TWI440841B - Method for designing heater specification of heat pipe testing instrument - Google Patents

Description

Design method of heater specifications for heat pipe testing equipment

The present invention relates to a heat pipe test apparatus, and more particularly to a method of designing a heater gauge for a heat pipe test apparatus.

Because the temperature distribution range is complex and variable in the high-temperature waste heat recovery system, the test for the performance limit of the heat pipe is an important indicator for judging the performance of the heat pipe.

Traditionally, when designing heaters, manufacturers have used the maximum heat transfer capacity of heat pipes as the design basis for heater performance. The design of the maximum heat transfer capacity of the heat pipe is mostly based on the heat pipe operation catalogue provided by the manufacturer to understand the heat transfer capability of the heat pipe, or rely on the staff's own previous design experience, and then design the heat pipe based on the information and experience. The wattage of the heating capacity of the performance test. The number of heating watts of the heat pipe designed by this method is also only applicable to the performance test stage of the maximum heat transfer amount of the heat pipe.

However, in the traditional design, the performance limits of the heat pipe, including the boiling limit (Boiling Limitation) and the splash limit (Entrainment Limitation), are not considered. Therefore, if the performance of the heat pipe boiling limit and the splash limit is designed to test the heating wattage based solely on the experience of the staff and the operating catalog provided by the manufacturer, the heating capacity may be insufficient. As a result, additional heaters with greater heating capacity are required to meet the requirements of heat pipe performance testing, resulting in waste of costs. In addition, some manufacturers have no relevant theoretical basis for designing performance tests of heat pipes, which will seriously affect the quality and capability of heat pipe testing.

Therefore, one aspect of the present invention is to provide a method for designing a heater specification of a heat pipe test apparatus, which can obtain the maximum heat pipe encountered when testing the boiling limit and the splash limit according to the heat pipe type and size to be tested for performance. Heat transfer. Therefore, the maximum heat transfer capacity can be used as a basis for designing the heater size for the performance limit test of the heat pipe.

Another aspect of the present invention is to provide a method for designing a heater specification of a heat pipe test apparatus, which can provide a heater required for a heat pipe for performance testing, thereby avoiding insufficient heating capability of the heater when the heat pipe performance test is performed Or the heater provides too much heat to cause the heat pipe to burn out and damage, which can improve the quality and capability of the heat pipe performance test.

Still another aspect of the present invention is to provide a method of designing a heater specification for a heat pipe test apparatus, which can provide a suitable heater according to the heat pipe type and size, so that waste can be avoided without separately purchasing a heater.

In accordance with the above object of the present invention, a method of designing a heater specification for a heat pipe test apparatus is provided, which comprises the following steps. Provide a plurality of specifications of a heat pipe. These specifications are used to calculate a plurality of spatter limit heat fluxes and corresponding plurality of boiling limit heat fluxes of the heat pipe at a plurality of operating temperatures. A first relationship between the spatter limit heat transfer amount and the operating temperature, and a second relationship between the boiling limit heat transfer amount and the operating temperatures are plotted. Wherein, the first relationship curve and the second relationship curve intersect at one point. The heat transfer amount corresponding to this point is used as the design basis for the heating capacity specification of the heater for the performance test of the heat pipe.

According to an embodiment of the invention, the specification parameters include a cross-sectional area of the working steam passing through the heat pipe, a latent heat of vaporization of the working vapor, a density of the working vapor, a hydraulic radius of the capillary structure of the heat pipe, a surface tension of the working liquid, and an evaporation end of the heat pipe. The length, the effective heat transfer coefficient of the heat pipe, the temperature of the working vapor, the inner radius of the heat pipe, the radius of the cross section of the working steam passing through the heat pipe, the nucleation radius of the working liquid and the capillary pressure difference of the heat pipe.

According to another embodiment of the present invention, the step of calculating the spatter limit heat transfer amount of the heat pipe comprises using a splash limit formula, which is the heat transfer amount per cut limit = cross-sectional area × latent heat of evaporation × [(surface tension) × density) / (2 × hydraulic radius)] ^1/2 .

According to still another embodiment of the present invention, the step of calculating the boiling limit heat transfer amount of the heat pipe comprises using a boiling limit formula which is each boiling limit heat transfer amount = [(2π × evaporation end length × effective heat conduction) Coefficient × temperature) / (evaporation latent heat × density × ln (inner tube radius / cross-sectional area radius))] × [(2 × surface tension / nucleation radius) - capillary pressure difference].

