Using the Taguchi Method and Grey Relational Analysis to Optimize the Performance of a Solar Air Heater

Solar energy is regarded as one of the promising renewable energy sources in the world.The main aim of this study is to use the Taguchi-Grey relational grade analysis to optimize the performance of two Solar Air Heaters(SAHs).A typical Grey–Taguchi method was applied.The Orthogonal Array,Signal-to-Noise ratio,Grey Relational Grade,and Analysis of Variance were employed to investigate the performance characteristics of SAH.Experimental observations were made in agreement with Jordanian climate 32°00′N latitude and 36°00′E longitude with a solar intensity of 500 W\m^(2).The operating factors selected for optimization are the tilt angle(T)with three levels(0°,22°,45°),inlet velocity(V)with two levels(1.2,1.8 m/s),and absorber plate material(M)with two levels(Aluminum,wood).In this study,the Grey–Taguchi approach is validated by performing 12 individual experiments.The results show that the process factors sequence required for a maximum SAH efficiency(SAHµ)is V>T>M.Using this approach,we combined the Orthogonal Array design with Grey Relational Analysis.As a result of that,the level of each operating conditions which optimizes both process responses(Temperature difference,ΔT and Solar air heater efficiency,SAHµ)can be specified with a minimum number of tests compared with classic Grey Relational Analysis.The optimal operating conditions of a SAH for multiple performance characteristics are determined as T2,M2,and V2,respectively,which are in congruence with the experimental results.

Experimental Performance Analysis of a Corrugation Type Solar Air Heater(CTSAH)

This paper explains the experimental performance evaluation of a Corrugated Type Solar Air Heater(CTSAH)for understanding its performance in a humid tropical climatic condition in Puducherry,India.This helps in understanding its effectiveness in using it for drying application of products like seafood,etc.Experiments were conducted at different mass flow rates and their effect on the heat gain,efficiency,friction factor heat transfer,etc.,was analyzed.Experiments were carried out at different mass flow rates,i.e.,M1=0.06 kg/s,M2=0.14 kg/s,M3=0.17 kg/s,M4=0.25 kg/s,M5=0.3 kg/s,and were conducted from 11:00 h to 14:00 h.The air inlet&air temperature is found to be at an average of 40°C whereas the incident solar radiation is at an average of 795 W/m2.Experimental results show that the optimum performance of the CTSAH is in the mass flow rate range of 0.14–0.25(kg/s).Also,the calculated useful heat produced,convective heat transfer coefficients,effective efficiency,optical efficiency provides knowledge on the potential use of the air heater.

Research and Development of Hot Primary Air Heater for Coal-Fired Boilers in Power Plant

The reasons of introducing cold air into pulverizer are analyzed for boilers with large capacity and high parameters. The temperature rises of the exhaust gas are calculated when varying the amount of the cold air. The hot primary air heater, a new technology, is developed to eliminate the cold air from the pulverized coal system. The applications, advantages and disadvantages are introduced in detail for the new device and system. It is concluded that introducing cold air into pulverizer is one of the major factors that causes the exhaust gas temperature of boilers with large capacity to be high. The amount of the cold air could be reduced signif icantly, even to zero in some cases by adopting the hot primary air heater, which drops the exhaust gas temperature of the boiler effectively. The hot primary air heater, which could play part roles of the steam-air heater or the hot air recirculation system, could also be used to adjust the exhaust gas temperature within the range of 20 ℃ by controlling the flow rate of the cooling medium. Moreover, the startup period of the steam-air heater or the hot air recirculation system will be shortened, which is a unique advantage of the hot primary air heater among the measures to drop the exhaust gas temperature.

