微型燃气轮机回热器

回热器是能源岛系统中微型燃气轮机的一个主要部件。根据回热器的运行特点及具体设计要求，介绍了国内外在回热器传热表面结构、回热器结构和材料等方面的研究状况，并指出回热器的研究趋势、研究方法和手段。图13表2参13     

空气回热的热泵木材干燥

彩热泵技术对木材进行干燥除湿具有节能效果显著，木材干燥周期短，木材不易开裂等优点。本文主要就循环空气采用回热的热泵除湿干燥系统进行热力学分析。热力学分析结果表明循环空气采用回热的热泵干燥机较不采用回热的热泵干燥的单位脱水耗比大大降低，增加回热器对热泵干材干燥机节约能源是有利的。     

船用燃气轮机一次表面回热器的设计分析

提出了一种新型紧凑式回热器——一次表面回热器(PSR)的设计技术。结合船用ICR燃气轮机一次表面回热器的研发，简述PSR的结构特点及其设计计算的理论依据，并给出了设计算例。研究表明，一次表面回热器具有极高的紧凑性和卓越的换热性能，因而这种先进的热交换装置必将替代那些常规的热交换器，在船用动力装置及先进热工程设施中发挥重要作用。     

具有热阻、热漏和回热损失的不可逆斯特林循环生态学性能系数优化分析研究

利用有限时间热力学分析了具有热阻、热漏和回热损失的不可逆斯特林循环生态学经济性能优化ECOP评判标准,推导了不可逆斯特林循环关于功率输出、效率、经济学函数和ECOP优化分析的数学表达式,利用数字分析以及热漏、回热时间和回热器效率研究上述参数之间的相互关系.研究结果表明:在最大ECOP工作条件下工作的斯特林循环比在最大生...     

基于回热循环的燃气轮机发电系统技术分析

为了提高燃气轮机系统的热力学性能．燃气轮机高温排气中的废热必须加以利用．这样就出现了各种各样的基于开式燃气轮机的回热循环的系统结构。本文对采用不同方式进行回热的燃气轮机循环的工作原理和性能特点进行了比较分析，从而为未来的燃气轮机发电系统的选择提供参考。     

具有等熵压缩,膨胀过程的闭式燃气轮机回热循环有限时间热力学性能

本文研究恒温和变温热源条件下具有等熵压缩、膨胀过程的闭式燃气轮机回热循环有限时间热力 学性能，导出两种情况下的功率输出和热效率与循环压比间的关系，由此可得最佳功率、效率特性。对于给定的热源条件，回热对循环功率有很大影响，这一结论与经典的分析明显不同。分析中计入了工质与高，低温热源间换热器和回热器的热阻损失，当不计高、低温侧换热器的热阻损失时，本文结果与经典结论一致。     

具有等熵压缩、膨胀过程的闭式燃气轮机回热循环有限时间热力学性能

本文研究恒温和变温热源条件下具有等熵压缩、膨胀过程的闭式燃气轮机回热循环有限时间热力学性能，导出两种情况下的功率输出和热效率与循环压比间的关系，由此可得最佳功率、效率特性．对于给定的热源条件，回热对循环功率有很大影响，这一结论与经典的分析明显不同．分析中计入了工质与高、低温热源间换热器和回热器的热阻损失．当不计高、低温侧换热器的热阻损失时，本文结果与经典结论一致．     

新型回热器结构设计及换热特性研究

回热器作为斯特林热机的关键部件,对于太阳能斯特林热机整机性能有着重要影响。为克服传统金属丝网回热器结构存在的填料单一,制造成本较高,工艺复杂问题,采用实用等温分析法,以回热器的长径比、通流面积、填料种类以及孔隙率各项回热器参数为基础,设计了一种新型斯特林热机回热器,该回热器具有轴向压降小,换热性能高,结构稳定,加工制造简单的特点。开展了新型回热器和传统金属丝网回热器的换热性能对比研究,采用振荡条件下的局部热平衡方法研究回热器的传热过程,对比传统金属丝网回热器和新型回热器的温度变化,速度变化以及压力变化。结果表明:在整体孔隙率相同的条件下,新型回热器和传统金属丝网回热器相比,整体启动速率相似,但新型回热器压降减少0.04 MPa,速度出现分段式变化,有利于回热器的换热和结构稳定。因此,新型回热器不但在结构上优于传统金属丝网回热器,在换热特性上也优于传统金属丝网回热器。     