According to still another embodiment of the present invention, the heat transfer amount corresponding to the above point is the maximum heat transfer amount of the heat pipe during high temperature operation, and the temperature during the high temperature operation is from 200 ° C to 350 ° C.

According to still another embodiment of the present invention, the heating capacity specification is that the maximum heat transfer amount provided by the heater to the heat pipe is equal to or less than the heat transfer amount corresponding to the point.

Please refer to FIG. 1 , which is a flow chart showing a method for designing a heater specification of a heat pipe testing device according to an embodiment of the present invention. In the present embodiment, when the method 100 for designing the heater specifications of the heat pipe test equipment is designed, as described in step 102, the specifications of the type and size of the heat pipe to be tested for performance are first provided.

In some embodiments, the specification of the heat pipe to be tested is included at different operating temperatures of the heat pipe: the cross-sectional area A _v of the working steam passing through the heat pipe, the latent heat of vaporization of the working vapor λ, and the density of the working vapor ρ _v , the hydraulic radius of the capillary structure of the heat pipe R _h,w , the surface tension σ of the working liquid with the heat pipe, the length L _e of the evaporation end of the heat pipe, the effective heat transfer coefficient k _{eff of the} heat pipe, the temperature T _{v of the} working steam, the tube of the heat pipe The inner radius r _i , the cross-sectional area radius r _{v of the} working vapor passing through the heat pipe, the nucleation radius r _{n of the} working liquid and the capillary pressure difference ΔP _{c,m of the} heat pipe.

Next, as described in step 104, using the specification parameters of the heat pipe to be tested, the corresponding spatter limit heat transfer amount and the corresponding boiling limit heat transfer amount are calculated at respective different operating temperatures. In step 104, when calculating the splash limit heat flux of the heat pipe, the relevant formula of the splash limit can be utilized: the splash limit heat transfer amount = the cross-sectional area of the heat pipe through which the working steam passes × the latent heat of vaporization of the working steam × [(working liquid Surface tension × density of working vapor) / (2 × hydraulic radius of capillary structure)] ^1/2 . that is:

Splash limit heat transfer q _ent =A _v λ .

On the other hand, when calculating the boiling heat transfer capacity of the heat pipe, the relevant formula of the boiling limit can be used: boiling limit heat transfer amount = [(2π × length of the evaporation end of the heat pipe × effective heat transfer coefficient of the heat pipe × temperature of the working vapor) / (Evaporation latent heat of working steam × density of working vapor × ln (radius inside the heat pipe / radius of cross section of working steam passing through the heat pipe))] × [(2 × surface tension of working liquid / nucleation radius of working liquid) - The capillary pressure difference of the heat pipe]. that is:

Boiling limit heat transfer .

Using the relevant formula of the splash limit and the boiling limit, the corresponding spatter limit heat transfer amount and the corresponding boiling limit heat transfer amount can be calculated at different operating temperatures. Then, as described in step 106, the operating temperature of the heat pipe is used as the abscissa, the heat transfer amount is the ordinate, and the operating temperature of the heat pipe and the corresponding calculated spatter limit heat transfer amount and boiling limit heat transfer amount are drawn. The relationship between the spatter limit heat transfer amount and the operating temperature, and the relationship between the boiling limit heat transfer amount and the operating temperature.

Please refer to FIG. 2, which is a graph showing the relationship between the spatter limit heat transfer amount of the heat pipe and the boiling limit heat transfer amount and the operating temperature according to an embodiment of the present invention. In this embodiment, the relationship curve 202 can be drawn by using the operating temperature of the heat pipe and the corresponding calculated heat pipe splash limit heat transfer amount. On the other hand, the relationship curve 200 can be drawn by using the operating temperature of the heat pipe and the corresponding calculated heat transfer temperature of the heat pipe boiling limit.

In the relationship between the operating temperature of Fig. 2 and the heat transfer amount of the heat pipe, the relationship between the splash limit heat transfer amount and the operating temperature curve 202 and the boiling limit heat transfer amount and the operating temperature is 200. Go to point 204. The heat transfer corresponding to this point 204 can represent the maximum heat transfer of the heat pipe at high temperatures. Thus, as described in step 108, the method 100 of the present embodiment utilizes the physical meaning represented by this point 204 to design the heating capability specification for the heater of the device for performance testing of the heat pipe. For example, the maximum heat transfer amount that the heater provides to the heat pipe is equal to or less than the heat transfer amount corresponding to point 204.

