液体除湿性能及系统的研究
|
摘要
随着人们生活水平的不断提高，人们对空气质量的要求也越来越高。从人体舒适的角度出发，人体感到舒适的温度范围为18℃～23℃，相对湿度范围是45％～65％，这对于高温高湿的环境来说，空气调节既要解决降温问题，又要除湿。倘若直接使用传统蒸气压缩式制冷来实现降温和除湿，必须将空气冷却到其露点温度以下，这必然会消耗大量的高位能量。
本文拟设计一种复合的液体除湿空调系统，在原来的传统蒸发压缩式空调系统中复合一液体除湿系统，同时进行除湿与制冷。从公开文献的研究结果发现，所有的液体除湿与空调的混合系统均采用了辅助热源来提高溶液的再生，这是造成整个系统热性能不高的主要原因之一。本研究将制冷系统中的冷凝热回收至除湿系统的再生部分，有效地利用低品位能源，达到节能的效果。而且除湿系统填料塔内采用一种新型的规整波纹纸作为填料，质量轻、廉价、防腐蚀而且比表面积大。
本文选取LiCl作为除湿剂，在规整型填料塔中研究了除湿溶液的再生和除湿性能。逐步分析了影响再生/除湿性能的主要运行参数(溶液温度、空气流量、溶液流量)和填料结构参数(高度和比表面积)。针对再生实验，开始了以下实验：
1．对填料高度变化(高度从10cm增加到50cm)对再生性能的影响的研究，结果发现在填料高度为20cm时，再生效果最为理想；
2．不同MR比对再生效果的影响(溶液流量固定为78L/H，进口风量从172m~3/h增大到688m~3/h)；
3．不同填料比表面积对再生性能的影响(比表面积分别为17.34 m~2/m~3和34.68 m~2/m~3)；
4．不同溶液温度对再生性能的影响(溶液温度从30℃变化到75℃，每变化5℃取一测量点)。
针对单一除湿性能同样做了与再生实验类似的实验，以及实验数据的处理：
1．通过改变填料高度，研究高度对除湿性能的影响；
2．改变溶液温度(从16℃增加到24℃)，看其对除湿量的变化；
3．不同的MR比下除湿效果的比较；
4．整理实验数据，推出除湿量的回归公式以及Sh数的回归公式。
最后，通过再生以及除湿实验的优化结果优化整机的设计，并对整机的除湿效果、再生效果以及整机的COP在不同工况下进行实验测量，验证系统的优化结果。
With the improvement of human living standard, the demand of air quality people ask for is getting higher and higher. In the temperatures between 18℃and 23℃, and the relative humidity between 45% and 65%, people feel cozy, which lead to double missions to the air-conditioner in a wet and hot place, that is cooling and dehumidification. Traditional air-compress method could solve both problems at the same time. It cools the room air below the dew point at first, so it can decrease the water content of room air. And then air is heated to the ideal cozy temperature again. This method could dehumidify and cool the air to the cozy range well, but it wastes a lot of energy to cool room air below dew point and reheat it.
Another method also could reach the ideal air condition, which is hybrid air-conditioner with liquid desiccant.
From the result of public literature, all the hybrid air-compress systems with liquid desiccant ask for another assistant heater to regenerate the solution(liquid desiccant) so as to the bad performance of the whole system. In this paper, a new hybrid air-compress cooling system with liquid desiccant is presented. However, this system reduced the assistant heater, which only regenerated the liquid desiccant through the condenser. And a new kind of honeycomb paper was used in the packed towers. LiCl was chosen as the desiccant in the regeneration experiment and dehumidification experiment.
Focusing on the regeneration experiment, tests as followed were carried out:
1. Increase the height of packed material, study the regeneration performance. And when height reaches 20cm, the performance was the best.
