上海地区多联机合理制热规模及除霜能力研究
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摘要
变容量多联式空调系统在部分负荷下的节能性较好，近年来其发展迅速。由于其制热性能受气象条件影响，存在结霜问题，热泵的制热能力随着结霜的增加而衰减；并且由于多联机系统的单元室外机可以对多台室内机，单元室外机的装机容量(额定制冷／制热量)不断升级，在增加单元室外机换热面积的同时加大了结霜的可能性，除霜频繁，所以多联机系统单元室外机容量受到冬季运行时结霜除霜的限制。本文深入研究上海地区变容量多联机的除霜性能以及室外机容量与结霜除霜的关系，为更好的设计该系统提供参考依据。
多联式空调系统常采用热气逆循环除霜，除霜时室内不制热，除霜时间越长越频繁，机组传热量就会下降越多。除霜时间与盘管上的结霜量有关，而结霜量受室外气象参数、盘管几何尺寸、盘管的几何特性等多种因素的影响，本文应用集总参数法建立多联式空调系统动态除霜模型。实验得出除霜运行时数码涡旋压缩机满负荷运转；单元室外机除霜过程分为4个阶段建立动态模型；室内机并联成一个换热器建立模型，不考虑室内机之间的耦合；由于室内机并联为一个换热器，电子膨胀阀模型也考虑为单个电子膨胀阀模型。
在一台数码涡旋多联式空调系统实验台上进行实测研究，验证了本文模型可以预测除霜性能的影响因素。除霜时间随着单元室外机换热面积增大而变长。除霜周期内实际总制热量开始随着单元室外机换热面积增大而增加，当增大到某一限值时，实际总制热量不再上升，反而下降。实验用机组实际总制热量在换热面积增大为2倍时达到峰值为138.19％。随着单元室外机装机容量上升，除霜时间增加，在现有多联机除霜标准下单元室外机装机容量存在上限。
Multi air-conditioning system develops quickly these years for its excellent performance under part load. But its heating capacity drops dramatically due to the frosting and defrosting problem under bad weather conditions. The unitary outdoor unit of multi air-conditioning system increase its capacity continually, however, the increment of the heat exchange area increase the possibility of frosting in winter, which in turn restricts the unitary outdoor unit capacity in winter. In this paper, the relationship between unitary outdoor unit capacity and frosting and defrosting performance in Shanghai is studied to optimize the system.
Hot gas reverse cycle is commonly used in multi air-conditioning system for defrosting, during which heat will not be brought into the room, so the heating capacity decreases with the frequency of defrosting. The defrosting time is related to the quantity of frost on the tube-fin which is influenced by several factors such as weather conditions, coil dimensions, and the geometric character of coils. According to the test result of a DVM (digital variable multi) air-conditioning system, the digital scroll compressor is found to be on full time load while defrosting. The unitary unit outdoor heat exchanger's model was set up into 4 stages using the lumped parameter method. All units could be merged as one heat exchanger model without considering their coupling. As the indoor units were merged into one, the EEV(electronic expansion valve) are also considered to be single one.
Based on a field test on a DVM air conditioning system, the model was validated. So the model could estimate the influencing factors of defrosting performance. With the rise of heat exchange area of unitary outdoor unit, the defrosting time rises, and the total heat output firstly rises and then goes down. For the DVM system, when heat exchange area of outdoor unit increased to be twice, the actual heat output increased to be maximum 138.19%. It is also analyzed that, the increase of unitary outdoor unit capacity would be limited by defrosting. The defrosting time increases with the unitary outdoor unit capacity, so the capacity is limited by the Standard GB/T18837-2002.
多联式空调系统常采用热气逆循环除霜，除霜时室内不制热，除霜时间越长越频繁，机组传热量就会下降越多。除霜时间与盘管上的结霜量有关，而结霜量受室外气象参数、盘管几何尺寸、盘管的几何特性等多种因素的影响，本文应用集总参数法建立多联式空调系统动态除霜模型。实验得出除霜运行时数码涡旋压缩机满负荷运转；单元室外机除霜过程分为4个阶段建立动态模型；室内机并联成一个换热器建立模型，不考虑室内机之间的耦合；由于室内机并联为一个换热器，电子膨胀阀模型也考虑为单个电子膨胀阀模型。
在一台数码涡旋多联式空调系统实验台上进行实测研究，验证了本文模型可以预测除霜性能的影响因素。除霜时间随着单元室外机换热面积增大而变长。除霜周期内实际总制热量开始随着单元室外机换热面积增大而增加，当增大到某一限值时，实际总制热量不再上升，反而下降。实验用机组实际总制热量在换热面积增大为2倍时达到峰值为138.19％。随着单元室外机装机容量上升，除霜时间增加，在现有多联机除霜标准下单元室外机装机容量存在上限。
Multi air-conditioning system develops quickly these years for its excellent performance under part load. But its heating capacity drops dramatically due to the frosting and defrosting problem under bad weather conditions. The unitary outdoor unit of multi air-conditioning system increase its capacity continually, however, the increment of the heat exchange area increase the possibility of frosting in winter, which in turn restricts the unitary outdoor unit capacity in winter. In this paper, the relationship between unitary outdoor unit capacity and frosting and defrosting performance in Shanghai is studied to optimize the system.
