CN102135511A - Method and device for testing heat transfer performance of fin surface of plate-fin heat exchanger - Google Patents

Abstract

The invention discloses a method and a device for testing heat transfer performance of a fin surface of a plate-fin heat exchanger. The device comprises a heating container, a pump, a valve, a flow meter, an experiment sample, a cooler used for cooling liquid, a connecting pipeline, a liquid medium, a data acquisition instrument and a computer by which a circulation loop is formed. Heat transfer thermal resistance of one side is separated by testing the flow of the liquid medium passing through the heat exchanger and the temperature of four inlets/outlets in real time and utilizing the principle of equal surface thermal resistance of a high-temperature side and a low-temperature side and thermal resistance separation, and a functional relation between the high-temperature side and the low-temperature side is further obtained by calculating heat transfer coefficient h of the fin surface and flow Reynolds number Re according to structural parameters and serves as basic data for design and calculation of the heat exchanger; moreover, a functional relation obtained from new fins serves as a reference and a basis for comparing and judging mould abrasion, service life and mould repair and is simultaneously used for comparing performance difference among the fins with different structural parameters. The method has the advantages of few measurement parameters, simple measurement device and high measurement accuracy.

Description

A kind of method of testing and device of plate-fin heat exchanger fin surface heat transfer performance

Technical field

The present invention relates to belong to the technical field of thermal conduction study and heat interchanger, specifically a kind of method of testing of heat transfer characteristic of plate-fin heat exchanger fin and proving installation.

Background technology

Plate-fin heat exchanger is because of its compact conformation, the characteristics such as efficient of conducting heat, fields such as widespread use automobile, chemical industry, space flight.Plate-fin heat exchanger is to utilize two kinds of working fluids with different inlet temperatures, flows in heat interchanger inside, realizes the transmission of heat.Wherein, be exactly the version of the various fins of plate-fin heat exchanger inside to the most key parameter of plate-fin heat exchanger heat transfer property influence.The form of different structure and structural parameters, under the different fluid flow velocity, its heat transfer characteristic difference is very big.How quantitative how to obtain the surface coefficient of heat transfer of the fin of high-efficiency compact plate-fin heat exchanger fin more and acquisition different structure parameter, this is one of thermal conduction study area research important content, and this also is the content that various heat exchange device producer lays siege to simultaneously.Obtaining various fin surface heat transfer coefficients, is to carry out in the heat interchanger performance history, carries out the basis and the prerequisite of performance computation and analysis.At present, although the fin surface heat transfer coefficient of many versions and the relational expression of flow state can obtain from document; But consider the difference of the production technology of different manufacturers, and different researchers' method of testing is different with precision, when using these formula, is very restricted.Simultaneously, along with continually developing of new fin, each heat interchanger producer is mostly in the process conditions in conjunction with oneself, and the heat transfer property of the fin of test different structure form and the relation of flow state are to set up heat exchanging device performance computation analysis ability.

How testing and analyze the relation of the flow state of various fin heat transfer properties and its fluid, is that heat interchanger researcher and the designer of heat interchanger producer are in the face of one of important topic.At present, the method for testing of widespread use in the industry cycle is by following several:

First kind is the inferior graphical method of Weir of utilizing inferior graphical method of Weir or correction.Its main principle is to utilize two kinds of fluids to carry out heat interchange, keeps a side liquid flow constant, changes the flow of an other side liquid, and measures flow, the out temperature of two side liquids respectively; Again according to the thermal resistance separation method, suppose the funtcional relationship of the angry Sai Er number of heat transfer that fluid flow changes a side and the power exponent of Reynolds number and as the horizontal ordinate of drawing, draw different flow point and total coefficient of heat transfer corresponding relation (overall heat transfer coefficient is an ordinate), further utilize the least square method of counting to fit to linear function, its linear function straight line is the fixing coefficient of heat transfer of fluid in the intercept of axis of ordinates.

Second kind is the method for utilizing thermal resistance to separate.Two kinds of fluids carry out heat interchange in heat interchanger experiment exemplar, by particular design and processing to the experiment exemplar, the surface film thermal conductance of one side liquid can be obtained by classical thermal conduction study formula, and then utilize the principle of thermal resistance separation, obtain the surface coefficient of heat transfer of unknown side.Wherein, the general side liquid that adopts of this method can be smooth regular passage, or utilizes a side liquid to undergo phase transition, and keeps this wing passage surface temperature constant.

