共查询到15条相似文献,搜索用时 31 毫秒
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运用当量温度概念对CO2跨临界水-水热泵供热系统进行了研究,指出根据实际情况选择气体冷却器的出口温度和压缩机的出口压力能提高系统的运行效率,并对供热过程中采用能量梯级利用进行了研究,结果表明对热水侧进行梯级利用可提高系统的制热性能系数。 相似文献
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在CO2跨临界循环系统中,节流损失相对较大。通过增加回热器的方法以提高跨临界CO2热泵系统的COP。根据相关的换热关联式对CO2热泵系统的回热器进行了设计计算并且进行了相关的实验研究。计算得到的回热器,长度为1.27 m,内管内径6 mm,外管内径13 mm,壁厚1 mm。并且在相同环境工况下,利用自行搭建的CO2热泵系统实验台,分别在有回热器与无回热器时进行了实验研究。实验结果表明:当系统引入回热器后,压缩机排气压力、温度上升,压缩机耗功上升速率加快,制热量增加速率亦加快,且制热量增加速率大于压缩机耗功增加速率,系统制热COP增加,带回热器时系统平均COP达到3.34,无回热器时系统平均COP为3.03,提高约10.2%。 相似文献
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提出了一套多功能CO2水源热泵驱动的溶液除湿新风系统,该系统以CO 2跨临界循环压缩机高温排气实现LiCl溶液再生,提高了热泵驱动溶液除湿系统的溶液再生效率,并以地下水为再冷源,减小了CO2跨临界循环节流损失.通过建立系统稳态数学模型,模拟分析了标准环境工况下,新风量、 除湿/再生内循环比、 溶液总流量、 再生空气流量等4个可控关键因素对系统性能的影响,并将系统应用于西安市某200 m2办公建筑,得到了4个可控参数设置的最佳组合. 相似文献
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In this study, a thermodynamic analysis on the performance of a transcritical cycle using azeotropic refrigerant mixtures of R32/R290 with mass fraction of 70/30 has been performed. The main purpose of this study is to theoretically verify the possibility of applying the chosen refrigerant mixture in small heat pumps for high temperature water heating applications. Performance evaluation has been carried out for a simple azeotropic mixture R32/R290 transcritical cycle by varying evaporator temperature, outlet temperature of gas cooler and compressor discharge pressure. Furthermore, the effects of an internal heat exchanger on the transcritical R32/R290 cycle have been presented at different operating conditions. The results show that high heating coefficient of performance (COPh) and volumetric heating capacity can be achieved by using this transcritical cycle. It is desirable to apply the chosen refrigerant mixture R32/R290 in small heat pump water heater for high temperature water heating applications, which may produce hot water with temperature up to 90 °C. 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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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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CO_2热泵与采用传统工质的热泵相比,具有低温适用性、环境友好性、设备紧凑、能够制取高温度热水等诸多优势。但是随着环境温度的降低,系统会出现排气温度升高、制热量下降等问题。通过对改进型单级压缩循环、双级压缩循环、准二级压缩循环、双极耦合系统、其他辅助加热方式的国内外研究现状进行对比分析,总结了各种循环方式主要的技术特点及不足,并提出了相关建议。这对于促进寒冷地区CO_2热泵系统的发展具有重要参考价值。 相似文献