—文了解:冷热电三联供系统CCHP

热电三联供系统(CCHP)是分布式能源系统中非常重要的形式之一,因在能耗、经济和环境等方面的显著综合效益,近年受到国内外的广泛关注和应用。木文介绍冷热电三联供系统的现状、工作原理和性能、发展趋势和前景。     

燃气内燃发电机在“三联供”系统中的应用和分析

介绍了燃气内燃机在冷、热、电“三联供”系统中的应用特点，分析了“三联供”系统的运行模式、节能效果、经济性，并筒述了燃气内燃发电机及“三联供”系统的推广应用前景。     

基于吸收式制冷的冷热电三联产系统的节能研究

通过冷热电三联产系统的正常运行可以实现能源梯级利用,基于吸收式制冷的冷热电三联产系统更是在节能的基础上保障高效利用能源,进而提升高能源综合利用率。本文就冷热电三联产系统及其节能性进行论述,并结合电压缩式制冷系统的特性,来剖析吸收式制冷技术下整个冷热电三联产系统的节能效果的变化,相比之下,基于吸收式制冷的冷热电三联产系统节能效果受发电效率因素的影响,即不同发电效率会产生不同的节能实效。本文通过建立联产与分产的一次能耗比模型,将吸收式制冷技术下的冷热电三联产系统的优势凸显出来,对该项研究课题的探究为实践带来有益的借鉴。     

电源技术

本会议录收集了会上发表的168篇论文,阿容涉及太阳能热电发电系统设计,采用纳米线阵列温差电材料制备的微温差电发电机,准一维有机晶体的温差电特性,光电组件冷却用热电模块,空气调节系统中热电学和光伏能量应用,热电氧化材料机械和化学稳定     

冷热电三联供系统的现状研究与应用前景

就目前我国的社会环境来看,冷热电三联供应系统是对广大平民百姓生活质量和社会发展的重要部分。在本文中,从我自己的经验,介绍了分布式供能理念的发展、天然气冷热电三联供近年来在国外市场的发展状况,进而分析了国内市场的状况、政策环境及其前景,同时提出了自己对其发展的一些建议。     

楼宇型天然气冷热电联供系统节能性探讨

指出天然气冷热电三联供CCHP系统的节能性判断应基于燃气轮机联合循环发电厂的发电效率。总结了常规冷热电分产CHPSS系统的能源综合利用效率的计算方法,结合实际工程案例,给出了几种常规的CHPSS系统的能源综合利用效率计算结果,结果表明基于常规电制冷冷水系统、地源热泵的CHPSS系统的能源综合利用效率优于CCHP系统,为工程实践提供参考借鉴。     

冷热电三联供在数据中心的应用

文中针对现阶段数据中心规划、建设中电力供应的难题,结合数据中心自身建设和运营的特点,提出了三联供系统在数据中心的多种应用模式。三联供系统的应用,大幅提高了数据中心的能源综合利用率,具有显著的经济和社会效益。通过对三联供系统关键设备及运行参数的分析比较,优化了运行模式,对今后三联供系统在数据中心的工程应用提供了指导。     

铁电液晶红外探测研究

某些碟状近晶相液晶具有铁电和热电性质。本文综述了铁电液晶的性质和介电、热电及脉冲响应特性;报道了我们对复合固体铁电液晶薄膜探测器的最新研究成果。     

空间大口径薄膜反射聚能系统

能源是航天器能够正常工作的基本保证,太阳能、引力能、真空能等太空即时补给能源是航天器供能的焦点。提出基于大口径薄膜反射的空间聚能系统的研究方案,利用充气式囊状薄膜反射镜结构聚焦太阳能,在焦斑处结合热电转换技术,实现了太阳能的汇集和能量的热电转换,并应用仿真软件模拟得到了不同焦距值的反射面聚焦效果的对比数据,验证了方案的可行性。所提出的以光、热、电三种能量形式为飞行器供能的设想为空间飞行器能源系统的设计提供了新思路和新技术。     

分布式能源系统中燃气轮机热电联产运行方式优化方法

为了对热电联产之中电负荷与热负荷变化进行协调,需对热电供需的不均衡问题进行处理,优化分布式能源的系统之中燃气轮机的热电联产运行方式.同时在传统以热定电与以电定热运行基础上,添加辅助的设备方式,对热电联产运行方式进行补充.本文主要分析了燃气轮机的热电联产两类运行方式,深入研究优化分布式能源的系统之中燃气轮机的热电联产运行方式,为相关研究提供参考.     