For above-mentioned two kinds of methods, very big limitation is all arranged, especially in the real exchanger industrial processes, there is significant limitation, all be to carry out heat interchange with two kinds of actuating mediums, test the mass rate, out temperature of two kinds of fluids etc. respectively, test volume is many, and the both sides coefficient of heat transfer is not easy to separate.Be embodied in:

The weak point that the inferior graphical method of first kind Weir exists need to be supposition one side liquid reynolds number Re and slave Sai Er to count the fixedly power exponent expression-form of Nu, and this is not easy to obtain often; And, must in test process, carry out a lot of test figure points and test in order to obtain fitting precision preferably; And whole experiment test equipment more complicated, need two flowmeters, 6 temperature sensors etc.

The method that second kind of thermal resistance that is adopted separated, its weak point be, surface film thermal conductance that must a known side liquid just can carry out the separation method of thermal resistance.This just requires the passage of a side liquid Design and Machining to become standard channel or smooth passage, and this in the design process of heat interchanger often the difficulty.Especially for the product of plate-fin heat exchanger.

Summary of the invention

What the present invention will solve is the weak point that existing two kinds of universal methods of surface film thermal conductance of finding the solution the plate-fin heat exchanger fin exist, aim to provide a kind of method of separating fast at plate-fin heat exchanger fin surface heat transfer coefficient, with and corresponding testing device.

For addressing the above problem, the present invention is by the following technical solutions: a kind of proving installation of plate-fin heat exchanger fin surface heat transfer performance, comprise heating container, pump, valve, flowmeter, the experiment exemplar, the refrigeratory that is used for cooling liquid, connecting line, liquid medium, data collecting instrument and computing machine, it is characterized in that described liquid medium is heated apparatus and is heated to design temperature in heating container, pass through pump more successively, valve, the high temperature side of flowmeter and test exemplar, the high-temp liquid that flows out from the high temperature side of test exemplar is after refrigeratory cools off, return experiment exemplar low temperature side, after carrying out heat interchange with the high temperature side liquid of experiment in the exemplar, return in the heating container, constitute a closed circuit; The high temperature side of described experiment exemplar is identical with the structure of low temperature side, and the import and export of both sides is equipped with temperature sensor.

According to the present invention, the preferred air cooler of described refrigeratory adopts the electronic fan cooling, and the rotating speed of electronic fan is to be controlled by test sample low temperature side liquid-inlet temperature, according to high temperature side in the actual test request and low temperature side liquid temperature differential, the rotating speed of control electronic fan.

According to the present invention, described liquid medium is water or oil, preferably the former.

According to the present invention, high temperature and the liquid medium reverse flow of low temperature both sides.

The present invention also provides a kind of method of testing of plate-fin heat exchanger fin surface heat transfer performance, and the flow of the high temperature side of experiment exemplar and the structure of low temperature side and liquid medium is identical, it is characterized in that carrying out according to the following steps:

1) the total heat of experiment with computing exemplar

Q ₁＝m*C _p*(t ₂-t ₁)，Q ₂＝m*C _p*(T ₁-T ₂)，

When

The time, enter step 2); When The time, finish to measure;

Wherein: (the greater-than sign mistake of expression formula is revised herein)

Q ₁Be the heat of low temperature side, Q ₂Be the heat of high temperature side,

M is the volumetric flow rate of liquid medium, and unit is kg/s,

C _pBe the specific heat of liquid medium,

T1 is the inlet temperature of high temperature side liquid medium,

T2 is the outlet temperature of high temperature side liquid medium,

T1 is the outlet temperature of low temperature side liquid medium,

T2 is the inlet temperature of low temperature side liquid medium;

2) experiment with computing exemplar radiating efficiency ε

$\mathrm{\&epsiv;}=\frac{t_1-t_2}{T_1-{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000041553550000011.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}$ Or $\mathrm{\&epsiv;}=\frac{T_1-T_2}{T_1-{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000041553550000011.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}$

