# Patent

## Title
Performance testing apparatus for heat pipes

## Abstract

A performance testing apparatus for a heat pipe includes an immovable portion having a cooling structure defined therein for cooling a heat pipe needing to be tested. A movable portion is capable of moving relative to the immovable portion. A receiving structure is located between the immovable portion and the movable portion for receiving the heat pipe therein. At least a temperature sensor is attached to at least one of the immovable portion and the movable portion for thermally contacting the heat pipe in the receiving structure for detecting temperature of the heat pipe. An enclosure encloses the immovable portion and the movable portions and has sidewalls thereof slidably contacting at least one of the immovable portion and the movable portion.

## Background
FIELD OF THE INVENTION
The present invention relates generally to testing apparatuses, and more particularly to a performance testing apparatus for heat pipes.
DESCRIPTION OF RELATED ART
It is well known that a heat pipe is generally a vacuum-sealed pipe. A porous wick structure is provided on an inner face of the pipe, and at least a phase changeable working media employed to carry heat is contained in the pipe. Generally, according to positions from which heat is input or output, a heat pipe has three sections, an evaporating section, a condensing section and an adiabatic section between the evaporating section and the condensing section.
In use, the heat pipe transfers heat from one place to another place mainly by exchanging heat through phase change of the working media. Generally, the working media is a liquid such as alcohol or water and so on. When the working media in the evaporating section of the heat pipe is heated up, it evaporates, and a pressure difference is thus produced between the evaporating section and the condensing section in the heat pipe. The resultant vapor with high enthalpy rushes to the condensing section and condenses there. Then the condensed liquid reflows to the evaporating section along the wick structure. This evaporating/condensing cycle continually transfers heat from the evaporating section to the condensing section. Due to the continual phase change of the working media, the evaporating section is kept at or near the same temperature as the condensing section of the heat pipe. Heat pipes are used widely owing to their great heat-transfer capability.
In order to ensure the effective working of the heat pipe, the heat pipe generally requires testing before being used. The maximum heat transfer capacity (Qmax) and the temperature difference (ΔT) between the evaporating section and the condensing section are two important parameters for evaluating performance of the heat pipe. When a predetermined quantity of heat is input into the heat pipe through the evaporating section thereof, thermal resistance (Rth) of the heat pipe can be obtained from ΔT, and the performance of the heat pipe can be evaluated. The relationship between these parameters Qmax, Rth and ΔT is Rth=ΔT/Qmax. When the input quantity of heat exceeds the maximum heat transfer capacity (Qmax), the heat cannot be timely transferred from the evaporating section to the condensing section, and the temperature of the evaporating section increases rapidly.
Conventionally, a method for testing the performance of a heat pipe is first to insert the evaporating section of the heat pipe into liquid at constant temperature; after a predetermined period of time and temperature of the heat pipe will become stable, then a temperature sensor such as a thermocouple, a resistance thermometer detector (RTD) or the like is used to measure ΔT between the liquid and the condensing section of the heat pipe to evaluate the performance of the heat pipe. However, Rth and Qmax can not be obtained from this test, and the performance of the heat pipe can not be reflected exactly by this test.
Referring to FIG. 6, a conventional performance testing apparatus for heat pipes is shown. The apparatus has a resistance wire 1 coiling round an evaporating section 2a of a heat pipe 2, and a water cooling sleeve 3 functioning as a heat sink and enclosing a condensing section 2b of the heat pipe 2. In use, electrical power controlled by a voltmeter and an ammeter flows through the resistance wire 1, whereby the resistance wire 1 heats the evaporating section 2a of the heat pipe 2. Simultaneously, by controlling flow rate and temperature of cooling liquid entering the cooling sleeve 3, the heat input at the evaporating section 2a can be removed from the heat pipe 2 by the cooling liquid at the condensing section 2b, whereby a stable operating temperature of adiabatic section 2c of the heat pipe 2 is obtained. Therefore, Qmax of the heat pipe 2 and ΔT between the evaporating section 2a and the condensing section 2b can be obtained by temperature sensors 4 at different positions of the heat pipe 2.
However, in the test, the conventional testing apparatus has drawbacks as follows: a) it is difficult to accurately determine lengths of the evaporating section 2a and the condensing section 2b which are important factors in determining the performance of the heat pipe 2; b) heat transference and temperature measurement may easily be effected by environmental conditions; c) it is difficult to achieve sufficiently intimate contact between the heat pipe and the heat source and between the heat pipe and the heat sink, which results in unsteady performance test results of the heat pipe. Furthermore, due to fussy and laborious assembly and disassembly in the test, the testing apparatus can be only used in the laboratory, and can not be used in the mass production of heat pipes.
In mass production of heat pipes, large number of performance testing apparatuses are needed, and the apparatus are used frequently over a long period of time; thus, the apparatuses not only require good testing accuracy, but also require easy and accurate assembly to the heat pipes to be tested. The testing apparatus effects the yield and cost of the heat pipes directly; thus testing accuracy, facility, speed, consistency, reproducibility and reliability need to be considered when choosing the testing apparatus. Therefore, the conventional testing apparatus needs to be improved in order to meet the demand for testing during mass production of heat pipes.
What is needed, therefore, is a high performance testing apparatus for heat pipes suitable for use in mass production of heat pipes.
SUMMARY OF THE INVENTION
A performance testing apparatus for a heat pipe in accordance with a preferred embodiment of the present invention comprises an immovable portion having a cooling structure defined therein for cooling a heat pipe requiring testing. A movable portion is capable of moving relative to the immovable portion. A receiving structure is located between the immovable portion and the movable portion for receiving the heat pipe therein. At least a temperature sensor is attached to at least one of the immovable portion and the movable portion for thermally contacting the heat pipe with the receiving structure for detecting temperature of the heat pipe. An enclosure encloses the immovable portion and the movable portions, and has sidewalls thereof slidably contacting at least one of the immovable portion and the movable portion.
Other advantages and novel features will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings, in which:



