并联双U形桩基埋管换热器热-力学特征的数值仿真研究
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摘要
桩基埋管换热器(能量桩)作为土壤源热泵的末端换热装置同时需承担常规桩基功能。因此,除其换热性能应满足空调供暖负荷需求之外,其间歇交替从周围土壤取、放热所引起的桩基应力变化亦不应危及上部建筑结构的稳定性。为了深刻揭示能量桩的热-力学特征,联合使用Comsol和Abaqus软件建立了并联双U形桩基埋管换热器的三维动态数值仿真模型,利用现场实测结果验证了仿真结果的正确性,分析了桩基内部的动态温度分布、轴力分布以及桩身位移状况;进一步探究了四种不同桩基长径比、流速情况下的双U形埋管以及三种不同埋管形式的桩基换热器的换热性能和力学特征,揭示了出口水温和单位桩深换热量等动态换热性能以及桩身轴力和桩顶位移等力学性能参数的时变特性。结果表明埋管形式和桩基长径比对桩基埋管换热器换热和力学性能的影响较显著,流速的影响较弱;长径比和流速越大,埋管的换热能力越大,但进、出口水温温差也越大,由温度变化所引起的附加桩身轴力、桩顶位移以及侧摩阻力也相应增大。
Pile-based borehole heat exchangers(energy piles) can be used as terminal heat transfer devices for ground source heat pumps, playing the role of conventional pile foundations at the same time. Thus, not only their heat transfer performances must be good enough to meet heating or cooling air conditioning demands, but also the stress changes caused by intermittent heat extraction and release alternatively from and to the soil surroundings should not endanger the stability of building structures above. To reveal the thermo-mechanical characteristics of energy piles sufficiently, the software of Comsol and Abaqus were implemented jointly to establish a threedimensional dynamic numerical simulation model for an energy pile with double-U pipes buried in parallel.Simulation results were validated by the data obtained during an in-situ test. Dynamic temperature distributions inside pile body, axial force distributions and the displacement of the pile body were analyzed. The heat transfer performances and mechanical characteristics of four energy piles in different ratios of pile length-to-diameter with double-U pipes buried in parallel were studied under the conditions of different water flow rates, as well as those of energy piles with three different forms of buried pipes. The results show that the influence of the form of the buried pipes and that of the length-to-diameter ratio of the pile on their heat transfer and mechanical performance are significant, and the influence of the flow velocity is weak. The larger the length-diameter ratio and the flow velocity,the greater the heat transfer capacity, the larger the temperature difference between the inlet and outlet water. And the additional pile axial forces, pile top displacements and side frictional resistances caused by temperature changes increase as well accordingly.
Pile-based borehole heat exchangers(energy piles) can be used as terminal heat transfer devices for ground source heat pumps, playing the role of conventional pile foundations at the same time. Thus, not only their heat transfer performances must be good enough to meet heating or cooling air conditioning demands, but also the stress changes caused by intermittent heat extraction and release alternatively from and to the soil surroundings should not endanger the stability of building structures above. To reveal the thermo-mechanical characteristics of energy piles sufficiently, the software of Comsol and Abaqus were implemented jointly to establish a threedimensional dynamic numerical simulation model for an energy pile with double-U pipes buried in parallel.Simulation results were validated by the data obtained during an in-situ test. Dynamic temperature distributions inside pile body, axial force distributions and the displacement of the pile body were analyzed. The heat transfer performances and mechanical characteristics of four energy piles in different ratios of pile length-to-diameter with double-U pipes buried in parallel were studied under the conditions of different water flow rates, as well as those of energy piles with three different forms of buried pipes. The results show that the influence of the form of the buried pipes and that of the length-to-diameter ratio of the pile on their heat transfer and mechanical performance are significant, and the influence of the flow velocity is weak. The larger the length-diameter ratio and the flow velocity,the greater the heat transfer capacity, the larger the temperature difference between the inlet and outlet water. And the additional pile axial forces, pile top displacements and side frictional resistances caused by temperature changes increase as well accordingly.
引文
[1]Morino K,Oka T.Study on heat exchanged in soil by circylating water in a steel pile[J].Energy and Buildings,1994,21(1):65-78.