Application of Response Surface Methodology for Analysing and Optimizing the Finned Solar Air Heater

In this research paper,a solar air heater with triangular fins has been experimentally analysed and optimized.Initially,an experimental set-up of a solar air heater having triangular fins has been developed at the location of 28.10°N,78.23°E.The heat transfer rate through fins and fins efficiency has been determined by the Finite Difference Method model equations.The experimental data and modeled data of response parameters have been optimized in MINITAB-17 software by the Response Surface Methodology tool.For creating the response surface design,three input parameters have been selected namely solar intensity,Reynolds number,and fin base-to-height ratio.The range of solar intensity,Reynolds number,and fin base-to-height ratio is 600 to 1000W/m^(2),4000 to 6000,and 0.4 to 0.8 respectively.The response surface design has been analyzed by calculating the outlet temperature,friction factor,Nusselt number,fin efficiency,thermal performance factor,and exergy efficiency.The optimum settings of input parameters:solar intensity is 1000 W/m^(2);Reynolds number is 4969.7,and the fin base to height ratio is 0.6060,on which these response:namely outlet temperature of 92.531℃,friction factor of 0.2350,Nusselt number of 127.761,thermal efficiency of 50.836%,thermal performance factor of 1.4947,and exergy efficiency of 8.762%.

Numerical analysis of the return flow solar air heater(RF-SAH)with assimilation of V-type artificial roughness

A novel design of Return Flow Solar Air Heater(RFSAH)with different arrangements of baffles especially V-Type Artificial roughness is simulated and numerically analyzed with energy balance equations.To enhance the effectiveness of baffles,numerous studies have been conducted.The performance of the RFSAH is studied in terms of thermal efficiency,thermo-hydraulic efficiency,and optimization of baffle parameters.Maximum Thermal efficiency and thermo-hydraulic efficiency are found in RFSAH with baffle on both sides of the absorber plate and mass flow rate above 0.2kg/s.Sensitivity analysis of the influencing parameters is carried out and reported the best performance of the system on selective geometrical parameters(ψ=0.7,β=20%,e/H=1,p/e=0.8,α=60°).The results obtained from the present model are validated with the published experimental results and have been found in quite reasonable agreement with an average error of 16.45%.Thermal and Thermohydraulic efficiency of RFSAH with a baffle on both sides of the absorber plate is maximum among baffles below,above,and on both sides of the absorber plate.It is observed that the thermal efficiency of RFSAH is greater than SF-SAH.The proposed optimum baffles roughness is suggested to increase the air upholding time period for more efficient output.

Thermodynamic Performance Analysis of a Low-Cost,Recycled and Energy-Efficient Solar Air Heater with Waste Beverage Cans:An Experimental Research

Solar air heaters are at the centre of interest owing to their widespread use for various purposes.In the study,thermal performance analysis of a solar air heater that can be easily produced from daily waste materials is done.The system has a low-cost structure with both waste material use and a simple design.The proposed system is tested under different climatic conditions,and the energetic and the exergetic performance figures are obtained for the first time in literature.It is observed from the experimental tests that the results are stable and coherent as well as in good accordance with the similar attempts in literature with some cost reductions and performance improvements.Thermodynamic performance analyses indicate that the maximum energy efficiency of the system is about 21%,whereas the exergy efficiency is 1.8%.The energetic and exergetic outputs of the system are also determined to be 27 W and 3 W,respectively,which is promising.

前置暖风器电站锅炉烟气余热回收系统多参数设计与变工况运行策略

针对前置暖风器烟气余热回收系统,建立了多参数设计优化与变工况特性计算模型,开展了系统的多参数优化,并提出了运行参数控制策略。结果表明:多参数优化后系统在设计工况下的节煤率为3.67 g/(kW·h);多参数优化后的系统在变工况下虽能保持较高的节煤率,但系统的安全性受到环境温度和负荷的严重制约;采用所提出的控制策略可使系统在100%额定负荷下,安全运行的环境温度下限从24℃扩展至-3℃,显著提高了系统优化的综合效果。

探究燃尽风对墙式对冲锅炉主再热汽温的影响

本文探究了燃尽风对墙式对冲燃烧锅炉主再热汽温的影响。关小燃尽风燃烧器拉杆,可以提高该区域的整体壁温,反之亦然。利用这一规律,可以有效调节主汽温度和再热汽温。

几种家用大功率负荷精细化建模研究

该文基于家用负荷的物理模型、用户的使用习惯和用户的舒适度要求,提出了家用大功率负荷的精细化建模方法,该方法可应用于家庭能量管理系统,具有良好的应用前景。首先,建立考虑电热水器负荷的精细化热力学动态模型,考虑气温、墙体等因素的空调房间的精细化热力学动态模型和电动汽车负荷的精细化储能模型;然后,建立这三种负荷的精细化控制模型,通过自定义家庭算例将不同个性化的精细化参数模型对比分析。MATLAB仿真结果表明,该文建立的精细化动态模型能够准确描述用户的用电规律,对用户积极参与到电力系统需求响应中去起到促进作用。

