杏鲍菇转轮除湿热泵干燥系统结构设计及工艺参数优化
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摘要
为了实现农产品低湿节能干燥,分析了典型转轮除湿干燥模式,基于能耗高、结构不合理等问题,开展转轮热泵联合除湿干燥系统优化设计与试验研究,研制出转轮除湿热泵干燥机。为了检验并提高转轮除湿热泵干燥机的作业性能,该文以杏鲍菇为研究对象,以降低杏鲍菇色差、除湿能耗比,提高复水性为目标,运用Box-Benhnken中心组合试验设计理论,对再生温度、干燥温度、转换点相对湿度影响其干燥品质与能耗的因素开展响应面试验。通过数据分析,建立了响应面模型,结合四维渲染图分析了上述3个考察指标受3个试验因素取值变化的影响机制,同时对各影响因素进行了综合优化与试验验证。结果表明,3个模型的R2均大于0.98,试验因素对干燥品质及能耗有较大影响,当再生温度87℃,干燥温度50℃,转换点相对湿度45%时,杏鲍菇复水比4.028,色差22.89,除湿能耗比(specific power consumption,SPC)2 633 k J/kg,与预测绝对值误差均低于6个百分点。该研究为转轮除湿热泵干燥设备的设计及干燥工艺优化提供参考。
Common methods of drying have three ways: radiation, conduction and convection. Convective drying has been widely used due to its simple equipment and wide application range. The parameters that can be optimized are temperature, wind speed and humidity, but the temperature has an upper limit in each drying stage. Exceeding the upper limit will destroy the quality of agricultural products. It's not conducive to sufficient heat exchange between wind and material if exceeding the optimum air volume. The humidity is unrestricted for most of the drying period. Low humidity can increase the drying rate and, so humidity is an ideal adjustment parameter. Wheel dehumidification is a common mode in solid dehumidification. However, the traditional wheel dehumidifier has problems such as high energy consumption and unreasonable structure, while heat pump has limited deep dehumidification capacity, but the energy saving effect. In view of the above problems, in this paper, we proposed a model of wheel dehumidifying and for the problems of high energy consumption and unsuitable for drying of agricultural products based on traditional structure of wheel dehumidifying, the optimization design of the dehumidifying structure and the dehumidification system was carried out. Firstly, a conversion mechanism was set up to solve the problem of reasonable conversion between fresh air and circulating air to realize energy-saving drying. Secondly, the surface cooler was replaced by an evaporator and a condenser was set up to recycle the energy. The heat released from the condenser was used to heat dry the inlet air or to regenerate the dehumidification wheel. In order to test and improve the performance of the wheel and heat pump combined dryer, in this paper, we took the sliced Pleurotus eryngii as the research object, and aimed to reduce the color difference of the Pleurotus eryngii, specific power consumption and improve the rehydration, using Box-Benhnken. In the central combined experimental design theory, we carried out three-factor and three-level response surface tests on three factors that affected the drying quality and energy consumption, such as regeneration temperature, dry temperature and conversion point relative humidity. Data analysis was carried out and the response surface mathematical model was established. The four-dimensional renderings was used to analyze the influence mechanism of the above three indicators on the changes of the three test factors. The results showed that the R2 was near to 1 and the test factors had a great influence on the drying quality and energy consumption. The order of importance of each factor to rehydration was dry temperature > regeneration temperature > conversion point relative humidity, the order of importance to aberration was regeneration temperature > conversion point relative humidity > drying temperature, the important influence order on SPC was dry temperature > regeneration temperature > conversion point relative humidity. The lower regeneration temperature resulted in the lower drying temperature, the higher rehydration ratio, and the lower relative humidity of the converse. The lower drying temperature, the smaller the relative humidity of the conversion point, and the lower chromatic aberration, and vice versa. The regeneration temperature, the drying temperature and the conversion point relative humidity to SPC showed a trend of low first and then high. When the regeneration temperature was 87 ℃, the drying temperature is 50 ℃, and the relative humidity of the conversion point was 45%. The rehydration ratio of Pleurotus eryngii was 4.028, the color difference was 22.89, SPC was 2633 kJ/kg, and the error between the predicted and absolute value was less than 6 percentage point. This study explored the critical dehumidification mechanism based on enthalpy point and improved the wheel dehumidification structure, and formulated the optimum dehumidification drying process of Pleurotus eryngii. The results can provide the basis for the design of wheel dehumidification and HPD combined dryer and the optimization of drying process.
