CN103604827A - Ice water heat exchange coefficient experimental apparatus and measurement method - Google Patents

Abstract

The invention provides an ice water heat exchange coefficient experimental apparatus which comprises a water tank 1, a water pump 3, a gate valve 4, a thermoregulator 5, a current meter 6, an ice thickness change measuring instrument 7 and a temperature recorder 8, wherein the water pump 3, the gate valve 4 and the thermoregulator 5 are sequentially connected through a pipeline 2 and form a loop; measurement probes of the current meter 6 and the temperature recorder 8 are positioned in the water tank 1; a measurement probe of the ice thickness change measuring instrument 7 is positioned in an ice layer 19 and water in the water tank. The invention also provides a method for measuring an ice water heat exchange coefficient by utilizing the device. The device well simulates reservoir icing and low-flow speed water flow conditions, acquires an ice water heat exchange coefficient of a corresponding reservoir and provides a design basis for water conservancy projects, also avoids the difficulty of developing reservoir ice water heat exchange coefficient prototype measurement in a rushing frigid zone reservoir area and provides great convenience and implementation possibility for research.

Description

A kind of frozen water heat exchange coefficient experimental provision and assay method

Technical field

The invention belongs to frozen water heat exchange coefficient experimental provision and determination techniques field, particularly experimental provision and the assay method of the frozen water heat exchange coefficient of a kind of flow velocity below 0.1m/s.

Background technology

At present, the hydraulic engineering construction of China advances to the refrigerant latitudes of high height above sea level just gradually.At refrigerant latitudes, build the ice formation issues that problem is exactly reservoir in winter that reservoir must be considered, after freezing, reservoir forms floating ice or stable ice sheet no matter be, first all the safety of reservoir shipping in winter, hydropower, canal system water delivery etc. will directly be had influence on, especially occur after the serious ice condition such as ice berg, ice dam, also can cause the disasteies such as Ling Hong, bring great loss to the people's property and life security; Secondly, winter reservoir ice sheet appearance also by heat, momentum and mass exchange between isolated reservoir surface water and atmosphere, and then affect the distribution of subglacial water gentleness water quality; Snow deposit, ice sheet, by hindering importing into of solar energy, affect the circulation of nutriment in water simultaneously, cause dissolved oxygen DO and nutriment in water to lack, and when serious, can cause fish kills in storehouse.

The ice condition that reservoir forms is relevant to factors, and wherein very important influence factor is distribution of water temperature, meteorological condition and the frozen water heat interchange of reservoir, and they will have influence on the freezing process of the different sections of reservoir, the type of freezing and intensity and deicing processes.Wherein the process of frozen water heat interchange, is a complicated two-phase flow problem with phase transformation, is specifically related to the subjects such as thermal conduction study, fluid mechanics, and ice sheet thickness, ice thickness rate of change, Kaijiang time, subglacial distribution of water temperature are all had to material impact.

At present, although aspect the frozen water heat exchange coefficient of sea ice, river ice, obtained some achievements in research (Ji Shunying, Yue Qianjin ，Bi Xiang army. the heat transfer coefficient between the frozen water of the Bohai Sea [J]. ocean circular .2002,21 (1): 10-15; Omstedt A and Wettlaufer J S.Ice growth and oceanic heat flux:Models and Measurements ［ J ］ .J.Geophys.Res., 1992,97 (C6): 9383～9390; Shirasawa K and Ingram G R.Currents and turbulent fluxes under the first-year sea ice in Resolute Passage; Northwest Territories, Canada ［ J ］ .J.Marine System, 1997; 11,21～32; Josberger E G.Bottom ablation and heat transfer coefficients from the 1983Marginal Ice Zone Experiment ［ J ］ .J.Geophys.Res., 1987,92 (C7): 7012～7016), but its achievement in research is mainly to adopt prototype measurement, directly for the frozen water heat interchange of sea ice, river ice, observes and getting.Because the subglacial water rate of flow of fluid of sea ice, river ice is very fast, generally more than 0.1m/s, and water body flow in reservoir is comparatively slow, generally below 0.1m/s, particularly at reservoir middle part to dam leading portion flow velocity, be generally grade, thereby the water quality situation of reservoir or flow velocity magnitude with study the river ice of acquisition, the applicable elements of sea ice frozen water heat exchange coefficient exists significant difference, more difficult its directly transplanting is adopted, and there is not yet report both at home and abroad for the research of the frozen water heat exchange coefficient of low flox condition lower storage reservoir.Thereby along with the gradually attention of China to environmental problem in the exploitation of frigid zone regional water resources, frozen water heat exchange coefficient obtains the bottleneck that just becomes the research of reservoir ice condition.

