相变面积对平行环路热管性能影响的研究

Effect of phase change area on the performance of parallel loop heat pipe

中文关键词: 倾斜管 相变面积 热管性能 传热系数

英文关键词: Tilt tube,phase change area,heat pipe performance,heat transfer coefficient

中文摘要:

      重力型环路热管作为一种高效的相变传热装置，其性能与运行时换热器的充注量及换热器倾斜角度密切相关。为了更深入研究在运行时充注量变化所引起的蒸发器、冷凝器实际相变换热面积的变化与换热器换热量、传热系数之间的关系，设计了一种蒸发器与冷凝器平行放置的新型热管系统。研究了在实际运行时相变实际换热面积与热管性能的关系。分析实验结果表明：蒸发器在固定角度下相变实际有效面积与换热量的函数关系呈单波峰，其波峰随着倾斜角的增加而向浸湿面积变小的方向移动。倾斜角度越大达到最佳换热效果所需的换热面积越小，但最大换热强度会减小。在热管进口温差固定时，倾斜角度大于45°才能较为有效的通过提升进口温度来提升换热量。在蒸发器未被完全浸润时，冷凝器换热量处于下降阶段，可以增加冷凝器管长来提升换热。在蒸发器被完全浸润时，增加冷凝器管长无法提升换热。蒸发器与冷凝器的传热系数与相变有效换热面积成线性下降关系，下降速率与角度近乎无关。

英文摘要:

      Gravity loop heat pipe is a device that transfers heat efficiently.It’s performance is related to the charge rate and tilt angle of the heat exchanger during operation.This paper designs a new type of heat pipe system in which the evaporator and the condenser are placed in parallel.The purpose of the design is to in-depth study the relationship between the heat transfer performance of the heat pipe , the heat transfer coefficient and the heat transfer area of the evaporator and the condenser.The experimental results are as follows:At a fixed angle, the actual effective area of the evaporator has a single peak as a function of the amount of heat exchange, and the peak moves to the direction where the wetted area becomes smaller as the tilt angle increases.The larger the tilt angle, the smaller the heat exchange area required to achieve the best heat exchange effect, but the maximum heat exchange intensity will decrease.When the temperature difference at the inlet of the heat pipe is fixed, the inclination angle is greater than 45°to effectively increase the heat exchange by increasing the inlet temperature.When the evaporator is not completely infiltrated, the performance of the condenser is in a poor stage.The condenser tube length can be increased to improve heat transfer.When the evaporator is completely wetted, increasing the condenser tube length cannot improve heat transfer.The heat transfer coefficient of the evaporator and the condenser decreases linearly with the effective heat transfer area of the phase change, and the rate of decrease is almost independent of the angle.