广义不可逆布雷逊热机的生态学性能优化

应用有限时间热力学方法和生态学优化准则对不可逆布雷逊热机循环的各种性能参数进行优化,导出了服从牛顿传热规律并考虑热阻、热漏和内不可逆性的布雷逊热机循环在生态学目标函数最大时输出功率和效率的表达式。讨论了热漏、内不可逆性对该热机各种性能参数的影响,同时还比较了最大输出功率和最大生态学目标函数下该热机各种优化性能参数间的关系。所得结果给实际热机的优化设计提供了理论依据。     

复杂热源下不可逆诺维科夫热机最大功率输出

考虑实际热机工作下的旁通热漏和内部耗散等不可逆因素,建立了包括连续均匀分布、三角形分布、二次分布和帕累托分布等四种不同的统计概率分布高温热源温度下的广义不可逆诺维科夫热机模型,导出了热机最大输出功率及相应的热效率和熵产率随高温热源温度、内部不可逆性等因素变化的关系式。结果表明：热漏和内部耗散分别对热机性能有着不同的影响,热漏使统计热源温度分布下最大功率输出对应的热效率减小,同时也增大了熵产率,但对热机的最大功率输出无影响;内部耗散不可逆性使热机的最大输出功率及相应热效率均明显减小,但使熵产率先增大后减小;熵产率随高温热源温度的标准差增大而减小。研究结果对太阳能发电厂性能提升具有一定理论指导意义。     

斯特林热机冷热电联产系统的可行性分析

斯特林热机对于促进能源的综合利用、减少环境污染具有重要的意义。文中通过对斯特林热机的斯特林循环及其热效率的分析,提出了三种不同形式的以斯特林热机为动力源的分散式冷热电三联产系统,并分别对其进行经济性分析。通过综合对比分析得出基于斯特林热机的分散式冷热电三联产是我国未来能源系统发展的一种环保的经济的选择。     

广义不可逆卡诺热机的生态学最优性能

以反映热机功率与熵产率之间最佳折衷的“生态学”准则为目标，综合考虑热阻、热漏及其它不可逆性对卡诺热机性能的影响，导出牛顿传热规律下循环的生态学最优性能，由数值计算分析比较了热漏、内不可逆性的影响特点。生态学优化以牺牲小部分输出功率为代价，较大地降低了循环的熵产率，而且在一定程度上提高了热机效率。因此，生态学目标函数不仅反映了输出功率和熵产率之间的最佳折衷，而且反映了输出功率和热效率之间的最佳折衷。     

斯特林热机膨胀腔与压缩腔的容积匹配研究

基于斯特林绝热模型对α型斯特林热机运行状况进行数值模拟,通过对热机各部件间的质量与功量传输的计算,模拟振荡流体对热机运行的影响。同时在不同工况下探讨斯特林热机膨胀腔与压缩腔的容积比对热机效率的影响,获得最大热效率,为斯特林热机的优化设计提供思路。     

流动阻力损失对斯特林热机功率和效率影响的理论分析

目前对斯特林热机的理论热工分析主要集中在热阻、热漏和回热损失对效率和功率的影响。讨论了在加进流动阻力损失后,对斯特林热机功率和效率的影响,并对功率和效率曲线进行了理论模拟。     

恒温热源不可逆闭式中冷回热燃气轮机循环的生态学优化

考虑循环过程的内外不可逆性,以生态学函数为目标,优化了总压比和中间压比分配,分析了高低温侧换热器、中冷器和回热器的性能参数对最大生态学函数及其参数的影响,并与以功率为优化目标时的循环性能进行了比较.结果表明:以生态学函数为优化目标时比以功率为优化目标时具有更高的效率,但功率相差不太多,反映了输出功率和效率间的最佳匹配.     

线性唯象传热规律下广义不可逆卡诺热机生态学性能系数优化

以反映热机循环输出功率和火用损失率之比的生态学性能系数(ECOP)为目标,用有限时间热力学理论和方法研究广义不可逆卡诺热机的循环性能。导出了线性唯象传热规律(Q∝Δ(T-1))下ECOP的解析式,通过数值计算分析了各种目标极值条件下ECOP与循环功率、效率、熵产率、生态学函数E之间的关系,主要研究了热源温比对最优性能的影响。     

热源间热机的_全息_热效率_功率谱

本文定义了输出功率弱化系数π及π函数因子①,建立了二源间内可逆循环的“全息”热效率——功率谱。借助克氏微循环或有限元循环概念,该全息谱能概括一切可能的任意热源间热机循环,可供热源间热机循环工作参数合理性的有限时间热力学分析。     

q∝△（T~（－1））传热时有限时间热机的生态学最优性能

本文以线性唯象定律ｑ∝△（Ｔ－１）为基础，以反映热机功率和热机熵产与低温热源温度乘积之间最佳折衷的“生态学”准则为优化目标，得到相应的效率界限和功率．     

A review of the applications of heat pipe heat exchangers for heat recovery

The waste heat recovery by heat pipes is accepted as an excellent way of saving energy and preventing global warming. This paper is a literature review of the application of heat pipes heat exchangers for the heat recovery that is focused on the energy saving and the enhanced effectiveness of the conventional heat pipe (CHP), two-phase closed thermosyphon (TPCT) and oscillating heat pipe (OHP) heat exchangers. The relevant papers were allocated into three main categories, and the experimental studies were summarized. These research papers were analyzed to support future works. Finally, the parameters of effectiveness of the CHP, TPCT and OHP heat exchangers were described. This review article provides additional information for the design of heat pipe heat exchangers with optimum conditions in the heat recovery system.     