2. Change the MR(the solution flow was fixed at 78L/h, air flow was between 17.34 m~2/m~3 and 34.68 m~2/m~3).
3. Different density of packed material effect on the regeneration performance.
4. Solution at different temperature effect on the regeneration performance.
Focusing the dehumidification performance, a series of tests just like before were carried out. And the regress formulas of dehumidification and Sh were shown in this thesis.
At last, through optimizing the hybrid system, tests of the regeneration performance, dehumidification performance and COP were also carried out in this thesis.
本文拟设计一种复合的液体除湿空调系统，在原来的传统蒸发压缩式空调系统中复合一液体除湿系统，同时进行除湿与制冷。从公开文献的研究结果发现，所有的液体除湿与空调的混合系统均采用了辅助热源来提高溶液的再生，这是造成整个系统热性能不高的主要原因之一。本研究将制冷系统中的冷凝热回收至除湿系统的再生部分，有效地利用低品位能源，达到节能的效果。而且除湿系统填料塔内采用一种新型的规整波纹纸作为填料，质量轻、廉价、防腐蚀而且比表面积大。
本文选取LiCl作为除湿剂，在规整型填料塔中研究了除湿溶液的再生和除湿性能。逐步分析了影响再生/除湿性能的主要运行参数(溶液温度、空气流量、溶液流量)和填料结构参数(高度和比表面积)。针对再生实验，开始了以下实验：
1．对填料高度变化(高度从10cm增加到50cm)对再生性能的影响的研究，结果发现在填料高度为20cm时，再生效果最为理想；
2．不同MR比对再生效果的影响(溶液流量固定为78L/H，进口风量从172m~3/h增大到688m~3/h)；
3．不同填料比表面积对再生性能的影响(比表面积分别为17.34 m~2/m~3和34.68 m~2/m~3)；
4．不同溶液温度对再生性能的影响(溶液温度从30℃变化到75℃，每变化5℃取一测量点)。
针对单一除湿性能同样做了与再生实验类似的实验，以及实验数据的处理：
1．通过改变填料高度，研究高度对除湿性能的影响；
2．改变溶液温度(从16℃增加到24℃)，看其对除湿量的变化；
3．不同的MR比下除湿效果的比较；
4．整理实验数据，推出除湿量的回归公式以及Sh数的回归公式。
最后，通过再生以及除湿实验的优化结果优化整机的设计，并对整机的除湿效果、再生效果以及整机的COP在不同工况下进行实验测量，验证系统的优化结果。
With the improvement of human living standard, the demand of air quality people ask for is getting higher and higher. In the temperatures between 18℃and 23℃, and the relative humidity between 45% and 65%, people feel cozy, which lead to double missions to the air-conditioner in a wet and hot place, that is cooling and dehumidification. Traditional air-compress method could solve both problems at the same time. It cools the room air below the dew point at first, so it can decrease the water content of room air. And then air is heated to the ideal cozy temperature again. This method could dehumidify and cool the air to the cozy range well, but it wastes a lot of energy to cool room air below dew point and reheat it.
Another method also could reach the ideal air condition, which is hybrid air-conditioner with liquid desiccant.
From the result of public literature, all the hybrid air-compress systems with liquid desiccant ask for another assistant heater to regenerate the solution(liquid desiccant) so as to the bad performance of the whole system. In this paper, a new hybrid air-compress cooling system with liquid desiccant is presented. However, this system reduced the assistant heater, which only regenerated the liquid desiccant through the condenser. And a new kind of honeycomb paper was used in the packed towers. LiCl was chosen as the desiccant in the regeneration experiment and dehumidification experiment.
Focusing on the regeneration experiment, tests as followed were carried out:
1. Increase the height of packed material, study the regeneration performance. And when height reaches 20cm, the performance was the best.
2. Change the MR(the solution flow was fixed at 78L/h, air flow was between 17.34 m~2/m~3 and 34.68 m~2/m~3).
3. Different density of packed material effect on the regeneration performance.
4. Solution at different temperature effect on the regeneration performance.
Focusing the dehumidification performance, a series of tests just like before were carried out. And the regress formulas of dehumidification and Sh were shown in this thesis.