Common methods of drying have three ways: radiation, conduction and convection. Convective drying has been widely used due to its simple equipment and wide application range. The parameters that can be optimized are temperature, wind speed and humidity, but the temperature has an upper limit in each drying stage. Exceeding the upper limit will destroy the quality of agricultural products. It's not conducive to sufficient heat exchange between wind and material if exceeding the optimum air volume. The humidity is unrestricted for most of the drying period. Low humidity can increase the drying rate and, so humidity is an ideal adjustment parameter. Wheel dehumidification is a common mode in solid dehumidification. However, the traditional wheel dehumidifier has problems such as high energy consumption and unreasonable structure, while heat pump has limited deep dehumidification capacity, but the energy saving effect. In view of the above problems, in this paper, we proposed a model of wheel dehumidifying and for the problems of high energy consumption and unsuitable for drying of agricultural products based on traditional structure of wheel dehumidifying, the optimization design of the dehumidifying structure and the dehumidification system was carried out. Firstly, a conversion mechanism was set up to solve the problem of reasonable conversion between fresh air and circulating air to realize energy-saving drying. Secondly, the surface cooler was replaced by an evaporator and a condenser was set up to recycle the energy. The heat released from the condenser was used to heat dry the inlet air or to regenerate the dehumidification wheel. In order to test and improve the performance of the wheel and heat pump combined dryer, in this paper, we took the sliced Pleurotus eryngii as the research object, and aimed to reduce the color difference of the Pleurotus eryngii, specific power consumption and improve the rehydration, using Box-Benhnken. In the central combined experimental design theory, we carried out three-factor and three-level response surface tests on three factors that affected the drying quality and energy consumption, such as regeneration temperature, dry temperature and conversion point relative humidity. Data analysis was carried out and the response surface mathematical model was established. The four-dimensional renderings was used to analyze the influence mechanism of the above three indicators on the changes of the three test factors. The results showed that the R2 was near to 1 and the test factors had a great influence on the drying quality and energy consumption. The order of importance of each factor to rehydration was dry temperature > regeneration temperature > conversion point relative humidity, the order of importance to aberration was regeneration temperature > conversion point relative humidity > drying temperature, the important influence order on SPC was dry temperature > regeneration temperature > conversion point relative humidity. The lower regeneration temperature resulted in the lower drying temperature, the higher rehydration ratio, and the lower relative humidity of the converse. The lower drying temperature, the smaller the relative humidity of the conversion point, and the lower chromatic aberration, and vice versa. The regeneration temperature, the drying temperature and the conversion point relative humidity to SPC showed a trend of low first and then high. When the regeneration temperature was 87 ℃, the drying temperature is 50 ℃, and the relative humidity of the conversion point was 45%. The rehydration ratio of Pleurotus eryngii was 4.028, the color difference was 22.89, SPC was 2633 kJ/kg, and the error between the predicted and absolute value was less than 6 percentage point. This study explored the critical dehumidification mechanism based on enthalpy point and improved the wheel dehumidification structure, and formulated the optimum dehumidification drying process of Pleurotus eryngii. The results can provide the basis for the design of wheel dehumidification and HPD combined dryer and the optimization of drying process.