Model of Heat Exchangers for Waste Heat Recovery from Diesel Engine Exhaust for Thermoelectric Power Generation

The performance and operating characteristics of a hypothetical thermoelectric generator system designed to extract waste heat from the exhaust of a medium-duty turbocharged diesel engine were modeled. The finite-difference model consisted of two integrated submodels: a heat exchanger model and a thermoelectric device model. The heat exchanger model specified a rectangular cross-sectional geometry with liquid coolant on the cold side, and accounted for the difference between the heat transfer rate from the exhaust and that to the coolant. With the spatial variation of the thermoelectric properties accounted for, the thermoelectric device model calculated the hot-side and cold-side heat flux for the temperature boundary conditions given for the thermoelectric elements, iterating until temperature and heat flux boundary conditions satisfied the convection conditions for both exhaust and coolant, and heat transfer in the thermoelectric device. A downhill simplex method was used to optimize the parameters that affected the electrical power output, including the thermoelectric leg height, thermoelectric n-type to p-type leg area ratio, thermoelectric leg area to void area ratio, load electrical resistance, exhaust duct height, coolant duct height, fin spacing in the exhaust duct, location in the engine exhaust system, and number of flow paths within the constrained package volume. The calculation results showed that the configuration with 32 straight fins was optimal across the 30-cm-wide duct for the case of a single duct with total height of 5.5?cm. In addition, three counterflow parallel ducts or flow paths were found to be an optimum number for the given size constraint of 5.5?cm total height, and parallel ducts with counterflow were a better configuration than serpentine flow. Based on the reported thermoelectric properties of MnSi_1.75 and Mg₂Si_0.5Sn_0.5, the maximum net electrical power achieved for the three parallel flow paths in a counterflow arrangement was 1.06?kW for package volume of 16.5?L and exhaust flow enthalpy flux of 122?kW.     

Modeling the Building Blocks of a 10% Efficient Segmented Thermoelectric Power Generator

This paper describes the development of a modeling tool used for design and analysis of the building blocks of thermoelectric generators (TEGs). The described model captures the performance of a thermoelectric couple at varying loads and temperatures. The model includes the effects of interfacial resistances and other thermal losses. Validation experiments have been conducted, and the results are discussed. Once validated, the model was then used to design a 10% efficient segmented TEG, which was then built and tested. With this effective design tool along with improving thermoelectric material performance, a 14% efficient TEG is within reach.     

热电式MEMS微波功率传感器的优化设计

为了提高热电式微波功率传感器的传热效率,改善传感器的性能,对热电式微波功率传感器的衬底结构进行了优化设计,得到了最优的衬底结构尺寸。首先研究衬底厚度对热电式微波功率传感器的影响,然后根据得到的最优衬底厚度,研究基底膜位置及尺寸对热电式微波功率传感器性能的影响,最后对所得最优衬底结构传感器的微波特性以及电磁场分布进行研究。结果表明,当传感器衬底的结构尺寸最优时,传感器的最高温度达到352.76 K,S参数小于-20.62 dB。该结构不仅减少了热量在衬底的堆积,提高了负载电阻到热电堆的热传输效率,而且具有良好的微波特性。     

Calculation of the Thermoelectric Properties of n- and p-Type Lead Telluride Using a Three-Band Model of the Electron Energy Spectrum

In this paper, we study theoretically the thermoelectric properties of n- and p-type PbTe in the wide temperature interval of 300–900 K. A three-band model of the PbTe electron energy spectrum is used in these calculations. The full set of the relevant kinetic characteristics is calculated including the electrical and thermal conductivities, the Seebeck coefficient, and the thermoelectric figure-of-merit. The calculated thermoelectric quantities are in good agreement with the available experimental data.     

Detailed Modeling and Irreversible Transfer Process Analysis of a Multi-Element Thermoelectric Generator System

Thermoelectric (TE) power generation technology, due to its several advantages, is becoming a noteworthy research direction. Many researchers conduct their performance analysis and optimization of TE devices and related applications based on the generalized thermoelectric energy balance equations. These generalized TE equations involve the internal irreversibility of Joule heating inside the thermoelectric device and heat leakage through the thermoelectric couple leg. However, it is assumed that the thermoelectric generator (TEG) is thermally isolated from the surroundings except for the heat flows at the cold and hot junctions. Since the thermoelectric generator is a multi-element device in practice, being composed of many fundamental TE couple legs, the effect of heat transfer between the TE couple leg and the ambient environment is not negligible. In this paper, based on basic theories of thermoelectric power generation and thermal science, detailed modeling of a thermoelectric generator taking account of the phenomenon of energy loss from the TE couple leg is reported. The revised generalized thermoelectric energy balance equations considering the effect of heat transfer between the TE couple leg and the ambient environment have been derived. Furthermore, characteristics of a multi-element thermoelectric generator with irreversibility have been investigated on the basis of the new derived TE equations. In the present investigation, second-law-based thermodynamic analysis (exergy analysis) has been applied to the irreversible heat transfer process in particular. It is found that the existence of the irreversible heat convection process causes a large loss of heat exergy in the TEG system, and using thermoelectric generators for low-grade waste heat recovery has promising potential. The results of irreversibility analysis, especially irreversible effects on generator system performance, based on the system model established in detail have guiding significance for the development and application of thermoelectric generators, particularly for the design and optimization of TE modules.     

