An integrated system-level and component-level optimization of heat transfer systems based on the heat current method

Abstract

Heat transfer system (HTS) optimization is a key for energy conservation. However, optimization of the structural/operating parameters of HTSs and the geometrical structures of single heat exchangers are usually separate and independent. Based on the heat current method together with computational fluid dynamic simulation, this paper optimizes the fluid flow rates and the heat transfer areas in a HTS with prescribed plate spacing of heat exchangers to minimize the total pumping power consumption. Then, by applying the downhill simplex search algorithm, a multi-level nested strategy is developed to optimize the plate spacing of heat exchangers simultaneously. The optimized results show that when the heat transfer rate is 1300 W, the minimum total pumping power consumption is 18.42 W, the optimal heat transfer areas of each heat exchanger are 0.046, 0.076 and 0.058 m2, respectively, and the optimal plate spacing of the studied heat exchanger is 3.5 mm. Meanwhile, the multi-level collaborative optimization reduces the total power consumption by 27% comparing that regardless of plate spacing optimization. Besides, larger flow resistances of working fluids in pipeline need more compact heat exchangers with smaller plate spacing for energy conservation.