引文
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[3]巨浩羽,肖红伟,郑霞,等.干燥介质相对湿度对胡萝卜片热风干燥特性的影响[J].农业工程学报,2015,31(16):296-304.Ju Haoyu,Xiao Hongwei,Zheng Xia,et al.Effect of hot air relative humidity on drying characteristics of carrot slabs[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2015,31(16):296-304.(in Chinese with English abstract)
[4]张雪飞,刘显茜.胡萝卜切片热风干燥对流传质系数的估算[J].机械与电子,2015(11):17-20.Zhang Xuefei,Liu Xianxi.Estimation of convective mass transfer coefficient of hot air drying of carrot slices[J].Machinery&Electronics,2015(11):17-20.(in Chinese with English abstract)
[5]Ju H Y,Zhang Q,Mujumdar A S,et al.Hot-air drying kinetics of yam slices under step change in relative humidity[J].International Journal of Food Engineering,2016,12(8):783-792.(in Chinese with English abstract)
[6]Rao D L N.Drying characteristics of red chillies:Mathematical modelling and drying experiments[J].International Journal of Engineering Sciences&Research Technology,2014,3(7):425-437.
[7]任广跃,李晖,段续,等.常压冷冻干燥技术在食品中的应用研究[J].食品研究与开发,2013,34(18):119-122.Ren Guangyue,Li Hui,Duan Xuan,et al.Application of atmospheric freeze drying technology in foods[J].Food Research And Development,2013,34(18):119-122.(in Chinese with English abstract)
[8]Wu X N,Ge T S,Dai Y J,et al.Review on substrate of solid desiccant dehumidification system[J].Renewable&Sustainable Energy Reviews,2018,82:3236-3249.
[9]段洁利,张馨予,吕恩利,等.仓储转轮除湿系统管道形式参数优化试验[J].农业工程学报,2016,32(15):255-260.Duan Jieli,Zhang Xinyu,LüEnli,et al.Optimization of pipe form parameters of desiccant rotary wheels of dehumidification system for storage[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2016,32(15):255-260.(in Chinese with English abstract)
[10]Borneo R,Alba N,Aguirre A.New films based on triticale flour:Properties and effects of storage time[J].Journal of Cereal Science,2016,68:82-87.
[11]Al-Alili A,Hwang Y,Radermacher R.Performance of a desiccant wheel cycle utilizing new zeolite material:Experimental investigation[J].Energy,2015,81:137-145.
[12]Antonellis S D,Joppolo C M,Molinaroli L,et al.Simulation and energy efficiency analysis of desiccant wheel systems for drying processes[J].Energy,2012,37(1):336-345.
[13]Yang Z,Zhu Z,Zhao F.Simultaneous control of drying temperature and superheat for a closed-loop heat pump dryer[J].Applied Thermal Engineering,2016,93:571-579.
[14]Jafari S M,Ghanbari V,Ganje M,et al.Modeling the drying kinetics of green bell pepper in a heat pump assisted fluidized bed dryer[J].Journal of Food Quality,2016,39(2):98-108.
[15]Aziz M,Prawisudha P,Prabowo B,et al.Integration of energy-efficient empty fruit bunch drying with gasification combined cycle systems[J].Applied Energy,2015,139:188-195.
[16]Apinyavisit K,Nathakaranakule A,Mittal G S,et al.Heat and mass transfer properties of longan shrinking from a spherical to an irregular shape during drying[J].Biosystems Engineering,2018,169:11-21.
[17]葛凤华,王剑,郭兴龙,等.热泵废热再生转轮除湿空调系统的性能研究[J].太阳能学报,2016,37(9):2326-2331.Ge Fenghua,Wang Jian,Guo Xinglong,et al.Performance study on hybrid desiccant wheel air-conditioning system with waste heat recover of heat pump[J].Journal of Solar Energy,2016,37(9):2326-2331.(in Chinese with English abstract)
[18]Sultan M,El-Sharkaw I I,Miyazaki T,et al.Experimental study on carbon based adsorbents for greenhouse dehumidification[J].Evergreen,2014,1:5-11.