At last, through optimizing the hybrid system, tests of the regeneration performance, dehumidification performance and COP were also carried out in this thesis.
引文
[1]ASHARE. Handbook of fundamentals American Society of Heating, Refrigeration and Air Conditioning[M]. Atlanta, 1993.
[2]G.O.G.LOF.Cooling with solar energy [J].Congress on Solar Energy, 1955:71-18.
[3]孙建．太阳能液体除湿空调系统的设计与实验研究[D]．南京，东南大学，2003．
[4]赵云．太阳能液体除湿空调系统的研究[D]．南京，东南大学，2002．
[5]贾春霞，代彦军．干燥剂除湿复合空调热力学特性研究[J]．工程热物理学报，2005，26(6)：11．
[6]董岩．溶液型空气除湿实验研究[J]．天津大学学报．2001，34(1)：1．
[7]S. alizadeh, W. Y. Saman. Modeling and performance of a forced flow solar collector/regenerator using liquid desiccant [J].Solar Energy, 2002, 72(2): 143-152.
[8]A. Barati, M. Kokabi. Modeling of liquid desiccant drying method for gelcast ceramic parts [J]. Ceramics International, 2003, 29:199-207.
[9]Arshad Y. Khan, Jorge L. Martinez. Modeling and parametric analysis of heat and mass transfer performance of a hybrid liquid desiccant absorber[J]. Energy Covers, 1998,39(10):1095-1112.
[10]W. Y. Saman, S. alizadeh. Modeling and performance analysis of a cross-flow type plate heat exchanger for dehumidification/cooling [J]. Solar Energy, 2001, 70(4):361-372.
[11]方承超，孙克涛．太阳能液体除湿空调系统模型的建立与分析[J]．太阳能学报，1997，18(2)：4．
[12]Novosol, Griffiths.Integrated Commercial Rooftop Cooling System. Final Report on Phase Ⅰ and Ⅱ, September 1986-October 1989, 97J Heating and Cooling Systems-89B Architectural Design and Environmental Engineering, Mar 1992
[13]Ryan, W.,Marsala, J., Lowenstein, Griffiths, W., "Laboratory and Field Experiment Result for a Residential Liquid Desiccant Dehumidifier", Proceedings of the Eleventh Annual ASME Solar Energy conference, San Diego, 1989:353-362
[14]Sunders, J. H., et al. "A hybrid space conditioning system combining a gas-fired chiller and liquid desiccant dehumidifier", Proceedings of the 11th annual ASME solar energy conference, San Diego, Calif, 1989.
[15]Swami. Theoretical and Computational Investigation of Algorithms for Simultaneous Heat and Moisture Transport in Buildings: Task 2 Final Report, Solar Energy-89B Oct 1988
[16]Lowenstein, Seasonal performance of a liquid-desiccant air conditioner, Proceedings of the 1995 ASHRAE Annual Meeting, Jan 29-Feb 1 1995
[17]T.A Ameel, G. G. Kevin and B. D. Wood. Performance prediction of alternative, low cost absorbents for open-cycle absorption solar cooling[J]. Solar Energy, 1995,54(2): 65-73.
[18]Gandhidasan. A simplified model for air dehumidification with liquid desiccant[J]. Solar Energy,2004,76:409-16.
[19]Martin, Goswami. Effectiveness of heat and mass transfer processes in a packed bed liquid desiccant dehumidifier/regenerator,_2000 Annual Meeting of the American Society of Heating, Refrigerating and Air-Conditioning Engineerings, INC, p 252, Jun 25-Jun 28 2000
[20]Elsayed. Analysis of air dehumidification using liquid desiccant system[J]. Renewable Energy, 1994, 4:519-528
[21]Fumo. Study of an aqueous lithium chloride desiccant system: air dehumidification and desiccant regeneration[J]. Solar Energy, 2002, 72:351-61.