3) the number of transfer units (NTU) NTU of experiment with computing exemplar

$\mathrm{NTU}=\frac{\mathrm{\&epsiv;}}{1-\mathrm{\&epsiv;}}$

4) calculate fin surface overall heat transfer coefficient KA

KA＝m*c _p*NTU

5) calculate fin surface heat transfer coefficient h

$h=\frac{2}{(\frac{1}{\mathrm{KA}}-\mathrm{\&delta;})*A}$ In the formula:

A is the fin surface heat transfer area

δ is the thermal conduction resistance of intermetallic metal wall

6) calculate fin flow state parameters R e and heat transfer dimensionless group Nu

$\mathrm{Re}=\frac{u*\mathrm{De}}{v},$ $\mathrm{Nu}=\frac{h*\mathrm{De}}{\mathrm{\&lambda;}},$ In the formula:

U is the flowing velocity of liquid medium between fin

De is the hydraulic diameter of fin

V is the viscosity of liquid medium

λ is the coefficient of heat conductivity of liquid medium

7) the angry Sai Er of the match fin funtcional relationship of counting Nu and reynolds number Re

By changing the flow of the liquid medium of testing exemplar, obtain the heat transfer coefficient under its different flow, and then obtain the corresponding relation of different Re and Nu, by the funtcional relationship of least square fitting Re and Nu.

Utilization of the present invention has the proving installation of the plate-fin heat exchanger fin heat transfer property of calculation control and computing function, the real-time testing liquid medium flows through flow and 4 out temperatures in the heat interchanger, utilize high temperature side and low temperature side surface resistance of heat transfer to equate the principle of separating with thermal resistance, isolate the heat transfer resistance of a side, further calculate fin surface heat transfer coefficient h and mobile reynolds number Re according to structural parameters; Obtain the funtcional relationship of heat transfer coefficient h and flow Reynolds, as the basic data of design of heat exchanger calculating; Simultaneously, funtcional relationship that new fin obtains as benchmark, is used to contrast and judge the foundation of die wear and serviceable life and repairing mould, is used for performance difference between the comparison different structure parameter fin simultaneously.Measurement parameter of the present invention is less, and measurement mechanism is simple, and the measuring accuracy height.

Description of drawings

At first proving installation of the present invention is described in detail below in conjunction with accompanying drawing, and then introduces the data analysis processing method of fin surface heat transfer coefficient in detail.

Fig. 1 is the structural representation of measurement mechanism of the present invention.

Embodiment

With reference to Fig. 1, plate-fin heat exchanger fin heat transfer characteristic proving installation of the present invention, be by heating vessel 1, electric heater with and corresponding by thyristor controlled heating power regulating device 8, liquid pump 2, control valve 3, mass flowmeter 4, plate-fin heat exchanger fin test sample 5, air cooler 6, electronic fan 7 and corresponding various pipeline, 4 temperature sensors, High Precision Digital Acquisition and computer measurement and control software are formed.The high temperature side of described experiment exemplar 5 is identical with the structure of low temperature side, and 4 temperature sensors are separately positioned on the import and export of high temperature side and low temperature side.Its liquid working medium adopts water.

The working cycle flow process of actuating medium (water) is: at first be that water is heated apparatus 8 is heated to design temperature (input that temperature sensor is used to control electric heater is set) in well heater in heating container 1, pass through pump 2 and valve 3 (wherein valve 3 be used for regulated fluid flow) again, mass rate through flowmeter 4 its experiment exemplars 5 that flow through of test, in test exemplar 5, high temperature side is tested out temperature T1 and T2 respectively; High temperature fluid from 5 outflows of experiment exemplar, again through after air cooler 6 cools off, again from newly getting back to experiment exemplar 5 low temperature side channel entrances, carry out heat interchange with high temperature fluid in the experiment exemplar 5 after, the temperature reduction returns in the heating container 8, finishes whole circulation.Wherein, what be connected with air cooler is an electronic fan 7, realizes the control signal of the temperature test signal of t2 as the electronic fan rotating speed also promptly used in the temperature control of low temperature side fluid in the experiment exemplar 5 by the rotating speed of regulating electronic fan.

Among the present invention, the purposes of described sensor is:

Temperature sensor is used for the out temperature of test experiments exemplar high temperature side and low temperature side liquid-working-medium;

Mass flowmeter is used for the mass rate of actuating medium in the test experiments exemplar.

