Experimental evaluation of heat transfer performance of falling film evaporator for wastewater source heat pump with backwash system

2020 ◽  
Vol 113 ◽  
pp. 80-93
Author(s):  
Qunli Zhang ◽  
Xinchao Zhang ◽  
Chaohui Yin ◽  
Fang Liu ◽  
Gang Wang
Keyword(s):  
Heat Transfer ◽  
Heat Pump ◽  
Experimental Evaluation ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Falling Film ◽  
Film Evaporator

Studying the Effect of Porosity of Porous Layer Coating on the Performance of the Horizontal Tubular Falling Film Evaporator

2021 ◽  
Author(s):  
Alaa Adel Ibrahim ◽  
Hassan Elgamal ◽  
Ahmed M. Nagib Elmekawy
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Numerical Simulations ◽  
Thermal Performance ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Falling Film ◽  
Film Evaporator ◽  
Porosity Ratio ◽  
Layer Coating

Abstract Through the recent decades, many studies have focused on finding efficient methods to enhance the heat transfer performance in heat exchangers. Therefore, using porous media attracted many researchers, as it is such a simple, efficient, and low-cost technique in enlarging the surface contact area of heat transfer through the fluid pass. Nevertheless, there is little work associated with using porous media to enhance the thermal performance of falling film evaporators. The present study seeks to discuss numerically the liquid flow behaviour over falling film evaporator tubes in the case of bare tubes and tubes with porous layer coating. The two-dimensional multi-phase numerical simulations are also carried out in order to investigate the effect of the porosity ratio of the porous medium added to the tubes in the heat transfer performance. Furthermore, deducing the way to select a decent porosity ratio to be used to get the best thermal performance is demonstrated through the study. Time-averaged results gained from the numerical simulations have been compared to those of bare-tube falling film evaporator to observe much higher heat transfer performance represented in the average surface Nusselt number (Nu) which increased by 3 times.

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