides a heat conductivity coefficient testing device and method of a vacuum insulation panel, which can directly measure the overall heat conductivity coefficient of the vacuum insulation panel containing 'edge effect' and provide a powerful evidence for evaluating the overall heat insulation performance of the vacuum insulation panel, and aims to solve the technical problems that the heat conductivity coefficient of the vacuum insulation panel is tested in the prior art, an error exists between a measured value and an actual value, the measured value cannot represent the effective heat conductivity coefficient of the whole vacuum insulation panel and cannot reflect the heat insulation performance of the whole vacuum insulation panel.
The first technical scheme adopted by the invention is as follows: a device for measuring the effective heat conductivity coefficient of a vacuum insulation panel by a protection hot plate method comprises a data acquisition and processing unit, a tested piece, a heating metering unit, a cooling unit and a protection jacket, wherein the tested piece consists of a vacuum insulation panel test board and heat preservation protective layers surrounding four side walls of the vacuum insulation panel test board, the area of a metering panel of the heating metering unit is equal to that of the vacuum insulation test board, and the area of a protection panel of the heating metering unit is equal to that of the heat preservation protective layers; the protective outer sleeve surrounds the tested piece, the heating metering unit and the cooling unit.
By adopting the technical scheme, the effective heat conductivity coefficient of the integral vacuum insulation panel containing the edge effect can be directly measured through the measuring panel, the intermediate error generated by adopting an indirect measuring method is reduced, and the measuring result is more accurate.
The second technical scheme adopted by the invention is an improvement on the first technical scheme, and the second technical scheme adopted by the invention is as follows: the vacuum insulation test board is a vacuum insulation board for detecting effective heat conductivity coefficient.
By adopting the technical scheme, when the vacuum insulation panel to be detected with the effective heat conductivity coefficient is small in overall size and suitable for overall detection, the detection step is simple and the accuracy is high by using the device.
The third technical scheme adopted by the invention is an improvement on the first technical scheme, and the third technical scheme adopted by the invention is as follows: the vacuum insulation test board is made of a core material, an outer coating film and a getter, wherein the core material, the outer coating film and the getter have the same structure as the vacuum insulation board with the effective heat conductivity coefficient to be detected, and the thickness, the central heat conductivity coefficient and the linear heat transfer coefficient of the vacuum insulation board are the same as those of the vacuum insulation board to be detected.
By adopting the technical scheme, when the vacuum insulation panel to be detected with the effective heat conductivity coefficient is large in overall size and is not suitable for overall detection, the vacuum insulation panel to be detected with the effective heat conductivity coefficient is made into a standard sample, and the effective heat conductivity coefficient lambda of the standard sample is detectedeffThen converting the effective heat conductivity coefficient lambda 'of the whole vacuum heat insulation plate'effThe device can accurately measure the effective heat conductivity coefficients of the vacuum insulation panels with different sizes.
The fourth technical scheme adopted by the invention is an improvement on the third technical scheme, and the fourth technical scheme adopted by the invention is as follows: the vacuum heat insulation test plate has a thickness of 5 mm-40 mm and a length and width dimension of 300mm multiplied by 300 mm.
By adopting the technical scheme, the standard sample is set to be 300mm multiplied by 300mm in standard size, the standard sample is consistent with the common size of the existing vacuum insulation panel, and the standard sample is selected as the standard size, so that the requirements of enterprises and users can be met more conveniently.
The fifth technical scheme adopted by the invention is an improvement on the first technical scheme, and the fifth technical scheme adopted by the invention is as follows: an anti-radiation patch is arranged between the vacuum thermal insulation test board and the thermal insulation protective layer.
By adopting the technical scheme, the influence of the thermal radiation of the edge of the sample on the test result can be effectively reduced, and the test accuracy is improved.
The sixth technical solution adopted by the present invention is an improvement of the fifth technical solution, and the sixth technical solution adopted by the present invention is: the radiation-proof patch is attached to the inner wall of the heat-insulation protective layer and is arranged at an interval of 1-3 mm with the vacuum heat-insulation plate.
The seventh technical solution adopted by the present invention is an improvement of the first technical solution, and the seventh technical solution adopted by the present invention is: the heat-insulating protective layer is made of glass fiber cotton or polyurethane foam, the whole body is in a shape like a Chinese character 'hui', and the size of a central gap of the heat-insulating protective layer is matched with the appearance size of the vacuum heat-insulating test board.
By adopting the technical scheme, the heat-insulating protective layer is made into the standard module, so that the use is convenient, and the detection efficiency can be improved.