[2]Donna A D,Loria A F R,Laloui L.Numerical study of the response of a group of energy piles under different combinations of thermo-mechanical loads[J].Computers&Geotechnics,2016,72:126-142.
[3]Murphy K D,Mccartney J S,Henry K S.Evaluation of thermomechanical and thermal behavior of full-scale energy foundations[J].Acta Geotechnica,2015,10(2):179-195.
[4]Cecinato F,Loveridge F A.Influences on the thermal efficiency of energy piles[J].Energy,2015,82:1021-1033.
[5]Zhao Q,Chen B,Liu F.Study on the thermal performance of several types of energy pile ground heat exchangers:U-shaped,W-shaped and spiral-shaped[J].Energy&Buildings,2016,133:335-344.
[6]Park S,Lee D,Choi H J,et al.Relative constructability and thermal performance of cast-in-place concrete energy pile:coiltype GHEX(ground heat exchanger)[J].Energy,2015,81:56-66.
[7]Zarrella A,Carli M D,Galgaro A.Thermal performance of two types of energy foundation pile:helical pipe and triple U-tube[J].Applied Thermal Engineering,2013,61(2):301-310.
[8]Xin L I,Fang L,Fang Z H,et al.Coil heat source model for embedded spiral tube-based geothermal heat exchangers and its analytical solutions[J].Journal of Engineering for Thermal Energy&Power,2011,26(4):475-345.
[9]Faizal M,Bouazza A,Rao M S.Heat transfer enhancement of geothermal energy piles[J].Renewable&Sustainable Energy Reviews,2016,57:16-33.
[10]赵海丰,桂树强,李强,等.螺旋型埋管能源桩桩内温度场分布特征及其影响因素分析[J].长江科学院院报,2017,34(8):153-158.Zhao H F,Gui S Q,Li Q,et al.Analysis of temperature field distribution characteristics and influencing factors in spiral buried energy piles[J].Journal of Yangtze River Scientific Research Institute,2017,34(8):153-158.
[11]Eskilson P.Thermal analysis of heat extraction boreholes[D].Lund,Sweden:Lund University,1987.
[12]Cui P,Li X,Man Y,et al.Heat transfer analysis of pile geothermal heat exchangers with spiral coils[J].Apply Energy,2011,88(11):4113-4119.
[13]Selamat S,Miyara A,Kariya K.Numerical study of horizontal ground heat exchangers for design optimization[J].Renewable Energy,2016,95:561-573.
[14]Cane R L D,Forgas D A.Modeling of GSHP performance[J].ASHRAE Trans.,1991,97(1):909-925.
[15]Dia N R,Cui P,Liu J H,et a1.R&D of the ground-coupled heat pump technology in China[J].Frontiers of Energy and Power Engineering in China,2010,4(1):47-54.
[16]Zhang W K,Yang H X,Lu L,et al.Investigation on heat transfer around buried coils of pile foundation heat exchangers for groundcoupled heat pump applications[J].International Journal of Heat and Mass Transfer,2012,55(21/22):6023-6031.
[17]Wang C L,Liu H L,Kong G Q,et al.Different types of energy piles with heating-cooling cycles[J].Geotechnical Engineering,2017,170(3):1-12.
[18]Gashti E H N,MalasKa M,Kujala K.Evaluation of thermomechanical behaviour of composite energy piles during heating/cooling operations[J].Engineering Structures,2014,75(2):363-373.
[19]赵强.螺旋埋管能量桩换热器的传热研究[D].济南:山东大学,2018.Zhao Q.Study on heat transfer of spiral buried energy pile heat exchanger[D].Jinan:Shandong University,2018.
[20]杨涛,花永盛,刘律智.悬浮能量桩热-力学基本特性的数值模拟[J].防灾减灾工程学报,2017,(4):518-524.Yang T,Hua Y S,Liu L Z.Numerical simulation of the basic characteristics of thermal-mechanical properties of suspended energy piles[J].Journal of Disaster Prevention and Mitigation Engineering,2017,(4):518-524.
[21]Brandl H.Energy foundations and thermo-active ground structures[J].Geotechnique.2006,56(2):81-122.
[22]Yuan L C,Jie Z,Fan R M.Techno-economic evaluation of multiple energy piles for a ground-coupled heat pump system[J].Energy Conversion and Management,2018,178:200-216.