[22]Adson A.K., Omar M. et al. Parametric study of an energy efficient air conditioning system using liquid desiccant[J]. Applied Thermal Engineering, 1997,18:327-335.
[23]C.S.Khalid Ahmed, P.Gandhisan and A.A.Al-Farayedhi Applied Thermal Engineering[J]. 1997, 17(2): 125-134.
[24]G.Grossman. Solar-powered systems for cooling, dehumidification and conditioning.Solar Energy, 2002, 72(1):53-62.
[25]杨英．液体除湿性的性能研究．天津，天津大学，2000
[26]S.Younus Ahmed. EGandhidasan and A.A.AL-Farayedhi, Thermodynamic analysis of liquid desiccants[J]. Solar Energy, 1998,62:11-18.
[27]Manuel R.Conde. Properties of aqueous solutions of lithium and calcium chlorides: formulations for use in air conditioning equipment design[J]. International Journal of thermal Sciences, 2004, 43:367-382.
[28]A Etas, E E Anderson, I Kiris. Properties of a New Liquid Desiccant Solution-lithium Chloride and Calcium Chloride Mixture[J].Solar Energy, 1992, 49(3):205-212.
[29]宫小龙，孙健，施明恒．除湿溶液蒸汽压的研究[J]．制冷学报，2004，11：27-30．
[30]宫小龙，孙健，施明恒等．除湿溶液除湿性能的对比实验研究[J]．制冷与空调，2005，5(5)：81-84．
[31]杨英，李心刚，李淮毅等．液体除湿性能的实验研究[J]．太阳能学报，2000，21：155-159．
[32]Y.Xuan, W. Roetel. Conception for heat transfer correlation of nanofluids[J]. Int. J. Heat Mass Transfer,2000,43: 3701-3707.
[33]A.Ali, K.Vafai. An investigation of heat mass transfer between air and desiccant film in an inclined parallel and counter flow channels[J]. International Journal of Heat and Mass Transfer,2004,47:1745-1760.
[34]张村．太阳能液体除湿空调系统除湿过程传热传质研究[D]．硕士学位论文，2004：34．
[35]K.J.Kim, T. A. Ameel and B. D. Wood, Performance evaluations of LiCl and LiBr for absorber design application in the open-cycle absorption refrigeration system[J]. ASME. J. of Solar Energy Engineering, 1997,119(5): 165-173.
[36]W.kessling,E.laevemann and M.Peltzer. Energy storage in open cycle liquid desiccant cooling systems [J]. Elsevier Science Ltd and ⅡR, 1998,21 (2): 150-156.
[37]G. Grossman, Simultaneous heat and mass transfer in film absorption under laminar flow, Int. J[J]. Heat Mass Transfer, 1983,26(3):357-371.
[38]G. Grossman. Simultaneous heat and mass transfer in absorption of gases in turbulent liquid films, Int. J[J]. Heat Mass Transfer,1984, 27(12):2365-2376.
[39]曹毅然．蓄能型太阳能液体除湿空调系统的研究[D]．南京，东南大学，2003．
[40]赵振国．冷却塔[M]．中国水利水电出版社，1997：374
[41] Y.J.Dal,R.Z.Wang,H.F.Zhang J.D.Yu.Use of liquid desiccant cooling to improve the performance of vapor compression air conditioning[J].Applied Thermal Engineering.2001,21:1185-1202．
[42] Patnaik S,Lenz TG,Lo"f GOG.Performances studies for an experimental solar open-cycle liquid desiccant air dehumidification system[J].Solar Energy,1990,44:123-135．
[43] Ertas A,Gandhidasan P,Kiris I,Anderson EE.Experimental study on the performance of a regeneration tower for various climatic conditions[J]..Solar Energy 1994,53:125-130．
[44] M.J.Huron and J.Vidal.New mixing rules in simple equation of state for representing vapor liquid equilibria of strongly non-ideal mixtures[J].Fluid Phase Equilibria,1979,3:255-270．
[45] P.R.Burns,J.W.Mitchell.Hybrid desiccant cooling in supermarket application[J].ASHRAE,1985,9(5) :457-468．
[2]G.O.G.LOF.Cooling with solar energy [J].Congress on Solar Energy, 1955:71-18.