船用燃气轮机复杂循环技术综述

本文总结了复杂循环船用燃气轮机的主要研发成果及应用状况,在间冷回热、喷水冷却蒸汽回注、化学回热、湿空气透平循环等研究中,对关注较多的舰船燃气轮机复杂循环技术进行了评述,重点分析了这些复杂循环技术的优缺点以及燃气轮机本体的改动情况,并对其装舰应用中各自存在的优势和瓶颈问题给出了客观的评价。     

9E级燃气轮机部分负荷进气加热提效技术研究与工程应用

本文在介绍燃气轮机设备运行特性和我国当前燃气轮机发电行业现状的基础上,对燃气轮机部分负荷运行情况进行了仿真计算研究和运行数据分析研究。根据实际运行数据分析,我国燃气电厂机组普遍存在实际运行负荷长期低于设计负荷、燃气轮机部分负荷运行效率衰减、高品位能源浪费巨大的问题。针对燃气电厂机组运行现状,本文通过对PG9171E型燃气轮机机组采用实际运行数据分析和仿真建模计算的方法,重点研究了燃气轮机入口空气温度调整对联合循环机组部分负荷工况性能的影响。根据研究结果,提出了一种利用燃气联合循环系统低品位余热作为热源的燃气轮机联合循环进气加热部分负荷提效技术,并对该技术在我国不同型号燃气轮机机组上的技术应用进行了分析。研究结论和实践结果表明,本文所述的燃气轮机部分负荷进气加热技术系统简洁,系统改造附加进气压损较小,能够适用于我国大部分在运燃气联合循环机组,并且能够显著提高联合循环部分负荷工况的运行效率。     

Recuperator considerations for future higher efficiency microturbines

First-generation microturbines are based on the use of existing materials and proven technology, and with low levels of compressor pressure ratio and modest turbine inlet temperatures, have thermal efficiencies approaching 30% for turbogenerators rated up to 100 kW. For such small machines the goal of advancing beyond this level of performance is unlikely to include more complex thermodynamic cycles, but rather will be realised with higher turbine inlet temperatures. Advancing engine performance in this manner has a significant impact on recuperator technology and cost. In the compact heat exchanger field very efficient heat transfer surface geometries have been developed over the last few decades but further improvements perhaps using CFD methods will likely be only incremental. Automated fabrication processes for the manufacture of microturbine recuperators are in place, and on-going developments to facilitate efficient higher temperature operation are primarily focused in the materials area. Based on the assumptions made in this paper it is postulated that in the 100 kW size the maximum thermal efficiency attainable for an all-metallic engine is 35%. To achieve this the recuperator cannot be designed in an isolated manner, and must be addressed in an integrated approach as part of the overall power conversion system. In this regard, temperature limitations as they impact the recuperator and turbine are put into perspective. In this paper there is strong focus on recuperator material selection and cost, including a proposed bi-metallic approach to establish a cost-effective counterflow primary surface recuperator for higher temperature service. If indeed there is a long-term goal to achieve an efficiency of 40% for small microturbines, it can only be projected based on the utilisation of ceramic hot end components. Alas, the high temperature component that has had the minimum development in recent years to realise this goal is the ceramic recuperator, and efforts to remedy this situation need to be undertaken in the near future.     