Summary of the invention

Primary and foremost purpose of the present invention is for the deficiencies in the prior art, and a kind of frozen water heat exchange coefficient experimental provision is provided.

Another object of the present invention is to provide a kind of method of utilizing said apparatus to measure frozen water heat exchange coefficient.

Frozen water heat exchange coefficient experimental provision provided by the invention, comprise tank, water pump, gate valve, thermosistor, current meter, ice thickness measure of the change instrument and moisture recorder, the water delivering orifice of tank is connected with water pump, gate valve and thermosistor successively by pipeline, thermosistor is connected with the water inlet of tank by pipeline again, and form loop, the measuring sonde of current meter measuring sonde and moisture recorder is all positioned at tank, and the measuring sonde of ice thickness measure of the change instrument is arranged in ice sheet and the water of tank.

Described in above experimental provision, tank is by the inlet segment being connected as a single entity, water exit end and be positioned at into, measuring section between water exit end forms, the longitudinal profile of inlet segment part tank is " ┛ " shape, its right side standing portion communicates with measuring section tank, left side horizontal component overlaps with the bottom of measuring section tank right-hand member head, one water inlet pipe is arranged at the bottom of inlet segment part tank, the water delivering orifice of water inlet pipe is arranged in the tank of inlet segment left side horizontal component, measuring section tank is a horizontal rectangular groove, water exit end tank is a vertical rectangular channel, its the first half communicates with measuring section tank, on the outer wall of the latter half, be connected with a rising pipe.

The double-decker that described in above experimental provision, the bottom of measuring section tank is hollow, and in water inlet end one side, be also provided with and double-decker base plate horizontal baffle that be connected as a single entity, that cantilever stretches out, horizontal baffle termination is positioned at the middle part of inlet segment tank right side standing portion.The bottom of this measuring section tank adopts the double-decker of hollow, can reduce the impact of environment temperature on test result, reach heat insulation object, and the horizontal baffle that cantilever stretches out is owing to being positioned at the upper right side of water inlet pipe water delivering orifice, thereby can eliminate current and enter the caused disturbance of water tank, avoid affecting the flow state of test section tank current, and then the accuracy of impact test.

The two ends of measuring section tank described in above experimental provision are also respectively arranged with dismountable vertical baffle or vertical rectification mesh screen.Dismountable vertical baffle is set, for tank test section being divided into interim water tank in experiment, to carry out freezing of initial ice thickness, while testing after frozen in ice is good, take off vertical baffle, change vertical rectification mesh screen into, increase the turbulivity of current, so that even, the stable inflow tank test section of water flow energy.

In the upper end of measuring section tank described in above experimental provision, also horizontal cross is provided with the batten being arranged in parallel, and the two ends of this batten are fixed on flume wall, and the spacing of every two battens is 20～30cm.The batten that horizontally set is arranged in parallel need to freeze in initial ice sheet when experiment starts, and to prevent from testing in experiment level and the vertical movement of ice sheet, guarantees the accuracy of the institute's ice thickness of surveying variation numerical value.

In above experimental provision, water pump adopts the commercially available slow-speed of revolution (≤1450r/min), large flow (>=25m ³/ h) water pump carries out water-pumping/draining circulation, to avoid as far as possible water pump to bring too much heat due to blade rotary and water body friction into experimental provision, and then the accuracy of impact test.

Thermosistor described in above experimental provision is that a snakelike metal winding pipe being formed by connecting by flange forms.Snakelike metal winding pipe preferably adopts the stainless pipe that heat-conduction coefficient is larger to make.According to the difference of measuring condition, thermosistor can adopt the stainless pipe of different tube diameters, to utilize the heat-conduction coefficient that stainless pipe is larger, different area of dissipation and regulation and control varying environment temperature to come balance because water pump blade rotates the heat of bringing into water body friction, guarantee to measure the stability of temperature.

The instrument of ice thickness measure of the change described in above experimental provision is to consist of sounding rod, measurement piece, survey measurements sleeve, support and firm banking, measure piece and be connected to termination, sounding rod one end, the other end of sounding rod is slidably connected with it through survey measurements sleeve, survey measurements sleeve is fixed on support upper end, and support lower end is connected with firm banking.

