PREVENTION OF WATER FREEZING BY AIR FLOW COOLING IN A CLOSED TUBE WITH HEATING
This paper is concerned with prevention of freezing of water in a closed vertical tube by using a tube heating and adiabatic material. The tube is cooled by air flow in a long duct of the length Hs which is three times of the duct height Hy (i.e., Hx = 3Hy). The parameters in this study are air flow-inlet velocity ua = 1 − 30 m/s, -inlet temperature Ta = −10°C and initial water temperature Tini = 8°C. The heat supply Qnf to prevent freezing safely needs much more heat compared with the heat QTh0 estimated by mean heat transfer coefficient in steady state. The rate of the heat, Qnf/QTh0(= n), increases with decrease of ua. An adiabatic material (expanded polystyrene) is useful to prevent freezing compared with bare tube without the material. However, freezing enhances with increase in the material’s thickness unexpectedly. Therefore, it is better to use the material of thin thickness, which is useful economically to design the heater of tubes.
prevention of freezing, tube heating, adiabatic material, numerical, solution.
Received: September 2, 2020; Accepted: December 6, 2020; Published: January 22, 2021
How to cite this article: M. Sugawara and M. Tago, Prevention of water freezing by air flow cooling in a closed tube with heating, JP Journal of Heat and Mass Transfer 22(1) (2021), 55-72. DOI: 10.17654/HM022010055
This Open Access Article is Licensed under Creative Commons Attribution 4.0 International License
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