Hot gas reverse cycle is commonly used in multi air-conditioning system for defrosting, during which heat will not be brought into the room, so the heating capacity decreases with the frequency of defrosting. The defrosting time is related to the quantity of frost on the tube-fin which is influenced by several factors such as weather conditions, coil dimensions, and the geometric character of coils. According to the test result of a DVM (digital variable multi) air-conditioning system, the digital scroll compressor is found to be on full time load while defrosting. The unitary unit outdoor heat exchanger's model was set up into 4 stages using the lumped parameter method. All units could be merged as one heat exchanger model without considering their coupling. As the indoor units were merged into one, the EEV(electronic expansion valve) are also considered to be single one.
Based on a field test on a DVM air conditioning system, the model was validated. So the model could estimate the influencing factors of defrosting performance. With the rise of heat exchange area of unitary outdoor unit, the defrosting time rises, and the total heat output firstly rises and then goes down. For the DVM system, when heat exchange area of outdoor unit increased to be twice, the actual heat output increased to be maximum 138.19%. It is also analyzed that, the increase of unitary outdoor unit capacity would be limited by defrosting. The defrosting time increases with the unitary outdoor unit capacity, so the capacity is limited by the Standard GB/T18837-2002.
引文
[1] Abdel-Wahed R.M., Hifni M.A., S.A.Sherif.Hot water defrosting of a horizontal flat plate cooling surface.Int.J.Refrigeration., 1983,6(3):152-154
[2] Alebrahim A.M., Sherif S.A..Electrical defrosting analysis of a finned-tube evaporator coil using the enthalpy method.J.Mechanical Engineering Science, 2002,216:655-673
[3] Allard J., Heinzen R..Adaptive defrost.IEEE Transaction on Industry Application, 1988, 24(1):39-42
[4] Baxter, V., Moyers, J., Air Source Heat Pump Field Measurements.of Cycling, Frosting, and Defrosting Losses.1981-1983.Oak Ridge Natl.Lab., ORNL/CON-150
[5] Browne M.W., Bansal P.K..Challengers in modeling vapor-compression liquid chillers.ASHRAE Trans., 1998, 104(1:474-486)
[6] Cole R.A..Refrigeration loads in a freezer due to hot gas defrost and their associated cost.ASHRAE Transaction, 1995, Part 2, 1149-1154
[7] Crawford R.R.and Shirey, D.B., 1987,.Dynamic modeling of a residential heap pump…racterization of plate fin-tube heat exchangers.Int.J.Refrig.,17, 49-57
[8] Krakow K.I., Yah L., Lin S..A model of hot gas defrosting of evaporators.ASHRAE Trans., 1992,98(2):451-474
[9] Krakow K.I., Lin S..An idealized model of reversed cycle hot gas defrosting.ASHRAE Trans., 1993,99(1):317-338
[10] Merrill E.Heat pumps on-off capacity control and defrost performance test using time-temperature defrost controls.ASHRAE Trans., 1981,87(1):381-393
[11] Najork.H.1975.Investigations of the dynamical behaviour of evaporators with thermostatic expansion valve.Proceedings IIR, Moscow, pp.759-769.
[12] O'Neal D.L., Peterson K.T.NK.Anand and J.S.Schliesing.Refrigeration system dynamics during the reverse cycle defrost.ASHRAE Trans.1989,95(2):689-698
[13] O'Neal D.L., Peterson K.T.A comparison of orifice and TXV control characteristics during the reverse cycle defrost.ASHRAE Trans., 1996, Part 1,337-343
[14] Payne V., O'Neal D.L..Defrost cycle performance for an air-source heat pump with a scroll and a reciprocating compressor.Int.J.Refrigeration.1995,18(2): p107-112,
[15] Rosell J., Morgan R., McMullan.Performance of heat pumps in service-a simulation study.International Journal of Energy Research..Vol.6, pp.83-99.Jan.-Mar.1982
[16] SAMSUNG DVM 数码中央空调系统．技术手册 苏州三星电子有限公司 2004．8
[17] Shah,M M.A general correlation for heat transfer during film condensation inside pipes.Int J Heat Mass Transfer,1979,22(4):547-556
[18] Sherif S.A., Hertz M.G..A semi-empirical model for electrical defrosting of a cylindrical coil cooler.Int.J.Energy Res., 1998,22(1):85-92
[19] Shih-Cheng Hu, Rong-Hwa Yang.Development and testing of a multi-type air conditioner without using AC inverters.Energy Conversion and Management.,2005;46:373-383.
