基于传热传质的荔枝预冷果温和质量损失率预测
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摘要
为掌握荔枝预冷过程传热传质规律,以果蔬气调保鲜试验平台为研究对象,依据热力学和水分迁移理论,建立了荔枝果实预冷过程传热传质数学模型,获得了果实在预冷过程中温度、质量损失率等参数的变化情况,分析了果实质量、初始温度对预冷时间、质量损失率变化的影响。经计算发现,同一堆放方式下,荔枝果实质量越大,果实失水速率越小;当荔枝果实质量为10 kg时,果实平均温度从25℃降至5℃约需350 min,平均质量损失率为2. 16%;果实初始温度低,可以减缓果实质量损失率上升。经试验验证,计算结果与模拟结果吻合较好,对应时刻果实温度最大偏差为2. 8 K,平均相对误差为13. 1%;质量损失率计算值与试验值最大偏差小于0. 3%,平均相对误差为10. 7%。
Pre-cooling is one of the key measurements for litchi fruit preservation after being harvested,and the performance of pre-cooling has a great influence on the quality change of litchi fruit. In order to investigate the heat and mass transfer during the pre-cooling process,a mathematical model was built to describe the heat and mass transfer phenomenon in the test bed with controlled atmosphere for fruits and vegetables. The mathematical model was built based on the theory in heat dynamic mass transfer,and the temperature and moisture loss of the litchi fruit during pre-cooling process was calculated. The effects of fruit weight and initial temperature on the process were investigated. After that,some results can be made. The time of pre-cooling became longer as the weight of fruit was increased,however,the speed of moisture loss would be decreased. When there were 10 kg litchi fruits,it took about 350 min for the temperature of fruit decrease from 25℃ to 5℃ by the same stack method,and the weight loss rate was roughly 2. 16% after pre-cooling. It can also be drawn that the speed of weight loss can be reduced by decreasing the initial temperature of litchi fruit. A test was done to verify the accuracy of the model,and the test results were matched well with the results from calculation,the maximum difference between them in fruit temperature and weight loss rate was 2. 8 K and 0. 3%,and the mean difference rate was 13. 1%and 10. 7%,respectively. The research results can be useful for the investigation of the heat and mass transfer mechanism in a cool room and can be used to predict the temperature and weight loss of fruits during pre-cooling process.
Pre-cooling is one of the key measurements for litchi fruit preservation after being harvested,and the performance of pre-cooling has a great influence on the quality change of litchi fruit. In order to investigate the heat and mass transfer during the pre-cooling process,a mathematical model was built to describe the heat and mass transfer phenomenon in the test bed with controlled atmosphere for fruits and vegetables. The mathematical model was built based on the theory in heat dynamic mass transfer,and the temperature and moisture loss of the litchi fruit during pre-cooling process was calculated. The effects of fruit weight and initial temperature on the process were investigated. After that,some results can be made. The time of pre-cooling became longer as the weight of fruit was increased,however,the speed of moisture loss would be decreased. When there were 10 kg litchi fruits,it took about 350 min for the temperature of fruit decrease from 25℃ to 5℃ by the same stack method,and the weight loss rate was roughly 2. 16% after pre-cooling. It can also be drawn that the speed of weight loss can be reduced by decreasing the initial temperature of litchi fruit. A test was done to verify the accuracy of the model,and the test results were matched well with the results from calculation,the maximum difference between them in fruit temperature and weight loss rate was 2. 8 K and 0. 3%,and the mean difference rate was 13. 1%and 10. 7%,respectively. The research results can be useful for the investigation of the heat and mass transfer mechanism in a cool room and can be used to predict the temperature and weight loss of fruits during pre-cooling process.
引文
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[9] DELELE M A,NGCOBO M,GETAHUN S T,et al. Studying airflow and heat transfer characteristics of a horticultural produce packaging system using a 3-D CFD model. PartⅡ:effect of package design[J]. Postharvest Biology and Technology,2013,86:546-555.
