共查询到19条相似文献,搜索用时 125 毫秒
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对存在不可逆热损耗的内可逆制冷循环进行有限时间热力学分析。求得最佳制冷系数及有关性能与过程进行速率的关系;制冷性能与过程间的时间配置的关系;制冷性能与传热能力及源汇温度的关系;得出在给定条件下循环周期的极限。 相似文献
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从经典热力学的基本理论出发,对理想可逆卡诺循环和实际不可逆卡诺循环的制冷系数进行了理论研究,证明了理想可逆卡诺循环的制冷系数是最高系数,分析了实际情况下制冷系的制约因素,为提高制冷系数提供了理论指导。 相似文献
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分析一系列高温和低温热源条件下连续流两热源制冷机的最佳制冷率密度与制冷系数间的关系,对存在制冷率极值情形求出了相应的性能界限。所讨论的制冷模型包括了以下四种情形:1)内,外部均不可逆;2)外部不可逆,内部可逆;3)外部可逆,内部不可逆;4)内外部均不可逆.假定所有不可逆性均由传热产生。制冷率密度人秋优化目标。 相似文献
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氦制冷在空间制冷技术中的应用 总被引:1,自引:0,他引:1
介绍了几种用于空间制冷中的氦制冷技术,如^He减压蒸发制冷,^3He压缩相变制冷,亚临界液氦制冷,超流氦制冷等。分别介绍了它们的原理,关键技术及其应用实例,最后提出了开展这方面工作的建议。 相似文献
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考虑全部传热不可逆性,导出了斯特林制冷机最佳制冷系数和制冷率间的关系。讨论了各因素对这种关系的影响。 相似文献
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不可逆布雷顿制冷循环的有限时间热力学分析 总被引:1,自引:0,他引:1
研究定常态流恒温热源和变温热源不可逆布雷顿制冷循环的有限时间热力学性能,并讨论了工质与热源间的最佳匹配和非共沸工质循环的优化问题。所得结果对实际制冷工程有一定指导意义。 相似文献
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A. M. Savin J. T. Flyktman F. Giazotto J. P. Pekola 《Journal of Superconductivity and Novel Magnetism》2006,19(1-2):11-14
The factors limiting cooling electrons by biased tunnel junctions have been considered. At low temperature range the deviation
from equilibrium, superconductor overheating and states within the superconductor gap limit the achievable minimum temperature.
Strong increase of electron–phonon coupling at higher temperature limits the temperature range of effective electron cooling
to sub-Kelvin region. Control of Josephson coupling in superconductor-normal metal-superconductor weak link by electron cooling
in normal electrode has been demonstrated experimentally. 相似文献
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Alberto Cavallini 《International Journal of Refrigeration》1996,19(8):485-496
The phasing out of fully halogenated halocarbons becomes effective at the end of 1995 by international agreement. Under the same ozone depletion issue, the companion fluids HCFCs are suffering a similar fate, as they are considered controlled substances with a virtual phase-out by 2020, and more drastic reductions may be proposed in the near future. Some international action might also be agreed upon on refrigerants with regard to the threatened environmental emergency of anthropogenic global warming. Therefore, in choosing replacement fluids primary concern must be given to minimising the total warming impact, which, for most applications, calls for improved energy efficiency. During recent years, industry has scrutinised and proposed a number of new synthesised products as immediate drop-in or long-term replacements for fluids harmful to the environment. Together with some single-component new generation refrigerants, quite a few two-component, three-component or even four-component mixtures, both with zeotropic and azeotropic behaviour, are being considered. The main issues associated with the use of the new generation refrigerants are discussed, such as behaviour with oil; flammability; efficient use of temperature glides, fractionation and heat-transfer degradation with zeotropic mixtures. The full environmentally friendly option of resorting to natural fluids is also considered by examining some recent innovative applications as refrigerants of some hydrocarbons, ammonia, carbon dioxide, water and air. 相似文献
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气动分置式斯特林制冷机的等温模型分析 总被引:1,自引:0,他引:1