回热器对HAT循环影响的分析

目前对HAT循环中回热器的理论分析大多采用传热温差法和表征回热器特性的回热度分析的方法。针对这两种不同的分析方法分别进行了计算,比较分析了它们对HAT循环的影响,结果表明,传热温差法更加适合于对HAT循环进行理论分析,但应当注意传热温差的选取。而回热度法更多应用于回热器的设计。     

Heat transfer correlations and NTU number for the longitudinal flow spiral recuperators

This paper reports experimental data for heat transfer in a longitudinal flow spiral recuperator. The primary measurements include flow rates as well as the inlet and outlet fluid temperature values for each fluid stream. The results of the experimental study are presented in a dimensionless form. The problem of determining correlations for average heat transfer coefficients is formulated as a parameter estimation problem, by selecting the functional form for the Nusselt number. The non-linear problem is solved using the least-squares estimation method. The results presented in this paper provide data for the longitudinal flow spiral recuperators application design.     

Energy savings in the combustion based process heating in industrial sector

Energy efficiency and savings strategies in the combustion based industrial process heating has been reviewed comprehensively and presented in this paper. This work compiles latest literatures in terms of thesis, journal articles, conference proceedings, web materials, reports, books, handbooks on industrial process heating systems in the industrial sector. Different types of equipment used (i.e., recuperator, regenerators, heat wheels, heat pipes, economizers, etc.) and energy savings are reviewed in various industrial processes heating. Based on the review results, it is found that significant amounts of energy could be saved by using heat recovery system in the industrial process heating. By using recuperator up to 25% energy can be saved in the furnace. In the case of boiler, by using economizers 10% to 20% energy can be saved. Economic analysis shows that the payback period of recuperator and economizer are normally less than 2 years. It is also found that the payback period is lower when operating hour is comparatively high.     

板翅式回热器传热性能的试验研究

采用等流量,变流量两种试验方法对板翅式回热器进行传热性能试验,并进行传热数据分析,获得有工程应用价值的Nu-Re准则关系式。通过数值模拟的方法,分析流道的温度场和流场分布情况,得出了此回热器可通过改变流道表面粗糙度或结构来提高其换热性能。图6表2参6     

Second law analysis of supercritical CO2 recompression Brayton cycle

In the present study, exergetic analyses and optimization of S-CO₂ recompression cycle have been performed to study the effect of operating parameters on the optimum pressure ratio, energetic and exergetic efficiencies and component irreversibilities. Effect of isentropic efficiency, recuperator effectiveness and component pressure drop on the second law efficiency is presented as well. Results show that the effect of minimum operating temperature on the optimum pressure ratio and cycle efficiencies is more predominant than the maximum operating temperature, whereas the effect of maximum cycle pressure is significant only for lower values and the optimum pressure ratio leads to near critical minimum cycle pressure. Result shows that the irreversibilities of heat exchangers are significantly more compared to that of turbo-machineries and the effect of operating parameters on irreversibility is also more significant for recuperators compared to turbo-machines. Effect of isentropic efficiency of turbine is more predominant (about 2.5 times) than that of compressors and effect of high temperature recuperator (HTR) effectiveness is more predominant (about double) than that of low temperature recuperator (LTR) on the second law efficiency. Effect of pressure drop in reactor is more significant compared to others components on the second law efficiency reduction.     

一次表面回热器动态特性的数值模拟与实验研究

对一次表面回热器(Primary Surface Recuperator,PSR)流量阶跃变化时的动态特性进行了数值分析和实验研究.根据能量守恒原理和一次表面回热器(PSR)的结构特点,导出回热器冷热流体和固体间壁非稳态温度变化的微分方程式,研究流体流量发生阶跃变化时PSR的响应时间.在冷热空气进口参数和换热量相同的条件下,当冷热侧流量分别增加为原来3倍的情况下,PSR的响应时间只有管壳式换热器的1/8,板翅式的1/3.数值分析结果与实验结果相符.由于PSR的固体壁面时间常数远小于板翅式和管壳式回热器,因此这种轻重量结构的先进回热器响应特性明显优于常规回热器.     