The eighth technical scheme adopted by the invention is as follows:
a testing method for the testing apparatus of the second aspect, comprising the steps of:
(8.1) preparing a heat preservation protective layer: the glass fiber cotton or polyurethane foam is adopted to manufacture a heat-insulating protective layer which is shaped like a Chinese character 'hui' and has the same area with the protective panel, the thickness of the heat-insulating protective layer is equal to that of the vacuum heat-insulating test board, a radiation-proof patch is pasted on the inner side surface of a central gap of the heat-insulating protective layer, and a gap is arranged between the radiation-proof patch and the vacuum heat-insulating test board;
(8.2) placing the vacuum insulation test plate on the metering panel to make full-area contact with the metering panel;
(8.3) compressing the vacuum heat insulation test board, and measuring the actual thickness of the vacuum heat insulation test board to be d;
(8.4) taking out the vacuum insulation test panel, and measuring the length a of the vacuum insulation test panel after being pressed1Width b1；
(8.5) placing the heat-insulating protective layer on the protective panel and enabling the heat-insulating protective layer to be in full-area contact with the protective panel, so that a proper distance is reserved between the radiation-proof patch and the outer side face of the vacuum heat-insulating test board;
(8.6) starting the test, and calculating the effective thermal conductivity coefficient lambda of the vacuum insulation test board according to the formula (1)eff；
λeff＝Qd/A(T1-T2) (1)
In the formula:
q-average heat flow of the metering part of the heating unit, wherein the value of the average heat flow is equal to the average heating power and the unit is W;
d-average thickness of the test piece, unit is m;
T1-average hot face temperature of the test piece in K;
T2-average cold face temperature of the test piece in K;
a-area of measurement (double test piece device needs to be multiplied by 2) in m2。
By adopting the technical scheme, the overall effective heat conductivity coefficient of the vacuum insulation panel can be accurately and quickly detected.
The ninth technical scheme adopted by the invention is as follows:
a testing method for the testing device of the third technical aspect, comprising the steps of:
(9.1) preparation of vacuum insulation test panels: preparing a vacuum insulation test board with standard size by adopting a core material, an outer coating and a getter which have the same structure as the vacuum insulation panel to be detected, wherein the thickness, the central heat conductivity coefficient and the linear heat transfer coefficient of the vacuum insulation test board are the same as those of the vacuum insulation panel to be detected;
(9.2) preparing a heat preservation protective layer: the glass fiber cotton or polyurethane foam is adopted to manufacture a heat-insulating protective layer which is shaped like a Chinese character 'hui' and has the same area with the protective panel, the thickness of the heat-insulating protective layer is equal to that of the vacuum heat-insulating test board, a radiation-proof patch is pasted on the inner side surface of a central gap of the heat-insulating protective layer, and a gap is arranged between the radiation-proof patch and the vacuum heat-insulating test board;
(9.3) placing the vacuum insulation test plate on the metering panel to make full-area contact with the metering panel;
(9.4) compressing the vacuum heat insulation test board, and measuring the actual thickness of the vacuum heat insulation test board to be d;
(9.5) taking out the vacuum insulation test panel, and measuring the length a of the vacuum insulation test panel after being pressed1Width b1；
(9.6) placing the heat-insulating protective layer on the protective panel to enable the radiation-proof patch to keep a set distance with the outer side face of the vacuum heat-insulating test plate;
(9.7) starting the test, and measuring the effective thermal conductivity of the vacuum insulation test board to be lambdaeff；
(9.8) the central thermal conductivity of the vacuum insulation panel to be detected tested by adopting the prior art is lambdacop；
(9.9) effective thermal conductivity coefficient lambda 'of vacuum insulation panel to be detected'effConversion according to the formula (3):
in the formula:
a1-the compacted length of the panel in meters (m);
b1-the compacted width of the panel in meters (m);
λeffeffective heat conduction of vacuum heat insulation test plateCoefficients, in units of (W/(m.K));
λcopthe central thermal conductivity coefficient of the vacuum insulation panel to be detected, which is tested by adopting the prior art, is (W/(m.K));
λ’eff-the effective thermal conductivity of the vacuum insulation panel to be detected, in units of (W/(m · K));
a2-the length of the vacuum insulation panel to be detected in meters (m);
b2-the width of the vacuum insulation panel to be detected, in meters (m).
