Impacts of Water Flow Rate on Freezing Prevention of Air-Cooled Heat Exchangers in Power Plants

Yonghong Guo, Huimin Wei, Xiaoru Yang, Weijia Wang, Xiaoze Du and Lijun Yang
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Yonghong Guo: Key Laboratory of Condition Monitoring and Control for Power Plant Equipments of Ministry of Education, School of Energy Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
Huimin Wei: Key Laboratory of Condition Monitoring and Control for Power Plant Equipments of Ministry of Education, School of Energy Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
Xiaoru Yang: Key Laboratory of Condition Monitoring and Control for Power Plant Equipments of Ministry of Education, School of Energy Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
Weijia Wang: Key Laboratory of Condition Monitoring and Control for Power Plant Equipments of Ministry of Education, School of Energy Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
Xiaoze Du: Key Laboratory of Condition Monitoring and Control for Power Plant Equipments of Ministry of Education, School of Energy Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
Lijun Yang: Key Laboratory of Condition Monitoring and Control for Power Plant Equipments of Ministry of Education, School of Energy Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China

Energies, 2018, vol. 11, issue 1, 1-15

Abstract: Under cold ambient conditions, the freezing risk of air-cooled heat exchangers, especially the frontal finned tube bundles, has been a critical concern in power plants. Based on the freezing conditions of the cooling deltas under windy conditions, the flow and heat transfer characteristics of natural draft dry cooling system (NDDCS) with 30%, 40% and 50% increased water flow rates are investigated in this work, and the outlet circulating water temperatures of the easily freezing cooling deltas and sectors are obtained. The results show that the deltas in the middle front and rear sectors become free from freezing at all wind speeds when the circulating water flow rate is increased. For the frontal sector with increased water flow rate, the outlet water temperatures of deltas increase conspicuously at 4 m/s and 8 m/s, while as the wind speed rises to 16 m/s, these deltas still face serious freezing risks due to the huge heat rejection to ambient air. Therefore, freezing prevention of air-cooled NDDCS heat exchangers can be achieved by increasing the water flow rates at small wind speeds, while as the wind speed becomes high, the water flow redistribution is suggested for the frontal and middle sectors due to their big performance difference.

Keywords: NDDCS air-cooled heat exchanger; cooling delta; anti-freezing; water flow rate; outlet water temperature (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
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