The method of utilizing said apparatus to measure frozen water heat exchange coefficient provided by the invention, the determination step of the method is as follows:

(1) at tank, water pump, gate valve, after thermosistor connects and to add water and be full of, vertical baffle is fixed on to tank measuring section two ends so that it forms the water tank of closed at both ends, and in the middle or postmedian along laterally choosing temperature survey section, in the following 5mm of water surface place, start the temperature chain that lets droop and formed by moisture recorder measuring sonde to arranging, preferably be positioned in the middle of water tank, upper tightly lower sparse, set rear start-up temperature registering instrument, and then after temperature survey section, choose ice thickness measure of the change section, put into the sounding rod of ice thickness measure of the change instrument and measure piece, and ice thickness measure of the change instrument is fixed on the wall of water tank limit,

(2) environment temperature is reduced and make to freeze in water tank at least after 0.02m ice sheet, adjusting ambient temperature to 0.0 ℃, on the ice sheet of water tank measuring section inlet end, choose again fluid-velocity survey section and cut a hole a through hole, putting into current meter measuring sonde, and current meter is fixed on the wall of water tank limit;

(3) vertical baffle at water tank two ends is taken off, and at the fixing rectification mesh screen of the entrance point of tank measuring section, then will fill into water introduces from tank inlet segment bottom, and open gate valve, start water pump, make water body at tank, circulation in pipeline and thermosistor, on the one hand making to fill into water mixes with the water at low temperature of tank inlet segment and is adjusted to experiment water temperature, by the number of turns of regulation gate valve, control on the other hand the flow velocity≤0.15m/s of water body in tank measuring section, treat water temperature in tank measuring section, when stablize in flow field and ice temperature approaches 0.0 ℃, to on the sounding rod of ice thickness measure of the change instrument, carry and the measurement piece upper surface of lower end and ice sheet lower surface are adjacent to, then from measurement, read sleeve and read ice thickness initial value, thereafter at interval of carrying sounding rod on 10-30 minute and making the measurement piece upper surface of lower end and after ice sheet lower surface is adjacent to, read follow-up ice thickness and change numerical value,

(4) the ice thickness changing value substitution following formula recording under measurement temperature, flow velocity, time and the respective conditions of setting is calculated and obtains frozen water heat exchange coefficient under corresponding conditions:

$\mathrm{\α}=\frac{\underset{0}{\overset{h}{\∫\∫\∫}}{\mathrm{\ρ}}_i{L}_i\mathrm{dh}}{\underset{0}{\overset{t}{\∫}}{T}_{\mathrm{ws}}\mathrm{dt}}=\frac{{\mathrm{\ρ}}_i{L}_i\mathrm{\Δh}}{T_{\mathrm{ws}}\mathrm{\Δt}}$

In formula, α is frozen water heat exchange coefficient, T _wsfor subglacial water temperature, L _ifor ice-out latent heat=33500J/kg, ρ _idensity=0.90g/cm for ice ³, Δ h is ice thickness changing value, Δ t is that ice thickness changes required time.

Convert as required different in flow rate, water temperature, repeat (2)-(4) step operation and can obtain frozen water heat exchange coefficient under corresponding conditions.

In above method, if tank measuring section height is 0.28m, number >=7 of described moisture recorder measuring sonde, preferably 7-15.The concrete number of measuring sonde can change according to the difference of water tank height, is not limited to the number that the present invention limits.

The preferred 0.02-0.05m of ice layer thickness freezing in water tank described in above method.

The flow velocity of controlling water body in tank measuring section described in above method is preferably 0.01-0.15m/s.

The formula that calculates frozen water heat exchange coefficient in above method is according to newton's convection heat transfer formula, obtains in such a way:

q _wi＝α(T _ws-T ₀)

Q in formula _wifor frozen water heat exchange amount, α is frozen water heat exchange coefficient, T ₀for frozen water interface temperature, T _wsfor subglacial water temperature.

According to ice-water interface heat balance is analyzed, the needed energy of thawing of ice sheet lower surface is mainly the heat conduction of ice sheet and the balance result that the heat between frozen water is transmitted, and the heat balance equation of therefore setting up ice-water interface is:

$q_i=q_{\mathrm{wi}}={\mathrm{\ρ}}_i{L}_i\frac{\mathrm{dh}}{\mathrm{dt}}$

Wherein, q _ifor the amount of thermal conduction of ice inside,

for frozen water heat exchange amount.

Due to 0.0 ℃ of ice sheet internal temperature convergence in the experiment period, can think q _i=0.0, therefore, simplification above formula integration are:

$\underset{0}{\overset{t}{\∫}}{q}_{\mathrm{wi}}\mathrm{dt}=\underset{0}{\overset{h}{\∫}}{\mathrm{\ρ}}_i{L}_i\mathrm{dh}$

Suppose frozen water interface T ₀=0.0, the temperature T of main flow area in experimentation _wsfor a certain stationary value, further arrange above formula and get final product:

$\mathrm{\α}=\frac{\underset{0}{\overset{h}{\text{\∫}}}{\mathrm{\ρ}}_i{L}_i\mathrm{dh}}{\underset{0}{\overset{t}{\∫}}{T}_{\mathrm{ws}}\mathrm{dt}}=\frac{{\mathrm{\ρ}}_i{L}_i\mathrm{\Δh}}{T_{\mathrm{ws}}\mathrm{\Δt}}$

According to above formula, can ask the frozen water heat exchange coefficient under different experiments operating mode.