[19]陆耀庆.实用供热空调设计手册[M].北京:中国建筑工业出版社,1993.
[20]陈东,谢继红.热泵技术手册[M].北京:化学工业出版社,2012.
[21]马最良王伟倪龙.空气源热泵技术与应用[M].北京:中国建筑工业出版社,2017.
[22]涂壤,刘晓华,江亿.不同固体除湿方式的热质交换过程分析及性能比较[J].化工学报,2013,64(6):1939-1947.Tu Rang,Liu Xiaohua,Jiang Yi.Heat and mass transfer analysis and performance comparison for different solid dehumidification methods[J].CIESC Journal,2013,64(6):1939-1947.(in Chinese with English abstract)
[23]吕君,魏娟,张振涛,等.基于等焓和等温过程的热泵烤烟系统性能的理论分析与比较[J].农业工程学报,2012,28(20):265-271.LüJun,Wei Juan,Zhang Zhentao,et al.Theoretical analysis and comparison of the performance of heat pump flue-cured tobacco system based on isothermal and isothermal processes[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),201228(20):265-271.(in Chinese with English abstract)
[24]王教领,宋卫东,王明友,等.微波热泵联合干燥机的设计与试验研究[J].农机化研究,2016(12):161-178.Wang Jiaoling,Song Weidong,Wang Mingyou,et al.The design of microwave heat hump drying machine and experimental research[J].Journal of Agricultural Mechanization Research,2016(12):161-178.
[25]颜建春,胡志超,吴朋来,等.热板-微波联合真空冷冻干燥茭白工艺优化[J].农业工程学报,2017,33(1):262-270.Yan Jianchun,Hu Zhichao,Wu Penglai,et al.Optimization of hot-plate and microwave combined vacuum freeze drying process of water-oat[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE)2017,33(1):262-270.(in Chinese with English abstract)
[26]黄略略.冻干-真空微波串联联合干燥苹果的保质和节能工艺模型研究[D].无锡:江南大学,2011.Huang Luelue.Studies on Quality,Saving Energy Technology and Model of Tandem Combined Freeze Drying-vacuum Microwave Dried Apple[D].Wuxi:Jiangnan University,2011.(in Chinese with English abstract)
[27]姚曜.排热回收式热泵密集烤烟房节能性研究[D].合肥:合肥工业大学,2017.Yao Yao.Energy Saving Efficiency of Heat Pump Tobacco Leaf Bulk Curing System with Heat Recovery Unit[D].Hefei:Hefei University of Technology,2017.
[28]陈君琛,杨艺龙,翁敏劼,等.即食杏鲍菇热风-真空联合干燥工艺优化[J].农业工程学报,2014,30(14):331-338.Chen Junchen,Yang Yilong,Weng Minjie,et al.Optimization of combined hot-air and vacuum drying technology for instant Pleurotus Eeryngii[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2014,30(14):331-338.(in Chinese with English abstract)
[29]刘春泉,严启梅,江宁,等.杏鲍菇真空微波干燥特性及动力学模型[J].核农学报,2012,26(3):494-499.Liu Chunquan,Yan Qimei,Jiang Ning,et al.Vacuum microwave drying characteristics and kinetic model of Pleurotus eryngii[J].Chinese Journal of Nuclear,2012,26(3):494-499.
