30 May 2005

DESIGN ANALYSIS OF A FINNED TUBE HEAT EXCHANGER FOR AN AIR-TO-WATER REVERSIBLE HEAT PUMP WORKING WITH PROPANE (R290) AS REFRIGERANT


The finned tube heat exchanger “coil” is widely used in refrigeration, air conditioners and heat pump
applications. In this study, a statistical method together with a simulation model were employed to analyze the
effects of several coil geometry factors on the performance (COP) of an air-to-water reversible heat pump in
both modes of operation. The main aim of this investigation is to find a coil design that improves the efficiency
of a heat pump working with R290 as refrigerant. As a result, it was found that certain relation exists between
the number of circuits and tube diameter for which are possible to obtain the maximum COP in heating or
cooling mode. In heating mode (coil as the evaporator), the combination of 9 circuits and tube diameter of 8.9
mm gives a maximum COP of 3.74 along with a pressure drop of 25.2kPa. For the coil acting as a condenser in
cooling mode, the optimum COP is obtained with 6 circuits and tube ID of 6.5 mm. This design yields a 5%
increase in the COP with a reduction of 49% and 27% in the refrigerant volume and total area with regard to
the baseline design configuration, respectively.