BRIEF DESCRIPTION OF THE DRAWINGS
Many aspects of the present apparatus can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present apparatus. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
FIG. 1 is an assembled view of a performance testing apparatus for heat pipes in accordance with a preferred embodiment of the present invention;
FIG. 2 is an exploded, isometric view of the testing apparatus of FIG. 1;
FIG. 3 shows an enclosure of FIG. 2 in an inverted manner;
FIG. 4 is an assembled view of a performance testing apparatus for heat pipes in accordance with an alternative embodiment of the present invention;
FIG. 5 is an exploded, isometric view of the testing apparatus of FIG. 5; and
FIG. 6 is a conventional performance testing apparatus for heat pipes.



DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1-3, a performance testing apparatus for heat pipes comprises an immovable portion 20 and a movable portion 30 movably mounted on the immovable portion 20.
The immovable portion 20 has good heat conductivity and is held on a platform of a supporting member such as a testing table (not shown) or so on. Cooling passageways (not shown) are defined in an inner portion of the immovable portion 20, to allow coolant flow therein. An inlet 22 and an outlet 22 communicate the passageways with a constant temperature coolant circulating device (not shown); therefore, the passageways, inlet 22, outlet 22 and the coolant circulating device corporately define a cooling system for the coolant circulating therein to remove heat from the heat pipe in test. The immovable portion 20 has a cooling groove 24 defined in a top face thereof, for receiving a condensing section of the heat pipe to be tested therein. Two temperature sensors 26 are inserted into the immovable portion 20 from a bottom thereof so as to position detecting portions of the sensors 26 in the cooling groove 24 and be capable of automatically contacting the heat pipe in order to detect a temperature of the condensing section of the heat pipe. In order to prevent heat in the immovable portion 20 from spreading to the supporting member, an insulating plate is disposed at a bottom of the immovable portion 20.
The movable portion 30, corresponding to the cooling groove 24 of the immovable portion 20, has a positioning groove 32 defined therein, whereby a testing channel 50 is cooperatively defined by the cooling groove 24 and the positioning groove 32 when the movable portion 30 moves to reach the immovable portion 20. Thus, an intimate contact between the heat pipe and the movable and immovable portions 30, 20 defining the channel 50 can be realized, thereby reducing heat resistance between the heat pipe and the movable and immovable portions 30, 20. Two temperature sensors 36 are inserted into the movable portion 30 from a top thereof to reach a position wherein detecting portions of the sensors 36 are located in the positioning groove 32 and capable of automatically contacting the heat pipe to detect the temperature of the condensing section of the heat pipe.
The channel 50 as shown in the preferred embodiment has a circular cross section enabling it to receive the condensing section of the heat pipe having a correspondingly circular cross section. Alternatively, the channel 50 can have a rectangular cross section where the condensing section of the heat pipe also has a flat rectangular configuration.
Generally, in order to ensure that the heat pipe is in close contact with the movable and immovable portions 30, 20, a supporting member 10 is used to support and assemble the immovable and movable portions 20, 30. The immovable portion 20 is fixed on the supporting member 10. A driving device 40 is installed on the supporting member 10 to drive the movable portion 30 to make accurate linear movements relative to the immovable portion 20 along a vertical direction, thereby realizing the intimate contact between the heat pipe and the movable and immovable portions 30, 20; thus, heat resistance between the condensing section of the heat pipe and the movable and immovable portions 30, 20 can be micro-controlled.
