We conducted a transient experimental investigation of steam–water direct contact condensation in the absence of noncondensible gas in a laboratory-scale column with the inner diameter of 325 mm and the height of 104...We conducted a transient experimental investigation of steam–water direct contact condensation in the absence of noncondensible gas in a laboratory-scale column with the inner diameter of 325 mm and the height of 1045 mm. We applied a new analysis method for the steam state equation to analyze the molar quantity change in steam over the course of the experiment and determined the transient steam variation. We also investigated the influence of flow rates and temperatures ofcooling water on the efficiency ofsteam condensation. Our experimental results show that appropriate increasing of the cooling water flow rate can significantly accelerate the steam condensation. We achieved a rapid increase in the total volumetric heat transfer coefficient by increasing the flow rate of cooling water, which indicated a higher thermal convection between the steam and the cooling water with higher flow rates. We found that the temperature ofcooling water did not play an important role on steam condensation. This method was confirmed to be effective for rapid recovering ofsteam.展开更多
为了研究苹果片的热风干燥特性,考察了切片厚度、热风温度和装样量对苹果片热风干燥过程的影响,比较了6种数学模型在苹果片热风干燥中的适用性.结果表明:切片厚度、热风温度和装样量均对苹果片的热风干燥过程影响较大,苹果片切片厚度越...为了研究苹果片的热风干燥特性,考察了切片厚度、热风温度和装样量对苹果片热风干燥过程的影响,比较了6种数学模型在苹果片热风干燥中的适用性.结果表明:切片厚度、热风温度和装样量均对苹果片的热风干燥过程影响较大,苹果片切片厚度越小,热风温度越高,热风干燥速率越大,装样量对干燥速率的影响呈现先增大后减小的趋势;苹果片的热风干燥过程可分为升速干燥阶段及降速干燥阶段,没有恒速阶段;Midilli-Kucuk模型对实验数据的拟合度最高,优于Page模型和Modified Page模型;热风温度从50℃增加到70℃,其有效水分扩散系数由1.10×10^(-9)m^2/s增加到1.83×10^(-9)m^2/s,苹果片的干燥活化能为13.58 k J/mol.展开更多
文摘We conducted a transient experimental investigation of steam–water direct contact condensation in the absence of noncondensible gas in a laboratory-scale column with the inner diameter of 325 mm and the height of 1045 mm. We applied a new analysis method for the steam state equation to analyze the molar quantity change in steam over the course of the experiment and determined the transient steam variation. We also investigated the influence of flow rates and temperatures ofcooling water on the efficiency ofsteam condensation. Our experimental results show that appropriate increasing of the cooling water flow rate can significantly accelerate the steam condensation. We achieved a rapid increase in the total volumetric heat transfer coefficient by increasing the flow rate of cooling water, which indicated a higher thermal convection between the steam and the cooling water with higher flow rates. We found that the temperature ofcooling water did not play an important role on steam condensation. This method was confirmed to be effective for rapid recovering ofsteam.
文摘为了研究苹果片的热风干燥特性,考察了切片厚度、热风温度和装样量对苹果片热风干燥过程的影响,比较了6种数学模型在苹果片热风干燥中的适用性.结果表明:切片厚度、热风温度和装样量均对苹果片的热风干燥过程影响较大,苹果片切片厚度越小,热风温度越高,热风干燥速率越大,装样量对干燥速率的影响呈现先增大后减小的趋势;苹果片的热风干燥过程可分为升速干燥阶段及降速干燥阶段,没有恒速阶段;Midilli-Kucuk模型对实验数据的拟合度最高,优于Page模型和Modified Page模型;热风温度从50℃增加到70℃,其有效水分扩散系数由1.10×10^(-9)m^2/s增加到1.83×10^(-9)m^2/s,苹果片的干燥活化能为13.58 k J/mol.