[30]邢亚阁,蒋丽,曹东,等.不同干燥方式对杏鲍菇营养成分的影响[J].食品工业,2015(4):1-3.Xing Yage,Jiang Li,Cao Dong,et al.Effects of different drying methods on the nutritional of Pleurotus eryngii[J].Food Industry,2015(4):1-3.(in Chinese with English abstract)
[2]谢永康,林雅文,朱广飞,等.基于加热均匀性的射频干燥系统结构优化与试验[J].农业工程学报,2018,34(5):248-255.Xie Yongkang,Lin Yawen,Zhu Guangfei,et al.Structure optimization and experiment of radio frequency dryer based on heating uniformity[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2018,34(5):248-255.(in Chinese with English abstract)
[3]巨浩羽,肖红伟,郑霞,等.干燥介质相对湿度对胡萝卜片热风干燥特性的影响[J].农业工程学报,2015,31(16):296-304.Ju Haoyu,Xiao Hongwei,Zheng Xia,et al.Effect of hot air relative humidity on drying characteristics of carrot slabs[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2015,31(16):296-304.(in Chinese with English abstract)
[4]张雪飞,刘显茜.胡萝卜切片热风干燥对流传质系数的估算[J].机械与电子,2015(11):17-20.Zhang Xuefei,Liu Xianxi.Estimation of convective mass transfer coefficient of hot air drying of carrot slices[J].Machinery&Electronics,2015(11):17-20.(in Chinese with English abstract)
[5]Ju H Y,Zhang Q,Mujumdar A S,et al.Hot-air drying kinetics of yam slices under step change in relative humidity[J].International Journal of Food Engineering,2016,12(8):783-792.(in Chinese with English abstract)
[6]Rao D L N.Drying characteristics of red chillies:Mathematical modelling and drying experiments[J].International Journal of Engineering Sciences&Research Technology,2014,3(7):425-437.
[7]任广跃,李晖,段续,等.常压冷冻干燥技术在食品中的应用研究[J].食品研究与开发,2013,34(18):119-122.Ren Guangyue,Li Hui,Duan Xuan,et al.Application of atmospheric freeze drying technology in foods[J].Food Research And Development,2013,34(18):119-122.(in Chinese with English abstract)
[8]Wu X N,Ge T S,Dai Y J,et al.Review on substrate of solid desiccant dehumidification system[J].Renewable&Sustainable Energy Reviews,2018,82:3236-3249.
[9]段洁利,张馨予,吕恩利,等.仓储转轮除湿系统管道形式参数优化试验[J].农业工程学报,2016,32(15):255-260.Duan Jieli,Zhang Xinyu,LüEnli,et al.Optimization of pipe form parameters of desiccant rotary wheels of dehumidification system for storage[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2016,32(15):255-260.(in Chinese with English abstract)
[10]Borneo R,Alba N,Aguirre A.New films based on triticale flour:Properties and effects of storage time[J].Journal of Cereal Science,2016,68:82-87.
[11]Al-Alili A,Hwang Y,Radermacher R.Performance of a desiccant wheel cycle utilizing new zeolite material:Experimental investigation[J].Energy,2015,81:137-145.
[12]Antonellis S D,Joppolo C M,Molinaroli L,et al.Simulation and energy efficiency analysis of desiccant wheel systems for drying processes[J].Energy,2012,37(1):336-345.
[13]Yang Z,Zhu Z,Zhao F.Simultaneous control of drying temperature and superheat for a closed-loop heat pump dryer[J].Applied Thermal Engineering,2016,93:571-579.
[14]Jafari S M,Ghanbari V,Ganje M,et al.Modeling the drying kinetics of green bell pepper in a heat pump assisted fluidized bed dryer[J].Journal of Food Quality,2016,39(2):98-108.
[15]Aziz M,Prawisudha P,Prabowo B,et al.Integration of energy-efficient empty fruit bunch drying with gasification combined cycle systems[J].Applied Energy,2015,139:188-195.
[16]Apinyavisit K,Nathakaranakule A,Mittal G S,et al.Heat and mass transfer properties of longan shrinking from a spherical to an irregular shape during drying[J].Biosystems Engineering,2018,169:11-21.
[17]葛凤华,王剑,郭兴龙,等.热泵废热再生转轮除湿空调系统的性能研究[J].太阳能学报,2016,37(9):2326-2331.Ge Fenghua,Wang Jian,Guo Xinglong,et al.Performance study on hybrid desiccant wheel air-conditioning system with waste heat recover of heat pump[J].Journal of Solar Energy,2016,37(9):2326-2331.(in Chinese with English abstract)
[18]Sultan M,El-Sharkaw I I,Miyazaki T,et al.Experimental study on carbon based adsorbents for greenhouse dehumidification[J].Evergreen,2014,1:5-11.