Low-cost compact primary surface recuperator concept for microturbines

By the year 2000, microturbines in the 25–75 kW power range are projected to find acceptance in large quantities in the distributed power generation field, their major attributes include low emissions, multifuel capability, compact size, high reliability and low maintenance. For this type of small turbogenerator, an exhaust heat recovery recuperator is mandatory in order to realize a thermal efficiency of 30% or higher. The paramount requirements for the recuperator are low cost and high effectiveness. These characteristics must be accomplished with a heat exchanger that has good reliability, high performance potential, compact size, light weight, proven structural integrity, and adaptability to automated high volume production methods. In this paper, a recuperator concept is discussed that meets the demanding requirements for microturbines. The proposed stamped and folded metal foil primary surface recuperator concept has as its genesis, a prototype heat exchanger module that was fabricated as part of an energy research program in Germany over two decades ago. This novel heat exchanger approach was clearly ahead of its time, and lacking an application in the late 1970s was, alas, not pursued and commercialized. Based on this earlier work, a further evolution of the basic concept is proposed, with emphasis placed on the following: (1) minimization of the number of parts, (2) use of a continuous fabrication process, (3) matrix overall shape and envelope flexibility (annular or platular geometry), (4) ease of turbogenerator/recuperator integration, and (5) a later embodiment of a bi-metallic approach, towards the goal of establishing a compact and cost-effective recuperator for the new class of very small gas turbines that are close to entering service. For a representative microturbine, an annular recuperator would have only five basic parts. The matrix cartridge would be essentially a plug-in component, analogous to an automobile oil filter element. In this paper, the important role that the recuperator has on turbogenerator performance is discussed, together with a summary of the early prototype heat exchanger development. The major requirements, features and cost goals for a compact primary surface recuperator for microturbine service, are also covered.     

A novel Swiss-Roll recuperator for the microturbine engine

The design and analysis of a Swiss-Roll recuperator are investigated using a theoretical approach, numerical simulation and an experimental approach. The novel Swiss-Roll recuperator is a primary surface-type heat exchanger for micro gas turbine engines. The preliminary design of the Swiss-Roll recuperator, which is based on theoretical analysis, provides the required channel width, number of turns and number of transfer units (NTUs) for a given effectiveness. Friction causing a pressure loss is also predicted. For a given recuperator design, model simulation was performed to provide insights and improve model performance. Comparison of numerical results and theoretical predictions for efficiency of heat recovery shows a 10% error; however, pressure drop predictions were consistent. Test results show that the engine with a recuperator has a thermal efficiency of 27%. Fuel consumption rate is 600 ml/min. Conversely, a microturbine without a recuperator has a thermal efficiency of 12%, and fuel consumption rate is 800 ml/min. This experimental result indicates the engine with a recuperator use at least 1.5 times less fuel than an engine without a recuperator. This experimental result is consistent with predictions from analytical and numerical solutions. An engine with a recuperator saves energy, is economical and produces low amounts of emissions.     

Analyzing a micro-solid oxide fuel cell system by global energy balances

A simple method to predict the thermal characteristics of a micro-SOFC system is presented in this study. The basic design requirements for a thermally self-sustaining operation at a stack temperature of about 550 °C are assessed. Based on steady-state global energy and mass balances, the influence of the electrical efficiency, the overall air-to-fuel ratio and the heat losses on the operating temperature is discussed. It was found that at high electrical efficiencies and, hence, low heat release rates, a recuperator is needed to achieve the desired operating temperature. At lower electrical efficiencies, in contrast, disposing the released heat becomes an issue and an efficient cooling of the stack is required. Whether a recuperator or additional cooling components are necessary also depends on the electrical power output, the stack size and the thermal insulation specifications. The threshold between cooling and recuperator mode is of special interest, since this operating point allows a simple design of the thermal system without recuperator and only a minimum of air to be supplied to the system. This threshold efficiency, which is the maximal electrical efficiency that allows a thermally self-sustaining operation without recuperator, is above 50% under adiabatic operating conditions. In a non-adiabatic system, the threshold efficiency is reduced to about 45% in a 20 W_el and to about 20% in a 2.5 W_el system even with a state-of-the art thermal insulation. The considered thermal insulations dominate the system volume. Therefore, the ability of heat loss minimization is highly dependent on the targeted volumetric power density of the system.