Performance Model for a Radiation Recuperator

A procedure has been developed to predict axial temperature distributions for the combustion gas. air, and walls of an annular radiation recuperator. It is based on using the zone method to treat radiation exchange between the combustion gas and its boundaries and on solving a system of nonlinear energy balance equations for the temperature distributions. The procedure may be used for a wide range of design and operating conditions, and parametric calculations have been performed to determine the effect of these conditions on recuperator performance.     

带中间冷却和回热的燃气轮机动态性能的研究

对某舰用燃气轮机进行了中间冷却和回热（ICR）的改造设计,采用按比例缩小压气机的方法,使改造设计后的燃气轮机各部件性能达到了良好的匹配.依照模块化建模的原理,建立了换热器等部件模块,在此基础上,在EASY 5仿真平台上搭建了ICR燃气轮机的系统模型,并对其进行了稳态和动态的仿真试验计算.结论认为,舰用燃气轮机改造为ICR燃气轮机,需要重新设计压气机以平衡由于中间冷却器造成的高压压气机入口折合流量降低的影响;ICR燃气轮机具有较高的效率和良好的变工况性能.图5表1参5     

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.     

Thermal design and model analysis of the Swiss-roll recuperator for an innovative micro gas turbine

For the advanced power systems based on the use of microturbines, the major considerations are higher power density as well as higher efficiency for energy-saving. In order to achieve higher efficiency, recuperated systems which recover the exhaust heat then become mandatory and the paramount requirements for the recuperator are high effectiveness and low pressure loss. Here, the thermal design and model analysis of a proposed Swiss-roll recuperator for future higher efficiency microturbines were made with both theoretical approach and numerical simulation. The proposed Swiss-roll recuperator is basically the primary surface type. It is composed of two flat plates that are wrapped around each other, creating two concentric channels of rectangular cross-section. The characteristics of Swiss-roll recuperator resemble the counter-flow spiral plate heat exchanger and have the excellent performance in effectiveness and pressure-loss. From a theoretical analysis, the thermal characteristics of the Swiss-roll recuperator were investigated and its preliminary designs at a given effectiveness for an innovative micro gas turbine were also demonstrated, including the determination of the number of turns, the corresponding channel widths and the required number of transfer unit (NTU). The consequent pressure loss through the recuperator was also predicted. For a given design of the recuperator, the model simulation was then made to provide the insights and needs for further improving the performance of the Swiss-roll recuperator.     

Performance evaluation of a tri-generation system with simulation and experiment

A test rig for a tri-generation system was set up in the laboratory to investigate the system performance and application feasibility. The rig was composed of three modules, a power component containing a microturbine, a refrigeration unit consisting of an absorption chiller with gas pipe connection, and a supermarket section containing a display cabinet. This system was supposed to be effectively applied into a supermarket energy control system where cooling, heating and electricity power are simultaneously required and subsequently, valuable test results have been produced. In the mean time, a simulation model for the particular tri-generation system has been established by integrating the component models of the system in accordance with the components’ actual flow paths and energy streams. These component models, which include a compressor, recuperator, combustion chamber, gas turbine, electric generator, gas pipes, generator (desorber), rectifier, absorbers, condenser and evaporator etc., were developed based upon the balance of heat and mass. The calculations of heat transfer and phase equilibrium were included in the component models and chemical reaction balances were considered in the model of the combustion chamber. The system model has been validated with the test results and has consequently been used to predict the system performance at different operating and design conditions, such as varied ambient temperature, fuel flow rate and pressure ratio etc. The ultimate results of the performance analysis formulated by the system model can contribute significantly to the optimal component and system designs in various practical applications.     