热电式MEMS微波功率传感器的封装研究

为了研究热电式MEMS微波功率传感器封装后的性能,提出了一种COB技术的封装方案。首先,采用有限元仿真软件HFSS仿真封装前后的微波特性;然后,基于GaAs MMIC技术对热电式MEMS微波功率传感器进行制备,并对制备好的芯片进行封装。最后,对封装前后传感器的微波特性及输出特性进行测试。实验结果表明,在8～12 GHz频率范围内,封装后回波损耗小于-10.50 dB,封装前的灵敏度为0.16 mV/mW@10 GHz,封装后的灵敏度为0.18 mV/mW@10 GHz。封装后的热电式微波功率传感器输出电压与输入功率仍有良好的线性度。该项研究对热电式MEMS微波功率传感器封装的研究具有一定的参考价值和指导意义。     

A Resistance Ratio Analysis for CoSb3-Based Thermoelectric Unicouples

In the search for desirable materials for use in thermoelectric generators, CoSb₃-based skutterudites have stimulated much scientific interest due to their high performance capabilities even at high temperatures. In this work, we tested the electrical power-generation characteristics of CoSb₃-based unicouples. We manufactured power-generation unicouples using n-type In_0.25Co_3.95Ni_0.05Sb₁₂ and p-type In_0.25Co_3.0Fe_1.0Sb₁₂ legs. The dimensions of the thermoelectric legs were 10?mm in diameter and 10?mm in height, with Cu sheets and Cu/Mo alloy as the electrode materials. For our unicouples, we evaluated the resistance ratio m?? (=R _o/R), which represents the ratio of the load resistance to the internal resistance of the unicouple. From this analysis of the resistance ratio m??, we obtained a considerable amount of information about the loss factors that caused the difference between the measured power output and the theoretical value. Through these analyses of two types of loss factors, we sought to improve the open-circuit voltage and internal resistance of a unicouple with CoSb₃/Ti/electrode interfaces. In addition, a long-term durability test of the unicouple at high temperature was performed to test the stability of the thermoelectric materials and of the interface between the electrodes and the thermoelectric legs at the same time.     

Design of a Concentration Solar Thermoelectric Generator

Thermoelectric technology can be another direct way to convert solar radiation into electricity, using the Seebeck effect. Herein, a prototype concentration solar thermoelectric generator (CTG) and a discrete numerical model for the evaluation of the whole system are presented. The model takes into account the temperature dependence of the thermoelectric material properties by dividing the thermoelectric leg into finite elements and is proved to be more accurate for calculation of the conversion efficiency of the thermoelectric modules when large temperature gradients occur in the CTG system. Based on the best available properties of various bulk thermoelectric materials reported in the literature, the best possible performance of the CTG system is predicted, and the CTG system design, including the selection of the concentration ratio and the cooling method for different thermoelectric materials, are discussed in detail.     

Flexible Thermoelectric Devices of Ultrahigh Power Factor by Scalable Printing and Interface Engineering

Printing is a versatile method to transform semiconducting nanoparticle inks into functional and flexible devices. In particular, thermoelectric nanoparticles are attractive building blocks to fabricate flexible devices for energy harvesting and cooling applications. However, the performance of printed devices are plagued by poor interfacial connections between nanoparticles and resulting low carrier mobility. While many rigid bulk materials have shown a thermoelectric figure of merit ZT greater than unity, it is an exacting challenge to develop flexible materials with ZT near unity. Here, a scalable screen‐printing method to fabricate high‐performance and flexible thermoelectric devices is reported. A tellurium‐based nanosolder approach is employed to bridge the interfaces between the BiSbTe particles during the postprinting sintering process. The printed BiSbTe flexible films demonstrate an ultrahigh room‐temperature power factor of 3 mW m^?1 K^?2 and ZT about 1, significantly higher than the best reported values for flexible films. A fully printed thermoelectric generator produces a high power density of 18.8 mW cm^?2 achievable with a small temperature gradient of 80 °C. This screen‐printing method, which directly transforms thermoelectric nanoparticles into high‐performance and flexible devices, presents a significant leap to make thermoelectrics a commercially viable technology for a broad range of energy harvesting and cooling applications.     

Theory and simulation of a thermally matched micromachined thermopile in a wearable energy harvester

In this paper, a new theoretical concept in the thermoelectric theory is discussed, which is important for design optimization of a thermoelectric energy harvester. The general conditions are defined, which are required to make a thermoelectric converter effective in energy harvester application. The necessity of the work has been prompted by the fact that while modeling the harvesters neither a constant temperature difference nor a constant heat flow can be assumed. It is shown that the proposed equations allow thermal optimization of energy harvesters to reach their top performance characteristics. The example of thermal optimization in case of MEMS thermopiles is discussed then. It is shown that the knowledge of thermal properties of the environment, i.e., those of a heat source and a heat sink, play the key role in the optimization procedure.