Plate heat exchangers；Heat recovery；Heat transfer enhancement; Computational Fluid Dynamics (CFD)
Du to scarce conventional energy resources, energy consumptions in the buildings occupied a large proportion of the overall energy consumptions. Therefore, many researchers pay more attentions to energy conservation in the buildings, including the heat recovery of air ventilation systems. Previous studies investigated the application of the plate heat exchangers in the heat recovery of air ventilation systems. The objective of this paper is to offer new methods to improve the thermal performance of heat recovery system and provide a guidance for the optimization design of a novel plate heat exchanger. This paper firstly compared the relevant results of numerical simulations with previous experimental results and verified the validation of the numerical simulations. Then, this paper used the Computational Fluid Dynamics (CFD) method to investigate the heat transfer characteristics and the pressure drop as well as the flow distributions in plate heat exchangers with two different corrugated surfaces (triangular and trapezoidal) and different heights of the channel spacing. In the paper, the numerical studies were carried out at a uniform wall heat flux, 580W/m2, for air as the working fluid. The Reynolds (Re) number varied from 500 to 2500 under three different channel heights and corrugated surfaces. The numerical results showed that, corrugated surfaces not only had a significant positive impact on heat transfer enhancement, but also led to an increase in the pressure drop through the channel. It can be seen that the effects of the corrugation patterns on the heat transfer and pressure drop were various for different channels with different Re numbers. In addition, the comparisons of comprehensive heat transfer factors identified that when the height of the channel spacing is larger, it is more appropriate to choose a triangular corrugated channel at a lower Re number. However, at a higher Re number, selecting the trapezoidal corrugated channel may be more suitable. Based on this study, it can be found that the plate heat exchangers with corrugated surfaces are of high efficiency and compactness. Therefore, a large amount of energy can be saved by using corrugated plate heat exchangers to recover heat.