共查询到20条相似文献,搜索用时 31 毫秒
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《Heat Recovery Systems and CHP》1990,10(3):177-185
A new absorption heat pump, using a mixture of three elements (ammonia-water-potassium hydroxide), is presented in this paper. The principal aim of the proposed machine is to solve practical problems which represent the most critical points of a traditional heat pump using ammonia-water system, i.e. high pressure and rectification of ammonia. For this new system, the general working scheme, the thermodynamic design data, its performance as a heat pump machine and a comparison with the ammonia-water absorption heat pump are presented. The research activity concerning this work has been supported by ENEA (Italy). 相似文献
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本文实验研究了回热器的回热率对跨临界CO2热泵系统性能的影响。结果表明:在一定压缩机频率下,随着排气压力的升高,系统制热量和COPh都存在最大值,并分别存在对应最大制热量和最大COPh的最优排气压力;在25Hz压缩机频率下,系统在低排气压力下运行时,引入回热器才能提高系统COPh,且引入回热器可在较低排气压力下,获得更高的系统COPh;在一定压缩机频率下,系统分别存在最大制热量、最高出水温度和最大COPh对应的最优回热率.在本实验条件下,如果以系统获得最大COPh为设计目标,系统回热率取15%左右为宜;如果以系统获得最高出水温度为设计目标,系统回热率取5%左右为宜。 相似文献
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《Heat Recovery Systems and CHP》1995,15(8):723-731
The cycle model of a heat-engine-driven heat pump is used to study the performance of an absorption heat pump affected by heat resistances. The coefficient of performance of the absorption heat pump is adopted to be the objective function for optimization. The optimal regions of the coefficient of performance and the specific heating load are determined. The optimal relations between the heat transfer areas of the four heat exchangers involved and the coefficient of performance, or the specific heating load of an absorption heat pump, are obtained. Problems concerning the optimal design of an absorption heat pump are also discussed. 相似文献
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有限时间热力学所得结果具有普适性,其研究结果已成为热物理学的一个重要基础.许多学者利用有限时间热力学方法对单级和多级正、反向两热源热力循环最优性能和最优构型进行了大量研究,获得了一些比经典热力学对于工程设计和优化更具有实际指导意义的新结论.综述了利用有限时间热力学理论对不同传热规律下单级和多级正、反向两热源热力循环最优性能和最优构型研究的最新进展,包括不同传热规律下内可逆和不可逆卡诺热机、制冷机和热泵循环的最优性能研究进展,两热源热机、制冷和热泵循环最优构型及多级复杂热力系统最优构型研究进展. 相似文献
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The fundamental optimal relation between heating load and coefficient of performance (COP) of a generalized irreversible Carnot
heat pump is derived based on a new generalized heat transfer law, which includes the generalized convective heat transfer
law and generalized radiative heat transfer law, q ∝ (ΔT
n
)
m
. The generalized irreversible Carnot heat pump model incorporates several internal and external irreversibilities, such as
heat resistance, bypass heat leakage, friction, turbulence and other undesirable irreversibility factors. The added irreversibilities
besides heat resistance are characterized by a constant parameter and a constant coefficient. The effects of heat transfer
laws and various loss terms are analysed. The heating load vs. COP characteristic of a generalized irreversible Carnot heat
pump is a parabolic-like curve, which is consistent with the experimental result of thermoelectric heat pump. The obtained
results include those obtained in many literatures and indicated that the analysis results of the generalized irreversible
Carnot heat pump were more suitable for engineering practice than those of the endoreversible Carnot heat pump. 相似文献
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文章报导了基于大基模体积的高能量飞秒钛宝石激光再生放大器的设计与实验研究,在重复频率10 Hz、抽运能量60 mJ的激励下,得到了单脉冲能量17.4 mJ的种子脉冲放大结果,压缩后的脉冲宽度为40.6 fs,能量为13.9 mJ.借助于此大基模体积再生腔,仅增加一级多通放大,实现了峰值功率达1.9 TW飞秒激光脉冲输出.结果表明,大模体积再生放大不仅降低了后续放大对抽运能量的要求,也可以单独压缩实现再生腔直接输出10 mJ量级的飞秒激光脉冲,是大能量高峰值功率飞秒激光系统的优质前端. 相似文献
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《Heat Recovery Systems and CHP》1995,15(3):249-256