By adopting the technical scheme, the effective heat conductivity coefficient lambda of the standard sample can be detectedeffThen converting the effective heat conductivity coefficient lambda 'of the whole vacuum heat insulation plate through a formula (3)'effEffectively avoids the heat transfer coefficient to the vacuum plate line in the theoretical calculation process by adopting the prior method
The estimation of one term has approximate values, which causes the problem that the calculated value has errors with the actual value.
The formula (3) adopted by the method is derived from the following formula:
assume that the length of the standard sample is a1Width of b1Thickness d, center thermal conductivity λcop，The linear heat transfer coefficient is psi (d) and the edge-induced increase in thermal conductivity is delta lambda, then its effective thermal conductivity lambdaeffComprises the following steps:
the length of the vacuum insulation panel to be measured with the effective heat conductivity coefficient is a2Width of b2Thickness d, center thermal conductivity λcop，The linear heat transfer coefficient psi (d) is the same as that of the standard sample, so that the effective heat transfer coefficient of the vacuum insulation panel to be measured is as follows:
comprises the following steps:
therefore, the method can calculate the effective thermal conductivity of the vacuum insulation panel to be measured only by calculating the effective thermal conductivity and the central thermal conductivity of the known standard sample, and does not need to calculate the linear thermal conductivity of the vacuum insulation panel to be psi (d).
The tenth technical solution adopted by the present invention is an improvement of the eighth or ninth technical solution, and the tenth technical solution adopted by the present invention is: and (3) after the heat-insulating protective layer is manufactured into a square-shaped firmware with the thickness consistent with that of the vacuum heat-insulating test board, packaging and sealing the firmware with a plastic film for later use.
By adopting the technical scheme, the heat-insulating protective layer is made into the standard module, so that the use is convenient, and the detection efficiency can be improved.
The invention has the beneficial effects that: the invention and the testing principle of the traditional heat conductivity tester are both based on the steady-state Fourier law, the invention uses the whole vacuum insulation panel of the effective heat conductivity coefficient to be tested or the whole vacuum insulation panel manufactured into a test board with standard size as the tested piece by improving the tested piece, so that the area of the metering panel is consistent with the area of the tested piece, the effective heat conductivity coefficient of the vacuum insulation panel of the effective heat conductivity coefficient to be tested is metered by full-area contact, meanwhile, the convection and radiation of a non-metering area are reduced by additionally protecting the edge of the tested piece, the heat leakage of the edges of the metering panel and the tested piece is prevented, and the testing accuracy is further improved. The detection method effectively avoids the heat transfer coefficient to the vacuum plate line in the theoretical calculation process by adopting the existing method
The estimate of a term presents an approximation, resulting in a calculated valueThe method has the problem of deviation, so that the test result of the method is closer to the true value.
Drawings
FIG. 1(a) is a schematic diagram of a vacuum insulation panel construction;
FIG. 1(b) is a schematic heat flow diagram of a vacuum insulation panel;
FIG. 2(a) is a schematic representation of the heat flux density of a conventional insulating material along its length;
FIG. 2(b) is a schematic representation of the heat flux density of a vacuum insulation panel along its length;
fig. 3 is a schematic structural view of embodiment 1 of the present invention.
Detailed Description
In order to better understand the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.
Example 1
Referring to fig. 3, the present embodiment provides a device for measuring the effective thermal conductivity of a vacuum insulation panel by a double-test-piece guarded hot plate method, which includes a data acquisition and processing unit, a tested piece, a heating and metering unit, a cooling unit and a protective jacket 13.
The protective outer sleeve 13 surrounds the periphery of the tested piece, the heating metering unit and the cooling unit, and is used for reducing heat loss of the heating metering unit and improving testing precision. The protective outer jacket 13 may be made of an existing thermal insulation material having a relatively low thermal conductivity.
The data acquisition and processing unit comprises a control acquisition system and a plurality of voltmeter and ammeter with adjustable measuring ranges, the preferred measuring range of the voltmeter is 50 muV-10V, the measuring range of the ammeter is 50 muA-2A, and the specific measuring range adopted by the voltmeter and the ammeter during the test can be reasonably selected according to the measured power. The control acquisition system is the prior art, and the control system of the existing measurement heat-conducting system of the heat-insulating material is suitable for the invention.