[19]陆耀庆.实用供热空调设计手册[M].北京:中国建筑工业出版社,1993.
[20]陈东,谢继红.热泵技术手册[M].北京:化学工业出版社,2012.
[21]马最良王伟倪龙.空气源热泵技术与应用[M].北京:中国建筑工业出版社,2017.
[22]涂壤,刘晓华,江亿.不同固体除湿方式的热质交换过程分析及性能比较[J].化工学报,2013,64(6):1939-1947.Tu Rang,Liu Xiaohua,Jiang Yi.Heat and mass transfer analysis and performance comparison for different solid dehumidification methods[J].CIESC Journal,2013,64(6):1939-1947.(in Chinese with English abstract)
[23]吕君,魏娟,张振涛,等.基于等焓和等温过程的热泵烤烟系统性能的理论分析与比较[J].农业工程学报,2012,28(20):265-271.LüJun,Wei Juan,Zhang Zhentao,et al.Theoretical analysis and comparison of the performance of heat pump flue-cured tobacco system based on isothermal and isothermal processes[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),201228(20):265-271.(in Chinese with English abstract)
[24]王教领,宋卫东,王明友,等.微波热泵联合干燥机的设计与试验研究[J].农机化研究,2016(12):161-178.Wang Jiaoling,Song Weidong,Wang Mingyou,et al.The design of microwave heat hump drying machine and experimental research[J].Journal of Agricultural Mechanization Research,2016(12):161-178.
[25]颜建春,胡志超,吴朋来,等.热板-微波联合真空冷冻干燥茭白工艺优化[J].农业工程学报,2017,33(1):262-270.Yan Jianchun,Hu Zhichao,Wu Penglai,et al.Optimization of hot-plate and microwave combined vacuum freeze drying process of water-oat[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE)2017,33(1):262-270.(in Chinese with English abstract)
[26]黄略略.冻干-真空微波串联联合干燥苹果的保质和节能工艺模型研究[D].无锡:江南大学,2011.Huang Luelue.Studies on Quality,Saving Energy Technology and Model of Tandem Combined Freeze Drying-vacuum Microwave Dried Apple[D].Wuxi:Jiangnan University,2011.(in Chinese with English abstract)
[27]姚曜.排热回收式热泵密集烤烟房节能性研究[D].合肥:合肥工业大学,2017.Yao Yao.Energy Saving Efficiency of Heat Pump Tobacco Leaf Bulk Curing System with Heat Recovery Unit[D].Hefei:Hefei University of Technology,2017.
[28]陈君琛,杨艺龙,翁敏劼,等.即食杏鲍菇热风-真空联合干燥工艺优化[J].农业工程学报,2014,30(14):331-338.Chen Junchen,Yang Yilong,Weng Minjie,et al.Optimization of combined hot-air and vacuum drying technology for instant Pleurotus Eeryngii[J].Transactions of the Chinese Society of Agricultural Engineering(Transactions of the CSAE),2014,30(14):331-338.(in Chinese with English abstract)
[29]刘春泉,严启梅,江宁,等.杏鲍菇真空微波干燥特性及动力学模型[J].核农学报,2012,26(3):494-499.Liu Chunquan,Yan Qimei,Jiang Ning,et al.Vacuum microwave drying characteristics and kinetic model of Pleurotus eryngii[J].Chinese Journal of Nuclear,2012,26(3):494-499.
[30]邢亚阁,蒋丽,曹东,等.不同干燥方式对杏鲍菇营养成分的影响[J].食品工业,2015(4):1-3.Xing Yage,Jiang Li,Cao Dong,et al.Effects of different drying methods on the nutritional of Pleurotus eryngii[J].Food Industry,2015(4):1-3.(in Chinese with English abstract)