The heat pipe heat exchanger: a review of its status and its potential for coolness recovery in tropical buildings

The heat pipe heat exchanger (HPHX) is a proven device for heat recovery in HVAC systems, and competes effectively with other available systems such as heat recovery wheels and run-around coils. This paper reviews major research work done on heat pipe heat exchangers (HPHXs) installed in HVAC systems since 1970. It reveals that research work on HPHXs for HVAC heat and coolness recovery has been done mostly in North America, Britain and Australia. Literature reviews further reveal that only limited research work on HPHXs for HVAC heat and coolness recovery has been conducted in subtropical and tropical climates and therefore, more HPHX research work for HVAC applications should be carried out in these regions in the interests of energy conservation and global green environment strategies. Practical applications: The review on recover heat or coolness in HVAC systems since 1970 described in this paper enables necessarily good understanding on recover heat or coolness technologies for the impact of energy consumption and dehumidification in buildings before actual research or retrofitting is conducted to the space's conditioning system. The results obtained from a considerable number of research work in subtropical and tropical climates could serve as a preliminary guide for mechanical and electrical (M&E) engineers and researchers who are intending to apply heat pipe heat exchangers as 'coolness' recovery and dehumidification devices in HVAC systems operating in tropical countries.