A study on the design of recuperative burner

Waste heat recovery from the exhaust gas of industrial furnaces and kilns that are high energy-consuming equipment is one of the effective energy conservation methods because of its high sensible heat contents. The recuperative burner integrated with a recuperator and burner is one of the combustion equipments with many advantages of simple installation, compactness and easy control which can be applied to various fields of industry. A recuperative burner with the capacity of 400 kW was designed using the design data from experimental results. Performance tests on this burner were made. The exhaust gas analysis, including NO_x, the measurement of the flame temperature, velocity, heat flux and heat flux analysis on the recuperative burner were the main topics of hot combustion tests. Design data from the experimental results are gas velocity, air velocity, air velocity, the tip-location of gas nozzle, the dimension of furnace suitable to burner capacity, the dimension of recuperator and the role of cross-shaped steel plate for increasing the energy efficiency in the recuperator. For uniform temperature distribution and good thermal efficiency, it is appropriate to maintain the furnace pressure at 2–3mmAq. © 1998 John Wiley & Sons, Ltd.     

4E Multi‐objective Optimization of Cogeneration Plant with Details Modeling of Recuperator

There are many works on improving the performance of a cogeneration plant such as the implementation of a recuperator. In previous works, the authors modelled a gas turbine cycle considering the recuperator as a black box. In this paper, a cogeneration plant is modeled and optimized with details of recuperator parameters. For this purpose, 13 design variables for a plant as well as a recuperator are selected. Then, a genetic algorithm is applied to optimize exergy efficiency and total cost rate, simultaneously. This work included Energy, Economy, and Environmental factors which with Exergy provided 4E analysis. A 36% decrease in total cost and a 33% increase in exergy efficiency in comparison with a simple gas turbine system were found. The above results for a gas turbine with a preheater and inlet cooling system reveal a 36% decrease in total cost and 35% increases in exergy efficiency. In addition, the optimum recuperator design parameters reveal that, higher effectiveness is more important than the investment cost. Moreover, a plant with higher exergy efficiency needs a recuperator with a lower pressure drop. Finally sensitivity analysis for variation of objectives functions with a change in fuel cost and interest rate are performed.     

The effect of heat transfer on the pressure drop through a heat exchanger for aero engine applications

This work is focused on the experimental study of the performance of a heat exchanger designed for aero engine applications. The heat exchanger is operating as a heat recuperator by taking advantage of the thermal energy of the exhaust gas of the aero engine in order to obtain a better combustion with less pollutant emissions. The experimental study has been performed in a wind-tunnel by taking detailed flow and thermal measurements on a 1:1 model of the heat exchanger under various operating conditions described by the hot gas inlet mass flow rates and its spatial direction (different angles of attack and inclination) towards the heat exchanger. The hot gas has been modeled with preheated air. Six sets of measurements have been carried-out for different hot gas inlet and outlet temperatures, including also isothermal measurements without any heat transfer in order to have a reference point for the pressure drop of the flow through the device. The experimental results showed that the effect of the angle of attack on the pressure drop is significant while the effect of the angle of inclination is negligible. Additionally, the pressure drop through the heat exchanger is greatly affected by the heat transfer.     

A thermodynamic analysis of a novel high efficiency reciprocating internal combustion engine—the isoengine

A novel concept for a high efficiency reciprocating internal combustion engine (the isoengine) is described and its cycle is analysed. The highly turbocharged engine configuration, which is intended primarily for on-site and distributed power generation, has a predicted electrical output of 7.3 MW. It has the option for co-generation of up to 3.2 MW of hot water at 95 °C supply temperature. The maximum net electrical plant efficiency is predicted to be about 60% on diesel fuel and 58% on natural gas. The key to the high electrical efficiency is the quasi-isothermal compression of the combustion air in cylinders, which are separate from the power cylinders. This achieves a significant saving in compression work and allows the recovery of waste heat back into the cycle, mainly from the exhaust gas by means of a recuperator. The construction of a first 3 MW_e prototype isoengine has been completed and its testing has begun. Relevant test results are expected in the near future.     

Performance analysis of metallic concentric tube recuperator in parallel flow arrangement

A performance model for parallel flow arrangement in metallic concentric tube recuperator that can be used to utilize the waste heat in the temperature range of 1100–1800 K is presented. The arrangement consists of metallic concentric shells wherein flue gases pass through the inner shell and air to be preheated passes through annular gap in the same direction. The recuperator height is divided into small elements and an energy balance is performed on each element. Necessary information about axial shell-surface, gas and air temperature distribution, and the influence of operating conditions on recuperator performance is obtained. The recuperative effectiveness is found to be increased with increasing inlet gas temperature and with decreasing fuel flow rate. The present model provides a valuable tool for metallic concentric tube recuperator performance considerations in parallel flow arrangement.     

