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针对一种以生活浊水为热源的热泵热水器的启动性能进行试验研究,得出了启动过程中压缩机吸排气压力、蒸发器过热度、热泵制热量、COP等机组主要性能参数随时间的变化规律.试验结果分析表明:系统启动时由于压缩机转速突然增大和膨胀阀调节的滞后性,导致蒸发压力急剧下降,冷凝压力急剧上升,过热度迅速增大;受换热系数及传热温差的影响,启动阶段系统吸热量和制热量都比较低;从系统启动特性曲线可以看出系统启动时间较短,系统设计合理. 相似文献
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提出了一种新型热泵热水器机组,利用浴室排风余热作为热源,通过热泵循环提高其能源品位后用于加热生活用水,并对其动态性能进行了实验研究.排风余热回收型热泵热水器全套装置全部置于室内,避免了空气源热泵机组在冬季工况下运行时室外换热器的结霜问题及热泵系统一年四季工况变化造成的压缩机压比过大、系统性能系数(COP)降低等问题,可在任何外界气候条件下高效稳定工作,且对浴室环境温度没有影响.实验结果表明,实验热泵热水器样机可在45 min内将85 kg水从18 ℃加热至出水温度50 ℃;当水箱出水温度在33~40 ℃时性能系数达到最大值为3.4,整个加热过程中的平均性能系数为3.15,平均耗功率为800 W.同时,实验发现冷凝盘管制冷剂上进下出布置方式可使水箱中水温产生严重的分层效应,从而产生较大的制冷剂过冷度,对于实验样机最大过冷度可达28 ℃. 相似文献
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介绍了一种新型商用跨临界CO2循环压缩机,并对此压缩机的关键部件,如壳体和连杆的设计及其应力分布进行分析,同时对压缩机内的油路进行设计,保证压缩机内油压平衡.在自行设计的跨临界CO2压缩机性能测试试验台对跨临界CO2压缩机及其热泵系统进行了系列实验研究,根据实验数据拟合出压缩机的等熵效率和容积效率公式.研究结果表明,在吸气压力为4.0 MPa,气冷器排气温度为25℃工况时,压缩机制热量在58~65 kW之间,制冷量在49~52 kW之间.跨临界CO2热泵系统在按照"一次加热"方式进行实验时,名义工况下出水温度分别为55℃和85℃时,热泵系统制热系数COPh分别为3.46和2.82.系统性能系数随着气体冷却器出水温度的升高而降低,但却随着蒸发器进水温度的升高而升高.冷却水进水温度越高,热泵系统效率越低,因此热泵热水器系统更适于"一次加热"供水系统. 相似文献
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对R410a直流变频和定频热泵热水器进行了性能试验研究,并对两系统的性能进行了比较分析.结果表明:在环境温度22℃、进水温度20℃、出水温度50℃,充满容量为200L的储水桶进行静态加热时,变频系统和定频系统的加热时间分别是31、37 min,变频系统的加热时间比定频系统缩短了19.4%,而且与定频系统相比,变频系统的COP提高了4.2%.同时发现,变频系统和定频系统的排气温度分别在水温25℃和45℃以上时维持在70℃以上.另外,定频系统的最高排气压力达3.7MPa,由于变频系统以较低频率运行,其最高排气压力为3.5MPa. 相似文献
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中高温热泵系统中在工业领域有广泛的应用,但其排气温度偏高。本文从降低压缩机排气温度角度,设计一种双级压缩新型热泵系统。系统由高低级压缩机、分凝器、两个节流机构等组成。以循环性能较好的两种工质R134a和R152a为系统循环工质,理论分析结果表明:在中高温工况下,新系统工质R152a循环性能系数COP优于R134a,在相同工况下工质R152a循环性能COP比R134a高7%8%;高温级压缩机排气温度均随中间压比的升高而降低;排气温度与传统单级压缩系统相比有38%;高温级压缩机排气温度均随中间压比的升高而降低;排气温度与传统单级压缩系统相比有312℃的降幅。 相似文献
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为了研究压缩机频率对复叠式热泵系统的影响,结合复叠式循环技术与压缩机变频技术,搭建变高温压缩机频率复叠热泵实验台。研究分析了压缩机排气温度、压缩机功率、系统制热量及系统COP(以下COP均指系统COP)随高温压缩机频率的变化,试验结果表明:当蒸发温度-30 ℃,冷凝温度46 ℃工况下,随高温压缩机频率增加,高温压缩机排气温度上升,上升速度逐渐加快,最高排气温度99.7 ℃,小于120 ℃,低温压缩机排气温度下降,下降速度逐渐缓慢;高温压缩机功率逐渐增大,低温压缩机功率逐渐减小,系统功率呈增加趋势;系统制热量呈线性增加趋势,COP随高温压缩机频率增加呈先增加后减小趋势,最大COP为2.7。 相似文献
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基于搭建的电动汽车热泵空调系统性能试验台,详细研究了EXV开度变化对系统的冷凝和蒸发压力、过冷度、热泵出风温度、制热量、压缩机功耗和性能系数COP的影响。结果表明:在压缩机转速、冷凝器进风温度和风量一定的条件下,随着EXV开度增加,冷凝压力减小而蒸发压力变化较小,过冷度、制热量和热泵出风温度均呈减小并当EXV开度增大到一定程度后减小幅度变缓,压缩机功耗先减小后基本维持不变,系统COP先增大后减小;冷凝器出口过冷度较大时,通过改变EXV开度可有效调节热泵出风温度,且在开度较小时增大EXV开度有利于获得较高的COP。研究结果可为纯电动汽车热泵空调系统性能的调节和控制策略制定提供参考。 相似文献
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Jeong Ji Hwan Park Sang-Goo Sarker Debasish Chang Keun Sun 《Journal of Mechanical Science and Technology》2012,26(4):1213-1226
Most modern refrigerators incorporate heat transfer between the refrigerant in a capillary tube and the refrigerant in a suction
line. This heat transfer is achieved by a non-adiabatic capillary tube called a capillary tube-suction line heat exchanger
and is supposed to improve the performance of the small vapor compression refrigeration cycle by removing some enthalpy of
the refrigerant at the evaporator entrance. To investigate the effects of this heat transfer on the refrigeration cycle, a
computer program was developed based on conservation equations of mass, momentum, and energy. The non-adiabatic capillary
tube model is based on a homogeneous two-phase flow model. The simulation results show that both the location and length of