Performance and Optimization of Air Source Heat Pump Water Heater with Cyclic Heating

A new type of microchannel condenser applied in the air source heat pump water heater(ASHPWH)with cyclic heating was proposed in this study.The operating performance of the ASHPWH was frst tested.Then,the structure of the microchannel condenser was optimized with the implement of vortex generators.Finally,a numerical model of the ASHPWH was established and the optimized microchannel condenser was studied.The experimental results showed that the average coefficient of performance(COP)of the 1HP(735 W)ASHPWH reached 3.48.In addition,the optimized microchannel condenser could be matched with a 3 HP(2430W)ASHPWH with an average heating capacity of 10.30 kW,and achieving an average COP of 4.24,14.6%higher than the limit value in the national standard.

燃煤发电机组调峰对回转式空气预热器的影响及应对措施

近年来,随着风电、太阳能等可再生能源装机容量的迅猛增长,以及居民用电和第三产业用电负荷的增加,相应的发电负荷和用电负荷具有更明显的日波动性。电网的调峰问题日益突出,需要我国电力的主要来源——燃煤发电机组具有更高的调峰以及快速响应能力。燃煤机组长时间低负荷运行、频繁的升降负荷乃至停炉热备用给配套的回转式空气预热器的安全稳定运行带来挑战,主要体现在快速升降负荷过程中预热器运行电流异常波动以及长时间低负荷下预热器堵灰问题,本文针对上述问题进行研究并提出应对措施。

家用和类似用途空气源热泵热水器热工性能测试分析

为更好地理解GB/T 23137—2020《家用和类似用途热泵热水器》,并准确测试空气源热泵热水器的热工性能,对空气源热泵热水器性能测试和计算方法进行解读。首先,为保证空气源热泵热水器性能测试的准确性,建议对标准中公式的疏漏进行修正,标准中对同一物理量的定义和单位应统一,同时,考虑大气压对测试结果的影响。其次,分析空气源热泵热水器热工性能相关参数的计算方法,指出采用单一发生时间获得的性能指标对热泵热水器进行评价存在局限性。最后,指出应及时更新空气源热泵热水器的能效标准或产品标准,使其评价机制保持一致。

一款改进的家用热回收空调热力性能实验研究

为提高家用空调器利用率并节能减排,通过改进得到一款具有制冷、供暖、全天候供热水和冷凝热回收制取热水四种功能的热回收空调器。热力性能实验结果表明,改进后的热回收空调器各模式运行可靠,节能效果显著。

Key Technology and Experimental Results of the Clean Air Heated Facility for Supersonic Combustion

The scramjet, which is the propulsion of hypersonic vehicle, has become the focus in many military developed countries. The ground tests play an important role in the research of scramjet. There is defect of test medium contamination （the thermochemical characteristic of the ground test medium is different from that of the flight medium） in existing ground test facilities for scramjet combustor experiment. To solve the problem of test medium contamination, the first clean air heated facility of China for scramjet combustor experiment is designed. The key technology of designing the clean air heated facility is summarized. By using bypass duct, combustor model is protected from high temperature. To reduce the switching time between main duct and bypass duct, solenoid valve and water-cooled system were used. Having centrosymmetric structure, the heat radiating area of the facility and heat loss of the facility are much lower than others. Clean air heated facility is adopted to conduct experiment, which is the first experiment of China in clean air inflow, research on hydrogen-fueled and ethylene-fueled ignition and combustion for scramjet combustor at different equivalence ratio. Successful ignition and sustained combustion of hydrogen has been achieved. Successful ethylene ignition and sustained main stream combustion is achieved with normal fuel injection and taking hydrogen as pilot flame. Experiment result shows that the wall pressure of combustor model rises when the equivalence ratio of hydrogen rises. As the wall pressure of combustor model rises, the pressure disturbance influences the shock train in the upstream.

