首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 72 毫秒
1.
本文基于有限时间热力学方法对具有回热的电化学制冷机性能进行了研究。系统的分析了参数对制冷机性能的影响。结果表明:电池的等温系数和电量密度越大越高,其性能系数和制冷功率越高。同时制冷机的工作范围也越广。存在最佳的高低温工作温度使制冷机的制冷功率,但是高性能的回热器不能显著增加制冷机的性能。冷热源温度对之比对最大制冷功率时制冷机的性能系数没有显著的影响,考虑到实际需求,制冷机应工作于最大制冷功率与最大性能系数之间,本文对电化学制冷机的设计和改进具有重大指导意义。  相似文献   

2.
为满足高温超导等工程应用项目的大冷量需求,对130W/70K大冷量单级G-M制冷机系统进行了结构设计、理论计算和制冷性能测试,测得其制冷性能为最低温度18.1K,制冷量131.2W/70K。由于回热器性能优劣对制冷机性能有所影响,通过回热器不同填料方式对制冷机性能进行测试,结果表明,相比于采用单一磷青铜网填料的制冷机,采用磷青铜网和铅球作为复合蓄冷材料可以提高制冷机的制冷性能。  相似文献   

3.
随着高频脉冲管制冷机技术的发展,为了进一步提高制冷机的性能,需要对制冷机内部机理进行进一步的深入分析.运用数值模拟方法对脉冲管制冷机进行仿真模拟,能够有效直观地研究脉冲管制冷机的内部工作机理.本文采用CFD软件(FLUENT(?)),建立了回热器的多孔介质模型对不同工况的高频脉冲管制冷机进行全三维模拟计算,得到了高频脉冲管制冷机内部的流动分布,并通过计算得到了频率和平均压力对制冷机的内部参数和性能的影响.将计算结果与实际制冷机的优化结合起来,为实验的优化提供一定的依据.优化并得到了一种高效率的高频脉冲管制冷机,其80 K的COP达到4%以上.  相似文献   

4.
回热器作为回热式低温制冷机的核心部件,其效率的提升对低温制冷机具有重要意义。对研制的60K斯特林制冷机回热器进行优化设计和试验研究,获得了最佳回热器填料。通过对回热器冷端换热器结构的优化,讨论了其空隙率及局部损失对整机性能的影响,得到了冷端换热器的最佳空隙率,有效提高了制冷机的制冷量及其温度稳定性。在制冷机质量小于2.0kg以下,获得了1.8W/60K@23℃制冷性能。  相似文献   

5.
用于传导冷却超导磁体系统的GM制冷机处于强磁场环境中,由于二级蓄冷器的填充材料其性能随外部磁场大小而变化;而且冷头电机本身是永磁电机,电机性能受磁场影响更明显.因此,为了不影响制冷机的性能,需要详细地分析制冷机附近的磁场分布,将制冷机布置在低场区域;但是,高场磁体系统本身磁场强度高、温度裕度低,为了降低磁体运行时的热点温度,不可能将制冷机布置在距离磁体较远的区域,这时就需要对制冷机采取屏蔽措施.本文以正在建造的8T传导冷却超导磁体系统为例,研究了磁场对制冷机位置的影响,并分析了铁磁屏蔽对制冷机附近磁场的屏蔽效果.  相似文献   

6.
王坤  鲁雪生  顾安忠 《低温与超导》2006,34(3):165-167,160
换热器的换热问题对于制冷机的性能有重要的影响。文中在脉管制冷机冷热端换热器中采用了一种新的材料—紫铜泡沫金属材料,进行了初步的制冷机性能测试,并和相同制冷机结构参数下采用紫铜丝网材料作为冷热端换热器填料的制冷机的性能进行比较,发现采用紫铜泡沫金属材料可以强化冷热端换热,能够降低脉管制冷机所能达到的最低温度。  相似文献   

7.
热端温度对小制冷量的微型脉冲管制冷机的性能有着较为显著的影响.本文针对所设计的两台高频微型同轴非金属脉冲管制冷机,实验研究了制冷机冷端无负荷最低温度和轴向导热损失随热端温度的变化规律.实验对其影响幅度进行了量化分析,并发现通过降低热端温度的方法可以对样机制冷机性能起到很好的促进作用.  相似文献   

