Heat transfer performance of finned-tube thermoacoustic heat exchangers in oscillatory flow

Heat exchangers are some of the most important parts in thermoacoustic devices. However, the lack of fundamental knowledge of the heat transfer in oscillatory flow causes difficulties in the design of thermoacoustic heat exchangers. In an oscillatory flow condition, the flow and temperature fields can be quite complex and will significantly affect heat transfer behaviour. Thus one cannot directly apply the conventional steady flow theory to deal with the design of heat exchangers working in oscillatory flow conditions. The aim of current work is to study the heat transfer performance of finned-tube heat exchangers experimentally in an oscillating flow field. The measurements to investigate the heat transfer performance of the selected heat exchangers in a range of operating conditions are carried out. The uncertainties associated with all the measured data are also considered. The relevant parameters considered in this experiment are fin interspacing, fin length, thermal penetration depth, gas displacement amplitude and the temperature difference between the inlet temperature of hot and cold heat exchanger. These parameters are formed into non-dimensional parameters such as ratio of fin spacing to thermal penetration depth or displacement amplitude to fin length. The effects of such dimensionless parameters on heat transfer are presented and discussed.