Experimental Study of Energy-Saving Air-Conditioner with Hot Water

Energy-saving air-conditioner with hot water is an air source heat pump air-conditioner,which can also supply hot water.The hot water is heated by a double pipe condenser connected with an air-cooled condenser in series in the system.This experiment of the energy-saving air-conditioner was carried out in the enthalpy-difference air-conditioner laboratory.The hot water temperature and the compressor's discharge and suction pressure were recorded in the working condition,where the ambient temperature was at 43 ℃,35 ℃,21 ℃,7 ℃,and 2 ℃ separately.The results showed that the system operated stably and reliably.This system can supply 240 L hot water at 50 ℃ in the whole year,and its coefficience of performance(COP)is much higher than the conventional air source heat pump system.Its energy conservation was proved by comparing the thermal efficiency with other sourece water heaters.

寒冷地区空气源热泵辅助太阳能热水器供暖性能

为提高太阳能热水器供暖的稳定性并大幅降低空气源热泵供暖的成本,提出空气源热泵辅助太阳能真空管热水器供暖构想,在甘肃省兰州市七里河区魏岭乡绿化村搭建空气源热泵辅助太阳能热水器供暖试验系统,详细研究了晴天、阴天及多云3种典型工况下系统的集热效率、热泵性能系数、系统太阳能保证率和系统能效比等.研究结果表明,晴天、阴天及多云工况下太阳能集热器有效得热量分别为75.5、4.1和49.2 kW·h,集热效率分别为61.3%、26.6%、55.2%,太阳能热泵平均性能系数(COP)分别为3.6、3.4、3.6,空气源热泵平均COP分别为0、2.9、3.1,系统实际供热量分别为113.4、125.9和124.8 kW·h,系统耗电量分别为33.4、50.5和42.7 kW·h,系统太阳能保证率分别为66.6%、3.3%、39.4%,系统能效比分别为3.4,2.5,2.9.研究证明了太阳能真空管集热器-空气源热泵系统用于寒冷地区供暖的可行性,为寒冷地区供暖提供了一种新途径.

甲烷/富氧空气同轴喷嘴燃烧性能研究

燃烧型空气加热器是开展地面试验时模拟高空来流的重要设备,一般采用同轴喷注燃烧方式。为满足设计总温1200 K的甲烷空气加热器正常运行的要求,本文开展了单元同轴喷嘴点火/稳焰的研究,分析了氧浓度、喷嘴构型对燃烧稳定性和燃烧效率的影响,并结合数值模拟获得燃烧室温度分布以及流场结构,对比甲烷/富氧空气与甲烷/氧气燃烧特性的异同。研究结果表明:直口型喷嘴出口壁厚较大,产生更大的稳焰回流区,为甲烷燃烧提供持续稳定的点火源,燃烧效率最高为99.98%;氧浓度对燃烧稳定性影响较大,随着氧浓度的降低,燃烧稳定性下降,当氧浓度低于39%时,燃烧室内不能形成稳定的火焰;甲烷/富氧空气燃烧依靠喷嘴出口回流区稳定火焰,喷嘴构型不会影响火焰稳定位置。

抛物面形凸起结构对太阳能空气集热器传热性能的影响

为改善太阳能空气集热器的综合性能,文章将吸热板表面按照V型方式离散地冲压下凹成抛物面形凸起结构,使用数值分析方法研究了不同雷诺数Re、抛物面形凸起结构的高径比(e/d)、气流攻击角(α)和相对节距(p/e)下,空气通道内的流动与传热特性,在综合传热系数最大时得到了凸起结构的最佳参数组合:e/d=1,α=60°,p/e=16。在所研究的雷诺数范围内,与光滑板结构相比,文章的最优结构将空气的进、出口温差平均提高了5.3℃,集热效率相应也平均提高了15%。采用集热效率和有效效率对此结构集热器性能的评价结果表明:文章所设计的抛物面形凸起结构集热器实现了热能利用效率与流体输运能效的有机统一。