电热水器能耗数值计算及保温性能优化分析
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摘要
电热水器中的能量传递过程主要包括电加热丝对内胆中水的加热过程,内胆中水的自然对流过程以及通过保温层的散热过程.本文采用多尺度数值模拟方法:用LBM确定保温材料导热系数作为基于连续介质的Fluent的输入数据,对发生在电热水器中的流动和耦合传热过程进行了数值模拟,并采用UDF来控制电加热丝的动态间歇加热工作过程,建立了模拟电热水器24 h固有能耗系数测试过程的数值模拟方法.采用该方法模拟得到的能耗系数与实验值符合良好,证明了该模型的准确性。同时模拟获得了电热水器中水在加热和散热阶段的流动特性、温度分布,以及各个区域的散热占比和热流密度。提出了优化电热水器保温隔热性能的判据,为电热水器保温结构的优化提供了依据.
In the electrically-heated water heater, several major energy transfer processes are involved: the heating process of the water, natural convection of the water and heat dissipation of the water through the insulation layer. In the present paper, multiscale numerical simulation was conducted to simulate the heat transfer and fluid flow in the water heater: LBM was adopted to predict the thermal conductivity of the porous media insulation layer which served as input data for Fluent in ANSYS Fluent. In addition, User Defined Function was developed to control the intermittent heating to the water. The energy consumption coefficients obtained by the simulations fit well with the experimental results. Fluid flow characteristics, temperature profile and heat dissipation distribution were also obtained to guide the optimization of the thermal insulation layer.
In the electrically-heated water heater, several major energy transfer processes are involved: the heating process of the water, natural convection of the water and heat dissipation of the water through the insulation layer. In the present paper, multiscale numerical simulation was conducted to simulate the heat transfer and fluid flow in the water heater: LBM was adopted to predict the thermal conductivity of the porous media insulation layer which served as input data for Fluent in ANSYS Fluent. In addition, User Defined Function was developed to control the intermittent heating to the water. The energy consumption coefficients obtained by the simulations fit well with the experimental results. Fluid flow characteristics, temperature profile and heat dissipation distribution were also obtained to guide the optimization of the thermal insulation layer.
引文
[1]中国国家标准化管理委员会.GB21519-2008储水式电热水器能效限定值及能效等级[S].北京:中国标准出版社,2008Standardization Administration of China.GB21519-2008Storage Type Electric Water Heaters Limited Values of Energy Efficiency and Rating Criteria[S].Beijing:Standards Press of China,2008
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[4]牛纪德,周遵凯,杨先亮.电热水器运行方式与能耗的理论分析[J].山西建筑,2012,38(26):213-214NIU Jide,ZHOU Zunkai,YANG Xianliang.Theoretical Analysis of Operation Mode of Electric Water Heaters and Energy Consumption[J].Shanxi Architecture,2012,38(26):213-214
[5]郑金玲,胡小芳,黄焕文.储水式电热水器的有限元能效分析[J].化工机械,2011,38(3):309 312ZHENG Jinling,HU Xiaofang,HUANG Huanwen.Finite Element Analysis of Energy Efficiency of Electric Water Heaters[J].Journal of Chemical Machinery,2011,38(3):309-312
[6]ANSYS FLUENT 14.0 Theory Guide.ANSYS Incorporated,USA,2011
[7]杨世铭,陶文铨.传热学[M].第4版.北京:高等教育出版社,2006YANG Shiming,TAO Wenquan.Heat Transfer[M].4~(th)Edition.Beijing:Higher Education Press,2006
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[9]陶文铨.数值传热学[M].第2版.西安:西安交通大学出版社,2001TAO Wenquan.Numerical Heat.Transfer[M].2~(nd)Edition.Xi'an:Xian Jiaotong University Press,2001
[2]董军.储水式电热水器能耗测试方法探讨[J].家电科技,2011(10):66-68DONG Jun.Study on Thermal Storage Type Electric Water Heaters Energy Consumption Test Methods[J].Science and Technology of Household Electric Appliance,2011(10):66-68
[3]Aguilar C,White D J,Ryan D L.Domestic Water Heating and Water Heater Energy Consumption in Canada[R].Canadian Building Energy End-Use Data and Analysis Centre,2005
[4]牛纪德,周遵凯,杨先亮.电热水器运行方式与能耗的理论分析[J].山西建筑,2012,38(26):213-214NIU Jide,ZHOU Zunkai,YANG Xianliang.Theoretical Analysis of Operation Mode of Electric Water Heaters and Energy Consumption[J].Shanxi Architecture,2012,38(26):213-214
[5]郑金玲,胡小芳,黄焕文.储水式电热水器的有限元能效分析[J].化工机械,2011,38(3):309 312ZHENG Jinling,HU Xiaofang,HUANG Huanwen.Finite Element Analysis of Energy Efficiency of Electric Water Heaters[J].Journal of Chemical Machinery,2011,38(3):309-312
[6]ANSYS FLUENT 14.0 Theory Guide.ANSYS Incorporated,USA,2011
[7]杨世铭,陶文铨.传热学[M].第4版.北京:高等教育出版社,2006YANG Shiming,TAO Wenquan.Heat Transfer[M].4~(th)Edition.Beijing:Higher Education Press,2006
[8]He Y L,Tao WQ.Multiscale Simulation of Heat Transfer and Fluid Flow Problems[J].ASME J Heat Transfer,2012,134:031018
[9]陶文铨.数值传热学[M].第2版.西安:西安交通大学出版社,2001TAO Wenquan.Numerical Heat.Transfer[M].2~(nd)Edition.Xi'an:Xian Jiaotong University Press,2001