Finned-tube heat exchanger optimization methodology

Heat exchangers play a dominant role in the performance of most energy systems; however, optimization of these components is a complex task due to the coupled nature of the design parameters involved. Anytime the heat transfer coefficient is increased in these components, there is a corresponding increase in frictional pressure drop; therefore, a delicate balance is required between these two effects in heat exchanger optimization. The finned-tube condenser heat exchangers used in residential air conditioning systems are examined in this study. Due to the intricate geometry of the finned-tube heat exchanger, there are no analytical optimization schemes available to optimize their design, while experimental trial and error is far too time consuming, considering the ten different design parameters that can be varied for optimization. This study develops a system model using available analytical and empirical correlations for the entire air conditioning cycle with great detail in the condenser component. An optimization algorithm then uses this model to find an optimum design for ten condenser design parameters using various constraints with a system COP figure of merit. The design optimization methodology is fully developed and presented in the paper so that it can be applied to other energy systems' heat exchanger optimization opportunities. The optimum condenser design was found to give the same performance as a coil optimized through a manual search costing 23% more. It is also shown that the optimum design is consistent with minimum entropy generation for the total system.