脫脂毛細結構對迴路式熱管之影響

Manufacturing and Investigation of the Effect of Sintered Nickel Wick Structures Produced by Debinding Process for Loop Heat Pipes

葉建志(Chien-Chih Yeh)

指導教授 ： 陳瑤明

國立臺灣大學/工學院/機械工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.01888

摘要

本文旨在研究小型化迴路式熱管之熱傳增強效應。首先進行毛細結構的乾涸限探討，其結果顯示：理想的熱傳能力存在於毛細壓力與滲透度間，受到有效毛細半徑與孔隙度的影響。唯有當有效毛細半徑小且滲透度高時，才能突顯其熱傳能力的增加。此外，孔隙度對有效毛細半徑與滲透度有相當大的影響。根據上述的結果，選定以增加開放性孔洞為主要探討的對象後，進行實驗研究。
在實驗過程中，利用脫脂加壓燒結法來控制有效毛細半徑，以獲得較高的毛細力，又因脫脂後所產生的開放性空孔數，使得滲透度增加，基於上述兩者優點來提升熱傳量。本實驗採用聚丙烯、石蠟、硬脂酸作為犧牲層，依據黏結劑的特性，將黏結劑加熱熔解並與鎳粉均勻混合，使黏結劑附著於鎳粉。藉由化學溶劑與加熱的方法能將黏結劑從毛細結構胚體中移除，進而形成較多的開放性孔洞
。
完成脫脂毛細結構後，將脫脂毛細結構應用於迴路式熱管，並測量其熱傳性能的表現。當有效孔徑約為4μm，孔隙度75%與滲透度為3×10^-12m^2的脫脂毛細結構置入迴路式熱管時，在容許溫度90℃與熱沉溫度40℃下，其最高熱傳量可達150W，熱阻為0.27℃/W。實驗結果顯示：脫脂毛細結構比起鬆粉毛細結構的熱傳性能約可增加40%。

關鍵字

迴路式熱管 ； 毛細結構 ； 脫脂 ； 黏結劑

並列摘要

This study reports the investigation of the heat transport capacity enhancement in miniature loop heat pipe (mini-LHP).First, the theoretical analysis about dry-out limits of wick structures has been performed. According as the result of the theoretical analysis is to show that, optimum values of heat transport capability occur due to the influence of the effective capillary radius of curvature and porosity on both capillary pressure and permeability values. Besides, porosity is the most important function of the effective capillary radius of curvature and permeability values. According to the above-mentioned result, open pores have been chosen to discuss principally in the study.
In the experiment, sintered nickel wick structures produced by debinding and pressuring process have been used in order to control the effective capillary radius of curvature and obtain higher capillary pressure. On the other hand, because of open pores produced by debinding process the permeability values can be increased. The maximum heat transport capability will improve on the basis of the foregoing two advantages. The binder system composed of polypropylene, paraffin wax, and stearic acid has been chosen to be the sacrificial layer in the study. Based on the properties of the binders, the binders are heated and uniformly mixed with nickel powders. The binders adhered to nickel powders. The binder system can be removed in order to form more open pores by chemical and heating ways.
After debindering stages of the wick structure, the wick structures will be applied to LHP and measured the performances of heat transport capability. Wick structure produced by debinding process with the porosity about 75%, the mean pore size lies in 4μm and the permeability of 3×10^-12m^2is installed into a LHP system. The maximum heat transport capability of present LHP system approaches 150W, and the thermal resistance is 0.27℃/W when the performance test is conducted under the operating temperature of 90℃ and the heat sink temperature of 40℃. The testing results show that, debinding wick structures are better in heat transport capability than only loose powder sintering wick structures because this method can increase 40% in heat transport capability.

並列關鍵字

loop heat pipe ； wick structure ； debinding ； binder

參考文獻

王鵬凱，“應用於迴路式熱管高分子毛細結構之製造研究”，國立台灣大學碩士論文，2004.

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