The method of testing of plate-fin heat exchanger fin surface heat transfer performance, utilize the above-mentioned fin heat transfer property proving installation that has computer control and computing function, real-time testing enters the flow V of the water of testing exemplar and out temperature T1 and T2 and the cryogenic liquid side out temperature t1 and the t2 of high temperature side liquid, and carries out according to the following steps:

1) the total heat of experiment with computing exemplar

Q ₁＝m*C _p*(t ₂-t ₁)，Q ₂＝m*C _p*(T ₁-T ₂)，

When

The time, enter step 2); When

The time, finish to measure;

Wherein:

Q ₁Be the heat of low temperature side, Q ₂Be the heat of high temperature side,

M is the volumetric flow rate of liquid medium, and unit is kg/s,

C _pBe the specific heat of liquid medium,

T1 is the inlet temperature of high temperature side liquid medium,

T2 is the outlet temperature of high temperature side liquid medium,

T1 is the outlet temperature of low temperature side liquid medium,

T2 is the inlet temperature of low temperature side liquid medium;

2) experiment with computing exemplar radiating efficiency ε

$\mathrm{\&epsiv;}=\frac{t_1-t_2}{T_1-{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000041553550000011.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}$ Or $\mathrm{\&epsiv;}=\frac{T_1-T_2}{T_1-{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA0000041553550000011.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}$

3) the number of transfer units (NTU) NTU of experiment with computing exemplar

Because experiment described in the present invention is that high temperature and low temperature both sides liquid medium are the adverse current form, and water equivalent (m*C _p) equate, so the computing formula of NTU is:

$\mathrm{NTU}=\frac{\mathrm{\&epsiv;}}{1-\mathrm{\&epsiv;}}$

4) calculate fin surface overall heat transfer coefficient KA

KA＝m*cp*NTU

5) calculate fin surface heat transfer coefficient h

$\frac{1}{\mathrm{KA}}=\frac{1}{{\mathrm{<figure-callout\; id="1"\; label="h"\; filenames="HDA0000041553550000011.png"\; state="\{\{state\}\}">h</figure-callout>}}_1*A_1}+\frac{1}{{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="HDA0000041553550000011.png"\; state="\{\{state\}\}">h</figure-callout>}}_2*A_2}+\mathrm{\&delta;}$

In the formula, h ₁Be low temperature side fin surface heat transfer coefficient, h ₂Be high temperature side fin surface heat transfer coefficient, A ₁Be low temperature side fin surface heat transfer area, A ₂Be high temperature side fin surface heat transfer area, δ is the thermal conduction resistance of intermetallic metal wall.Because experiment exemplar high temperature and low temperature structure on two sides parameter are identical, under its identical flowing velocity, its surface coefficient of heat transfer is identical.So h ₁=h ₂=h, A ₁=A ₂=A, above-mentioned simplified formula can get

$h=\frac{2}{(\frac{1}{\mathrm{KA}}-\mathrm{\&delta;})*A}$

6) calculate fin flow state parameters R e and heat transfer dimensionless group Nu

$\mathrm{Re}=\frac{u*\mathrm{De}}{v},$ $\mathrm{Nu}=\frac{h*\mathrm{De}}{\mathrm{\&lambda;}},$ In the formula:

U is the flowing velocity of liquid medium between fin

De is the hydraulic diameter of fin

V is the viscosity of liquid medium

λ is the coefficient of heat conductivity of liquid medium

7) the angry Sai Er of the match fin funtcional relationship of counting Nu and reynolds number Re

By changing the flow of the liquid medium of testing exemplar, obtain the heat transfer coefficient under its different flow, and then obtain the corresponding relation of different Re and Nu, by the funtcional relationship of least square fitting Re and Nu.

What should be understood that is: the foregoing description is just to explanation of the present invention, rather than limitation of the present invention, and any innovation and creation that do not exceed in the connotation scope of the present invention all fall within protection scope of the present invention.

