Effect of Air Gap on thermohydraulic performance of finned tube bundles

Abstract

The air gap between the consecutive tube bundle row fins is one of the most important parameters that have not been evaluated in terms of their impact on the performance of air-cooled condensers. In this paper, the effect of this air gap on the thermo-hydraulic performance of the tube bundle air-side flow is investigated. The importance of this parameter lies in the fact that it can change the heat transfer coefficient and pressure drop in the tube bundle air-side flow. Moreover, changing the air gap will vary the overall length of the condenser and the dimensions of the main cooling system and consequently imposes a change in the costs of construction and operation. In this study, the effect of inlet air velocity on fin and ambient functioning temperature conditions is investigated at various air gaps on the thermo-hydraulic performance of the tube bundle air-side flow. The results indicate that the air gap for the proper thermo-hydraulic performance of the tube bundle air-side flow is independent of the air inlet velocity of the tube bundle and the ambient temperature conditions of the power plant. Moreover, it was found that the tube bundle air-side flow at a 1-mm air gap will have better thermo-hydraulic performance. The behavior of tube bundle air-side flow of the condenser of a 484 MW power plant was also studied. The results indicated that the tube bundle air-side flow at this state will also have better performance at a 1-mm air gap such that the overall length of the condenser in this state will increase by 1.7% compared to the state where the air gap is zero