The heat pipe heat exchangers are used in heat recovery applications to cool the incoming fresh air in air conditioning applications.
Two streams of fresh and return air have been connected with heat pipe heat exchanger to investigate the thermal performance and effectiveness
of heat recovery system. Ratios of mass flow rate between return and fresh air of 1, 1.5 and 2.3 have been adapted to validate the
heat transfer and the temperature change of fresh air. Fresh air inlet temperature of 32–40 C has been controlled, while the inlet return
air temperature is kept constant at about 26 C. The results showed that the temperature changes of fresh and return air are increased
with the increase of inlet temperature of fresh air. The effectiveness and heat transfer for both evaporator and condenser sections are also
increased to about 48%, when the inlet fresh air temperature is increased to 40 C. The effect of mass flow rate ratio on effectiveness is
positive for evaporator side and negative for condenser side. The enthalpy ratio between the heat recovery and conventional air mixing is
increased to about 85% with increasing fresh air inlet temperature. The optimum effectiveness of heat pipe heat exchanger is estimated
and compared with the present experimental data. The results showed that the effectiveness is close to the optimum effectiveness at fresh
air inlet temperature near the fluid operating temperature of heat pipes.