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In this paper, a new refrigeration cycle (NRC) using the binary non-azeotropic refrigerant mixture R32/R134a is presented, which can be an alternative refrigeration cycle applied in residential air-conditioner. In the NRC, refrigerant circuit of the evaporator is separated into two branches. Because the non-azeotropic mixture has the characteristic of temperature glide, an important benefit of such configuration is that the Lorentz cycle can be realized. Compared with that of conventional cycle configuration, the new cycle efficiency can be improved. The calculating results show that, in the conventional refrigeration cycle (CRC), the mixture R32/R134a has a close performance to that is obtainable with pure refrigerant R22. However, the mixture R32/R134a in the NRC will result in a better performance. The maximal COP can be improved in a range of 8–9% over that of the CRC, and the volumetric refrigerating capacity can be approximately increased by 9.5%. 相似文献
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This study presents a novel vapor compression heat pump cycle in which an ejector associated with a subcooler is applied to enhance the heating performance for air-source heat pump water heater application. The heating coefficient of performance (COPh) and heating capacity of the novel cycle using the non-azeotropic mixture refrigerant R417A are theoretically investigated, for the ranges of evaporating temperature (−15 to 10 °C) and condensing temperature (55-60 °C). The theoretical results show that the COPh and volumetric heating capacity of the novel cycle are better than that of the conventional heat pump cycle. It is found that for the operating conditions considered, the maximum COPh and volumetric heating capacity can be improved by up to 1.62-6.92% and 15.20-37.32% over the conventional heat pump cycle, respectively. The performance characteristics of the novel cycle show its promise in air-source heat pump water heater applications. 相似文献
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《Energy and Buildings》2004,36(7):690-695
A combined air conditioning and tap water heating plant using carbon dioxide (CO2) as refrigerant has been investigated theoretically and experimentally. The system is suitable for countries with year around cooling demand, such as Indonesia or Singapore, and a need for hot tap water. A unique CO2 transcritical cycle characteristic for heating process can afford an improvement to a CO2 air conditioning system when rejected heat from the system is recovered. Some parameters affecting performance of the combined system are discussed. 相似文献
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为探讨热泵型空调器更换R290后的供暖特性,在重庆地区开展了供暖工况下充注R290空调器与原R22空调器的对比实验,测试了空调器的送回风温湿度、耗电量、风量等数据。研究了两组空调器的送回风温湿度差异及与室外温度变化的关系,比较了2台空调供热量、耗电功率及COP等数据。结果表明:在重庆地区热泵型空调中替代充注R290后,空调器制热效果良好,室内空气温湿度与原空调器处理的空气温湿度较为接近;但由于制冷剂质量流量减小,平均供热量降低14.6%;尽管COP整体降低了7.5%,但在运行稳定后COP能接近原空调器。 相似文献
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理论分析了R32作为空气源热泵热水器制冷剂的可行性,并设计搭建带有喷气增焓装置的实验系统,分别充注R32和R410A制冷剂进行性能对比测试。实验结果表明:对于本实验系统R410A的最佳充注量为1.4 kg,R32的最佳充注量比R410A减少约25%,且名义工况下R32热泵系统的COP要高出R410A热泵系统约4.2%;低温工况下,采用双级压缩系统的压缩比最高在3左右,有效缓解了常规热泵系统低温工况下压缩比过高的问题;低温工况下,R32热泵系统的COP明显高于R410A热泵系统。 相似文献
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ABSTRACTThe thermodynamic analysis has been presented in this article using nitrous oxide as the refrigerant in a two-stage transcritical cycle with the vortex tube (TSTCVT) instead of the expansion valve and its results are compared with the two-stage transcritical cycle with the expansion valve (TSTCEV). The evaporator and the gas cooler temperature ranges in both the cycles have been considered between ?55°C to 5°C and 35°C to 60°C for the analysis. Gas cooler and intercooler pressures are simultaneously optimised to obtain the maximum cooling coefficient of performance (COP). The COP of the TSTCVT improves by 1.97–27.19% in comparison to TSTCEV. A decrease in evaporator temperature and an increase in gas cooler exit temperature reduce the COP of TSTCVT. The comparison of refrigerants N2O and CO2 in TSTCVT shows that N2O exhibits higher cooling COP, higher second law of efficiency and lower optimum gas cooler pressure under the considered operating conditions. 相似文献
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The application of nano-fluids in refrigerating systems is considered to be a potential way to improve the energy efficiency and reliability of HVAC&R facilities and to make economic the use of environment-friendly refrigerants. In this paper, we report a method that uses nanoparticles to enhance the energy efficiency of retrofitted residential air conditioners (RAC) employing HFCs as alternative refrigerants. The reliability and performance of RAC with nanoparticles in the working fluid have been investigated experimentally. A new mineral-based nano-refrigeration oil (MNRO), formed by blending some nanoparticles (NiFe2O4) into naphthene based oil B32, was employed in the RAC using R410a as refrigerant. A method showing how to disperse the NiFe2O4 nanoparticles in the mineral oil refrigeration lubricants is presented together with an investigation of their stability. The solubilities of the new MNRO in R134a, R407C, R410a and R425a were measured. The performances of the RAC, such as the cooling/heating capacity, the power input and the energy efficiency ratio, were determined. The results indicate that the mixture of R410a/MNRO works normally in the RAC. The cooling/heating EER of the RAC increased about 6% by replacing the Polyol-Easter oil VG 32 lubricant with MNRO. 相似文献
