A simplified model of heat transfer in heat exchangers and stack plates of thermoacoustic refrigerators

A simplified model of heat transfer was developed to investigate the thermal behavior of heat exchangers and stack plates of thermoacoustic devices. The model took advantage of previous results describing the thermal behavior of the thermoacoustic core and heat transfer in oscillating flow to study the performance of heat exchangers attached to the core. The configuration considered is a flat tube (with a working fluid flowing in the tube) of the thickness of the stack plate attached to both ends of the stack plate. Geometrical and operational parameters as well as thermophysical properties of the heat exchangers, transport fluids in the heat exchangers, stack plate and the thermoacoustic working fluid were organized into dimensionless groups that allowed accounting for their impact on the performance of the heat exchangers. Two types of thermal boundary conditions were considered: constant temperature and constant heat flux along the heat exchanger tubes. Numerical simulations were carried out with the model introduced in the paper. The temperature distributions and heat fluxes near the edge of the stack plate were found to be nonlinear. The influence of system parameters on the thermal performance of the heat exchangers was analyzed.