8.
基于线性热声理论,通过数值计算定量分析了双向进气对脉冲管制冷机性能的影响,指出:在惯性管已经为脉冲管制冷机提供了所需的最佳阻抗时,双向进气不能提高脉冲管制冷机的性能,只有在惯性管没有为制冷机提供作需的最佳阻抗时,双向进气模式才能发挥积极的作用。  相似文献   

9.
自由活塞斯特林制冷机具有高可靠性、高效率、结构紧凑等优点,在高温强电超导和气体液化等领域有较广阔的应用前景。本文针对一台液氮温区大冷量自由活塞斯特林制冷机展开了实验和计算研究.实验中,输入声功2.35 kW时,制冷机在80 K获得了215 W制冷量,相对卡诺效率为24.9%。数值计算表明室温端换热器的性能不足对制冷机性能影响较大,此外,结构缺陷导致的回热器轴向孔隙率不均匀可能是制约制冷机性能的主要因素。针对上述问题优化系统有望显著提升制冷机性能。  相似文献   

10.
自由活塞型斯特林制冷机热力学参数的无量纲分析   总被引:1,自引:0,他引:1  
自由活塞斯特林制冷机由于其结构紧凑、制冷效率高、可靠性好而不断受到重视。自由活塞斯特林制冷机的热力学参数对整机制冷性能具有决定性影响。基于等温模型,对自由活塞斯特林制冷机进行了无量纲分析,通过引入无量纲制冷量,详细研究了死容积比、扫气容积比、温度比、位移相位角对整机热力性能的影响。其研究结果为不同温区的自由活塞斯特林制冷机热力参数设计提供了参考意见。  相似文献   

11.
李俊  陈林根  戈延林  孙丰瑞 《物理学报》2013,62(13):130501-130501
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   

12.
A model of an irreversible quantum Carnot heat engine with heat resistance, internal irreversibility and heat leakage and many non-interacting harmonic oscillators is established in this paper. Based on the quantum master equation and semi-group approach, equations of some important performance parameters, such as power output, efficiency, exergy loss rate and ecological function for the irreversible quantum Carnot heat engine are derived. The optimal ecological performance of the heat engine in the classical limit is analyzed with numerical examples. Effects of internal irreversibility and heat leakage on the ecological performance are discussed. A performance comparison of the quantum heat engine under maximum ecological function and maximum power conditions is also performed.  相似文献   

13.
热漏、内不可逆性和导热规律对制冷机最优性能的影响   总被引:6,自引:0,他引:6  
1引言有限时间热力学研究制冷循环性能已取得了一批成果。已发表了热阻加热漏模型[1-4]、热阻加内不可逆模型问研究各种损失对卡诺循环性能的影响。本文作者用一常数项q表示热漏流率,用常系数表示热阻和热漏外的其余内不可逆性,建立了一类广义不可逆制冷机模型[6-7],并分析了牛顿传热定律下的最优性能。本文将基于此模型和较为普遍的导热规律,导出制冷机的制冷率、制冷系数最佳特性关系。2广义不可逆卡诺制冷机及其最优性能考虑一类工作在两个恒温热源之间的定常态流卡诺制冷机,循环中存在热阻、热漏和其它内不可逆性[6…  相似文献   

14.
An irreversible Ericsson refrigeration cycle model is established, in which multi-irreversibilities such as finite-rate heat transfer, regenerative loss, heat leakage, and the efficiency of the regenerator are taken into account. Expressions for several important performance parameters, such as the cooling rate, coefficient of performance (COP), power input, exergy output rate, entropy generation rate, and ecological function are derived. The influences of the heat leakage and the time of the regenerative processes on the ecological performance of the refrigerator are analyzed. The optimal regions of the ecological function, cooling rate, and COP are determined and evaluated. Furthermore, some important parameter relations of the refrigerator are revealed and discussed in detail. The results obtained here have general significance and will be helpful in gaining a deep understanding of the magnetic Ericsson refrigeration cycle.  相似文献   

