PLIF measurement of the time-resolved temperature field distribution around the fins of a thermoacoustic heat exchanger in oscillatory flow

In thermoacoustic devices, two heat exchangers ("hot" and "cold") impose a temperature gradient within the " regenerator" or "stack", where the thermoacoustic effect takes place. Unfortunately, heat transfer characteristics of the heat exchangers in an acoustically induced oscillatory flow are not very well understood. Most handbook data are for heat exchangers in steady flow, few relevant experiments and calculations have been done for heat exchangers in oscillating flow. This paper investigates the temperature field around fins of a pair of model heat exchangers in the oscillatory flow, using acetone-based Planar Laser Induced Fluorescence (PLIF). The hot and cold heat exchanger fins are kept at constant temperatures by virtue of resistive heating and water cooling, respectively. The temperature field distributions for the whole acoustic cycle have been achieved. The time-dependent local convection heat transfer coefficients are also estimated from the temperature gradients in the thermal boundary layer.