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Dehumidification Using Finned Tubing Condensation System

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  MBSK 10-200,  ASABE/CSBE North Central Intersectional Meeting. (doi: 10.13031/2013.36279) @2010
Authors:   Zhu Gao, Huiqing Guo, Yueming Yuan, Robert Brad
Keywords:   Dehumidification, finned tubing, condensation rate, energy efficiency

One major challenge greenhouse producers face is the high relative humidity (RH) during mild and cold seasons which result in fungus diseases and reduction in yield and quality. As one of the potential options for greenhouse dehumidification, finned tubing with cold water flowing through can condense water vapor to reduce RH. The condensation rate is unknown in the literature but is needed in order to design the dehumidification system for the greenhouses. In this study, a chilled water condensation system was designed and tested in an environmental chamber. The system used a 1.2 m long copper tubing with 0.1 m by 0.1 m aluminum fins with approximately 30 inclined angle and chilled water was supplied by a water bath located outside of the chamber. The condensation from the finned tubing was collected and weighed. Condensation rate varied with water temperature and water flow rate. Water temperature has two levels, 0C and 5C and water flow rate five levels,, 0.65, 0.85, 1.05, 1.25 and 1.45 l/s. The tests were conducted under nine chamber environment conditions, i.e., the combination of: three temperatures (16C, 20C and 24C) and three RH levels (70%, 80% and 90%). Three repetitions for each test were conducted and the average was found. The condensation rates and moisture removal efficiency (MRE) were then calculated for each treatment. The results showed that the peak condensation rate occurred when using 0C water and 0.85 l/s flow rate for most of the chamber environment conditions. The most energy efficient treatments mostly appeared at high temperature and RH conditions, which means that finned tubing chilled water dehumidification system is suitable for greenhouse dehumidification under humid warm weather conditions.

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