[3]孙建．太阳能液体除湿空调系统的设计与实验研究[D]．南京，东南大学，2003．
[4]赵云．太阳能液体除湿空调系统的研究[D]．南京，东南大学，2002．
[5]贾春霞，代彦军．干燥剂除湿复合空调热力学特性研究[J]．工程热物理学报，2005，26(6)：11．
[6]董岩．溶液型空气除湿实验研究[J]．天津大学学报．2001，34(1)：1．
[7]S. alizadeh, W. Y. Saman. Modeling and performance of a forced flow solar collector/regenerator using liquid desiccant [J].Solar Energy, 2002, 72(2): 143-152.
[8]A. Barati, M. Kokabi. Modeling of liquid desiccant drying method for gelcast ceramic parts [J]. Ceramics International, 2003, 29:199-207.
[9]Arshad Y. Khan, Jorge L. Martinez. Modeling and parametric analysis of heat and mass transfer performance of a hybrid liquid desiccant absorber[J]. Energy Covers, 1998,39(10):1095-1112.
[10]W. Y. Saman, S. alizadeh. Modeling and performance analysis of a cross-flow type plate heat exchanger for dehumidification/cooling [J]. Solar Energy, 2001, 70(4):361-372.
[11]方承超，孙克涛．太阳能液体除湿空调系统模型的建立与分析[J]．太阳能学报，1997，18(2)：4．
[12]Novosol, Griffiths.Integrated Commercial Rooftop Cooling System. Final Report on Phase Ⅰ and Ⅱ, September 1986-October 1989, 97J Heating and Cooling Systems-89B Architectural Design and Environmental Engineering, Mar 1992
[13]Ryan, W.,Marsala, J., Lowenstein, Griffiths, W., "Laboratory and Field Experiment Result for a Residential Liquid Desiccant Dehumidifier", Proceedings of the Eleventh Annual ASME Solar Energy conference, San Diego, 1989:353-362
[14]Sunders, J. H., et al. "A hybrid space conditioning system combining a gas-fired chiller and liquid desiccant dehumidifier", Proceedings of the 11th annual ASME solar energy conference, San Diego, Calif, 1989.
[15]Swami. Theoretical and Computational Investigation of Algorithms for Simultaneous Heat and Moisture Transport in Buildings: Task 2 Final Report, Solar Energy-89B Oct 1988
[16]Lowenstein, Seasonal performance of a liquid-desiccant air conditioner, Proceedings of the 1995 ASHRAE Annual Meeting, Jan 29-Feb 1 1995
[17]T.A Ameel, G. G. Kevin and B. D. Wood. Performance prediction of alternative, low cost absorbents for open-cycle absorption solar cooling[J]. Solar Energy, 1995,54(2): 65-73.
[18]Gandhidasan. A simplified model for air dehumidification with liquid desiccant[J]. Solar Energy,2004,76:409-16.
[19]Martin, Goswami. Effectiveness of heat and mass transfer processes in a packed bed liquid desiccant dehumidifier/regenerator,_2000 Annual Meeting of the American Society of Heating, Refrigerating and Air-Conditioning Engineerings, INC, p 252, Jun 25-Jun 28 2000
[20]Elsayed. Analysis of air dehumidification using liquid desiccant system[J]. Renewable Energy, 1994, 4:519-528
[21]Fumo. Study of an aqueous lithium chloride desiccant system: air dehumidification and desiccant regeneration[J]. Solar Energy, 2002, 72:351-61.
[22]Adson A.K., Omar M. et al. Parametric study of an energy efficient air conditioning system using liquid desiccant[J]. Applied Thermal Engineering, 1997,18:327-335.
