Iranian Journal of Mechanical Engineering Transactions of ISME

Iranian Journal of Mechanical Engineering Transactions of ISME

Experimental study of dehumidification of humid air over a finned tube by free convection

Authors
Kamran Hirbodi
Mahmood Yaghoobi
Abstract
In this study, dehumidification of humid air over a horizontal annular finned-tube by free convection for various relative humidities is investigated experimentally. The finned-tube is placed in an isolated test room in order to perform pure natural convection. The test room ambient air temperature and relative humidity are controlled by air cooling and heating cycles and humidifying system. Measurements are carried out for an annular finned-tube with outer tube diameter 25.4 mm, fin thickness 0.4 mm, fin outer diameter 56.0 mm, and fin density 11 FPI (433 FPM). For experimental measurements, ambient air and fin base temperature are taken 30°C and 8°C, respectively and relative humidity is changed from 25% to 70%. All measurements are made from beginning of cooling until steady state condition approached. For each test, flow structure, heat transfer and condensation rate are discussed. It is found that condensation rate, drop coalescence, and heat transfer rate depend mainly on the relative humidity. When relative humidity increases, heat and mass transfer rate are increased.
Also, natural dehumidification shows that the drops form mainly on the tip of the fins and no condensation is observed between the fins which is mainly due to small fin spacing and no air movement between the fins.
Keywords
Natural convection
Dehumidification
Relative humidity
Finned tube
condensation
Dew point
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Iranian Journal of Mechanical Engineering Transactions of ISME
Volume 15, Issue 2 - Serial Number 31
Fluid Mechanics and Heat Transfer
Summer 2013
Pages 62-77

  • Receive Date 23 August 2013