Compared with prior art, the present invention has following beneficial effect:

1, because experimental provision provided by the invention is the ingehious design carrying out on the basis by and flow velocity prototype measurement extensively and profoundly icing to reservoir, thereby it not only can well be simulated, and reservoir freezes and low flow velocity current situation, obtain the frozen water heat exchange coefficient of corresponding reservoir, for hydraulic engineering construction provides design considerations, the difficulty that Reservoir region, frigid zone carries out the prototype measurement of reservoir frozen water heat exchange coefficient of also having avoided hurrying back and forth, for research provides larger facility and the possibility of enforcement.

2, because the tank measuring section vertical baffle designing in experimental provision provided by the invention and rectification mesh screen are dismountable connected mode, can change according to the required condition difference of experiment, both can be divided into interim water tank, form hydrostatic, convenient freezing, again can be in the vertical height of tank inlet segment and water exit end bottom surface under the coupling lower than the vertical height of tank measuring section, make current even, stablize and flow into tank measuring section at the state that increases current turbulivity, in addition there is again the horizontal baffle of design to coordinate energy dissipating, thereby the experiment water body that makes tank section is not subject to the impact of extraneous current, guaranteed the accuracy of the calculating of frozen water heat exchange coefficient.

3, due to the double-decker that in experimental provision provided by the invention, not only tank measuring section back-plane design is hollow, can play heat-blocking action, the fluctuation of avoiding variation of ambient temperature to bring, and also the icing position horizontally set above tank measuring section the some fixing battens of ice sheet, to avoid ice sheet moving influence experiment effect in experiment, simultaneously again by fluid-velocity survey section determination at water tank measuring section inlet end, near rectification screen cloth, temperature survey section and ice thickness measure of the change section are determined successively at water tank measuring section middle part or postmedian, thereby the data accuracy recording is high, reliability is strong.

4, owing to both having adopted the water pump of the slow-speed of revolution, large flow in experimental provision provided by the invention, mated again thermosistor, thereby can conveniently control a series of important parameters that water temperature, subglacial flow velocity etc. affect frozen water heat exchange coefficient, to realize the quantitative examination to frozen water heat interchange problem.

5, experimental provision provided by the invention is simple in structure, installs, regulates and measure conveniently, and material requested and equipment cost are low, and practical, have application value.

6, due to provided by the invention, utilize above-mentioned experimental provision to carry out measuring method, not only can measure subglacial flow velocity, the variable quantity of subglacial water temperature and ice sheet lower surface ice layer thickness, also can pass through the energy balance equation of the ice-water interface of foundation, the frozen water heat exchange coefficient of acquisition under corresponding conditions, thereby can study cold district reservoir water temperature, ice condition development law, as the law-analysing of the growth of ice thickness and ablation procedure and subglacial distribution of water temperature and calculating simulation, there is important scientific meaning and using value, filled up the blank of the frozen water heat exchange coefficient of simulating under low flox condition, for the ecological environmental protection of the Coupling Research Ji Han district reservoir of water temperature of reservoir and ice condition provides strong technical support.

Accompanying drawing explanation

Fig. 1 is the annexation structural representation of each parts of experimental provision of the present invention;

Fig. 2 is the longitudinal profile structural representation of tank in experimental provision of the present invention;

Fig. 3 be the structure of ice thickness measure of the change instrument in experimental provision of the present invention and measure in the relativeness schematic diagram of ice sheet;

Fig. 4 is the partial enlarged drawing of the survey measurements sleeve at circle position in Fig. 3;

Fig. 5 is the structural representation of thermosistor in experimental provision of the present invention;

In figure, 1-tank, 2-pipeline, 3-water pump, 4-gate valve, 5-thermosistor, 6-current meter, 7-ice thickness measure of the change instrument, 8-moisture recorder, 9-horizontal baffle, 10-vertical baffle, 11-rectification screen cloth, 12-fluid-velocity survey section, the horizontal batten of 13-, 14-ice thickness measure of the change section, 15-temperature survey section, 16-inlet segment, 17-water exit end, 18-measuring section, 19-ice sheet, 20-water inlet pipe, 21-rising pipe, 51-stainless pipe, 52-flange, 71-sounding rod, 72-measures piece, 73-survey measurements sleeve, 74-support, 75-firm banking.

