热声发动机热缓冲管损失的实验研究

Experimental Investigation on the Heat Loss in the Thermal Buffer Tube of the Thermoacoustic Heat Engine

热缓冲管是热声发动机的关键部件之一,位于高温换热器和次室温换热器之间,理想情况下可避免在高温换热器附近往复运动的气体接触室温环境,造成热量损失。不过由于换热器流道的特殊结构,使热缓冲管两端会产生射流等现象,带来流动紊乱、热量损失等问题。本文设计并搭建了研究热缓冲管损失的实验平台,主要考查在热缓冲管两端分别添加不同层流化丝网对系统性能的影响。实验结果表明,未添加层流化丝网会使热量损失急剧增大,热声效率大幅下降;而过多添加层流化丝网会使阻力损失增大,同样降低热声效率;当两端分别添加3片层流化丝网时,所需加热量最少,热声转换效率最高。

The thermal buffer tube sandwiched between the hot and the secondary ambient temperature heat exchangers is the key component of the thermoacoustic heat engine.It can isolate the hot region from the room temperature to prevent other components from working within a hot environment.However,due to the structural characteristic of the heat exchangers,a complicate flow state caused by oscillating jet-flow in the thermal buffer tube will appear and result in a high heating power loss.In this paper,a test rig is built to experimentally investigate the heat loss of the thermal buffer tube under different acoustic field condition.Our experimental results indicate that the heat losses are very large and can greatly decrease the system efficiency when the flow straightener is not used at the two ends of the thermal buffer tube.In addition,more screens will dissipate more acoustic work.When three pieces of screens are used at both ends,the heating power is the least and the thermoacoustic efficiency is the highest.