热电制冷的热力学机理分析研究

把热电制冷的机理与一般相变制冷的机理作比较，分析热电制冷过程的热力学原理。由分析结果得知，在理想工作条件下，电流通过半导体材料进行制冷时，同时存在的帕尔帖效应、汤姆逊效应和傅立叶效应三种效应共同耦合作用的制冷效果可以分解为电子循环与两种不可逆效应的叠加。其中的作用力是二种材料的电子化学势，最大的影响因素是二种不可逆热效应。     

滚筒式冷渣器冷却水系统改造

为提高焦作某电厂滚筒冷渣器冷却水系统安全和经济性,对冷渣器冷却水系统长期运行状况进行了分析研究,提出冷渣器冷却水系统的能源回收利用改造方案,并据此对冷渣器的冷却系统进行了改造。改造后系统的运行结果表明,该系统改造不仅解决了冷渣器超温问题,降低了冷渣器的故障率,而且具有显著的节能效益和环境效益。系统的改造成功的实现了排渣余热回收利用,提高了机组的安全经济性。     

汽轮发电机定子冷却水冷却器的技术改造

原有冷却器在运行中存在出力不足和工质泄漏两个方面的问题,经分析研究,找出了存在问题的原因,并提出了解决措施,研制开发了新型全逆流管壳式冷却器。     

Effect of Convection Heat Transfer on Performance of Waste Heat Thermoelectric Generator

Efficiency of energy conversion processes can be improved if waste heat is converted to electricity. A thermoelectric generator (TEG) can directly convert waste heat to electricity. The TEG typically suffers from low efficiency due to various reasons, such as ohmic heating, surface-to-surrounding convection losses, and unfavorable material properties. In this work, the effect of surface-to-surrounding convection heat transfer losses on the performance of TEG is studied analytically and numerically. A one-dimensional (1-D) analytical model is developed that includes surface convection, conduction, ohmic heating, and Peltier, Seebeck, and Thomson effects with top and bottom surfaces of TEG exposed to convective boundary conditions. Using the analytical solutions, different performance parameters (e.g., heat input, power output, and efficiency) are calculated and expressed graphically as functions of thermal source and sink temperatures and convection heat transfer coefficient. Finally, a two-dimensional (2-D) mathematical model is solved numerically to observe qualitative results of thermal and electric fields inside the TEG. For all calculations, temperature-dependent thermal/electric properties are considered. Increase in thermal source temperature results in an increase in the power output with adiabatic side wall conditions. A change in boundary condition to convection heat transfer from adiabatic boundary has a large impact on thermal efficiency.     

Achieving Better Super-cooling in a Two-Stage Transient Thermoelectric Device with Constraint-Free Pulse Current by Multi-Objective Optimization

As a promising energy conversion technology,transient thermoelectric device has potential applications in temperature control and refrigeration.The performance ...     

Performance Optimization of Irreversible Air Heat Pumps Considering Size Effect

Considering the size of an irreversible air heat pump (AHP), heating load density (HLD) is taken as thermodynamic optimization objective by using finite-time thermodynamics. Based on an irreversible AHP with infinite reservoir thermal-capacitance rate model, the expression of HLD of AHP is put forward. The HLD optimization processes are studied analytically and numerically, which consist of two aspects: (1) to choose pressure ratio; (2) to distribute heat-exchanger inventory. Heat reservoir temperatures, heat transfer performance of heat exchangers as well as irreversibility during compression and expansion processes are important factors influencing on the performance of an irreversible AHP, which are characterized with temperature ratio, heat exchanger inventory as well as isentropic efficiencies, respectively. Those impacts of parameters on the maximum HLD are thoroughly studied. The research results show that HLD optimization can make the size of the AHP system smaller and improve the compactness of system.     

冷却塔冷却性能的评价模型

冷却塔是汽轮发电机组重要的冷端设备之一，其运行性能对电站的经济和安全运行有重要的影响。通过建立自然通风冷却塔出水温度和冷却性能的计算模型，为冷却塔的经济运行提供依据，并且还可以为冷却塔的检修和改造提供指导。     

Development of an Oil Gallery Cooling Model for Internal Combustion Engines Considering the Cocktail Shaker Effect

An internal combustion engine oil gallery cooling model was developed, which can predict average heat transfer coefficients by considering the cocktail shaker effect due to the reciprocal motion of the engine piston. The model prediction showed good agreement with available experimental data. Using the gallery cooling model and a computational fluid dynamics code which was developed to predict the combustion process, the influence of various oil cooling methods was studied numerically. Comparing the peak temperature of air cooling and oil jet-with-gallery cooling cases, the difference of the piston surface temperature was predicted to be as much as 300 K.     

在南京铁路南站地区实施热电冷三联供的探讨

简要介绍了热电冷三联供优越性和存在的经营风险,分析了在南京铁路南站地区实施热电冷三联供项目的必要性和优越性,提出了实施项目需要的政策支持。对该地区实现热电冷三联供项目有一定的引导性。     

基于有限元的某柴油机冷却水冷却器强度分析

某柴油机内部产生的热量除热辐射外全部都在冷却水冷却器进行热交换,其可靠性关系着整个柴油机的运行安全。针对某柴油机冷却水冷却器在实际使用过程中,由于采用不恰当的预紧力矩出现的压板断裂问题,利用有限元软件、三维建模软件及载荷分析理论,开展预紧力矩及承受载荷对其结构强度的影响分析,得出冷却水冷却器安装使用时所能承受的最大力矩及最佳安装方式。经过现场试验验证,解决了某柴油机冷却水冷却器压板断裂、密封失效和淡水泄漏故障。     

