Environmental Engineering Reference
effectiveness of heat pipe heat exchanger is calculated and compared with the experimental
Numerous investigations have been made to obtain the thermal performance, ensure
efficient and reliable operation of heat pipe heat exchangers [13-17]. Soleymez 
presented a thermoeconomic optimization analysis is presented yielding a simple algebraic
formula for estimating the optimum HPHE effectiveness for energy recovery applications.
Lin et al  also carried out a thermal model for simulating the performance of a heat pipe
system for recovering waste heat in the drying cycle in a domestic appliance. Noie 
presented experimental and theoretical research carried out to investigate the thermal
performance of an air-to-air thermosyphon heat exchanger. Many factors affect the thermal
performance of thermosyphon heat exchangers including velocity and temperature of input
air, type and filling ratio of the working fluid, and pipe material. Several experiments were
carried out under different operating conditions by varying the parameters in order to
determine and investigate their effect on the thermal performance of the thermosyphon heat
The heat pipe recuperator is a super-conducting device comprising of an array of tubes,
each of which is sealed at both ends. These tubes are the actual heat pipes. Each heat pipe
consists of an envelope (the tube), a wick, and a working fluid.
Heat applied to one end evaporates the working fluid from the wick, the vapour flows to
the cold end of the tube where it is condensed and returned by the wick to the hot end for re-
evaporation, thus completing the cycle.
The heat pipe device is arranged over a metal bank bench. The following photograph
(Figure 6) shows the heat pipe system and its set-up. The heat pipe exchanger built only
recovers sensible heat from the airstreams expelled outdoors.
Figure 6. The HP device.