Zhileng xuebao (Jan 2021)
Study on the Characteristics of Air Side Heat Transfer for Finned Tube Condenser in Low-pressure Environment
Abstract
In this study, a pressure-adjustable closed environment chamber was built, and the effect of different tube rows and circulating hot water temperatures on the characteristics of air-side convective heat transfer for a finned tube condenser at a low-pressure environment of 40–101 kPa were studied. The results show that under the same Reynolds number, the reduction in ambient pressure leads to a reduction in air-side convective heat transfer. When the air-side Reynolds number is 400, the ambient pressure decreases from 101 kPa to 40 kPa, and the convective heat transfer coefficient decreases by 44.1%. As the ambient pressure decreases, the number of tubes has a weaker effect on the air-side convective heat transfer. In a low-pressure environment, changing the heating temperature of the circulating water does not have a significant impact on the heat transfer coefficient. As the ambient pressure decreases, the air-side convective heat transfer coefficient deviates from the calculation results of the normal atmospheric pressure model. As the ambient pressure decreases from 101 kPa to 40 kPa, the average deviation increases from 17.3% to 77.5%. Based on the experiment results, the air-side heat transfer model of the finned tube is modified at normal pressure according to the influence of the ambient pressure and the tube rows on the air-side convective heat transfer.