[23]C.S.Khalid Ahmed, P.Gandhisan and A.A.Al-Farayedhi Applied Thermal Engineering[J]. 1997, 17(2): 125-134.
[24]G.Grossman. Solar-powered systems for cooling, dehumidification and conditioning.Solar Energy, 2002, 72(1):53-62.
[25]杨英．液体除湿性的性能研究．天津，天津大学，2000
[26]S.Younus Ahmed. EGandhidasan and A.A.AL-Farayedhi, Thermodynamic analysis of liquid desiccants[J]. Solar Energy, 1998,62:11-18.
[27]Manuel R.Conde. Properties of aqueous solutions of lithium and calcium chlorides: formulations for use in air conditioning equipment design[J]. International Journal of thermal Sciences, 2004, 43:367-382.
[28]A Etas, E E Anderson, I Kiris. Properties of a New Liquid Desiccant Solution-lithium Chloride and Calcium Chloride Mixture[J].Solar Energy, 1992, 49(3):205-212.
[29]宫小龙，孙健，施明恒．除湿溶液蒸汽压的研究[J]．制冷学报，2004，11：27-30．
[30]宫小龙，孙健，施明恒等．除湿溶液除湿性能的对比实验研究[J]．制冷与空调，2005，5(5)：81-84．
[31]杨英，李心刚，李淮毅等．液体除湿性能的实验研究[J]．太阳能学报，2000，21：155-159．
[32]Y.Xuan, W. Roetel. Conception for heat transfer correlation of nanofluids[J]. Int. J. Heat Mass Transfer,2000,43: 3701-3707.
[33]A.Ali, K.Vafai. An investigation of heat mass transfer between air and desiccant film in an inclined parallel and counter flow channels[J]. International Journal of Heat and Mass Transfer,2004,47:1745-1760.
[34]张村．太阳能液体除湿空调系统除湿过程传热传质研究[D]．硕士学位论文，2004：34．
[35]K.J.Kim, T. A. Ameel and B. D. Wood, Performance evaluations of LiCl and LiBr for absorber design application in the open-cycle absorption refrigeration system[J]. ASME. J. of Solar Energy Engineering, 1997,119(5): 165-173.
[36]W.kessling,E.laevemann and M.Peltzer. Energy storage in open cycle liquid desiccant cooling systems [J]. Elsevier Science Ltd and ⅡR, 1998,21 (2): 150-156.
[37]G. Grossman, Simultaneous heat and mass transfer in film absorption under laminar flow, Int. J[J]. Heat Mass Transfer, 1983,26(3):357-371.
[38]G. Grossman. Simultaneous heat and mass transfer in absorption of gases in turbulent liquid films, Int. J[J]. Heat Mass Transfer,1984, 27(12):2365-2376.
[39]曹毅然．蓄能型太阳能液体除湿空调系统的研究[D]．南京，东南大学，2003．
[40]赵振国．冷却塔[M]．中国水利水电出版社，1997：374
[41] Y.J.Dal,R.Z.Wang,H.F.Zhang J.D.Yu.Use of liquid desiccant cooling to improve the performance of vapor compression air conditioning[J].Applied Thermal Engineering.2001,21:1185-1202．
[42] Patnaik S,Lenz TG,Lo"f GOG.Performances studies for an experimental solar open-cycle liquid desiccant air dehumidification system[J].Solar Energy,1990,44:123-135．
[43] Ertas A,Gandhidasan P,Kiris I,Anderson EE.Experimental study on the performance of a regeneration tower for various climatic conditions[J]..Solar Energy 1994,53:125-130．
[44] M.J.Huron and J.Vidal.New mixing rules in simple equation of state for representing vapor liquid equilibria of strongly non-ideal mixtures[J].Fluid Phase Equilibria,1979,3:255-270．
[45] P.R.Burns,J.W.Mitchell.Hybrid desiccant cooling in supermarket application[J].ASHRAE,1985,9(5) :457-468．