The test device comprises two tested pieces, wherein each tested piece consists of a vacuum insulation panel test board 19 and a heat insulation protective layer 16 surrounding four side walls of the vacuum insulation panel test board, an aluminum foil radiation-proof patch 15 with the thickness of 1-2 mm is attached to the inner side surface of each heat insulation protective layer 16, and the aluminum foil radiation-proof patch 15 and the vacuum insulation panel are arranged at an interval of 1-3 mm. The vacuum insulation test board 19 is made of a core material, an outer coating film and a getter which have the same structure as the vacuum insulation board with the effective heat conductivity coefficient to be detected, and the thickness, the central heat conductivity coefficient and the linear heat transfer coefficient of the vacuum insulation board are the same as those of the vacuum insulation board to be detected. The vacuum insulation panel test board 19 has the dimensions of 300mm multiplied by 300mm and the thickness of 5mm to 40 mm. The heat preservation protective layer 16 is a standard 'return' module made of glass fiber cotton, and the size of the central gap of the module is matched with the external size of the vacuum heat insulation test board 19. The ratio of the thickness of the heat-preservation protective layer to the thickness of the tested piece is controlled to be 1-1.3, heat-preservation protective cotton with different specifications can be manufactured in advance according to the thickness of the tested piece, and if standard modules with the manufacturing thicknesses of 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm and 40mm are manufactured, the standard modules are packaged and sealed by plastic films for later use.
The heating metering unit comprises a metering panel 11, a protective panel 10, a metering heater 12, a protective heater 9, a thermal unit surface temperature thermocouple 6 and a balance temperature difference thermocouple 7. The metering heater 12 is clamped between two metering panels 11, the two metering panels 11 are respectively in full-area contact with two vacuum insulation panel test boards 19, the protection panel 10 is in full-area contact with a heat preservation protection layer 16, the thermal unit surface temperature thermocouple 6 is used for measuring the surface temperature of the metering panels 11, and the balance temperature difference thermocouple 7 is used for measuring the surface temperature difference between the metering panels 11 and the protection panel 10.
The cooling unit comprises a cold plate 14 and a cold unit surface temperature thermocouple 5, the cold plate 14 is in full-area contact with a tested piece, the cold unit surface temperature thermocouple 5 is used for measuring the surface temperature of the cold plate 14, the cold plate 14 is the prior art, the structure of the cold plate 14 of the existing heat-conducting system for measuring the heat-insulating material is suitable for the invention, and the structure and the principle are not repeated.
The cold unit surface temperature thermocouple 5, the hot unit surface temperature thermocouple 6 and the balance temperature difference thermocouple 7 are respectively connected with the control acquisition system through leads, and the metering heater 12 and the protective heater 9 are respectively connected with the voltmeter and the ammeter through leads.
Example 1 the test apparatus of the present invention is described in detail with a double test piece as a representative, and the test apparatus of the present invention is also applicable to the test by the single test piece hot plate shield method.
Example 2
This embodiment provides a method for testing an effective thermal conduction system of a vacuum insulation panel using the apparatus of embodiment 1, including the following steps:
(1) preparation of vacuum insulation test panels 19: preparing a vacuum insulation test board with the thickness of 300 multiplied by 300mm and the thicknesses of 10mm, 11mm, 12mm and 17mm by adopting a core material, an outer coating film and a getter which have the same structure as the vacuum insulation panel to be detected, wherein the thickness, the central heat conductivity coefficient and the linear heat transfer coefficient of the vacuum insulation test board are the same as those of the vacuum insulation panel to be detected;
(2) preparing a heat preservation protective layer 16: the glass fiber cotton is adopted to manufacture a heat-insulating protective layer in a shape like a Chinese character 'hui' with the same area as the protective panel 10, the thickness of the heat-insulating protective layer corresponds to the vacuum heat-insulating test board 19 one by one, and the radiation-proof patch 15 is pasted on the inner side surface of the central gap of the heat-insulating protective layer 16, so that a 1-3 mm interval is reserved between the radiation-proof patch 15 and the vacuum heat-insulating test board 19;
(3) placing the vacuum insulation test plate 19 on the metering panel 11 so that it is in full-area contact with the metering panel;
(4) the vacuum heat insulation test board 19 is pressed tightly, and the actual thickness of the vacuum heat insulation test board is measured to be d;
(5) the vacuum insulation test board 19 is taken out, and the length a of the vacuum insulation test board after being pressed is measured1Width b1；
