热声热机换热器的基本换热特性研究

Study on Heat Transfer Characteristic of Thermoacoustic Heat Exchanger

基于弱非线性热声理论,对热声换热器的基本换热特性进行了理论分析。在前人研究基础上,增加了换热器内纵向温度梯度的影响,获得了二阶周期平均热流的解析表达式,并定义了适合表征热声换热器换热特征的无量纲换热量。计算分析了无量纲参数声导率Ya,对流与压缩性比Γ,动态雷诺数Re_w对换热器时均换热量的影响。分析表明,换热器产生时均吸热还是时均放热特性主要由临界声导率幅值央定,存在时均纵向温度梯度时,还取决于Re_w;声导率的相位角对时均热流的影响相对较小,但其影响会随着|Γ|和|Ya|的增大而增大;|Γ|的存在增强了换热;存在临界的Re_w值使得二阶周期平均热流取得极值。本文所定义的无量纲换热量能合理表征换热器换热特性,对热声换热器基本换热特征的研究将为进一步考察其实际复杂工作机理提供理论指导。

Based on the weakly nonlinear theory of thermoacoustic energy conversion, the basic heat transfer characteristics of thermoacoustic heat exchanger are analyzed in this paper. Mean time longitudinal temperature gradient is considered. A nondimensional heat flux is defined and it’s mainly influenced by parameters such as dynamic Reynolds number Reω, acoustic admittance Ya, and the temperature ratio Γ. The analytical expressions show that there exists a critical acoustic admittance making the heat flux being zero. And the existence of ｜Г｜ enhanced heat transfer. This work can improve the understanding of heat transfer in oscillating flow and can be useful for intensive study of practical thermoacoustic heat exchangers.