The supporting member 10 comprises a seat 12 which may be an electromagnetic holding chuck, using which the testing apparatus can be easily fixed at any desired position which is provided with a platform made of ferroalloy. A first plate 14 is secured on the seat 12; a second plate 16 hovers over the first plate 14; a plurality of supporting rods 15 interconnect the first and second plates 14, 16 for supporting the second plate 16 above the first plate 14. The seat 12, the first and second plates 14, 16 and the rods 15 constitute a mainframe for assembling and positioning the immovable and movable portions 20, 30 therein. The first plate 14 has the immovable portion 20 fixed thereon. In order to prevent heat in the immovable portion 20 from spreading to the first plate 14, the insulating plate 28 is disposed between the immovable portion 20 and the first plate 14. The insulating plate 28 has an elongated slot 282 defined in a bottom face thereof, wherein the bottom face abuts the first plate 14, and two through holes (not labeled) vertically extend therethrough and communicate with the slot 282, for extension of wires (not shown) of the temperature sensors 26 to connect with a monitoring computer (not shown).
In order to ensure that the immovable portion 20 and the movable portion 30 have good linear movement relative to each other, and keep the grooves 24, 32 of the immovable and movable portions 20, 30 in positions corresponding to each other, a cuboid enclosure 60 without bottom covers the immovable and movable portions 20, 30, and is located between the first and second plates 14, 16 of the supporting member 10. The enclosure 60 has four sidewalls (not labeled) thereof slidably contacting side faces of the immovable portion 20 all along. One of the sidewalls of the enclosure 60 defines an opening 62 located corresponding to the channel 50 between the immovable and movable portions 20, 30, for disposing the heat pipe into the channel 50 therefrom. An opposite one of the sidewalls of the enclosure 60 defines an arced hatch 63 for the inlet and outlet 22 extending therethrough. A ceiling of the enclosure 60 contacts a top face of the movable portion 30 and defines therein a through hole (not shown) and two apertures 66 located at two sides of the through hole.
The driving device 40 in this preferred embodiment is a step motor, although it can be easily apprehended by those skilled in the art that the driving device 40 can also be a pneumatic cylinder or a hydraulic cylinder. The driving device 40 is installed on the second plate 16 of the supporting member 10. The driving device 40 is fixed to the second plate 16 above ceiling of the enclosure 60. A shaft (not labeled) of the driving device 40 extends through the second plate 16 of the supporting member 10. The shaft has a threaded end (not shown) threadedly engaging with a bolt 42 which is secured to the movable portion 30 and extends through the through hole in the ceiling of the enclosure 60. When the shaft rotates, the bolt 42, the movable portion 30 and the enclosure 60 move upwardly or downwardly. The temperature sensors 36 have wires (not labeled) thereof extending through the apertures 66 of the enclosure 60 to connect with the monitoring computer. In use, the driving device 40 drives the movable portion 30 and the enclosure 60 to make accurate linear movement relative to the immovable portion 20. For example, the movable portion 30 and the enclosure 60 can be driven to depart a certain distance such as 5 millimeters from the immovable portion 20 to facilitate the condensing section of the heat pipe which needs to be tested to be inserted into the channel 50 or withdrawn from the channel 50 from the opening 62 of the enclosure 60 after the heat pipe has been tested. Or in another example, the movable portion 30 and the enclosure 60 can be driven to move toward the immovable portion 20 to thereby realize an intimate contact between the condensing section of the heat pipe and the immovable and movable portions 20, 30 during which the test is performed. During the movement of the movable portion 30 and the enclosure 60, the sidewalls of the enclosure 60 slidably contact the side faces of the immovable portion 20. Accordingly, the requirements for testing, i.e. accuracy, ease of use and speed can be realized by the testing apparatus in accordance with the present invention. Furthermore, the enclosure 60 has good adiabatic property, which constructs a steady environment for testing the heat pipes.