(6) Placing the heat-insulating protective layer 16 on the protective panel 10 and enabling the heat-insulating protective layer to be in full-area contact with the protective panel, wherein a distance of 1-3 mm is reserved between the radiation-proof patch 15 and the outer side face of the vacuum heat-insulating test board;
(7) starting the test, selecting a voltmeter of 5V and an ammeter of 10A, collecting ammeter information after heat flow is stable, and calculating the effective heat conductivity coefficient lambda of the vacuum heat insulation test plate 19 according to the formula (1)eff；
λeff＝Qd/A(T1-T2) (1)
In the formula:
q-average heat flow of the metering part of the heating unit, wherein the value of the average heat flow is equal to the average heating power and the unit is W;
d-average thickness of the test piece, unit is m;
T1-average hot face temperature of the test piece in K;
T2-average cold face temperature of the test piece in K;
a-area of measurement (double test piece device needs to be multiplied by 2) in m2。
Further, assume that the length of the vacuum insulation panel to be tested for effective thermal conductivity is a2，a2>a1(ii) a Width b2，b2>b1(ii) a The thickness, the central thermal conductivity coefficient and the linear heat transfer coefficient are the same as those of the vacuum heat insulation test plate 19, and then the effective thermal conductivity coefficient of the vacuum heat insulation plate to be detected is obtained according to the following method:
(A) the central heat conductivity coefficient of the vacuum insulation panel to be detected tested by adopting the prior art is lambdacop；
(B) Effective heat conduction coefficient lambda 'of vacuum insulation panel to be detected'effConversion according to the formula (3):
the foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (7)
1. A test method for a device for measuring the effective heat conductivity coefficient of a vacuum insulation panel by a guarded hot plate method comprises a data acquisition and processing unit, a tested piece, a heating metering unit, a cooling unit and a protective jacket, and is characterized in that the tested piece consists of a vacuum insulation test board and heat preservation protective layers surrounding four side walls of the vacuum insulation test board, the area of a metering panel of the heating metering unit is equal to that of the vacuum insulation test board, and the area of a protective panel of the heating metering unit is equal to that of the heat preservation protective layers; the protective outer sleeve surrounds the tested piece, the heating metering unit and the cooling unit; the vacuum insulation test board is a vacuum insulation board with effective heat conductivity coefficient to be detected;
the test method comprises the following steps:
(1.1) preparing a heat preservation protective layer: the glass fiber cotton or polyurethane foam is adopted to manufacture a heat-insulating protective layer which is shaped like a Chinese character 'hui' and has the same area with the protective panel, the thickness of the heat-insulating protective layer is equal to that of the vacuum heat-insulating test board, a radiation-proof patch is pasted on the inner side surface of a central gap of the heat-insulating protective layer, and a gap is arranged between the radiation-proof patch and the vacuum heat-insulating test board;
(1.2) placing the vacuum insulation test plate on the metering panel to make full-area contact with the metering panel;
(1.3) compressing the vacuum heat insulation test board, and measuring the actual thickness of the vacuum heat insulation test board to be d;
(1.4) taking out the vacuum insulation test panel, and measuring the length a of the vacuum insulation test panel after being pressed1Width b1；
(1.5) placing the heat-insulating protective layer on the protective panel and enabling the heat-insulating protective layer to be in full-area contact with the protective panel, so that a proper distance is reserved between the radiation-proof patch and the outer side face of the vacuum heat-insulating test board;
(1.6) starting the test, and calculating the effective thermal conductivity coefficient lambda of the vacuum insulation test board according to the formula (1)eff；
λeff=Qd/A(T1-T2) (1)
In the formula:
q-average heat flow of the metering part of the heating unit, wherein the value of the average heat flow is equal to the average heating power and the unit is W;
d-average thickness of the test piece, unit is m;
t1-average value of the hot surface temperature of the test piece, and the unit is K;
t2-average value of the cold surface temperature of the test piece, with the unit of K;
a-area of measurement (double test piece device needs to be multiplied by 2) in m2。
2. A test method for a device for measuring the effective heat conductivity coefficient of a vacuum insulation panel by a guarded hot plate method comprises a data acquisition and processing unit, a tested piece, a heating metering unit, a cooling unit and a protective jacket, and is characterized in that the tested piece consists of a vacuum insulation test board and heat preservation protective layers surrounding four side walls of the vacuum insulation test board, the area of a metering panel of the heating metering unit is equal to that of the vacuum insulation test board, and the area of a protective panel of the heating metering unit is equal to that of the heat preservation protective layers; the protective outer sleeve surrounds the tested piece, the heating metering unit and the cooling unit; the vacuum insulation test board is made of a core material, an outer coating film and a getter, wherein the core material, the outer coating film and the getter have the same structure as the vacuum insulation board with the effective heat conductivity coefficient to be detected, and the thickness, the central heat conductivity coefficient and the linear heat transfer coefficient of the vacuum insulation board are the same as those of the vacuum insulation board to be detected;
