An experimental and analytical investigation of thermoacoustic convection heat transfer in gravity and zero-gravity environments

An experimental and analytical study of Thermoacoustic Convection heat transfer in gravity and zero-gravity environments is presented. The experimental apparatus consisted of a cylinder containing air as a fluid. The side wall of the cylinder was insulated while the bottom wall was allowed to remain at the ambient temperature. The enclosed air was rapidly heated by the top surface which consisted of a thin stainless steel foil connected to a battery pack as the power source. Thermocouples were used to measure the transient temperature of the air on the axis of the cylinder. The ouput of the thermocouples was displayed on digital thermometers and the temperature displays were recorded on film using a high-speed movie camera. Temperature measurements were obtained in the zero-gravity environment by dropping the apparatus in the 2-Seconds Zero-Gravity Drop Tower Facilities of NASA Lewis Research Center. In addition, experiments were also performed in the gravity environment and the results are compared in detail with those obtained under zero-gravity conditions

HEAT EXCHANGE AND CONDENSATION IN REDUCED GRAVITY

ABSTRACT The present investigation was sponsored by the NASA Reduced Gravity Student Flight Opportunity Program and was conducted by the University of Tennessee students aboard KC-135 in parabolic flights. The goal of the experiment was to study saturated air-water mixture to simulate the dynamics of condensation and heat exchange in two-phase flows and gain a better understanding of condensation under reduced gravity condition. In the experimental apparatus saturate air/water mixture is pumped through a one-inch cooled horizontal test pipe (condenser). Sets of thermocouples record change of temperature of liquid water, temperature of saturated air across the condenser, and temperature of liquid and fog after the test section. The water temperature measurements indicate lower water temperature and larger exit fog temperature at the condenser exit under reduced gravity as compared with normal gravity results. It was also observed that for relatively small water flow rate and velocity heat exchange between air and water streams was larger for reduced gravity conditions relative to normal gravity conditions