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将具有燃爆性制冷剂R290(丙烷)分别与物理抑制剂CO2和化学抑制剂R13I1(三氟碘甲烷)混合,根据混合制冷剂的热物性参数确定R290的占比。实验结果表明:R13I1与R290组成的混合工质可直接替代传统制冷剂,根据所要替代的现有制冷剂的热物性参数可确定配比。用可燃气体/蒸气爆炸试验测试装置测试R290分别与CO2和R13I1混合后的爆炸参数,实验得出CO2和R13I1环境下,二者的体积分数分别为26.5%和6.42%时,R290不再具有燃爆性。同时,针对R290,推导出化学抑制剂最小惰化浓度的预测理论公式。 相似文献
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In recent years, global warming has reached critical levels and this has caused a gradual decrease in the use of refrigerants. In the 1997 Kyoto Conference, it was announced that after 2011, use of refrigerants which have higher global warming potential (GWP) of 150 will be restricted. Hence, it was foreseen that R410A, with a GWP of 2088, which has been used in residential heating, ventilating and air conditioning systems, will be prohibited in the near future. This study investigates the thermodynamic performance using R32, which is a potential alternative because of its low GWP, and R410A in variable refrigerant flow (VRF) systems. As a result of theoretical analysis, it was observed that the coefficient of performance of R32 is 5% higher in heating mode and 6% higher in cooling mode than that of R410A. Considering all of this, it was confirmed that R32 can be used in VRF systems as a replacement for R410A in terms of performance. 相似文献
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The heat pump for simultaneous heating and cooling (HPS) carries out space heating, space cooling and hot water production
for small office and residential buildings. It works under heating, cooling and simultaneous modes to produce hot and chilled
water according to the thermal demand of the building. A subcooler connected to a water tank is placed after the condenser
to recover some energy by subcooling of the refrigerant during a heating mode. The water loop at a higher temperature than
ambient air is used subsequently as a source for a water evaporator. Average winter performance is improved compared to a
standard reversible heat pump (HP). The air evaporator is defrosted by a two-phase thermosiphon without stopping the heat
production. The operation of the HPS is modelled using TRNSYS software. The model is validated using results of an experimental
study carried out on a HPS prototype working with R407C. Annual simulations of the HPS coupled to a hotel are run in order
to evaluate annual performance and energy consumption of the system. The results are compared to the ones of a standard reversible
HP. Depending on the scenario, savings in electric energy consumption and annual performance improvement can reach respectively
55% and 19%. 相似文献
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选择对臭氧层无破坏作用的R32/R134a混合工质作为家用空调器工质R22的替代物,对其与润滑油的相溶性,可燃性等进行了实验研究,并对使用这种工质的压缩机,空调器进行了实验。 相似文献
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In the present study, vortex tube is used in transcritical vapour compression cycle as expansion device to improve the coefficient of performance (COP). The thermodynamic analysis has been performed using nitrous oxide in transcritical cycle with vortex tube (TCVT) and its results are compared with those of a transcritical cycle with expansion valve (TCEV). The evaporator and the gas cooler temperatures have been varied between ?55°C and 5°C and between 35°C and 60°C, respectively, for the analysis. The COP of the TCVT improves by 1.72–27.01% compared to TCEV. A decrease in evaporator temperature and an increase in gas cooler exit temperature result in a decrease in COP. The increase in cold mass fraction brings a negligible increase in maximum COP. The performance comparison of N2O and CO2 in TCVT shows that maximum cooling COP for N2O is higher than for CO2, but the optimum pressure required for N2O is lower than for CO2. 相似文献
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The article describes the economy of exploiting heat from low-temperature geothermal sources for high-temperature heating of buildings using a heat pump. For the exploitation of low-temperature geothermal sources, a two stage heat pump with a heat exchanger was planned. The pump consists of two single stage heat pumps which use different refrigerants at each stage. At stage 1, the calculation of the heat pump is conducted with refrigerant R407c; at stage 2 of the heat pump, the refrigerant R600a is used. The main operational characteristics of a two stage heat pump are presented in the form of diagrams. For the exploitation of heat from geothermal water with a temperature of 45 °C, a profitability evaluation of the investment in the heat pump was carried out, using the method of the net present value. In the research, also the coefficient of profitability and the period of time in which the investment is going to return itself were established. 相似文献