Experimental study on the effect of oil-based coating on the growth of frost layer
The influence of oily coatings on the growth of frost layer was studied by experiments.The frost growth character-istics of three types of coating surface,namely guide rail oil,anti-rust oil,and industrial semi-solid butter,were compared with those of oil-free surface.The changes in frost height and quality at different times were obtained,and the effects of butter coating surface temperature and wind speed on frost growth were analyzed.The results show that all three different oil-based coatings delay the time of frost crystal formation.Under the wall temperature of-25 ℃ and no wind speed,there is no frost branch formation period on the oil-coated wall because of the large thermal resistance,and thus the frost column formation peri-od is entered instead.The sublimation frost is formed on the surface of both anti-rust oil and oil-free coatings,while the con-densation frost is formed on the surface of the guide rail oil coating.As the temperature of the cold surface decreases,the height and mass of the frost layer on the butter coating surface gradually increases.The frost height and mass on the oil-free surface are larger than those on the anti-rust oil,guide rail oil and butter coating surface,in that order.In 40 minutes,the frost height on the butter coating surface always increases with the increase of the wind speed when it is less than 3.9 m/s.The increase of the wind speed will shorten the time of the sustained increase of the frost height when the wind speed is greater than 3.9 m/s.
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万方数据