15.
An irreversible combined Carnot cycle model using ideal quantum gases as a working medium was studied by using finite-time thermodynamics. The combined cycle consisted of two Carnot sub-cycles in a cascade mode. Considering thermal resistance, internal irreversibility, and heat leakage losses, the power output and thermal efficiency of the irreversible combined Carnot cycle were derived by utilizing the quantum gas state equation. The temperature effect of the working medium on power output and thermal efficiency is analyzed by numerical method, the optimal relationship between power output and thermal efficiency is solved by the Euler-Lagrange equation, and the effects of different working mediums on the optimal power and thermal efficiency performance are also focused. The results show that there is a set of working medium temperatures that makes the power output of the combined cycle be maximum. When there is no heat leakage loss in the combined cycle, all the characteristic curves of optimal power versus thermal efficiency are parabolic-like ones, and the internal irreversibility makes both power output and efficiency decrease. When there is heat leakage loss in the combined cycle, all the characteristic curves of optimal power versus thermal efficiency are loop-shaped ones, and the heat leakage loss only affects the thermal efficiency of the combined Carnot cycle. Comparing the power output of combined heat engines with four types of working mediums, the two-stage combined Carnot cycle using ideal Fermi-Bose gas as working medium obtains the highest power output.  相似文献   

16.
A new model of a quantum refrigeration cycle composed of two adiabatic and two isomagnetic field processes is established. The working substance in the cycle consists of many non-interacting spin-1/2 systems. The performance of the cycle is investigated, based on the quantum master equation and semi-group approach. The general expressions of several important performance parameters, such as the coefficient of performance, cooling rate, and power input, are given. It is found that the coefficient of performance of this cycle is in the closest analogy to that of the classical Carnot cycle. Furthermore, at high temperatures the optimal relations of the cooling rate and the maximum cooling rate are analysed in detail. Some performance characteristic curves of the cycle are plotted, such as the cooling rate versus the maximum ratio between high and low "temperatures" of the working substances, the maximum cooling rate versus the ratio between high and low "magnetic fields" and the "temperature" ratio between high and low reservoirs. The obtained results are further generalized and discussed, so that they may be directly applied to describing the performance of the quantum refrigerator using spin-J systems as the working substance. Finally, the optimum characteristics of the quantum Carnot and Ericsson refrigeration cycles are derived by analogy.  相似文献   

17.
四热源吸收式制冷机的传热面积优化   总被引:11,自引:0,他引:11  
本文提出了一种不可逆的四热源四温度位吸收式制冷机模型,研究其最佳制冷率,性能系数和传热面积之间的优化关系,并进行了讨论,获得了一些有意义的新结论;可以为四热源吸收式制冷机的优化设计和最佳运行工况的选择提供理论指导.  相似文献   

18.
Prandtl number and thermoacoustic refrigerators   总被引:2,自引:0,他引:2  
From kinetic gas theory, it is known that the Prandtl number for hard-sphere monatomic gases is 2/3. Lower values can be realized using gas mixtures of heavy and light monatomic gases. Prandtl numbers varying between 0.2 and 0.67 are obtained by using gas mixtures of helium-argon, helium-krypton, and helium-xenon. This paper presents the results of an experimental investigation into the effect of Prandtl number on the performance of a thermoacoustic refrigerator using gas mixtures. The measurements show that the performance of the refrigerator improves as the Prandtl number decreases. The lowest Prandtl number of 0.2, obtained with a mixture containing 30% xenon, leads to a coefficient of performance relative to Carnot which is 70% higher than with pure helium.  相似文献   

19.
Jun Li  Lingen Chen  Fengrui Sun 《Pramana》2010,74(2):219-230
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   

20.
程海涛  何济洲* 《物理学报》2013,62(3):30503-030503
研究了一维晶格中费曼棘齿-棘爪热机模型. 用粒子的概率主方程来描述粒子在晶格中的动力学特性, 推导出热流、 功率和效率的表达式. 通过数值计算分析势垒高度、 外力和温比对热流以及热机功率和效率的影响. 研究表明: 在粒子稳态概率流为零时, 存在非零的热流从高温库流入低温库, 类似于经典不可逆卡诺模型中的热漏; 热漏的存在使得热机的效率远远小于卡诺效率, 功率与效率之间为闭合的关系曲线, 热机为不可逆热机; 对热机性能参数进行优化, 可以使热机工作在最优性能状态下.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号