Research has been carried out on the theory, design and construction of heat pipes, especially their use in heat pipe heat exchangers for energy recovery, reduction of air pollution and environmental conservation. A heat pipe heat exchanger has been designed and constructed for heat recovery in hospital and laboratories, where the air must be changed up to 40 times per hour. In this research, the characteristic design and heat transfer limitations of single heat pipes for three types of wick and three working ¯uids have been investigated, initially through computer simulation. Construction of heat pipes, including washing, inserting the wick, creating the vacuum, injecting the ¯uid and installation have also been carried out. After obtaining the appropriate heat ¯ux, the air-to-air heat pipe heat exchanger was designed, constructed and tested under low temperature (15±558C) operating conditions, using methanol as the working ¯uid. Experimental results for absorbed heat by the evaporator section are very close to the heat transfer rate obtained from computer simulation. Considering the fact that this is one of the ®rst practical applications of heat pipe heat exchangers, it has given informative results and paved the way for further research. 7 2000 Elsevier Science Ltd. All rights reserved.

Keywords