As can be seen from Fig. 2, the heat transfer amount corresponding to the intersection 204 of the relationship curves 200 and 202 is close to 20 kW. Therefore, according to the heat transfer amount, the heating capacity of the heater of the heat pipe test apparatus can be designed to be close to 20 kW. In some examples, the temperature range at which the heat pipe operates at high temperatures may range, for example, from 200 °C to 350 °C.

In addition, through the drawing of the boiling limit curve and the splash limit curve, the field staff can also use this pattern to understand the effective temperature of the heat pipe operation to be tested for performance and the various limits that the heat pipe will encounter.

It can be seen from the above embodiments that an advantage of the design method of the heater specification of the heat pipe testing device of the present invention is that the design method can obtain the heat pipe when testing the boiling limit and the splash limit according to the heat pipe type and size to be tested for performance. The maximum heat flux encountered. Therefore, the maximum heat transfer capacity can be used as a basis for designing the heater size for the performance limit test of the heat pipe.

It can be seen from the above embodiments that another advantage of the design method of the heater specification of the heat pipe testing device of the present invention is that the heating method required for the heat pipe performance test can be avoided because the design method can provide the heater required for the heat pipe for performance testing. The heating capacity of the device is insufficient, or the heater provides excessive heat, which causes the heat pipe to be burned and damaged, thereby improving the quality and capability of the heat pipe performance test.

According to the above embodiments, another advantage of the design method of the heater specification of the heat pipe testing device of the present invention is that the method can provide a suitable heater according to the heat pipe type and size, so that the heater can be purchased separately. Prevent wastage.

While the present invention has been described above by way of example, it is not intended to be construed as a limitation of the scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

100. . . method

102. . . step

104. . . step

106. . . step

108. . . step

200. . . Relationship lines

202. . . Relationship lines

204. . . point

The above and other objects, features, advantages and embodiments of the present invention will become more apparent and understood.

1 is a flow chart showing a method of designing a heater specification of a heat pipe testing device in accordance with an embodiment of the present invention.

2 is a graph showing the relationship between the spatter limit heat transfer amount of the heat pipe and the boiling limit heat transfer amount and the operating temperature according to an embodiment of the present invention.

100. . . method

102. . . step

104. . . step

106. . . step

108. . . step

Claims (6)

A method for designing a heater specification of a heat pipe test device, comprising: providing a plurality of specification parameters of a heat pipe; using the specification parameters to calculate a plurality of splash limit heat fluxes corresponding to the heat pipe at a plurality of operating temperatures and corresponding a plurality of boiling limit heat fluxes; drawing a first relationship between the spatter limit heat fluxes and the operating temperatures, and a second of the boiling limit heat fluxes and the operating temperatures a relationship curve, wherein the first relationship curve intersects the second relationship curve; and designing a heating capacity specification of one of the heaters according to a heat transfer amount corresponding to the point. The method for designing a heater specification of the heat pipe testing device according to claim 1, wherein the specification parameters include a cross-sectional area of a working vapor passing through the heat pipe, a latent heat of vaporization of the working vapor, a density of the working vapor, a hydraulic radius of one of the capillary structures, a surface tension of a working liquid, an evaporation end length of the heat pipe, an effective heat transfer coefficient of the heat pipe, a temperature of the working vapor, an inner radius of the heat pipe, The working vapor passes through a cross-sectional area radius of the heat pipe, a nucleation radius of the working liquid, and a capillary pressure difference of one of the heat pipes. The method for designing a heater specification of a heat pipe testing device according to claim 2, wherein the step of calculating the spatter limit heat flux of the heat pipe comprises using a splash limit formula, each of which is a splash limit Heat transfer amount = the cross-sectional area × the latent heat of evaporation × [(the surface tension × the density) / (2 × the hydraulic radius)] ^1/2 . The method for designing a heater specification of a heat pipe testing device according to claim 2, wherein the step of calculating the boiling limit heat flux of the heat pipe comprises using a boiling limit formula, each of which is a boiling limit Heat transfer amount = [(2π × length of the evaporation end × the effective heat transfer coefficient × the temperature) / (the latent heat of evaporation × the density × ln (the inner radius of the tube / the radius of the cross-sectional area))] × [(2 × Surface tension / the nucleation radius) - the capillary pressure difference]. The method for designing a heater specification of the heat pipe test device according to claim 1, wherein the heat transfer amount corresponding to the point is a maximum heat transfer amount of the heat pipe at a high temperature operation, and the temperature during the high temperature operation From 200 ° C to 350 ° C. A method of designing a heater specification of a heat pipe test apparatus according to claim 1, wherein the heating capacity specification is that a maximum heat transfer amount of the heat pipe provided to the heat pipe is equal to or less than the heat transfer amount.