Fig. 6 is the layout schematic diagram of temp probe on temperature survey section in the embodiment of the present invention 2;

Fig. 7 is the linear relationship chart of frozen water heat exchange coefficient and flow velocity.

Embodiment

Below in conjunction with specific embodiment and accompanying drawing, apparatus of the present invention and method are further described, but content of the present invention is not limited to content related in embodiment, those skilled in the art can be as required, expand experimental trough size, the water pump of configuration different capacity, carries out the research of frozen water heat exchange coefficient under high, medium and low flow velocity.

What deserves to be explained is:

Instrument and equipment source used in following examples is as follows:

1) moisture recorder adopts the LG93-22 thermometer that Hangzhou Lu Ge Science and Technology Ltd. produces, and temperature accuracy is ± 0.1 ℃;

2) current meter is selected the little prestige dragon of Norway Vectrino point type current meter, and fluid-velocity survey scope is ± 0.03, and 0.1,1.0,2.5,4.0m/s is adjustable, and measuring accuracy is measured value ± 0.5% ± 0.001m/s;

3) water pump adopts the large flow water pump of the slow-speed of revolution that above SeaBird Xin Beng industry Manufacturing Co., Ltd produces, rated flow 25m ³/ h, rated power 0.75KW, rotating speed 1450r/min;

4) ice thickness measure of the change instrument is to convert voluntarily on the basis of Pitot tube speed measuring device, and measuring accuracy is ± 0.0001m;

5) stainless pipe that thermosistor adopts is of a size of Ф 0.06m * 6m (L);

6) pipeline adopts the plastic round tube that internal diameter is 0.06m;

8) to adopt heat-conduction coefficient be that the polyethylene foams of 0.035W/ (mK) is incubated tank outside;

9) material of tank, vertical baffle and horizontal baffle is organic glass.

Embodiment 1

In the present embodiment, the structure of frozen water heat exchange coefficient experimental provision as Figure 1-5, comprise tank 1, water pump 3, gate valve 4, thermosistor 5, current meter 6, ice thickness measure of the change instrument 7 and moisture recorder 8, the water delivering orifice of tank is connected with water pump 3, gate valve 4 and thermosistor 5 successively by pipeline 2, thermosistor 5 is connected with the water inlet of tank by pipeline 2 again, and form loop, the measuring sonde of current meter 6 and moisture recorder 8 measuring sondes is all positioned at tank, and the measuring sonde of ice thickness measure of the change instrument 7 is arranged in ice sheet 19 and the water of tank.

Tank is by the inlet segment 16 being connected as a single entity, water exit end 17 and be positioned at into, measuring section 18 between water exit end forms, the longitudinal profile of inlet segment 16 part tanks is " ┛ " shape, its right side standing portion communicates with measuring section 18 tanks, left side horizontal component overlaps with the bottom of measuring section 18 tank right-hand member heads, one water inlet pipe 20 is arranged at the bottom of inlet segment 16 part tanks, the water delivering orifice of water inlet pipe 20 is arranged in the tank of inlet segment 16 left side horizontal components, measuring section 18 tanks are a horizontal rectangular groove, water exit end 17 tanks are a vertical rectangular channel, its the first half communicates with measuring section 18 tanks, on the outer wall of the latter half, be connected with a rising pipe 21.

The double-decker that the bottom of measuring section 18 tanks is hollow, and be also provided with and double-decker base plate horizontal baffle 9 that be connected as a single entity, that cantilever stretches out in water inlet end one side, its termination is positioned at the middle part of inlet segment 16 tank right side standing portion.Measuring section tank two ends can bonding vertical baffle 10, and vertical baffle 10 can be divided into tank measuring section the interim water tank of long 1.7m, wide 0.2m, high 0.28m.While testing after frozen in ice is good, vertical baffle can take off, and changes vertical rectification mesh screen 11 into.In water tank upper end, also horizontal cross is provided with the batten 13 being arranged in parallel, and the two ends of this batten 13 are connected on tank 1 wall with organic glass is gluing, and the spacing of every two battens 13 is 30cm.

Thermosistor is the snake bend that stainless pipe 51 connects and composes by flange 52.

Ice thickness measure of the change instrument 7 is to consist of sounding rod 71, measurement piece 72, survey measurements sleeve 73, support 74 and firm banking 75, measure piece 72 and be connected to sounding rod 71 terminations, one end, the other end of sounding rod 71 is slidably connected with it through survey measurements sleeve 73, survey measurements sleeve 73 is fixed on support 74 upper ends, and support 74 lower ends are connected with firm banking 75.

