Condensation in a steady-flow thermoacoustic refrigerator

Condensation may occur in an open-flow thermoacoustic cooler with stack tem peratures below the saturation temperature of the flowing gas. In the exper imental device described here the flowing gas, which is also the acoustic m edium, is humid air, so the device acts as a flow-through dehumidifier. The humid air stream flows through an acoustic resonator. Sound energy generat ed by electrodynamic drivers produces a high-amplitude standing wave inside of the resonator, which causes cooling on a thermoacoustic stack. Condensa tion of water occurs as the humid air passes through the stack and is coole d below its dew point, with the condensate appearing on the walls of the st ack. The dry, cool air passes out of the resonator, while the condensate is wicked away from the end of the stack. Thermoacoustic heat pumping is stro ngly affected by the form of the condensate inside of the stack, whether co ndensed mostly on the stack plates, or largely in the form of droplets in t he gas stream. Two simple models of the effect of the condensate are matche d to a measured stack temperature profile; the results suggest that the the rmoacoustic effect of droplets inside the stack is small. (C) 2000 Acoustic al Society of America. [S0001-4966(00)02210-4].