The optimal performance of an absorption heat transformer, i.e. a type II absorption heat pump, is investigated by using the cyclic model with continuous flow. The effect of thermal resistances between the heat transformer and the heat reservoirs is considered in the model. A general expression related to the rate of heat-pumping, the coefficient of performance and the overall heat transfer area of the heat transformer is derived. The expression is used to optimise the main performance parameters of the heat transformer. The maximum rate of heat-pumping and the corresponding coefficient of performance are calculated. For a given overall heat transfer area of the heat transformer, the optimal relation of the heat transfer areas of the heat exchangers is obtained. The problems concerning the optimal choices of other performance parameters are discussed. The results obtained here can not only enrich the theory of finite time thermodynamics, but also provide some new theoretical bases for the optimal design and operation of real absorption heat transformers. 相似文献
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《Heat Recovery Systems and CHP》1989,9(3):233-247
A thermally driven heat pump using a solid/vapor adsorption/desorption compression process in a vapor compression cycle is thermodynamically analyzed. The cycle utilizes a simple heat transfer fluid circulating loop for heating and cooling two solid adsorbent beds. This heat transfer fluid loop also serves to transmit heat recovered from the adsorbing bed being cooled to the desorbing bed being heated. This heat recovery process greatly improves the efficiency of the single stage solid/vapor adsorption process without the complication of a two stage cycle. During the heating and cooling processes a thermal wave profile travels through the beds. This paper uses a square wave representation for the true shape of the thermal wave. However, this square wave is assumed to stop short of the bed ends to account for realistic finite waveforms. The square wave model is integrated into a thermodynamic cycle which provides detailed information on the performance of the beds as well as the COP and the heating and cooling outputs of the heat pump system. Significant cycle design and operating parameters are varied to determine their effect on cycle performance. 相似文献
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《Heat Recovery Systems and CHP》1994,14(6):599-612
This paper presents a system of regenerative heating incorporating an absorption heat pump in a Rankine steam cycle which can improve cycle efficiency. A simulation has been performed to estimate the Rankine cycle efficiency in the proposed Absorption Heat Pump Regeneration (AHPRG) heating system using the working pair R213-DMETEG. The results show that the cycle efficiency can be improved considerably without reducing the work output by the incorporation of AHPRG for low-temperature heating of steam condensate. Further, the temperature of the heat-pump evaporator which absorbs the heat rejected at the steam condenser plays a predominant role in the cycle efficiency. 相似文献
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《Heat Recovery Systems and CHP》1988,8(2):87-93
A thermodynamic analysis of the vapour absorption heat pump working on R22-DMETEG pair is made and the results are presented in the form of graphs and correlations. These data can be used to estimate the idealised system performance parameters such as heat quantities, flow rates, pump work, COP and second law efficiency. The procedure for using the data for above computations is described. 相似文献
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对流换热过程的热力学优化与传热优化 总被引:1,自引:0,他引:1
为了进一步明确对流换热过程中热力学优化与传热优化之间的差异,本文分别利用熵产最小原理、(火积)耗散极值原理针对两种边界条件下的对流换热问题进行分析,讨论熵产,(火积)耗散与有用能损失以及对流换热能力之间的关系.结果表明:熵产最小意味着系统的有用能损失最小,但并不反映系统的对流换热能力的强弱;而(火积)耗散取极值意味着系统的对流换热能力最强,但与系统的有用能损失不存在对应关系.因此,对于将降低有用能损失作为优化目标的换热问题应采用熵产最小原理进行分析;而对于需要将提高换热能力作为优化目标的对流换热问题应采用(火积)耗散极值原理进行分析. 相似文献
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《Heat Recovery Systems and CHP》1988,8(3):271-278
This paper deals with the effect of a snowcover on the coefficient of performance (COP) of a residential heat pump with a single layer ground heat exchanger for maritime climatic conditions (Fredericton, NB, Canada). A computer program was used to simulate a snowcover and heat and moisture transfer in the ground. Results obtained show that an increased thickness of a snowcover may evoke an increase of the COP of the ground heat pump system. Noticeable changes of the COP are observed within a snow-depth range from 0 to 10 cm. A further increase in snow depth does not significantly improve the COP which hereafter appears to be independent on a depth of a horizontal ground heat exchanger. 相似文献