Embodiment 2

The method of utilizing the device mensuration frozen water heat exchange coefficient in embodiment 1, the determination step of the method is as follows:

(1) after tank 1, water pump 3, gate valve 4, thermosistor 5 connects and adds water and be full of, be connected on tank measuring section 18 two ends so that it forms the water tank of closed at both ends by vertical baffle 10 use organic glass are gluing, and filling water to depth of water 0.26m, the depth of water is for flooding batten 0.01m.And in the middle along laterally choosing temperature survey section 15, in the following 5mm of water surface place, start temperature chain from 7 moisture recorder 8 measuring sondes to layout that let droop and formed by, upper tightly lower sparse.Set rear start-up temperature registering instrument 8, and then after temperature survey section 15, choose ice thickness measure of the change section 14, put into the sounding rod 71 of ice thickness measure of the change instrument 7 and measure piece 72, and ice thickness measure of the change instrument 7 is fixed on the wall of water tank limit;

(2) environment temperature being down to-20 ℃ makes to freeze after 0.02m ice sheet in water tank, adjusting ambient temperature to 0.0 ℃, on the ice sheet 19 of water tank measuring section 18 inlet ends, choose again fluid-velocity survey section 12 and cut a hole the through hole that a diameter is 2.5cm, put into current meter 6 measuring sondes, and current meter 6 is fixed on the wall of water tank limit;

(3) vertical baffle at water tank two ends 10 is taken off, and at the fixing rectification mesh screen 11 of the entrance point of tank measuring section 18, then will fill into water introduces from tank 1 inlet segment bottom, and open gate valve 4, start water pump 3, make water body at tank 1, pipeline 2 and the interior circulation of thermosistor 5, on the one hand making to fill into water mixes with the water at low temperature of tank inlet segment 16 and is adjusted to experiment water temperature, by the number of turns of regulation gate valve 4, control on the other hand the flow velocity (as shown in table 1) of tank measuring section 18 interior water bodys, treat water temperature in tank measuring section, when stablize in flow field and ice temperature approaches 0.0 ℃, to on the sounding rod 71 of ice thickness measure of the change instrument 7, carry and measurement piece 72 upper surfaces of lower end and ice sheet 19 lower surfaces are adjacent to, then from measurement, read sleeve 73 and read ice thickness initial value, thereafter at interval of carrying sounding rod 71 on 20 minutes and making measurement piece 72 upper surfaces of lower end and after ice sheet 19 lower surfaces are adjacent to, read follow-up ice thickness and change numerical value,

(4) by measurement temperature, flow velocity, time, the ice-out latent heat set, the ice thickness changing value substitution following formula recording calculates and obtains frozen water heat exchange coefficient:

$\mathrm{\α}=\frac{\underset{0}{\overset{h}{\text{\∫}}}{\mathrm{\ρ}}_i{L}_i\mathrm{dh}}{\underset{0}{\overset{t}{\∫}}{T}_{\mathrm{ws}}\mathrm{dt}}=\frac{{\mathrm{\ρ}}_i{L}_i\mathrm{\Δh}}{T_{\mathrm{ws}}\mathrm{\Δt}}$

In formula, α is frozen water heat exchange coefficient, T _wsfor subglacial water temperature, ice-out latent heat L _i=33500J/kg, the density p of ice _i=0.90g/cm ³, Δ h is ice thickness changing value, Δ t is that ice thickness changes required time.

Convert as required different in flow rate, water temperature, repeat (2)-(4) step operation and can obtain frozen water heat exchange coefficient under corresponding conditions.

The combination of conversion different in flow rate, water temperature, the present embodiment has carried out 22 groups of experiments altogether, and experiment condition and result are as table 1.

Table 1

According to experimental result, can draw: under the certain condition of the interior flow velocity of main flow area measuring section 18, the linear dependence degree of ice thickness variable quantity and subglacial current main flow area water temperature is all higher.In experimental section fluidised form, be turbulent flow, inducer 16 mean flow raties are under 0.11m/s, 0.084m/s, 0.055m/s, 0.024m/s condition, and ice thickness variable quantity and subglacial current main flow area water temperature linearly dependent coefficient are respectively up to 0.99,0.97,0.96,0.96.Its rule shows as, under same flow conditions, ice thickness change present that main flow area water temperature is lower, ice thickness changes littlely, main flow area water temperature is higher, ice thickness changes rule greatly; Under different in flow rate, close water temperature condition, variable quantity and the flow velocity of experiment ice sheet lower surface also present obvious linear change, and the related coefficient at 3.0 ℃～3.3 ℃ of water temperatures, at 1.4 ℃～1.6 ℃ of water temperatures reaches respectively 0.99,0.97.As can be seen here, ice thickness variable quantity becomes obvious linear relationship with flow velocity, water temperature.