[23]Lazaros A,Paul C,Georgios F.A review of the design aspects of ground heat exchangers[J].Renewable and Sustainable Energy Reviews,2018,92:753-773.
[24]黄旭,孔纲强,刘汉龙,等.不封底PCC能量桩与传统能量桩换热效率对比研究[J].防灾减灾工程学报,2018,38(5):867-873.Huang X,Kong G Q,Liu H L,et al.Comparative study on heat transfer efficiency between PCC energy piles and traditional energy piles without sealing[J].Journal of Disaster Prevention and Mitigation Engineering,2018,38(5):867-873.
[25]Laloui L,Moreni M,Vulliet L.Comportement d'un pieu bifonction,fondation etéchangeur de chaleur[J].Canadian Geotechnical Journal,2003,40(2):388-402(15).
[26]Bourne-Webb P G,Amatya B,Soga K,et al.Energy pile test at Lambeth College,London:geotechnical and thermodynamic aspects of pile response to heat cycles[J].Geotechnique,2009,59(3):237-248.
[27]桂树强,程晓辉.能源桩换热过程中结构响应原位试验研究[J].岩土工程学报,2014,36(6):1087-1094.Gui S Q,Cheng X H.In-situ experimental study on structural response of energy piles during heat transfer[J].Chinese Journal of Geotechnical Engineering,2014,36(6):1087-1094.
[28]Go G H,Lee S R,Yoon S,et al.Design of spiral coil PHC energy pile considering effective borehole thermal resistance and groundwater advection effects[J].Applied Energy,2014,125:165-178.
[29]王成龙,刘汉龙,孔纲强,等.不同埋管形式下能量桩热力学特性模型试验研究[J].工程力学,2017,34(1):85-91.Wang C L,Liu H L,Kong G Q,et al.Model test study on thermodynamic characteristics of energy piles under different buried pipes[J].Engineering Mechanics,2017,34(1):85-91.
[30]Batini N,Loria A F R,Conti P,et al.Energy and geotechnical behaviour of energy piles for different design solutions[J].Applied Thermal Engineering,2015,86:199-213.
[2]Donna A D,Loria A F R,Laloui L.Numerical study of the response of a group of energy piles under different combinations of thermo-mechanical loads[J].Computers&Geotechnics,2016,72:126-142.
[3]Murphy K D,Mccartney J S,Henry K S.Evaluation of thermomechanical and thermal behavior of full-scale energy foundations[J].Acta Geotechnica,2015,10(2):179-195.
[4]Cecinato F,Loveridge F A.Influences on the thermal efficiency of energy piles[J].Energy,2015,82:1021-1033.
[5]Zhao Q,Chen B,Liu F.Study on the thermal performance of several types of energy pile ground heat exchangers:U-shaped,W-shaped and spiral-shaped[J].Energy&Buildings,2016,133:335-344.
[6]Park S,Lee D,Choi H J,et al.Relative constructability and thermal performance of cast-in-place concrete energy pile:coiltype GHEX(ground heat exchanger)[J].Energy,2015,81:56-66.
[7]Zarrella A,Carli M D,Galgaro A.Thermal performance of two types of energy foundation pile:helical pipe and triple U-tube[J].Applied Thermal Engineering,2013,61(2):301-310.
[8]Xin L I,Fang L,Fang Z H,et al.Coil heat source model for embedded spiral tube-based geothermal heat exchangers and its analytical solutions[J].Journal of Engineering for Thermal Energy&Power,2011,26(4):475-345.
[9]Faizal M,Bouazza A,Rao M S.Heat transfer enhancement of geothermal energy piles[J].Renewable&Sustainable Energy Reviews,2016,57:16-33.
[10]赵海丰,桂树强,李强,等.螺旋型埋管能源桩桩内温度场分布特征及其影响因素分析[J].长江科学院院报,2017,34(8):153-158.Zhao H F,Gui S Q,Li Q,et al.Analysis of temperature field distribution characteristics and influencing factors in spiral buried energy piles[J].Journal of Yangtze River Scientific Research Institute,2017,34(8):153-158.
[11]Eskilson P.Thermal analysis of heat extraction boreholes[D].Lund,Sweden:Lund University,1987.
