Thermal-hydraulic design of fan-supplied tube-fin condensers for refrigeration cassettes aimed at minimum entropy generation

The method of minimum entropy generation is used to assess the effects of several design parameters on the performance of fan-supplied tube-fin condensers for light commercial refrigeration applications (heat transfer duty ∼1 kW). A simplified mathematical model is put forward to simulate the thermal-hydraulic behavior of the condenser, and validated against experimental data obtained elsewhere, showing a good agreement between calculated and measured counterparts. The dimensionless rate of entropy generation due to heat flow across nonzero temperature difference and to viscous fluid flow is calculated for different condenser designs (number of fins and tubes, tube spacing and outer diameter) at fixed operating conditions (heat transfer duty, flow rates, inlet temperatures). It is shown that there do exist optima values for the face velocity, fin density, tube diameter and heat exchanger effectiveness that minimize the production of entropy, so that some design guidelines are proposed.