Claims (8)

1. the proving installation of a plate-fin heat exchanger fin surface heat transfer performance, comprise heating container (1), pump (2), valve (3), flowmeter (4), experiment exemplar (5), the refrigeratory (6) that is used for cooling liquid, connecting line, liquid medium, data collecting instrument and computing machine, it is characterized in that described liquid medium is heated apparatus (8) and is heated to design temperature in heating container (1), pass through pump (2) more successively, valve (3), the high temperature side of flowmeter (4) and test exemplar (5), the high-temp liquid that flows out from the high temperature side of test exemplar (5) is after refrigeratory (6) cools off, return experiment exemplar (5) low temperature side, after interior high temperature side liquid carries out heat interchange with testing exemplar (5), return in the heating container (6), constitute a closed circuit; The high temperature side of described experiment exemplar (5) is identical with the structure of low temperature side, and the import and export of both sides is equipped with temperature sensor.

2. the proving installation of plate-fin heat exchanger fin surface heat transfer performance as claimed in claim 1 is characterized in that described refrigeratory (6) is an air cooler.

3. the proving installation of plate-fin heat exchanger fin surface heat transfer performance as claimed in claim 2 is characterized in that adopting electronic fan (7) cooling.

4. the proving installation of plate-fin heat exchanger fin surface heat transfer performance as claimed in claim 3, the rotating speed that it is characterized in that described electronic fan (7) is to be controlled by test sample (5) low temperature side liquid-inlet temperature, according to high temperature side in the actual test request and low temperature side liquid temperature differential, the rotating speed of control electronic fan.

5. the proving installation of plate-fin heat exchanger fin surface heat transfer performance as claimed in claim 1 is characterized in that described medium is a water.

6. as the proving installation of any one described plate-fin heat exchanger fin surface heat transfer performance of claim 1-5, it is characterized in that high temperature and the liquid medium reverse flow of low temperature both sides.

7. the method for testing of a plate-fin heat exchanger fin surface heat transfer performance, the flow of the high temperature side of experiment exemplar (5) and the structure of low temperature side and liquid medium is identical, it is characterized in that carrying out according to the following steps:

1) the total heat of experiment with computing exemplar

Q ₁＝m*C _p*(t ₂-t ₁)，Q ₂＝m*C _p*(T ₁-T ₂)，

When

The time, enter step 2); When

The time, finish to measure;

Wherein:

Q ₁Be the heat of low temperature side, Q ₂Be the heat of high temperature side,

M is the volumetric flow rate of liquid medium, and unit is kg/s,

C _pBe the specific heat of liquid medium,

T1 is the inlet temperature of high temperature side liquid medium,

T2 is the outlet temperature of high temperature side liquid medium,

T1 is the outlet temperature of low temperature side liquid medium,

T2 is the inlet temperature of low temperature side liquid medium;

2) experiment with computing exemplar radiating efficiency ε

$\mathrm{\&epsiv;}=\frac{t_1-t_2}{T_1-t_2}$ Or $\mathrm{\&epsiv;}=\frac{T_1-T_2}{T_1-t_2}$

3) the number of transfer units (NTU) NTU of experiment with computing exemplar

$\mathrm{NTU}=\frac{\mathrm{\&epsiv;}}{1-\mathrm{\&epsiv;}}$

4) calculate fin surface overall heat transfer coefficient KA

KA＝m*cp*NTU

5) calculate fin surface heat transfer coefficient h

$h=\frac{2}{(\frac{1}{\mathrm{KA}}-\mathrm{\&delta;})*A}$ In the formula:

A is the fin surface heat transfer area

δ is the thermal conduction resistance of intermetallic metal wall

6) calculate fin flow state parameters R e and heat transfer dimensionless group Nu

$\mathrm{Re}=\frac{u*\mathrm{De}}{v},$ $\mathrm{Nu}=\frac{h*\mathrm{De}}{\mathrm{\&lambda;}},$ In the formula:

U is the flowing velocity of liquid medium between fin

De is the hydraulic diameter of fin

V is the viscosity of liquid medium

λ is the coefficient of heat conductivity of liquid medium

7) the angry Sai Er of the match fin funtcional relationship of counting Nu and reynolds number Re

By changing the flow of the liquid medium of testing exemplar, obtain the heat transfer coefficient under its different flow, and then obtain the corresponding relation of different Re and Nu, by the funtcional relationship of least square fitting Re and Nu.

8. the method for testing of plate-fin heat exchanger fin surface heat transfer performance as claimed in claim 7 is characterized in that high temperature and the liquid medium reverse flow of low temperature both sides.

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