铝用阳极生产过程的热平衡分析及余热利用

在我国节能减排的能源政策的指导下，铝用炭素阳极生产作为一种高能源消耗的行业，尤其需要在余热利用等方面开展工作，以提高能源利用效率。通过对某企业铝用炭素阳极生产工艺进行调研分析，考核了热、质流向及平衡情况，着重对生产过程中主要能耗环节进行分析，找出可以利用的余热，提出了相应的余热利用方式，并进行了可行性分析。本文结果对提高铝用炭素阳极生产工艺能源使用效率具有一定的参考价值。     

Determining the best type of heat exchangers for heat recovery

It is a common problem to choose the most appropriate heat exchanger configuration for heat recovery. In this study, a new model has been developed for determining the area and type of the most appropriate waste heat recovery heat exchanger for maximum net gain. A non-dimensional E number has been defined based on known technical and economic parameters such as the life-time, unit area cost of the heat exchanger, lower heating value of the fuel, overall heat transfer coefficient of heat exchanger, boiler efficiency, operation time per year, heat exchanger effectiveness, ratio of heat capacities, annual variation of the temperature of fluids supplied to the heat exchanger and present worth factor. The non-dimensional E numbers has been demonstrated in graphical forms as a function of NTU and ratio of heat capacities and corresponding heat exchanger area giving maximum net gain can easily be obtained from these graphs. The best heat exchanger type and its area can be determined comparing net gains or effectiveness of heat exchangers at NTU_max. Application of the new method has been given with a case study as a sample calculation.     

Turning down the heat

This paper presents how Australia's fast-growing electricity sector ramps up its global warming initiatives.     

The heat transfer and pressure loss characteristics of a heat exchanger for recovering latent heat (the heat transfer and pressure loss characteristics of the heat exchanger with wing fin)

In recent years the requirement for reduction of energy consumption has been increasing to solve the problems of global warming and the shortage of petroleum resources. A latent heat recovery type heat exchanger is one of the effective methods of improving thermal efficiency by recovering latent heat. This paper described the heat transfer and pressure loss characteristics of a latent heat recovery type heat exchanger having a wing fin (fin pitch: 4 mm, fin length: 65 mm). These were clarified by measuring the exchange heat quantity, the pressure loss of heat exchanger, and the heat transfer coefficient between outer fin surface and gas. The effects of condensate behavior in the fins on heat transfer and pressure loss characteristics were clarified. Furthermore, the equations for predicting the heat transfer coefficient and pressure loss which are necessary in the design of the heat exchanger were proposed. ©2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(4): 215–229, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20154     

Combined heat flow and heat generation measurements in the Bohemian massif

All available heat flow data together with temperature gradients and thermal conductivities of rocks from deep holes in the area forming the contact zone between the Bohemian massif and the western Carpathians are summarized. These data include 20 previously published values and 12 new values. The technique of measurement of the underground temperature, as well as the laboratory determination of the coefficient of thermal conductivity is briefly described. The most important result is the increase of the geothermal activity along the Carpathian foredeep from the south to the north and the generally high heat flow in the area of Permo-carboniferous sedimentation known as the Ostrava-Karviná coal basin in the north.     

利用热泵技术回收城市污水中的热能

阐述了城市污水热能利用的主要特点，分析了评价了把城市污水用做热泵水源的可行性，介绍了利用水源热泵回收城市污水热能的方式，讨论了城市污水源热泵系统在运动中可能存在的问题及应采取的措施。     

紧凑式两相换热器中管式换热元件沸腾传热实验研究

以烃类物质（丙烷和正戊烷）作为工质,进行了紧凑式换热器中带有加工配置表面的管式换热元件池沸腾实验研究。其中,单管实验温度工况为２５３Ｋ￣２９３Ｋ（饱和工质）。实验中所采用的换热元件为重入式结构加工配置表面的强化传热管和光管以及低助管。针对由４５根光管或带有加工配置表面的管子所构成的叉排管束进行了实验研究,实验工质为丙烷和正戊烷,实验温度分别为两种工质在２６３Ｋ和３０８Ｋ之间的饱和和温度。并将所得实     

Experimental study on the heat transfer at the heat exchanger of the thermoacoustic refrigerating system

Oscillatory flow heat transfer at the heat exchanger of the thermoacoustic refrigeration system was studied. The study identified significant factors that influence this heat transfer as well as the construction of the system. The results from the experimental study were correlated in terms of Nusselt number, Prandtl number and Reynolds number to obtain a useful new correlation for the heat transfer at the heat exchangers. Results show that using straight flow heat transfer correlations for analyses and design of this system could result in significant errors. Results also show the relationship between the oscillatory heat transfer coefficient at the heat exchangers, the mean pressure and frequency of oscillation. Higher mean pressures result in greater heat transfer coefficients if the thermoacoustic refrigerating system operates at the corresponding resonant frequency. However, a compromise has to be reached to accommodate construction of the stack.