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Design and experiment on artificial radiation-frost chamber based on temperature difference between leaves and air dew point
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: 2018 ASABE Annual International Meeting 1800331.(doi:10.13031/aim.201800331)
Authors: Yongzong Lu, Yongguang Hu, Jintao Tian, Huan Song, Richard L. Synder
Keywords: Frost; Frost formation; Radiation-frost chamber; Leaf-air temperature difference; CFD simulation
Abstract. Radiation frost occurs frequently in the early spring during calm and clear nights which causes huge damage on crops, leading to quality reduction and huge economic losses for the growers. Frost factors are difficult to be controlled in field experiment due to complexity and variability of agro-micrometeorological environment. This research was focused on designing an artificial radiation frost chamber to serve the frost-related research. The micro-meteorological data and frost formation processing during the typical radiation frost night were monitored and analyzed. Radiation frost chamber model and main parameters were confirmed to conduct the CFD simulation on leaf-air temperature difference. The radiation cooling system including heat load calculation, thermodynamics calculation and cooling unit were finished. Frost forming experiment was conducted to test the performance of the chamber. Observation results showed that biggest temperature difference was -2.3 ℃ and the de-sublimation speed of air vapor was higher than sublimation which caused the frost could easily form on the leaf. CFD simulation results showed that 40W heating power and -40℃ radiation sink was better applied in the chamber. Calculation of heat load was 189W and the compressor type was PH60G0C (rated power is 345 W, cooling ability is 985 W and COP is 2.86), Heat transfer area of fin and tube is 2.0 m2.Testing results showed that leaf temperature slowed down after a rapid decrease which is similar to the natural condition, and the frost formation on the leaf is obvious.
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