[20] Strong A.P..Hot gas defrost for industrial refrigeration.Heating/Piping/Air Conditioning, July 1988, 71-83
[21] Williams S.J..Energy equations for five defrost methods.Refrigerating Engng., 1952,8:859-863
[22] 陈汝东，许东晟．风冷热泵空调器除霜控制的研究．流体机械，1999，27(2)：55-57
[23] 陈芝久，阙雄才，丁国良．制冷系统热动力学．北京：机械工业出版社．1998
[24] 丁国良．小型制冷装置动态仿真与优化．上海交通大学博士学位论文，1993
[25] 丁国良，张春路，李灏．神经网络在空调器仿真中的应用研究．制冷学报，1999，2：p31-37
[26] 丁国良，张春路．制冷空调装置仿真与优化．北京：科学出版社．2001
[27] 杜海存 数码涡旋与变频VRV中央空调系统性能比较．江西能源2005年第1期
[28] 阚安康 数码涡旋技术在冷藏集装箱上的应用．压缩机技术2005年第6期
[29] 黄虎．风冷热泵冷热水机组除霜控制研究．西安交通大学博士学位论文．2000
[30] 黄虎，李志浩，束鹏程．低温环境风冷热泵机组设计中的两个问题．暖通空调，1999．6(29)：22-24
[31] 黄虎，李志浩，虞维平．风冷热泵冷热水机组除霜过程仿真．东南大学学报(自然科学版)，2001．31(1)：51-56
[32] 黄虎．风冷热泵冷热水机组结霜工况下运行特性的实验研究．流体机械．2000年第26卷第12期p43～47
[33] 李永洪 郑学林 卢士勋 浅谈数码涡旋技术在空调系统节能中的应用．家电科技2005．10
[34] 刘维华．变环境参数HFC134a汽车空调系统动态性能研究及系统优化．上海交通大学博士学位论文，1995
[35] 腾英武，薛卫华，刘传聚，大金变频控制热泵式VRV空调机组制冷运行特性的实验研究，制冷技术，2000年第4期
[36] 王广军，辛国华．热力系统动力学及其应用．北京：科学出版社，1997
[37] 王贻任 美国谷轮公司压缩机应用技术讲座 第九讲 数码涡旋技术．制冷技术2003年第1期
[38] 姚杨．空气源热泵冷热水机组冬季结霜工况的模拟与分析．哈尔滨工业大学博士学位论文，2002．3
[39] 杨刚．数码涡旋多联式空调系统夏季运行特性的实验研究．同济大学硕士学位论文，2006年3月
[40] 张春路．基于模型的制冷空调装置智能仿真方法基础研究：上海交通大学博士学位论文，1999
[41] 朱乐琪，张旭，杨洁．数码涡旋多联式空调系统冬季运行特性的现场测试．暖通空调，2006年12月
[42] 周道 数码涡旋中央空调的特性分析与应用．医药工程设计杂志2005年第3期
[43] 周子成．房间空调器热泵运行时的瞬态仿真．制冷学报，1998，4：p14-18
[2] Alebrahim A.M., Sherif S.A..Electrical defrosting analysis of a finned-tube evaporator coil using the enthalpy method.J.Mechanical Engineering Science, 2002,216:655-673
[3] Allard J., Heinzen R..Adaptive defrost.IEEE Transaction on Industry Application, 1988, 24(1):39-42
[4] Baxter, V., Moyers, J., Air Source Heat Pump Field Measurements.of Cycling, Frosting, and Defrosting Losses.1981-1983.Oak Ridge Natl.Lab., ORNL/CON-150
[5] Browne M.W., Bansal P.K..Challengers in modeling vapor-compression liquid chillers.ASHRAE Trans., 1998, 104(1:474-486)
[6] Cole R.A..Refrigeration loads in a freezer due to hot gas defrost and their associated cost.ASHRAE Transaction, 1995, Part 2, 1149-1154
[7] Crawford R.R.and Shirey, D.B., 1987,.Dynamic modeling of a residential heap pump…racterization of plate fin-tube heat exchangers.Int.J.Refrig.,17, 49-57
[8] Krakow K.I., Yah L., Lin S..A model of hot gas defrosting of evaporators.ASHRAE Trans., 1992,98(2):451-474
[9] Krakow K.I., Lin S..An idealized model of reversed cycle hot gas defrosting.ASHRAE Trans., 1993,99(1):317-338
[10] Merrill E.Heat pumps on-off capacity control and defrost performance test using time-temperature defrost controls.ASHRAE Trans., 1981,87(1):381-393
[11] Najork.H.1975.Investigations of the dynamical behaviour of evaporators with thermostatic expansion valve.Proceedings IIR, Moscow, pp.759-769.