It can be understood, positions of the immovable portion 20 and the movable portion 30 can be exchanged, i.e., the movable portion 30 is located on the first plate 14 of the supporting member 10, and the immovable portion 20 is fixed to the second plate 16 of the supporting member 10, and the driving device 40 is positioned to be adjacent to the immovable portion 20. Alternatively, the driving device 40 can be installed to the immovable portion 20. In a further alternative, each of the immovable and movable portions 20, 30 has one driving device 40 installed thereon to move them toward/away from each other.
In use, the condensing section of the heat pipe is received in the channel 50 when the movable portion 30 is moved away from the immovable portion 20. Then the movable portion 30 is moved to reach the immovable portion 20 so that the condensing section of the heat pipe is tightly fitted into the channel 50. The sensors 26, 36 are in thermal connection with the condensing section of the heat pipe; therefore, the sensors 26, 36 work to accurately send detected temperatures of the condensing section of the heat pipe to the monitoring computer. Based on the temperatures obtained by the plurality of sensors 26, 36, an average temperature can be obtained by the monitoring computer very quickly; therefore, performance of the heat pipe can be very quickly decided.
Referring to FIGS. 4 and 5, a performance testing apparatus for heat pipes in accordance with a alternative embodiment of the present invention is shown. The performance testing apparatus for heat pipes is similar to the preferred embodiment, the main difference from the first embodiment is that an enclosure 60a further comprising a bottom wall 66a replaces the enclosure 60 and first and second plates 14, 16 of the supporting member 10 of the preferred embodiment. The enclosure 60a is directly positioned on the seat 12. An entrance 63a is defined in a side face of the enclosure 60a. The immovable and movable portions 20, 30 are disposed in the enclosure 60a from the entrance 63a. The bottom wall 66a defines a slot 662a for extension of wire of the temperature sensor 26 to connect with the monitoring computer. The driving device 40 is fixed to a ceiling of the enclosure 60a. The shaft of the driving device 40 threadedly engages with the bolt 42 which is secured to a board 34 of the movable portion 30 and extends through a through hole 64a defined in the ceiling of the enclosure 60a. When the driving device 40 operates, the shaft rotates, the bolt 42 with the board 34, and the movable portion 30 move upwardly or downwardly relative to the immovable portion 20 in the enclosure 60a. 
According to the embodiments of the present invention, the immovable and movable portions 20, 30 are disposed in the enclosure 60, thereby producing an accurate relative position to the immovable and movable portions 20, 30, therefore the accurate linear movement of the immovable and movable portions 20, 30 can be realized when the driving device 40 works. Furthermore, the enclosure 60, 60a provides a steady environment for testing performance of the heat pipes.
Additionally, in the present invention, in order to lower cost of the testing apparatus, the immovable portion 30, the insulating plate 28, the board 34, and the enclosure 60, 60a can be made from low-cost material such as PE (Polyethylene), ABS (Acrylonitrile Butadiene Styrene), PF(Phenol-Formaldehyde), PTFE (Polytetrafluoroethylene) and so on. The immovable portion 20 can be made from copper (Cu) or aluminum (Al). The immovable portion 20 can have silver (Ag) or nickel (Ni) plated on an inner face in the groove 24 to prevent the oxidization of the inner face.
It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.