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[11]王强,陈焕新,董德发,等.黄金梨差压通风预冷数值分析与实验验证[J].农业工程学报,2008,24(8):262-266.WANG Qiang,CHEN Huanxin,DONG Defa,et al. Numeral analysis and experimental verification of pressure pre-cooling of golden pears[J]. Transactions of the CSAE,2008,24(8):262-266.(in Chinese)
[12] FERRUA M J,SINGH R P. Modeling the forced-air cooling process of fresh strawberry packages,partⅡ:experimental validation of the flow model[J]. International Journal of Refrigeration,2009,32(2):349-358.
[13] LAGUERRE O,DURET S,HOANG H M,et al. Simplified heat transfer modeling in a cold room filled with food products[J]. Journal of Food Engineering,2015,149:78-86.
[14] JALALI A,SEIIEDLOU S,LINKE M,et al. A comprehensive simulation program for modified atmosphere and humidity packaging(MAHP)of fresh fruits and vegetables[J]. Journal of Food Engineering,2017,206:88-97.
[15] LAGUERRE O,FLICK D. Temperature prediction in domestic refrigerators:deterministic and stochastic approaches[J].International Journal of Refrigeration,2010,33(1):41-51.
[16] LAGUERRE O,HOANG M H,FLICK D. Heat transfer modeling in a refrigerated display cabinet:the influence of operating conditions[J]. Journal of Food Engineering,2012,108:353-364.
[17] HOANG H M,LAGUERRE O,MOUREH J,et al. Heat transfer modelling in a ventilated cavity loaded with food product:application to a refrigerated vehicle[J]. Journal of Food Engineering,2012,113(3):389-398.
[18]王娟,谭金翠,王相友.风速对双孢蘑菇预冷过程的影响[J/OL].农业机械学报,2013,44(10):203-208.WANG Juan,TAN Jincui,WANG Xiangyou. Effect of air velocity on pre-cooling process of agaricus bisporus[J/OL].Transactions of the Chinese Society for Agricultural Machinery,2013,44(10):203-208. http:∥www. j-csam. org/jcsam/ch/reader/view_abstract. aspx? file_no=20131033&flag=1. DOI:10. 6041/j. issn. 1000-1298. 2013. 10. 033.(in Chinese)
[19]李锦,谢如鹤,刘广海,等.冷藏车降温数学模型建立与影响因素分析[J/OL].农业机械学报,2013,44(6):175-182.LI Jin,XIE Ruhe,LIU Guanghai,et al. Establishment of cooling mathematical model and analysis of influence factors for refrigerated trucks[J/OL]. Transactions of the Chinese Society for Agricultural Machinery,2013,44(6):175-182. http:∥www. j-csam. org/jcsam/ch/reader/view_abstract. aspx? file_no=20130630&flag=1. DOI:10. 6041/j. issn. 1000-1298.2013. 06. 030.(in Chinese)
[20] Fluent,Inc. FLUENT 6. 1 user's guide[M]. Lebanon,NH:Fluent,Inc.,2003.
[21]徐凤英.荔枝真空红外热辐射干燥传热传质机理研究[D].广州:华南农业大学,2006.XU Fengying. Study on mechanism heat and mass transfer in litchi vacuum&IR combined drying[D]. Guangzhou:South China Agricultural University,2006.(in Chinese)
[22]郭嘉明,吕恩利,陆华忠,等.盒装荔枝果实降温特性数值分析与验证[J/OL].农业机械学报,2016,47(5):218-224.GUO Jiaming,LEnli,LU Huazhong,et al. Numerical analysis and verification on characteristics of temperature decreasing of litchi fruits with packages[J/OL]. Transactions of the Chinese Society for Agricultural Machinery,2016,47(5):218-224. http:∥www. j-csam. org/jcsam/ch/reader/view_abstract. aspx? file_no=20160530&flag=1. DOI:10. 6041/j. issn.1000-1298. 2016. 05. 030.(in Chinese)
[23] SONG Y,VORSA N,YAM K L. Modeling respiration-transpiration in a modified atmosphere packaging system containing blueberry[J]. Journal of Food Engineering,2002,53(2):103-109.
[24] LE PAGE J F,CHEVARIN C,KONDJOYAN A,et al. Development of an approximate empirical-CFD model estimating coupled heat and water transfers of stacked food products placed in airflow[J]. Journal of Food Engineering,2009,92(2):208-216.
[25]刘晖,张洪涛,肖红.水饱和蒸汽压的Antoine方程常数的比较[J].内蒙古石油化工,2009(13):32-34.