Study of molten carbonate fuel cell—microturbine hybrid power cycles

The interaction realized by fuel cell—microturbine hybrids derive primarily from using the rejected thermal energy and combustion of residual fuel from a fuel cell in driving the gas turbine. This leveraging of thermal energy makes the high temperature molten carbonate fuel cells (MCFCs) ideal candidates for hybrid systems. Use of a recuperator contributes to thermal efficiency by transferring heat from the gas turbine exhaust to the fuel and air used in the system.Traditional control design approaches, consider a fixed operating point in the hope that the resulting controller is robust enough to stabilize the system for different operating conditions. On the other hand, adaptive control incorporates the time-varying dynamical properties of the model (a new value of gas composition) and considers the disturbances acting at the plant (load power variation).     

利用金属辐射网强化换热器烟气侧传热的研究

提出了用金属辐射网来强化高温烟气／空气换热器传热的方法，并通过实验研究了金属辐射网对其传热特性的影响。得出了烟气温度越高、流速越低、空气侧传热系数越大，则辐射网的效果越好等结论，为换热器传热的强化提供了一个新的途径。     

激波风洞中超声速燃烧现象的初步实验研究

激波风洞可以提供超声速燃烧现象研究需要的高速和高温实验模拟条件,而且在实验时间上优于膨胀管和重活塞风洞,但是由于其技术难度,很少用于超声速燃烧现象研究。文章介绍了启用激波风洞进行燃烧研究所作的改造和得到的初步实验结果。实验除测量常规流场参数和模型表面的动态参数外,主要使用二维实验模型,利用高温气体的自发光和燃烧伴随的发光现象,采用高速摄影技术来观测燃烧现象,记录到高焓流场中叠加燃料喷射和燃烧的流场,观察到自由边界条件下扩控制的超声速燃烧现象。结果表明激波风洞用于超声速燃烧研究的一些必要的技术问题已基本解决。     

New weighted‐sum‐of‐gray‐gases model for typical pressurized oxy‐fuel conditions

Pressurized oxy‐fuel combustion technology has received considerable attention due to its ability to improve the overall system efficiency and to control CO₂ emissions. The characteristics of radiation heat transfer are significant for pressurized oxy‐fuel gas mixture and different from those under atmospheric conditions. Therefore, to calculate the radiation characteristics of pressurized oxy‐fuel gas mixture quickly and accurately, new weighted‐sum‐of‐gray‐gases (WSGG) model for pressurized oxy‐fuel conditions was first presented in this paper, which was applied in 3 typical high pressure conditions: 5, 10, and 15 bar. The new WSGG model correlations were suitable for pressurized conditions with a molar ratio range of 0.125‐2, temperature range of 400‐2500 K, and path length range of 0.1‐20 m. Calculations for a variety of typical pressurized oxy‐fuel combustion cases showed that the new WSGG model can accurately predict the radiation characteristics and heat transfer characteristics of the gas mixtures compared with the SNB model benchmark. In addition, the application of the previous atmospheric WSGG models yielded non‐ideal results under pressurized conditions. Consequently, the new model can provide efficient and accurate radiation heat transfer results for pressurized oxy‐fuel conditions and can be used to design pressurized oxy‐fuel combustion furnaces or boilers.     

微型燃气轮机外燃循环的分析

介绍了微型燃气轮机结构及其回热循环,阐述了微型燃气轮机的外燃循环的结构和特点,以及外燃循环在可再生能源利用方面的贡献,并采用MATLAB软件建立了以生物沼气为燃料的微型燃气轮机外燃循环的数学模型,对其在额定工况和变工况下进行了稳态分析,给出了各个运行参数对其性能的影响曲线和最佳运行曲线.结果表明:与采用天然气为燃料的回热循环相比,微型燃气轮机外燃循环具有较好的热经济性,在变工况下保持了较高的热效率,发电效率可达到30%左右,为可再生能源在热电联供中的应用提供了一种有前途、高效和廉价的供能方式.     

