Objective:A surface evaporation concentration device were designed to concentrate thermosensitive feed liquid at low temperature under normal pressure with low energy consumption.Methods:Based on an introduction to the working principle of the device,the basic equations of the device were given.The changes of volumetric evaporation flux and energy saving ratio with flow rate of the feed liquid,feed liquid temperature,sweeping gas flow rate,sweeping gas temperature were calculated and analyzed.Designed an experimental platform and obtained a set of optimal performance parameters through experiments.Results:The results showed that when the flow rate of the feed liquid was 0.02 kg/s,the device had the highest energy saving ratio and higher volumetric evaporation flux;When the temperature of the feed liquid increased from 30 ℃ to 50 ℃,the volumetric evaporation flux increased by 224.68％,but the energy saving ratio decreased by 12.42％;When the sweeping gas flow rate increased from 0.004 kg/s to 0.006 kg/s,the volumetric evaporation flux increased by 23.45％,but the energy saving ratio decreased by 7.74％;When the temperature of the sweeping gas increased from 10 ℃ to 30 ℃,the volumetric evaporation flux decreased by 22.92％,but the energy saving ratio increased by 37.49％;An experimental device was established to test orange juice with a sugar content of 15 °Brix,the results showed that when the feed liquid temperature was 38 ℃ and the sweeping gas temperature was 26 ℃,the volumetric evaporation flux of the device could reach 219 kg/(m3·h),and the energy saving ratio could reach 3.3.Conclusion:The heat pump assisted random filler surface evaporation device has the characteristics of low temperature concentration under atmospheric pressure and low energy consumption when concentrating thermosensitive feed liquid.
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