[12]Cui P,Li X,Man Y,et al.Heat transfer analysis of pile geothermal heat exchangers with spiral coils[J].Apply Energy,2011,88(11):4113-4119.
[13]Selamat S,Miyara A,Kariya K.Numerical study of horizontal ground heat exchangers for design optimization[J].Renewable Energy,2016,95:561-573.
[14]Cane R L D,Forgas D A.Modeling of GSHP performance[J].ASHRAE Trans.,1991,97(1):909-925.
[15]Dia N R,Cui P,Liu J H,et a1.R&D of the ground-coupled heat pump technology in China[J].Frontiers of Energy and Power Engineering in China,2010,4(1):47-54.
[16]Zhang W K,Yang H X,Lu L,et al.Investigation on heat transfer around buried coils of pile foundation heat exchangers for groundcoupled heat pump applications[J].International Journal of Heat and Mass Transfer,2012,55(21/22):6023-6031.
[17]Wang C L,Liu H L,Kong G Q,et al.Different types of energy piles with heating-cooling cycles[J].Geotechnical Engineering,2017,170(3):1-12.
[18]Gashti E H N,MalasKa M,Kujala K.Evaluation of thermomechanical behaviour of composite energy piles during heating/cooling operations[J].Engineering Structures,2014,75(2):363-373.
[19]赵强.螺旋埋管能量桩换热器的传热研究[D].济南:山东大学,2018.Zhao Q.Study on heat transfer of spiral buried energy pile heat exchanger[D].Jinan:Shandong University,2018.
[20]杨涛,花永盛,刘律智.悬浮能量桩热-力学基本特性的数值模拟[J].防灾减灾工程学报,2017,(4):518-524.Yang T,Hua Y S,Liu L Z.Numerical simulation of the basic characteristics of thermal-mechanical properties of suspended energy piles[J].Journal of Disaster Prevention and Mitigation Engineering,2017,(4):518-524.
[21]Brandl H.Energy foundations and thermo-active ground structures[J].Geotechnique.2006,56(2):81-122.
[22]Yuan L C,Jie Z,Fan R M.Techno-economic evaluation of multiple energy piles for a ground-coupled heat pump system[J].Energy Conversion and Management,2018,178:200-216.
[23]Lazaros A,Paul C,Georgios F.A review of the design aspects of ground heat exchangers[J].Renewable and Sustainable Energy Reviews,2018,92:753-773.
[24]黄旭,孔纲强,刘汉龙,等.不封底PCC能量桩与传统能量桩换热效率对比研究[J].防灾减灾工程学报,2018,38(5):867-873.Huang X,Kong G Q,Liu H L,et al.Comparative study on heat transfer efficiency between PCC energy piles and traditional energy piles without sealing[J].Journal of Disaster Prevention and Mitigation Engineering,2018,38(5):867-873.
[25]Laloui L,Moreni M,Vulliet L.Comportement d'un pieu bifonction,fondation etéchangeur de chaleur[J].Canadian Geotechnical Journal,2003,40(2):388-402(15).
[26]Bourne-Webb P G,Amatya B,Soga K,et al.Energy pile test at Lambeth College,London:geotechnical and thermodynamic aspects of pile response to heat cycles[J].Geotechnique,2009,59(3):237-248.
[27]桂树强,程晓辉.能源桩换热过程中结构响应原位试验研究[J].岩土工程学报,2014,36(6):1087-1094.Gui S Q,Cheng X H.In-situ experimental study on structural response of energy piles during heat transfer[J].Chinese Journal of Geotechnical Engineering,2014,36(6):1087-1094.
[28]Go G H,Lee S R,Yoon S,et al.Design of spiral coil PHC energy pile considering effective borehole thermal resistance and groundwater advection effects[J].Applied Energy,2014,125:165-178.
[29]王成龙,刘汉龙,孔纲强,等.不同埋管形式下能量桩热力学特性模型试验研究[J].工程力学,2017,34(1):85-91.Wang C L,Liu H L,Kong G Q,et al.Model test study on thermodynamic characteristics of energy piles under different buried pipes[J].Engineering Mechanics,2017,34(1):85-91.
[30]Batini N,Loria A F R,Conti P,et al.Energy and geotechnical behaviour of energy piles for different design solutions[J].Applied Thermal Engineering,2015,86:199-213.