A theoretical investigation is presented about a double evaporator ejector refrigeration cycle(DEERC).Special attention is paid to take into account the influence of the sub-cooling and superheating effects induced by...A theoretical investigation is presented about a double evaporator ejector refrigeration cycle(DEERC).Special attention is paid to take into account the influence of the sub-cooling and superheating effects induced by an internal heat exchanger(IHX).The ejector is introduced into the baseline cycle in order to mitigate the throttling process losses and increase the compressor suction pressure.Moreover,the IHX has the structure of a concentric counter-flow type heat exchanger and is intentionally used to ensure that the fluid at the compressor inlet is vapor.To assess accurately the influence of the IHX on the DEERC performance,a mathematical model is derived in the frame of the dominant one-dimensional theory for ejectors.The model also accounts for the friction effect in the ejector mixing section.The equations of this model are solved using an Engineering Equation Solver(EES)for different fluids.These are:R134a as baseline fluid and other environment friendly refrigerants used for comparison,namely,R1234yf,R1234ze,R600,R600a,R290,R717 and R1270.The simulation results show that the DEERC with an IHX can achieve COP(the coefficient of performance)improvements from 5.2 until 10%.展开更多
汽车空调系统(Heating ventilating air condition)主要是为车内提供制冷、制热、通风等功能,其构成包含压缩机、空调管路、冷凝器、空调箱、空调风道等组件。膨胀阀(安装在空调箱内)、空调管路(制冷剂运输媒介)是影响汽车空调制冷性能...汽车空调系统(Heating ventilating air condition)主要是为车内提供制冷、制热、通风等功能,其构成包含压缩机、空调管路、冷凝器、空调箱、空调风道等组件。膨胀阀(安装在空调箱内)、空调管路(制冷剂运输媒介)是影响汽车空调制冷性能的两个最大因素,体现在膨胀阀限制流过蒸发器的制冷剂流量,空调管路运输制冷剂到各个空调部件,以此达到制冷剂通过管路进入蒸发器与空气换热给乘员舱带来冷量的目的,降低了乘员舱内温度,两者相互协同作用促使空调系统在乘员舱内快速降温。展开更多
国产镍基高温合金GH3128在高温下具有良好的强度,有望成为超高温气冷堆(very high temperature reactor,VHTR)核心部件中间换热器(intermediate heat exchanger,IHX)的主要结构材料。该文针对美国机械工程师协会(American Society of Me...国产镍基高温合金GH3128在高温下具有良好的强度,有望成为超高温气冷堆(very high temperature reactor,VHTR)核心部件中间换热器(intermediate heat exchanger,IHX)的主要结构材料。该文针对美国机械工程师协会(American Society of Mechanical Engineers,ASME)标准应用于GH3128时无法在全温度段得到一致可靠设计余量的不足,采用正态分布直接计算的方法,通过整体多项式、分段多项式以及分段指数这3种拟合方式,对拉伸性能设计许用值进行了计算。分析结果表明:针对现有的GH3128拉伸性能数据,应分别采用分段多项式拟合及分段指数拟合来求抗拉强度和屈服强度的设计许用值,并且这种方法给出的设计许用值曲线可以在全温度区间给出一致可靠的设计余量,可作为超高温气冷堆中间换热器结构设计的参考依据。展开更多
文摘A theoretical investigation is presented about a double evaporator ejector refrigeration cycle(DEERC).Special attention is paid to take into account the influence of the sub-cooling and superheating effects induced by an internal heat exchanger(IHX).The ejector is introduced into the baseline cycle in order to mitigate the throttling process losses and increase the compressor suction pressure.Moreover,the IHX has the structure of a concentric counter-flow type heat exchanger and is intentionally used to ensure that the fluid at the compressor inlet is vapor.To assess accurately the influence of the IHX on the DEERC performance,a mathematical model is derived in the frame of the dominant one-dimensional theory for ejectors.The model also accounts for the friction effect in the ejector mixing section.The equations of this model are solved using an Engineering Equation Solver(EES)for different fluids.These are:R134a as baseline fluid and other environment friendly refrigerants used for comparison,namely,R1234yf,R1234ze,R600,R600a,R290,R717 and R1270.The simulation results show that the DEERC with an IHX can achieve COP(the coefficient of performance)improvements from 5.2 until 10%.
文摘汽车空调系统(Heating ventilating air condition)主要是为车内提供制冷、制热、通风等功能,其构成包含压缩机、空调管路、冷凝器、空调箱、空调风道等组件。膨胀阀(安装在空调箱内)、空调管路(制冷剂运输媒介)是影响汽车空调制冷性能的两个最大因素,体现在膨胀阀限制流过蒸发器的制冷剂流量,空调管路运输制冷剂到各个空调部件,以此达到制冷剂通过管路进入蒸发器与空气换热给乘员舱带来冷量的目的,降低了乘员舱内温度,两者相互协同作用促使空调系统在乘员舱内快速降温。
文摘国产镍基高温合金GH3128在高温下具有良好的强度,有望成为超高温气冷堆(very high temperature reactor,VHTR)核心部件中间换热器(intermediate heat exchanger,IHX)的主要结构材料。该文针对美国机械工程师协会(American Society of Mechanical Engineers,ASME)标准应用于GH3128时无法在全温度段得到一致可靠设计余量的不足,采用正态分布直接计算的方法,通过整体多项式、分段多项式以及分段指数这3种拟合方式,对拉伸性能设计许用值进行了计算。分析结果表明:针对现有的GH3128拉伸性能数据,应分别采用分段多项式拟合及分段指数拟合来求抗拉强度和屈服强度的设计许用值,并且这种方法给出的设计许用值曲线可以在全温度区间给出一致可靠的设计余量,可作为超高温气冷堆中间换热器结构设计的参考依据。
