Experimental and numerical analysis of heat transfer in a dimple pattern heat exchanger channel

Abstract

In contrast to the predominant herringbone shape of heat plates, a microplate heat exchanger has an array of relatively small dimples. Its number and shape define the characteristics of such a plate heat exchanger. Literature, however, of the flow characteristics in such kinds of channels is scarce. Precise knowledge of the flow specifics in such a channel is of key importance to develop efficient new products. Single-phase water flow and heat transfer in microplate heat exchanger was investigated with the laboratory experiments and use of computational fluid dynamics simulations. A novel and innovative laboratory experiment was developed where flow characteristics and heat transfer in the microplate heat exchanger were measured. Experimental results were directly used as boundary conditions in numerical simulations. With this approach a direct validation of the results of numerical simulations were obtained. Heat transfer simulations were performed with three turbulence models: k- ε, k-ω SST and the Reynolds stress model. The most reliable results in heat transfer analysis were obtained using the Reynolds stress model where results are on average 7.05% lower compared to the results of the laboratory experiment. When all experimental uncertainty contributions were analysed, the simulation results were in the band between − 11% and 1.8% compared to the results of the laboratory experiment. Numerical simulations show that the heat transfer coefficient in the channel is proportional to Re0.64 in the analysed geometry of a microplate heat exchanger. The heat transfer coefficient was calculated and was between 9740 and 21990 W/m2K at Reynolds numbers 1170 and 4170 respectively.