Abstract:

Flat finned tube bundle is the basic radiating element of direct air-cooling system in thermal plant, so the study on its structure feature, flow and heat transfer property has important significance to the optimization design and efficient operation of air-cooling system in power plant. Taking the typical continuous serpentine fin flat tubes of direct air-cooling system as examples, this paper studied the impact of different fin spacings on the flow and heat transfer property of the cooling air and the changes of fins heat transfer performance under vertical and tilt flow conditions. The result shows that the heat transfer coefficient of fin grows up with the decrease of its spacing at the constant wind speed, while its resistance coefficient varies complexly. Under the experimental conditions, the flat tube with fin spacing of 56.8 mm has the best property. When the fin spacing is constant, with the growth of wind speed, the heat transfer coefficient increases and the resistance coefficient decreases gradually. However, the trends become gentle at high wind speed. The research results can provide basic datas for the further optimization of the structure of continuous flat tube fin.

Key words: direct air-cooling, serpentine fin flat tube, fin spacing, flow and heat transfer