柴油机EGR冷却器综合性能分析及改进

利用ANSYS软件对某款EGR冷却器的流场、温度场及热负荷进行数值模拟,并通过试验验证其合理性与准确性。通过对柴油机工作过程进行一维建模,得到EGR冷却器的冷却效率的提高对柴油机工作过程具有重要意义的结果。最后通过改变冷却管的结构,并用数值模拟的方法对其分析;结果表明,结构改进使冷却器的冷却效率提升了5.36%,这对以后EGR冷却器开发研制提供了一定的参考。     

FORGO型电站空冷器冷却单元气压试验泄露分析

简要介绍了冷却单元的结构、组装与压力试验工艺、压力试验的泄漏分析等。     

核电厂汽轮机滑油冷却器新结构性能研究

为了克服传统弓形折流板管壳式滑油冷却器的固有缺点,提出了双层连续螺旋折流板管壳式滑油冷却器.采用Realizable k-ε湍流模型结合标准壁面函数的方法,对比分析了弓形折流板管壳式以及单、双层连续螺旋折流板管壳式滑油冷却器的壳侧流线分布及传热和阻力性能.结果表明:与弓形折流板相比,连续螺旋折流板壳侧不存在流动死区,壳侧传热系数有所增大,压降有所降低,综合性能显著提高;双层连续螺旋折流板的壳侧传热系数介于弓形折流板和单层连续螺旋折流板之间,压降最低,综合性能与单层连续螺旋折流板相当.     

汽车冷却系统水温对发动机性能的影响

阐述了冷却系统水温异常对发动机性能的影响,并对汽车冷却系统水温异常的原因作了简要分析.     

Performance evaluation of the recuperative heat exchanger in a miniature Joule–Thomson cooler

To develop effective heat exchangers for miniature and micro-Joule–Thomson (J–T) cooling system, the performance of the recuperative heat exchanger in a miniature J–T cooler is analyzed and evaluated. The evaluation is based on a theoretical model of the Hampson-type counter-flow heat exchanger. The effect of the pressure and temperature-dependent properties and longitudinal heat conduction are considered. The results of the numerical simulation are validated with the corresponding experimental measurements. The performance of the heat exchanger on effectiveness, flow and various heat conduction losses as well as liquefied yield fraction are analyzed and discussed. The simulation model provides a useful tool for miniature J–T cooler design.     

横向风对湿式冷却塔热力特性影响数值研究

基于CFD软件和湿冷塔相关理论,建立了基于Poppe理论的填料区数值求解模型,对喷淋区和雨区采用离散相模型计算.模拟了横向风对冷却塔热力特性和飘水损失的影响;提出了沿塔周设置回流槽的措施,以减少飘水损失.结果表明:横向风对出塔水温影响很大;无风时,出塔水温最低,随着风速的增加,出塔水温先升高后降低,并且,随着环境温度、湿度的不同,在横向风速为5m/s～7m/s间取得极大值.     

管带式散热器结构的变化对冷却系统性能的影响

传统的冷却系统(主要包括水箱和中冷器在内)设计主要只考虑散热面积的多少以及流过冷却系统的冷却水流量,通过提高散热面积(或加大体积)来提高冷却性能,而没有考虑到通过散热器本身的结构参数的调节去改变或者提高散热性能。基于同一发动机性能参数,在改变散热器结构参数的情况下作了多个水箱和中冷器的样品,针对不同的组合作了多组对比试验,通过试验结果来分析冷却系统结构参数上的变化对散热性能的影响。     

新型管芯式散热器热工性能试验研究

通过试验,对新型管芯式散热器进行了研究,根据国家标准建立了一套汽车散热器热力性能试验系统;运用该系统对管芯式散热器进行了较为系统的试验研究,获得了它的三种水管排数下的传热与阻力特性的试验数据;运用最优化方法通过计算机编制程序,对数据进行处理和计算,从而得到了管芯式散热器的三种管排数的空气侧与水侧的对流换热准则方程式.     

The Effect of Windbreak Walls on the Thermal Performance of Natural Draft Dry Cooling Towers

A three-dimensional study using the standard k-? turbulence model to simulate airflow in and around a natural draft dry cooling tower (NDDCT) has been conducted using a general-purpose CFD code. This investigation considered the location and the porosity of windbreak walls' structure on the NDDCT thermal performance. In addition, the effect of the windbreak walls on the thermal performance of two NDDCTs with different capacities has been investigated. Two parameters have been used to show the effect of the windbreak walls on the NDDCT thermal performance. At the reference heat exchanger temperature, the thermal effectiveness parameter has been employed. At the reference rejected heat from the NDDCT, the change in the cooling tower approach parameter has been employed. The results in this paper show an improvement in the NDDCT thermal performance due to the introduction of windbreak walls. Moreover, optimizing the location of the windbreak walls has been shown to have a more significant effect on the NDDCT thermal performance than the porosity of the walls. In addition, the effect of the windbreak walls on the thermal performance is similar for the two NDDCT with different capacities.     

Performance Characteristics of a Closed-Circuit Cooling Tower With Multiple Paths

The performance of a closed-circuit wet cooling tower (CWCT) with multiple paths having a rated capacity of 9 kW has been studied experimentally. When the CWCT has to operate with a partial load, the required quantity of cooling water reduces and thereby the velocity of the process fluid inside the tubes decreases. The velocity of the process fluid can be increased by installing blocking tubes in the heat exchanger. The test section in this experiment has multiple paths that have been used as the inlet for cooling water that flows from the top part of the heat exchanger. The heat exchanger consists of eight rows and 12 columns and the tubes are in a staggered arrangement. Heat and mass transfer coefficients and temperature drops were calculated with several variations including multiple paths. The results obtained from this study were compared with those reported and found to conform well. The investigation indicates that a CWCT operating with two paths has higher heat and mass transfer coefficients than with one path.