## Claims

1. A performance testing apparatus for a heat pipe comprising:
an immovable portion having a cooling structure defined therein for cooling a heat pipe needing to be tested;
a movable portion capable of moving relative to the immovable portion;
a receiving structure located between the immovable portion and the movable portion for receiving the heat pipe therein;
at least a temperature sensor attached to at least one of the immovable portion and the movable portion for thermally contacting the heat pipe in the receiving structure for detecting temperature of the heat pipe; and
an enclosure enclosing the immovable portion and the movable portions and having sidewalls thereof slidably contacting at least one of the immovable portion and the movable portion.

2. The testing apparatus of claim 1, wherein the receiving structure is a channel defined between the immovable portion and the movable portion.

3. The testing apparatus of claim 2, wherein the at least a temperature sensor has a portion thereof exposed to the channel.

4. The testing apparatus of claim 3, wherein at least one of the immovable portion and the movable portion has at least a positioning structure communicating with the channel, the at least a temperature sensor being positioned in the at least a positioning structure.

5. The testing apparatus of claim 2, wherein the one of the enclosure sidewalls corresponding to the channel defines an opening for disposing the heat pipe into the channel therefrom.

6. The testing apparatus of claim 5, wherein the enclosure has an opposite one of the sidewalls thereof opened, the cooling structure of the immovable portion has an inlet and an outlet extending through the opposite one of the sidewalls of the enclosure.

7. The testing apparatus of claim 2 further comprising a supporting member having a seat for locating the testing apparatus at a required position.

8. The testing apparatus of claim 7, wherein the supporting member comprises a first plate positioned on the seat, and a second plate supported by a plurality rods extending from the first plate.

9. The testing apparatus of claim 8, wherein the immovable portion is positioned on the first plate of the supporting member, the enclosure is located between the first and second plates of the supporting member, and has a ceiling thereof contacting the movable portion.

10. The testing apparatus of claim 9, wherein the enclosure has the sidewalls thereof slidably contacting side faces of the immovable portion.

11. The testing apparatus of claim 9 further comprising a driving device for driving the movable portion to move away and toward the immovable portion, wherein the driving device is mounted on the second plate of the supporting member and connects with the movable portion and the ceiling of the enclosure via a bolt.

12. The testing apparatus of claim 9, wherein an insulating plate is sandwiched between the immovable portion and the first plate of the supporting member.

13. The testing apparatus of claim 7, wherein the enclosure has a bottom wall sitting on the seat of the supporting member, and a ceiling thereof positioned over the movable portion.

14. The testing apparatus of claim 13, wherein the enclosure slidably contacts side faces of the movable portion.

15. The testing apparatus of claim 13 further comprising a driving device for driving the movable portion to move away and towards the immovable portion, wherein the driving device is mounted on the ceiling of the enclosure and connects with the movable portion via a bolt.

16. The testing apparatus of claim 13, wherein an insulating plate is sandwiched between the immovable portion and the seat of the supporting member.

17. A testing apparatus comprising:
an enclosure;
an immovable portion received in the enclosure and fluidically communicated with a cooling liquid supply whereby cooling liquid can flow through the immovable portion;
a movable portion received in the enclosure and movable relative to the immovable portion, wherein a channel is defined between the movable and immovable portions for receiving a condensing portion of a heat pipe to be tested by the testing apparatus;
a driver connecting with the movable portion for driving the movable portion to have a linear movement in the enclosure; and
thermal sensors extending through at least one of the movable and immovable portions into the channel to detect a temperature of the condensing portion of the heat pipe received in the channel.