According to the relevant test data of following formula and table 1, calculate the frozen water heat exchange coefficient under the different experiments operating mode try to achieve, as table 2:

$\mathrm{\α}=\frac{\underset{0}{\overset{h}{\text{\∫}}}{\mathrm{\ρ}}_i{L}_i\mathrm{dh}}{\underset{0}{\overset{t}{\∫}}{T}_{\mathrm{ws}}\mathrm{dt}}=\frac{{\mathrm{\ρ}}_i{L}_i\mathrm{\Δh}}{T_{\mathrm{ws}}\mathrm{\Δt}}$

Table 2

As can be seen from Table 2, variation multiple proportions and the flow velocity multiple proportions of the frozen water heat exchange coefficient under different in flow rate operating mode are basic identical, and the evenly heat exchange coefficient that is 0.11m/s as flow velocity reaches 513w/m ²/ k, and the evenly heat exchange coefficient that flow velocity is 0.024m/s reaches 120w/m ²/ k, the multiple proportions of the multiple proportions of flow velocity, evenly heat exchange coefficient is respectively 4.4,4.3, has further confirmed the linear relationship of frozen water heat exchange coefficient and flow velocity.

The factor that affects frozen water heat exchange coefficient mainly contains flow velocity u, surfaceness n, characteristic dimension L, orientation θ, and physical parameter is as density p, specific heat C _p, its functional relation is:

α＝f(L,ρ,n,C _P,u,θ)

Characteristic dimension, orientation in experiment immobilize; Experiment ice body is crystallization ice body, and it is identical that surfaceness can be considered; The density causing due to temperature contrast, specific heat etc. change also less, are also considered as constantly, so frozen water heat exchange coefficient can be considered the single function of flow velocity.Get under same flow velocity average frozen water heat exchange coefficient, the relational expression of matching itself and flow velocity.Fitting result shows, frozen water heat exchange coefficient is that highly linear is relevant to flow velocity, and its related coefficient, up to 1.0, is shown in Fig. 7.

The frozen water heat exchange coefficient of matching and the relational expression of flow velocity are:

α＝4594.8u _w

To sum up, the present embodiment is by the frozen water heat exchange coefficient of many groups combination experiment gained of different in flow rate, water temperature and the relational expression of flow velocity, fill up the blank of the frozen water heat exchange coefficient under low flox condition, for ice sheet generating and vanishing process and the subglacial distribution of water temperature analyzed with quantitatively calculating cold district reservoir, there is important academic significance and using value.

Claims (10)

1. a frozen water heat exchange coefficient experimental provision, it is characterized in that this device comprises tank (1), water pump (3), gate valve (4), thermosistor (5), current meter (6), ice thickness measure of the change instrument (7) and moisture recorder (8), the water delivering orifice of tank by pipeline (2) successively with water pump (3), gate valve (4) is connected with thermosistor (5), thermosistor is connected with the water inlet of tank (1) by pipeline (2) again, and form loop, the measuring sonde of the measuring sonde of current meter (6) and moisture recorder (8) is all positioned at tank (1), the measuring sonde of ice thickness measure of the change instrument (7) is arranged in ice sheet (19) and the water of tank.

2. frozen water heat exchange coefficient experimental provision according to claim 1, it is characterized in that tank described in this device is by the inlet segment being connected as a single entity (16), water exit end (17) and be positioned at into, measuring section between water exit end (18) forms, the longitudinal profile of inlet segment (16) part tank is " ┛ " shape, its right side standing portion communicates with measuring section (18) tank, left side horizontal component overlaps with the bottom of measuring section (18) tank right-hand member head, one water inlet pipe (20) is arranged at the bottom of inlet segment (16) part tank, the water delivering orifice of water inlet pipe (20) is arranged in the tank of inlet segment (16) left side horizontal component, measuring section (18) tank is a horizontal rectangular groove, water exit end (17) tank is a vertical rectangular channel, its the first half communicates with measuring section (18) tank, on the outer wall of the latter half, be connected with a rising pipe (21).

3. frozen water heat exchange coefficient experimental provision according to claim 2, the double-decker that the bottom that it is characterized in that measuring section described in this device (18) tank is hollow, and in water inlet end one side, be also provided with and double-decker base plate horizontal baffle that be connected as a single entity, that cantilever stretches out (9), horizontal baffle (9) termination is positioned at the middle part of inlet segment tank right side standing portion.

4. frozen water heat exchange coefficient experimental provision according to claim 2, is characterized in that measuring section described in this device (18) tank two ends are also respectively arranged with dismountable vertical baffle (10) or vertical rectification mesh screen (11).

