Rotex heat pump

Enhancement techniques may be conveniently divided into two classes - passive methods and active techniques. Extended surfaces which require no direct application of external power fall within the passive category. Rotation (as used in the Rotex heat pump initially mentioned in Chapter 1) is an active technique, as obviously energy is needed to rotate the device. Additionally, each technique may be applicable to one or more modes of heat transfer (e.g. forced convection, boiling, condensation, etc.) and compound enhancement - the use of more than one technique on a single heat exchanger - is practised. 

In this final applications chapter, we have examined a number of applications where PI has been applied. Some, such as the Rotex heat pump, have arisen out of the work of chemical engineers and others have been spawned out of electronics or propulsion technologies. The message from aU of the examples is that technology transfer can be extremely valuable and an appreciation of a broad range of engineering fields is essential if the full potential of PI is to be exploited. 

SWEP is a manufacturer of highly compact plate heat exchangers, including specialised units it supplied to the Rotex heat pump. 

A high-intensity heat pump, called Rotex, has been developed taking advantage of the enhanced heat and mass transfer performance of rotating discs (44). This single device carries out the processes of evaporation, condensation, absorption, and heat transfer to a working fluid. 

Figure 1.6 The Rotex absorption cycle heat pump. 

Another point worth making here, illustrated later in the chapter, is the time between concept and practical application of some intensified units - although the area of application may be one in which progress is seen to be made very rapidly by consumers. The Rotex absorption heat pump/chiller is a case in point and is an object lesson in patience. The chapter concludes with our third Key Table, summarising PI applications. 

Both absorption and adsorption are inhibited in their intensification potential by heat and mass transfer limitations. The method applied in Rotex above has been successful in intensifying the absorption cycle, but the adsorption refiigerator or heat pump uses a solid and a gas as working media and active enhancement of the solid can be difficult. 

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