涉及的气动分置式斯特林制冷机实验性能为40 W输入80 K/1 W,是上海技术物理研究所三期创新研究项目,本文采用等温模型对该制冷机的制冷性能进行理论计算,计算结果与实验值基本一致。另外,还对制冷机一些参数对理论制冷量、冷损、有效制冷量等的影响进行分析,为合理选取这些参数提供理论依据。 相似文献
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As a result of direct automation of the industrial refrigerating plants the efficiency is generally reduced by: (1) not limiting the peaks of refrigeration demand; (2) not profiting by the permissible temperature variations of the stored goods; (3) allowing unstable cycles of production and distribution. From this ascertainment the authors investigate the advantages of the different forms of storing thermal energy.The conventional thermal energy storage methods are compared such as: (1) the most popular sensible heat storage by means of water or chilled water tank: (2) the storage below freezing by means of liquid solutions (salt, alcohol, glycerol, glycol…); (3) the ice accumulation systems; (4) the eutectic-plate systems. Moreover, temperature fluctuations of the stored goods in a cold store are contemplated as a posible method of storing sensible heat, if moderate (4K for frozen and 2K for fresh goods).The above-mentioned methods, using either sensible or latent heat, are compared in terms of: utilization temperature, accumulation temperature range, and storage capacity per unit mass and unit volume. Loading and unloading rates of the storage device are also significant characteristics.The development of new storage methods are then investigated mainly in respect of energy savings in the field of agro-industries requiring both refrigeration and heating. (1) The accumulation of warm water, using either electric supply during low-fare periods, or heat pumps associated to heat rejection recovery of refrigerating plants, or any combination of both sources; (2) the latent heat accumulation which allows an important space saving compared to sensible heat accumulation.The most important recent improvements are mentioned: (1) physico-chemical (supercooling, non-reversibility of the change-of-phase process, crystallizing rate and heterogeneous crystallization); (2) heat exchange problems; (3) technological constraints; (4) financial amortization.As an illustration of the advantages of heat storage, the authors present a possible application for slaughter houses aiming at energy savings by means of: (1) heat recovery from refrigerant condensation for preheating of process water, with or without thermodynamical amplification (heat pump); (2) optimization of the running cycles of the compressors and adjustment of condensing and evaporating temperature levels. The example of a 10,000 t/year slaughterhouse is presented where an eutectic accumulation device is included in the glycol-water distribution system, allowing for the transfer of a 1250 kWh refrigeration capacity from peak to low level demand periods, with a reduced volume of 25 m3.As a conclusion, the authors review the main types of application of heat storage. 相似文献
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太阳能制冷技术的应用与发展 总被引:13,自引:1,他引:12
太阳能制冷具有环保节能的优点,是当前制冷界的研究热点。本文综合介绍了各种太阳能制冷技术的原理和特点。以及一些当前最新的研制成果,并对太阳能制冷技术的发展和应用前景作了分析。 相似文献
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半导体制冷片因其体积小、制冷速度快的优点在冷藏链运输领域具有很强的应用潜力。为测试半导体制冷箱的制冷效率,本文搭建了制冷储藏箱性能测试实验台,对应用两片TEC1-12706型及TEC1-12712型半导体制冷片的制冷储藏箱的工作性能进行实验研究。实验中分别在储藏箱中加入2 000 m L冰块开始实验及应用1 500 mL冰块与3 kg食材及3瓶500 mL矿泉水的组合开始实验,两次实验中同时改变热端散热方式及冷端风扇吹风方式。结果表明:对于同型号半导体制冷片,水冷方式时制冷效果更好,但持久性不强;同型号半导体制冷片冷端风扇下吹方式与侧吹方式相比气流组织更好。当容积为0. 1 m3的储藏箱面向冷藏需求时,可应用两片采取热端风冷方式的TEC1-12706型半导体制冷片,此时10 h内箱体中心温度最大约为6℃,最小约为0℃;当容积为0. 1 m3的储藏箱面向冷冻需求时,可应用两片TEC1-12712型半导体制冷片结合水冷式热端和风扇下吹式冷端,能维持3 h箱体内温度不高于0℃。 相似文献