Numerical investigation of small plate heat exchangers performance having different surface profiles

Abstract

In the present study, the numerical investigation of single-phase and steady-state water flow in a small-sized plate heat exchanger with a chevron type corrugation pattern, is performed in three-dimensional. For validating the numerical modeling, an empirical model of a commercial PHE is designed and a good agreement between the results of experimental tests and numerical modeling is obtained. Moreover, the influence of flow regime (150 < Re 〈550), as well as geometrical parameters of chevron angle (β), corrugation depth (b), and corrugation pitch (λ) on the performance of the PHE are evaluated. In all corrugation depths and corrugation pitches, the maximum Nu-number and friction coefficient occur at β=60° and β=30°, respectively. Considering the simultaneous effect of heat transfer and friction, the JF factor is defined. The reducing trends of heat transfer and the increasing trends of friction are inferred by decreasing Re-number; however, the JF factor is increased. Besides, β=60° is the most favorable case from the performance point of view due to the formation of different flows. In this case, the JF factor increases compared to the other chevron angles. On the other hand, the increasing behavior of this factor is observed with increasing corrugation depth (b), which is 55% at β=60° and λ = 8.3 mm compared to the commercial PHE. The decrease in the corrugation pitch (λ) also has a similar effect on the JF factor and increases it by 40% at β=60° and b = 2.3 mm compared to the commercial PHE. In general, it is inferred that the superior performance of the small-sized PHEs is associated with the decreased mass flow rate, the chevron angle of 60°, and the increased bλ ratio. By increasing the corrugation depth or decrementing the corrugation pitch, the weight and volume of the PHE showed an enhancement. In small PHEs, however, this weight and volume gain versus performance improvement can be ignored. It is recommended to reduce the corrugation pitch rather than increasing its depth as a decline in corrugation pitch does not enhance the volume of the small PHE.