5. according to the frozen water heat exchange coefficient experimental provision described in any one in claim 2-4, it is characterized in that in measuring section described in this device (18) tank upper end, going back horizontal cross is provided with the batten (13) being arranged in parallel, the two ends of this batten (13) are fixed on the wall of tank (1), and the spacing of every two battens is 20～30cm.

6. according to the frozen water heat exchange coefficient experimental provision described in any one in claim 2-4, it is characterized in that thermosistor described in this device (5) is that a snakelike metal winding pipe (51) being formed by connecting by flange (52) forms.

7. frozen water heat exchange coefficient experimental provision according to claim 5, is characterized in that thermosistor described in this device (5) is that a snakelike metal winding pipe (51) being formed by connecting by flange (52) forms.

8. according to the frozen water heat exchange coefficient experimental provision described in any one in claim 2-4, it is characterized in that the instrument of ice thickness measure of the change described in this device (7) is by sounding rod (71), measures piece (72), survey measurements sleeve (73), support (74) and firm banking (75) formation, measure piece (72) and be connected to sounding rod (71) termination, one end, the other end of sounding rod (71) is slidably connected with it through survey measurements sleeve (73), survey measurements sleeve (73) is fixed on support (74) upper end, and support (74) lower end is connected with firm banking (75).

9. according to the frozen water heat exchange coefficient experimental provision described in any one in claim 7, it is characterized in that the instrument of ice thickness measure of the change described in this device (7) is by sounding rod (71), measures piece (72), survey measurements sleeve (73), support (74) and firm banking (75) formation, measure piece (72) and be connected to sounding rod (71) termination, one end, the other end of sounding rod (71) is slidably connected with it through survey measurements sleeve (73), survey measurements sleeve (73) is fixed on support (74) upper end, and support (74) lower end is connected with firm banking (75).

10. utilize device described in claim 1 to measure a method for frozen water heat exchange coefficient, the determination step of the method is as follows:

(1) in tank (1), water pump (3), gate valve (4), after thermosistor (5) connects and to add water and be full of, vertical baffle (10) is fixed on to tank measuring section (18) two ends so that it forms the water tank of closed at both ends, and in the middle or postmedian along laterally choosing temperature survey section (15), in the following 5mm of water surface place, start the temperature chain that lets droop and formed by moisture recorder (8) measuring sonde to arranging, start-up temperature registering instrument (8), and then after temperature survey section, choose ice thickness measure of the change section (14), put into the sounding rod (71) of ice thickness measure of the change instrument (7) and measure piece (72), and ice thickness measure of the change instrument (7) is fixed on the wall of water tank limit,

(2) environment temperature is reduced and make to freeze in water tank at least after 0.02m ice sheet, adjusting ambient temperature to 0.0 ℃, on the ice sheet of water tank measuring section (18) inlet end, choose again fluid-velocity survey section (12) and cut a hole a through hole, put into current meter (6) measuring sonde, and current meter (6) is fixed on the wall of water tank limit;

(3) vertical baffle at water tank two ends (10) is taken off, and at the fixing rectification mesh screen (11) of the entrance point of tank measuring section (18), then the water filling into is introduced from tank inlet segment (16) bottom, and open gate valve (4), start water pump (3), make water body in tank (1), in pipeline (2) and thermosistor (5), circulation mixes, flow velocity≤the 0.15m/s of the interior water body of tank measuring section (18), treat water temperature in tank measuring section, when stablize in flow field and ice temperature approaches 0.0 ℃, to on the sounding rod (71) of ice thickness measure of the change instrument (7), carry and measurement piece (72) upper surface of lower end and ice sheet (19) lower surface are adjacent to, then from measurement, read sleeve (73) and read ice thickness initial value, thereafter at interval of carrying sounding rod (71) on 10-30 minute and making measurement piece (72) upper surface of lower end and after ice sheet (19) lower surface is adjacent to, read follow-up ice thickness and change numerical value,

(4) the ice thickness changing value substitution following formula recording under measurement temperature, flow velocity, time and the respective conditions of setting is calculated and obtains frozen water heat exchange coefficient under corresponding conditions:

$\mathrm{\α}=\frac{\underset{0}{\overset{h}{\text{\∫}}}{\mathrm{\ρ}}_i{L}_i\mathrm{dh}}{\underset{0}{\overset{t}{\∫}}{T}_{\mathrm{ws}}\mathrm{dt}}=\frac{{\mathrm{\ρ}}_i{L}_i\mathrm{\Δh}}{T_{\mathrm{ws}}\mathrm{\Δt}}$

In formula, α is frozen water heat exchange coefficient, T _wsfor subglacial water temperature, L _ifor ice-out latent heat, ρ _ifor the density of ice, Δ h is ice thickness changing value, and Δ t is that ice thickness changes required time.

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