Experimental Study of Heat and Mass Transfer Performance of Annular Elliptic Finned Tube Evaporative Condenser

This study introduces an annular elliptical finned-tube evaporative condenser. The heat and mass transfer performance and operation characteristics of the evaporative condenser under different circulating water ratios, different regional environments, and four different operating modes are determined by the experimental system of the evaporative condenser, in which the air-cooled, water-cooled, evaporative-cooled, and full working modes are studied. The results show that the heat flux of the "full working" mode is higher than that of the "air-cooled" and "evaporative-cooled" modes under the same conditions; the "water-cooled" mode has the highest heat flux because its heat transfer area is much smaller than that of other modes. Under the "full working" mode with a fixed air volumetric flow rate and the total amount of circulating water, the heat flux increases first and then decreases with the increase in the water circulating ratio, where the best flow rate ratio between spray water and cooling water is 2∶5. The total heat flux of the "full working" mode in dry cold areas, cold areas, and hot summer and warm winter areas is 5879.64 W/m², 3964.28 W/m², and 2933.05 W/m², respectively. Hence, the heat transfer performance of the "full working" mode varies significantly in different regions, and the "full working" mode of the condenser has better heat transfer performance when the spray and cooling water temperature ranges from 13 to 18 ℃. Under the same conditions, the mass transfer coefficient of the water film in the "evaporative-cooled" mode is higher than that in the "full working" mode, which of both modes increases and then decreases with the increase of the spray density.