带烟气回流W型辐射管加热装置的性能分析

实验研究了某采用烟气回流技术的W型辐射管加热装置的性能。研究认为,烟气回流和分级燃烧不仅能保证燃料的完全燃烧,而且还可有效抑制NOx的生成,烟气中NOx含量小于70×10-6。高效换热器可提高热回收效率,换热器的热效率大于51％,辐射管综合热效率达到77.1%。由于一次风量过少,空气、煤气喷出口处一级燃烧强度低,烧嘴喷头处温度低,辐射管温度均匀性较差。     

Effects of spray characteristics on combustion performance of a liquid fuel spray in a gas turbine combustor

Spray characteristics like mean drop diameter and spray cone angle play an important role in the process of combustion within a gas turbine combustor. In order to study their effects on wall and exit temperature distributions and combustion efficiency in the combustor, a numerical model of a typical diffusion controlled spray combustion in a can‐type gas turbine combustion chamber has been made. A simple k–ϵ model with wall function treatment for near‐wall region has been adopted for the solution of conservation equations in carrier phase. The initial spray parameters are specified by a suitable PDF for size distribution and a given spray cone angle. A radiation model for the gas phase, based on modified first order moment method, and in consideration of the gas phase as a grey absorbing–emitting medium, has been adopted in the analysis. It has been recognized that an increase in mean drop diameter improves the pattern factor. However, the combustion efficiency attains its maximum at an optimum value of the mean diameter. Higher spray cone angle increases the combustion efficiency and improves the pattern factor, but at the same time, increases the wall temperature. Copyright © 1999 John Wiley & Sons, Ltd.     

微型燃气轮机的建模研究(上)--动态特性分析

以模块化建模方法建立了微型燃气轮机的全工况的动态数学模型,并通过流体网络对其进行了求解。计算及研究了微型燃气轮机从100%到0%范围内的全工况运行的动态特性及甩负荷动态特性,指出回热器壁温蓄能对微型燃气轮机动态特性具有较大的影响。图15表1参4     

PSR波纹板片的热强度分析

提出一种新型紧凑式回热器——一次表面回热器(PSR)的强度设计技术。结合船用ICR燃气轮机一次表面回热器研发,以3．7MW燃气轮机为背景,根据热弹性力学和传热学理论,建立PSR板片热强度分析物理数学模型,并对波纹曲线为椭圆、正弦波和抛物线的3种常见波纹传热板片所受热应力做了对比计算,分析了板片厚度,两侧压差,本身温度及形状对板片热强度的影响。给出基于Von Mise等效应力极值σrmax的板片最小设计厚度δmin,还研究了波纹板片在典型工况下的弹性变形情况。本文工作对PSR的结构设计有重要参考价值：     

Design and optimization of a non-TEMA type tubular recuperative heat exchanger used in a regenerative gas turbine cycle

A special non-TEMA type tubular recuperative heat exchanger used as a regenerator of a gas turbine cycle is considered for multi-criteria optimization. It is assumed that the recuperator is designed for an existing gas turbine cycle to be retrofitted. Three scenarios for optimization of the proposed system have been considered. In one scenario, the objective is minimizing the cost of recuperator; while in another scenario maximizing the cycle exergetic efficiency is considered. In third scenario, both objectives are optimized simultaneously in a multi-objective optimization approach. Geometric specification of the recuperator including tubes length, tubes outside/inside diameters, tube pitch in the tube bundle, inside shell diameter, outer and inner tube limits of the tube bundle and the total number of disc and doughnut baffles are considered as decision variables. Combination of these objectives and decision variables with suitable engineering and physical constraints (including NO_x and CO emission limitations) makes a set of MINLP optimization problem. Optimization programming in MATLAB is performed using one of the most powerful and robust multi-objective optimization algorithms namely NSGA-II. This approach which is based on the Genetic Algorithm is applied to find a set of Pareto optimal solutions. Pareto optimal frontier is obtained and a final optimal solution is selected in a decision-making process. It is shown that the multi-objective optimization scenario can be considered as a generalized optimization approach in which balances between economical viewpoints of both heat exchanger manufacturer and end user of recuperator.