碱金属热电转换器(AMTEC)的电极极化过程分析

从电化学动力学的角度，对碱金属热电转换器的电极极化过程及对其特性的影响进行了讨论。分析认为，阳极极化过电压对碱金属热电转换器输出电压的影响比阴极极化过电压要小得多。影响阴极过电压的因素很多，除电极电流密度的大小外，电极反应本身的性质、BASE本身的性质、电极反应所依附的电极多孔薄膜材料的性质、电极多孔薄膜的形貌等都会对其大小产生影响。选择合适的电极材料，优化电极多孔薄膜的制备工艺，对改善AMTEC的电特性将是十分重要的。     

碱金属热电直接发电装置的热辐射损失

寄生热辐射损失，特别是BASE管外表面的热辐射是影响碱金属热电转换器(AMTEC)高效运行的主要因素之一。为了量化BASE管外表面的热辐射对碱金属热电转换器热电转换效率的影响程度，文章用一简化模型，计算了采用不同层数遮热屏的碱金属热电转换器中的BASE管外表面的净热辐射量。结果表明，恰当设计AMTEC装置的结构，并在BASE管外加数层遮热屏，可使BASE管外单位电极表面的净热辐射损失在其工作温度范围内控制在1W／cm^2以下。     

热电冷三联产的经济分析

本文简要介绍了热电冷三联产的基本生产工艺，通过对采用溴化锂制冷和中央空调以电制冷两种制冷方式的投资及运行费用进行比较，提出了发展热电冷三联产的良好前景的结论。     

超市热电联供系统余热利用及热电冷联供系统研究

通过建立数学模型对热电冷联供系统在超市中应用的可行性进行了分析。利用该模型对系统的节能效果、投资回收期、发动机组容量、等效满负荷运行时间等特性参数进行了研究，并对不同控制方式对系统性能的影响进行了讨论，为超市热电冷联供系统的方案优化提供了依据。     

600 MW双机热电联供系统智能优化方法研究

以600 MW双机热电联供系统为研究对象,引入基于灰狼捕食行为模拟的群智能优化算法,针对其繁琐更新机制导致热电负荷分配时效性差的问题,进一步提出改进的灰狼优化算法(GGWO),利用前3等级狼的位置和高斯采样进行种群进化机制更新。通过EBSILON平台开展仿真试验,揭示600 MW双机热电联供系统的热电耦合特性和系统运行特性,并将改进的灰狼优化算法应用于该系统的热电负荷优化分配。结果表明：两台机组电负荷一定时,尽可能增大抽凝机组的抽汽供热量可减小系统总热耗量;通过智能热电负荷运行优化,可有效降低系统总热耗量,提高系统经济效益。     

考虑风电消纳的含P2G-CCS虚拟电厂优化调度

针对热电联供(CHP)运行过程中产生大量CO2以及“以热定电”运行方式导致的弃风问题,提出一种考虑风电消纳的含电转气和碳捕集系统(P2G-CCS)虚拟电厂优化调度方案。首先,在虚拟电厂(VPP)中引入P2GCCS耦合模型,并使其与CHP能源流动形成循环,将CO₂作为CHP的燃料来源;其次,在VPP中加入地源热泵(GSHP),与P2G-CCS协同运行,实现CHP的热电解耦,促进风电消纳;最后,将电、气综合需求响应引入负荷侧,进一步促进风电消纳。以华北某地区VPP为例进行算例分析,结果表明所提调度方案可以有效促进风电消纳,同时碳排放和运行成本也更低。     

高低压旁路供热改造对机组调峰能力的影响分析

针对现阶段热电联产机组供热期调峰能力不足的问题,以某350 MW超临界燃煤机组为案例,介绍了其高低压旁路供热改造方案,并以改造后机组的实际运行数据为基础,对改造前后机组的运行特性和调峰能力进行了详细的对比分析。结果表明：案例机组进行高低压旁路供热改造后,在保证机组供热期热负荷和热段再热蒸汽流速不超限的情况下,机组电负荷调峰下限可由原来的230.9 MW降至161.4 MW,降低30.1%;当案例机组两个中压调节汽门关至42%时,机组电负荷调峰下限可进一步降至140.8 MW;旁路供热蒸汽量占比可由原来的56.3%提高至61.9%,提高5.6%,机组的调峰能力得到进一步提高。     

供热机组间热电负荷优化分配的研究

通过分析供热机组间热、电负荷分配的特点,建立了热、电负荷优化分配的数学模型。利用复形调优法,对宁波中华纸业有限公司热电厂2台供热机组间热、电负荷最优分配方案进行了优化分析计算。实际运行表明：该优化方法性能可靠,操作方便,可提高热电机组运行的经济性。     