[26] KOCA R W,HELLICKSON M L,CHEN P M. Mass transfer from‘d’Anjou'pears in CA storage[J]. American Society of Agricultural Engineers,1993,36(3):821-826.
[27] DELELE M A,NGCOBO M,GETAHUN S T,et al. Studying airflow and heat transfer characteristics of a horticultural produce packaging system using a 3-D CFD model. Part I:model development and validation[J]. Postharvest Biology and Technology,2013,86:536-545.
[2]颜丽萍,刘升,饶先军.预冷、冷藏运输和销售方法对青花菜品质的影响[J].食品与机械,2012,28(2):174-176.YAN Liping,LIU Sheng,RAO Xianjun. Effect of pre-cooling,low temperature transportation and retailing methods on quality of broccoli[J]. Food&Machinery,2012,28(2):174-176.(in Chinese)
[3]王伟锋.番茄差压通风预冷理论分析及实验研究[D].济南:山东建筑大学,2013.WANG Weifeng. Theoretical and experimental study on pressure precooling of tomato[D]. Ji'nan:Shandong Jianzhu University,2013.(in Chinese)
[4]刘斌,申江,邹同华,等.果蔬预冷风速与风机能耗和预冷效果的实验研究及分析[J].制冷学报,2005,26(4):17-19,24.LIU Bin,SHEN Jiang,ZOU Tonghua,et al. Theoretical and experimental analyses of influences of pre-cooling air velocities on energy consumption of air fan and pre-cooling effects[J]. Journal of Refrigeration,2005,26(4):17-19,24.(in Chinese)
[5]何晖,申江,管萍.垂直通风差压球形果蔬预冷的数学模型[J].流体机械,2003,31(9):46-49.HE Hui,SHEN Jiang,GUAN Ping. Mathematical model of spherical fruit and vegetable during pressure pre-cooling for vertical ventilation[J]. Fluid Machinery,2003,31(9):46-49.(in Chinese)
[6]周慧娟,叶正文,苏明申,等.预冷与冷链运输和货架期间桃果热传导性能及品质差异[J].经济林研究,2013,31(3):116-120.ZHOU Huijuan,YE Zhengwen,SU Mingshen,et al. Difference of peach heat conduction and quality during precooling,cold chain transportation and shelf periods[J]. Nonwood Forest Research,2013,31(3):116-120.(in Chinese)
[7] CHOURASIA M K,GOSWAMI T K. Simulation of transport phenomena during natural convection cooling of bagged potatoes in cold storage,part 1:fluid flow and heat transfer[J]. Biosystems Engineering,2006,94(1):33-45.
[8] CHOURASIA M K,GOSWAMI T K. Three dimensional modeling on airflow,heat and mass transfer in partially impermeable enclosure containing agricultural produce during natural convective cooling[J]. Energy Conversion and Management,2007,48(7):2136-2149.
[9] DELELE M A,NGCOBO M,GETAHUN S T,et al. Studying airflow and heat transfer characteristics of a horticultural produce packaging system using a 3-D CFD model. PartⅡ:effect of package design[J]. Postharvest Biology and Technology,2013,86:546-555.
[10] TUTAR M,ERDOGDU F,TOKA B. Computational modeling of airflow patterns and heat transfer prediction through stacked layers'products in a vented box during cooling[J]. International Journal of Refrigeration,2009,32(2):295-306.
[11]王强,陈焕新,董德发,等.黄金梨差压通风预冷数值分析与实验验证[J].农业工程学报,2008,24(8):262-266.WANG Qiang,CHEN Huanxin,DONG Defa,et al. Numeral analysis and experimental verification of pressure pre-cooling of golden pears[J]. Transactions of the CSAE,2008,24(8):262-266.(in Chinese)
[12] FERRUA M J,SINGH R P. Modeling the forced-air cooling process of fresh strawberry packages,partⅡ:experimental validation of the flow model[J]. International Journal of Refrigeration,2009,32(2):349-358.
[13] LAGUERRE O,DURET S,HOANG H M,et al. Simplified heat transfer modeling in a cold room filled with food products[J]. Journal of Food Engineering,2015,149:78-86.
