Experimental study on the heat recovery characteristic of a plate heat pipe heat exchanger in room ventilation

A plate heat pipe heat exchanger for use in a room ventilation system to cool or heat outdoor fresh air was designed in this study. One fresh air duct and one exhaust air duct were joined with the heat pipe heat exchanger to study the thermal performance of the thermal recovery system. A ratio of 1 for air volume flow rate between fresh and exhaust air was used to investigate the heat recovery effectiveness and the change in fresh air temperature. The fresh air temperature in the inlet duct was controlled in the range of 27 to 40 degrees C under summer simulation conditions and in the range of 2 to 15 degrees C under winter simulation conditions, whereas the temperature of exhaust air was controlled at approximately 24 and 18C to simulate summer and winter conditions, respectively. The experimental results show that the temperature variations of fresh and exhaust air increase with increasing inlet fresh air temperature under summer conditions but decrease with increasing inlet temperature of fresh air under winter conditions. The maximum heat recovery effectiveness of the plate heat pipe heat exchanger was 58% in summer and 62% in winter. The change in effectiveness is moderate with different vacuum levels. At a vacuum of 1 x 10(-3) Pa, the maximum effectiveness occurred when the filling ratio was 1:3. The experimental results showed that the heat pipe heat exchanger gained a high efficiency of heat recovery with low flow resistance. The energy conservation effect of this heat-pipe heat exchanger was evident.