热电联产机组集成吸收式热泵的热电解耦与能耗特性理论研究

以某330MW热电联产机组为例,对于集成吸收式热泵的热电解耦性能及能耗特性展开了理论研究。结果表明:耦合吸收式热泵扩大了热电联产机组的安全运行范围,提高了热电联产机组的最大热电比,降低了热电联产机组的最低电负荷率。当供热量为300MW时,热电联产机组电功率上调与下调能力分别增加40.53%、84.76%,最低电负荷率降低16.24%。当发电量为200MW时,其最大热电比提高了0.56。最后,对集成吸收式热泵的节能潜力进行了计算和分析。     

提高油田燃气轮机热电联产系统运行效率的研究

对某燃气轮机热电联产系统进行了运行特性和热力学分析，找出了某运行效率低的主要原因，并据此提出了一些改进建议。在借鉴已有成果的基础上，完善了燃气轮机热电联产系统的热力学分析方法，为全面分析燃气轮机热电联产系统的用能特性提供了依据。     

An overview of advanced space/terrestrial power generation device: AMTEC

Alkali metal thermal electric converter (AMTEC) technology offers several advantages over conventional forms of electric generation. Some of these advantages are high efficiency, high density, reliability, absence of moving parts, and competitive manufacturing costs. These and other advantages make AMTECs ideally suited for several space, aerospace, military and domestic applications.Current AMTEC designs suffer from some drawbacks that need to be rectified if the full potential of the technology is to be realized. These are current cell efficiencies that are still at values below the theoretically possible, and the adverse power–time characteristic of the cell. The PX-3A AMTEC cell, for instance, shows decreasing values of the maximum power output with time. Maximum power decreases from 2.54 W at the end of 172 h to 1.27 W at 18,000 h of cell operation. This latter problem, called power degradation, in particular, will preclude the use of the cell for applications that require operation of the cell for long periods of time.This paper discusses in detail the advantages of AMTEC technology and the problems with current designs. In particular, the problem of power degradation is dealt with in some detail and some measures are suggested that will help arrest this loss of power with time.     

The role of electrodes in power degradation of AMTEC: analysis and simulation

During the testing of the alkali metal thermal to electric converter (AMTEC) in laboratory, maximum power output of the AMTEC was found to be decreasing from 2.48 to 1.27 W after 18,000 h of operation with the hot side temperature of 1023 K and the condenser side temperature of 600 K. Electrode is one of the components in AMTEC which has effective lifetime. In this study, the role of the electrode on the overall power degradation has been investigated and reasons of the degradation are established qualitatively and quantitatively. The electrode is found 17% on average responsible for the overall degradation of power output.     

Temperature effect on lifetimes of AMTEC electrodes

The alkali metal thermal to electric converter (AMTEC) is perhaps one of the most desirable devices for directly converting heat into electrical energy, particularly for deep space exploration, where time can be prolonged from a decade to a score of years. Its stability is expected to last for a long time, 15 years or more. The two major components responsible for power output of AMTEC are the electrolyte and the electrode. In this work, we describe research on the AMTEC electrodes, which might function without much power degradation as a function of time.     

A review on advances in alkali metal thermal to electric converters (AMTECs)

The alkali metal thermal to electric converter (AMTEC) is one of the most promising technologies for direct conversion of thermal energy to electricity and has been receiving attention in the field of energy conversion and utilization in the past several decades. This paper aims to present a comprehensive review of the state of the art in the research and development of the AMTEC, including its working principles and types, historical development and applications, analytical models, working fluids, electrode materials, as well as the performance and efficiency improvement. The current two major problems encountered by the AMTEC, the time‐dependent power degradation and relatively low efficiency compared to its theoretical value, are discussed in depth. In addition, a brief comparison of the AMTEC with other direct thermal to electric converters (DTECs), such as the thermoelectrics converter (TEC), thermionics converter, and thermophotovoltaics converter, is given, and combinations of different DTECs to further improve DTECs' power generation and overall conversion efficiency are demonstrated. Future research and development directions and the issues that need to be further investigated are also suggested. It is believed that this comprehensive review will be beneficial to the design, simulation, analysis, performance assessment, and applications of various types of AMTECs. Copyright © 2009 John Wiley & Sons, Ltd.     