the test method comprises the following steps:
(2.1) preparation of vacuum insulation test panels: preparing a vacuum insulation test board with standard size by adopting a core material, an outer coating and a getter which have the same structure as the vacuum insulation panel to be detected, wherein the thickness, the central heat conductivity coefficient and the linear heat transfer coefficient of the vacuum insulation test board are the same as those of the vacuum insulation panel to be detected;
(2.2) preparing a heat preservation protective layer: the glass fiber cotton or polyurethane foam is adopted to manufacture a heat-insulating protective layer which is shaped like a Chinese character 'hui' and has the same area with the protective panel, the thickness of the heat-insulating protective layer is equal to that of the vacuum heat-insulating test board, a radiation-proof patch is pasted on the inner side surface of a central gap of the heat-insulating protective layer, and a gap is arranged between the radiation-proof patch and the vacuum heat-insulating test board;
(2.3) placing the vacuum insulation test plate on the metering panel to make full-area contact with the metering panel;
(2.4) compressing the vacuum heat insulation test board, and measuring the actual thickness of the vacuum heat insulation test board to be d;
(2.5) taking out the vacuum insulation test panel, and measuring the length a of the vacuum insulation test panel after being pressed1Width b1；
(2.6) placing the heat-insulating protective layer on the protective panel to enable the radiation-proof patch to keep a set distance with the outer side face of the vacuum heat-insulating test plate;
(2.7) starting the test, and calculating the effective thermal conductivity coefficient lambda of the vacuum insulation test board according to the formula (1)eff；
λeff=Qd/A(T1-T2) (1)
In the formula:
q-average heat flow of the metering part of the heating unit, wherein the value of the average heat flow is equal to the average heating power and the unit is W;
d-average thickness of the test piece, unit is m;
t1-average value of the hot surface temperature of the test piece, and the unit is K;
t2-average value of the cold surface temperature of the test piece, with the unit of K;
a-area of measurement (double test piece device needs to be multiplied by 2) in m2；
(2.8) the central thermal conductivity of the vacuum insulation panel to be detected tested by adopting the prior art is lambdacop；
(2.9) effective thermal conductivity coefficient lambda of vacuum insulation panel to be detected’ effConversion according to the formula (3):
in the formula:
a1-the compacted length of the panel in meters (m);
b1-the compacted width of the panel in meters (m);
λeff-effective thermal conductivity in (W/(m.K));
λcopthe central thermal conductivity coefficient of the vacuum insulation panel to be detected, which is tested by adopting the prior art, is (W/(m.K));
λ’ eff-the effective thermal conductivity of the vacuum insulation panel to be detected, in units of (W/(m · K));
a2of vacuum insulation panels to be testedLength in meters (m);
b2-the width of the vacuum insulation panel to be detected, in meters (m).
3. The test method as set forth in claim 1 or 2, wherein the vacuum insulation test plate has a thickness of 5mm to 40mm and a length and width dimension of 300mm x 300 mm.
4. The method according to claim 1 or 2, wherein a radiation-proof patch is disposed between the vacuum insulation test panel and the heat-insulating protective layer.
5. The test method according to claim 4, wherein the radiation-proof patch is attached to the inner wall of the heat-insulating protective layer and is spaced from the vacuum heat-insulating plate by 1-3 mm.
6. The test method according to claim 1 or 2, wherein the thermal insulation protective layer is made of glass fiber cotton or polyurethane foam, and is integrally formed in a shape like a Chinese character 'hui', and the size of the central gap of the thermal insulation protective layer is matched with the external size of the vacuum thermal insulation test board.
7. The method according to claim 1 or 2, wherein the heat-insulating protective layer is formed into a clip-shaped member having a thickness corresponding to that of the vacuum insulation test panel, and then sealed with a plastic film.
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| CN102012382B (en) * | 2010-10-25 | 2012-07-25 | 上海海事大学 | Heat conductivity coefficient quick test device and method of vacuum insulating board |
| CN202171579U (en) * | 2011-05-19 | 2012-03-21 | 绍兴文理学院 | Double test piece protection hot plate method heat conducting instrument |
| CN102645449A (en) * | 2012-04-18 | 2012-08-22 | 天津大学 | Protective heat flow meter method thermal conductivity coefficient measuring instrument for realizing vacuum insulation and thickness measurement function |
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