[12] O'Neal D.L., Peterson K.T.NK.Anand and J.S.Schliesing.Refrigeration system dynamics during the reverse cycle defrost.ASHRAE Trans.1989,95(2):689-698
[13] O'Neal D.L., Peterson K.T.A comparison of orifice and TXV control characteristics during the reverse cycle defrost.ASHRAE Trans., 1996, Part 1,337-343
[14] Payne V., O'Neal D.L..Defrost cycle performance for an air-source heat pump with a scroll and a reciprocating compressor.Int.J.Refrigeration.1995,18(2): p107-112,
[15] Rosell J., Morgan R., McMullan.Performance of heat pumps in service-a simulation study.International Journal of Energy Research..Vol.6, pp.83-99.Jan.-Mar.1982
[16] SAMSUNG DVM 数码中央空调系统．技术手册 苏州三星电子有限公司 2004．8
[17] Shah,M M.A general correlation for heat transfer during film condensation inside pipes.Int J Heat Mass Transfer,1979,22(4):547-556
[18] Sherif S.A., Hertz M.G..A semi-empirical model for electrical defrosting of a cylindrical coil cooler.Int.J.Energy Res., 1998,22(1):85-92
[19] Shih-Cheng Hu, Rong-Hwa Yang.Development and testing of a multi-type air conditioner without using AC inverters.Energy Conversion and Management.,2005;46:373-383.
[20] Strong A.P..Hot gas defrost for industrial refrigeration.Heating/Piping/Air Conditioning, July 1988, 71-83
[21] Williams S.J..Energy equations for five defrost methods.Refrigerating Engng., 1952,8:859-863
[22] 陈汝东，许东晟．风冷热泵空调器除霜控制的研究．流体机械，1999，27(2)：55-57
[23] 陈芝久，阙雄才，丁国良．制冷系统热动力学．北京：机械工业出版社．1998
[24] 丁国良．小型制冷装置动态仿真与优化．上海交通大学博士学位论文，1993
[25] 丁国良，张春路，李灏．神经网络在空调器仿真中的应用研究．制冷学报，1999，2：p31-37
[26] 丁国良，张春路．制冷空调装置仿真与优化．北京：科学出版社．2001
[27] 杜海存 数码涡旋与变频VRV中央空调系统性能比较．江西能源2005年第1期
[28] 阚安康 数码涡旋技术在冷藏集装箱上的应用．压缩机技术2005年第6期
[29] 黄虎．风冷热泵冷热水机组除霜控制研究．西安交通大学博士学位论文．2000
[30] 黄虎，李志浩，束鹏程．低温环境风冷热泵机组设计中的两个问题．暖通空调，1999．6(29)：22-24
[31] 黄虎，李志浩，虞维平．风冷热泵冷热水机组除霜过程仿真．东南大学学报(自然科学版)，2001．31(1)：51-56
[32] 黄虎．风冷热泵冷热水机组结霜工况下运行特性的实验研究．流体机械．2000年第26卷第12期p43～47
[33] 李永洪 郑学林 卢士勋 浅谈数码涡旋技术在空调系统节能中的应用．家电科技2005．10
[34] 刘维华．变环境参数HFC134a汽车空调系统动态性能研究及系统优化．上海交通大学博士学位论文，1995
[35] 腾英武，薛卫华，刘传聚，大金变频控制热泵式VRV空调机组制冷运行特性的实验研究，制冷技术，2000年第4期
[36] 王广军，辛国华．热力系统动力学及其应用．北京：科学出版社，1997
[37] 王贻任 美国谷轮公司压缩机应用技术讲座 第九讲 数码涡旋技术．制冷技术2003年第1期
[38] 姚杨．空气源热泵冷热水机组冬季结霜工况的模拟与分析．哈尔滨工业大学博士学位论文，2002．3
[39] 杨刚．数码涡旋多联式空调系统夏季运行特性的实验研究．同济大学硕士学位论文，2006年3月
[40] 张春路．基于模型的制冷空调装置智能仿真方法基础研究：上海交通大学博士学位论文，1999
[41] 朱乐琪，张旭，杨洁．数码涡旋多联式空调系统冬季运行特性的现场测试．暖通空调，2006年12月
[42] 周道 数码涡旋中央空调的特性分析与应用．医药工程设计杂志2005年第3期
[43] 周子成．房间空调器热泵运行时的瞬态仿真．制冷学报，1998，4：p14-18