共查询到18条相似文献,搜索用时 78 毫秒
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压缩式热泵循环热力学分析方法 总被引:1,自引:0,他引:1
以热力学分析原理为基础,探讨了压缩式热泵的热力学评价方法,指出了传统热泵Yong分析方法存在的缺陷,提出了供Yong系数新概念,建立了全新的压缩式热泵热力学分析方法体系。 相似文献
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燃气机热泵变负荷特性的试验研究 总被引:4,自引:0,他引:4
燃气机热泵是一项高效节能技术,在试验条件下其一次能源利用率PER为1.13~1.79。为了解交负荷时燃气机热泵的性能,通过试验得到了燃气机热泵的发动机负荷特性、发动机余热回收和燃气机热泵的总体特性曲线。结果表明:随着发动机转速的增加,燃气机热泵的COP和PER是下降的,但下降的幅度较为平缓,且保持较高的数值。通过对IPL Vcop值的分析,发现燃气机热泵的IPL Vcop比热泵系统的大,这说明燃气机热泵的部分负荷性能好,可以很好地实现交负荷运行。 相似文献
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对压缩式热泵系统Yong效率的定义式进行了分析,指出了该定义式在实际应用过程中存在的一些不足。即当低温热源为环境时,此定义式合理,否则即使热泵系统内部可逆,系统大用效率仍不为1,文中对产生这一问题的原因进行了分析。以热泵系统的Yong平衡方程为依据,参照Yong效率定义方法及Yong效率的基本特征,对压缩式热泵的系统Yong效率进行了重新定义。通过对两个不违背Yong效率定义特征的表达式的对比分析,确定了热泵系统合理的Yong效率表达式。最后说明,在压缩式制冷系统中当高温热源不为环境时,Yong效率定义也存在同样缺陷,改进方法与本文类似。 相似文献
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水源热泵系统的热力学分析 总被引:3,自引:0,他引:3
本文通过对水源热泵系统进行热力学分析,既评价了水源热泵系统的能质利用和损失状况.又明确了系统能量损失的主要环节和程度,从而为进一步分析系统用能改进的技术措施提供指导。通过对一实例的分析,指出压缩机、蒸发器和冷凝器都是需要技术改进和进一步节能的部分。 相似文献
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燃气机热泵可以通过改变燃气机转速调节系统容量,系统容量的调节和压缩机转速的变化,需要电子膨胀阀调节制冷剂流量与之相匹配。采用实验方法建立蒸发器过热度模型,通过理论分析和实验测试,研究了燃气机热泵系统变转速调节和当过热度设定值改变时蒸发器过热度的控制策略。提出采用增益调度控制策略实现蒸发器过热度的控制,实验结果表明:改变燃气机转速时,过热度控制比较精确,波动范围在±0.5℃以内;过热度设定值改变时,最大超调量小于2℃,过热度响应速度快,具有很好的动态响应特性,达到稳态的时间不超过200 s。 相似文献
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A thermodynamic theory of exergy analysis for a stationary flow system having several heat inputs and outputs at different temperature levels is presented. As a new result a relevant reference temperature of the surroundings is derived for each case. Also a general formula which combines exergy analysis with a modified Carnot efficiency is derived. The results are illustrated by numerical examples for mechanical multi-circuit heat pump cycles, for a Brayton process and for an absorption heat pump. 相似文献
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In this study heat pump systems having different heat sources were investigated experimentally. Solar‐assisted heat pump (SAHP), ground source heat pump (GSHP) and air source heat pump (ASHP) systems for domestic heating were tested. Additionally, their combination systems, such as solar‐assisted‐ground source heat pump (SAGSHP), solar‐assisted‐air source heat pump (SAASHP) and ground–air source heat pump (GSASHP) were tested. All the heat pump systems were designed and constructed in a test room with 60 m2 floor area in Firat University, Elazig (38.41°N, 39.14°E), Turkey. In evaluating the efficiency of heat pump systems, the most commonly used measure is the energy or the first law efficiency, which is modified to a coefficient of performance for heat pump systems. However, for indicating the possibilities for thermodynamic improvement, inadequate energy analysis and exergy analysis are needed. This study presents an exergetic evaluation of SAHP, GSHP and ASHP and their combination systems. The exergy losses in each of the components of the heat pump systems are determined for average values of experimentally measured parameters. Exergy efficiency in each of the components of the heat pump systems is also determined to assess their performances. The coefficient of performance (COP) of the SAHP, GSHP and ASHP were obtained as 2.95, 2.44 and 2.33, whereas the exergy losses of the refrigerant subsystems were found to be 1.342, 1.705 and 1.942 kW, respectively. The COP of SAGSHP, SAASHP and GSASHP as multiple source heat pump systems were also determined to be 3.36, 2.90 and 2.14, whereas the exergy losses of the refrigerant subsystems were approximately 2.13, 2.996 and 3.113 kW, respectively. In addition, multiple source heat pump systems were compared with single source heat pump systems on the basis of the COP. Exergetic performance coefficient (EPC) is introduced and is applied to the heat pump systems having various heat sources. The results imply that the functional forms of the EPC and first law efficiency are different. Results show that Exloss,total becomes a minimum value when EPC has a maximum value. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Gas engine-driven heat pump (GEHP) is a heating and cooling system with the advantage of reducing the electric power in both heating and cooling modes of operation. 相似文献
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