A parabolic dish/AMTEC solar thermal power system and its performance evaluation

This paper proposes a parabolic dish/AMTEC solar thermal power system and evaluates its overall thermal–electric conversion performance. The system is a combined system in which a parabolic dish solar collector is cascaded with an alkali metal thermal to electric converter (AMTEC) through a coupling heat exchanger. A separate type heat-pipe receiver is selected to isothermally transfer the solar energy from the collector to the AMTEC. To assess the system’s overall thermal–electric conversion performance, a theoretical analysis has been undertaken in conjunction with a parametric investigation by varying relevant parameters, i.e., the average operating temperature and performance parameters associate with the dish collector and the AMTEC. Results show that the overall conversion efficiency of parabolic dish/AMTEC system could reach up to 20.6% with a power output of 18.54 kW corresponding to an operating temperature of 1280 K. Moreover, it is found that the optimal condenser temperature, corresponding to the maximum overall efficiency, is around 600 K. This study indicates that the parabolic dish/AMTEC solar power system exhibits a great potential and competitiveness over other solar dish/engine systems, and the proposed system is a viable solar thermal power system.     

Characteristics of electrodes materials and their lifetime modeling for AMTEC

One major problem in the power output of alkali metal thermal to electric converter (AMTEC) is its decay with time. From the 18,000 h of laboratory testing on AMTEC, it was found that power output decreased from 2.48 to 1.27 W. One of the major causes of this decay is the grain growth of the electrodes. In this study, three electrodes have been studied in terms of their grain growth and a comparison of their performance has been made. Materials for those three electrodes, namely, RhW, Rh₂W, and TiN have been tried. From this analysis, RhW was found to be the best electrode, whereas Rh₂W was found to be the better electrode over TiN electrode. It was observed that power degradation of RhW electrode is 3.63% from grain growth effect. Power degradation by Rh₂W and TiN electrodes were calculated to be 6.45 and 10.89%, respectively, due to grain growth.     

Simulation and analysis of time-dependent degradation behavior of AMTEC

Alkali metal thermal-to-electric converter (AMTEC) technology is ideally suited for a wide range of applications from space, aerospace and military to domestic and other terrestrial civilian applications.In spite of its many advantages, existing AMTEC technology has some drawbacks that prevent the realization of the full potential of the technology. The problem is that the cell efficiency is still below its theoretically achievable value, and the cell has an adverse power-time characteristic. The maximum power output of the cell was observed to decrease from 2.54 W at the end of 172 h to 1.27 W during its 18,000 h of cell operation. This problem may preclude the use of the cell for applications that require operation of the cell for long periods of time.This paper deals with the factors responsible for this degradation and discusses in detail the simulation model used to study and predict the performance of the cell as a function of time. It is shown that the β-alumina solid electrolyte is a major cause of this degradation and a model to simulate its performance is developed and compared with available experimental data to establish the role of the electrolyte.     

Optimization of the TIEC/AMTEC cascade cell for high efficiency

A mathematical modeling of a system consisting of a cascade of a thermionic energy conversion (TIEC) device and an alkali metal thermal to electric converter (AMTEC) device has been performed to optimize the efficiency of the cell. The TIEC is heated by electronic bombardment, which converts heat partially into electricity and rejects the remaining heat. The AMTEC utilizes the rejected heat of the TIEC. Cascading these two cells provides lots of advantages. A mathematical model for the cascade converter has been developed to analyze the effects of key parameters such as power level, heat fluxes and temperatures. In this effort, a 12-node system of non-linear simultaneous equations has been constructed which is solved by MATCAD and a locally optimized efficiency has been derived. Thus, efficiency of the cascaded cell is improved, so that it is greater than the highest efficiency among the TIEC and AMTEC and lower than the sum of their individual efficiencies.     

Experimental evaluation of electrode conversion efficiency of alkali metal thermal to electric converter

The alkali metal thermal to electric converter (AMTEC) system which utilizes the sodium ion conductivity of a beta″‐alumina solid electrolyte (BASE) is expected to have high conversion efficiency above 30% including practical heat losses. However, the achieved experimental efficiencies have been around 15%. In this paper, current–voltage characteristics and heat and mass transfer processes on a single cell have been examined experimentally and thermal electrode conversion efficiency has been discussed. Measured electrode conversion efficiency without thermal losses showed that it was about 40% at a power density of 0.3 W/cm². A theoretical analysis on the thermal losses has also been conducted and these losses are estimated to be 0.3 W/cm² in a practical tube type cell, so that an actual cell system efficiency of 30% is expected. © 2001 Scripta Technica, Heat Trans Asian Res, 30(3): 234–244, 2001