the heat exchange section influence the coefficient of performance (COP) as well as the cooling capacity. It is noteworthy
that the influence was not monotonic; that is, the performance may be deteriorated under certain conditions. 相似文献
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变径毛细管在正向流动和反向流动时其制冷剂流量特性不同,因而可以作为节流元件代替现有冷暖空调器中使用的毛细管组件。为实现这一目的,利用制冷剂流量试验台,先测定原毛细管组件制冷、制热时的制冷剂流量特性,然后通过调整变径毛细管规格尺寸,使变径毛细管制冷、制热时的流量特性与原毛细管组件基本一致,再安装在空调器整机上进行整机性能对比试验。试验表明,在标准工况下,新空调器与原空调器相比,其制冷量减少0.5%,制冷能效比增加0.3%,制热量减少1.1%,制热性能系数增加1.4%。因此可以得出,变径毛细管经过精确匹配,完全可以作为节流元件代替现有冷暖空调器中使用的毛细管组件。 相似文献
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毛细管辐射采暖热源方案技术经济分析 总被引:2,自引:0,他引:2
首先介绍毛细管辐射采暖地面和顶棚构造,并采用试验方法分析热泵机组供热性能,然后采用BIN法计算不同热源方案毛细管采暖系统能耗,分析其节能性;最后分析各热源方案的初投资和运行费用以及其对环境影响。通过研究得出:(1)地源热泵机组提供28~35℃的低温热水时的COP值与制取40~50℃热水相比大大提高,节能效果显著;(2)在冬季采暖总耗煤量方面,地源热泵系统最小,与风冷热泵、天然气燃气炉相比分别节省了32.9%、129%的耗煤量;(3)采用天燃气采暖炉为热源时,污染物排放量最少,对环境破坏最小;(4)从经济方面分析,风冷热泵冷热水机组是最优的热源方案。 相似文献
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The machine tool coolers are the best managers of coolant temperature in avoiding the deviation of spindle centerline for machine tools. However, the machine coolers are facing the compressed schedule to phase out the HCFC (hydro-chloro-floro-carbon) refrigerant and little attention has been paid to comparative study on sizing capillary tube for retrofitted HFC (hydro-floro-carbon) refrigerant. In this paper, the adiabatic flow in capillary tube is analyzed and modeled for retrofitting of HFC-407C refrigerant in a machine tool cooler system. A computer code including determining the length of sub-cooled flow region and the two phase region of capillary tube is developed. Comparative study of HCFC-22 and HFC-407C in a capillary tube is derived and conducted to simplify the traditional trial-and-error method of predicting the length of capillary tubes. Besides, experimental investigation is carried out by field tests to verify the simulation model and cooling performance of the machine tool cooler system. The results from the experiments reveal that the numerical model provides an effective approach to determine the performance data of capillary tube specific for retrofitting a HFC-407C machine tool cooler. The developed machine tool cooler system is not only directly compatible with new HFC-407C refrigerant, but can also perform a cost-effective temperature control specific for industrial machines. 相似文献
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This study focuses on the effect of outdoor coil fan speed on the performance variation of the heat pump system by adopting
the hot gas bypass method, and on the performance improvement with hot gas bypassing using the time step method to defrost.
Tests were conducted for fan speeds 90, 60 and 30% of the normal speed of the outdoor coil together with the stationary case.
Performance of the heat pump is compared with the conventional time step defrosting method for coefficient of performance
(COP) and total heat capacity. Results show that the integrated heating capacity with hot gas bypassing is highest at 60%
(780 rpm) of the fan speed and is 8.6% higher than that of the time step defrosting method. The averaged COP of the heat pump
in this case is higher by 3.8% than the time step defrosting method and 2.8% higher than that of the stationary fan. 相似文献