[14] JALALI A,SEIIEDLOU S,LINKE M,et al. A comprehensive simulation program for modified atmosphere and humidity packaging(MAHP)of fresh fruits and vegetables[J]. Journal of Food Engineering,2017,206:88-97.
[15] LAGUERRE O,FLICK D. Temperature prediction in domestic refrigerators:deterministic and stochastic approaches[J].International Journal of Refrigeration,2010,33(1):41-51.
[16] LAGUERRE O,HOANG M H,FLICK D. Heat transfer modeling in a refrigerated display cabinet:the influence of operating conditions[J]. Journal of Food Engineering,2012,108:353-364.
[17] HOANG H M,LAGUERRE O,MOUREH J,et al. Heat transfer modelling in a ventilated cavity loaded with food product:application to a refrigerated vehicle[J]. Journal of Food Engineering,2012,113(3):389-398.
[18]王娟,谭金翠,王相友.风速对双孢蘑菇预冷过程的影响[J/OL].农业机械学报,2013,44(10):203-208.WANG Juan,TAN Jincui,WANG Xiangyou. Effect of air velocity on pre-cooling process of agaricus bisporus[J/OL].Transactions of the Chinese Society for Agricultural Machinery,2013,44(10):203-208. http:∥www. j-csam. org/jcsam/ch/reader/view_abstract. aspx? file_no=20131033&flag=1. DOI:10. 6041/j. issn. 1000-1298. 2013. 10. 033.(in Chinese)
[19]李锦,谢如鹤,刘广海,等.冷藏车降温数学模型建立与影响因素分析[J/OL].农业机械学报,2013,44(6):175-182.LI Jin,XIE Ruhe,LIU Guanghai,et al. Establishment of cooling mathematical model and analysis of influence factors for refrigerated trucks[J/OL]. Transactions of the Chinese Society for Agricultural Machinery,2013,44(6):175-182. http:∥www. j-csam. org/jcsam/ch/reader/view_abstract. aspx? file_no=20130630&flag=1. DOI:10. 6041/j. issn. 1000-1298.2013. 06. 030.(in Chinese)
[20] Fluent,Inc. FLUENT 6. 1 user's guide[M]. Lebanon,NH:Fluent,Inc.,2003.
[21]徐凤英.荔枝真空红外热辐射干燥传热传质机理研究[D].广州:华南农业大学,2006.XU Fengying. Study on mechanism heat and mass transfer in litchi vacuum&IR combined drying[D]. Guangzhou:South China Agricultural University,2006.(in Chinese)
[22]郭嘉明,吕恩利,陆华忠,等.盒装荔枝果实降温特性数值分析与验证[J/OL].农业机械学报,2016,47(5):218-224.GUO Jiaming,LEnli,LU Huazhong,et al. Numerical analysis and verification on characteristics of temperature decreasing of litchi fruits with packages[J/OL]. Transactions of the Chinese Society for Agricultural Machinery,2016,47(5):218-224. http:∥www. j-csam. org/jcsam/ch/reader/view_abstract. aspx? file_no=20160530&flag=1. DOI:10. 6041/j. issn.1000-1298. 2016. 05. 030.(in Chinese)
[23] SONG Y,VORSA N,YAM K L. Modeling respiration-transpiration in a modified atmosphere packaging system containing blueberry[J]. Journal of Food Engineering,2002,53(2):103-109.
[24] LE PAGE J F,CHEVARIN C,KONDJOYAN A,et al. Development of an approximate empirical-CFD model estimating coupled heat and water transfers of stacked food products placed in airflow[J]. Journal of Food Engineering,2009,92(2):208-216.
[25]刘晖,张洪涛,肖红.水饱和蒸汽压的Antoine方程常数的比较[J].内蒙古石油化工,2009(13):32-34.
[26] KOCA R W,HELLICKSON M L,CHEN P M. Mass transfer from‘d’Anjou'pears in CA storage[J]. American Society of Agricultural Engineers,1993,36(3):821-826.
[27] DELELE M A,NGCOBO M,GETAHUN S T,et al. Studying airflow and heat transfer characteristics of a horticultural produce packaging system using a 3-D CFD model. Part I:model development and validation[J]. Postharvest Biology and Technology,2013,86:536-545.