相变储能箱耦合太阳能空气源热泵供热系统参数优化

为解决相变储能箱耦合太阳能空气源热泵供热系统关键参数的设计问题,设计了基于TRNSYS软件的相变储能箱耦合太阳能空气源热泵供热系统模型。利用GENOPT软件调用Hooke Jeeves算法,以费用年值为优化函数,针对集热器面积、空气源热泵制热量、集热器倾角、集热器方位角、相变储能箱体积以及体积因子等关键参数进行优化分析,并以单位体积下相变储能箱蓄/放热量、集热器逐月平均效率及系统性能系数COPS为优化前后评价指标。结果表明：集热器面积取187 m2、空气源热泵制热量取40.5 kW、集热器倾角取44.1°、集热器方位角取-1°、相变储能箱体积取4 m3、体积因子取0.1时得最小费用年值,费用年值同比降低21%;优化后单位体积下,相变储能箱年放热量提升了15.1%,年蓄热量提升了16.5%;以系统性能系数COPS为评价指标,优化后系统整体性能受环境因素影响下降,系统更趋于稳定运行。     

基于正交法的太阳能耦合污水源热泵系统运行优化

为了回收利用洗浴废水中大量的低品位热能,该文通过TRNSYS仿真模拟软件,搭建了太阳能—污水源热泵系统,并采用正交试验法对系统进行3因素（集热器面积、水箱体积、热泵制热量）4水平的实验设计,以年能耗、费用年值为评价指标分别确定了3个影响因素的主次顺序。最后采用综合平衡法确定了系统的最佳参数组合,将其带入仿真模型进行全年运行分析,优化后全年太阳能集热量提高了19.2%、太阳能保证率提高了6%、污水源系统COP提高了3%、年能耗减少了21%、费用年值减少了8%。此研究方法与成果可为设计与优化太阳能耦合热泵系统提供参照。     

大庆地区太阳能地板辐射采暖研究与经济分析

设计了太阳能地板辐射采暖系统,给出了系统的工作原理。探讨了集热器单位面积有效利用能和集热器效率的计算方法。通过经济分析,得到大庆市某60 m2平顶民房安装太阳能地板辐射采暖的年计算费用为1 485元;安装散热器采暖年计算费用为1991元。经济分析结果表明,太阳能地板辐射采暖系统具有良好的经济效益。     

太阳能热水系统集热器面积与倾角的组合优化

集热器面积与倾角是太阳能热水工程设计中的重要参数。综合考虑气候、用水方式、太阳辐射和热水负荷的季节性等因素,建立完整的组合优化计算模型,在合理年太阳能保证率的前提下确定集热器面积,以年辅热量最小的原则确定与集热器面积相配的倾角,并以3个城市为例进行计算。结果表明,当太阳辐射与热水负荷变化趋势相反,最佳倾角随集热器面积增加而增大;当太阳辐射与热水负荷变化趋势相同,最佳倾角随集热器面积增加基本不变。     

太阳能开水器的经济性分析

太阳能开水器以电作为补充能源进行开水供应。本文利用动态的年计算费用法将这种供应形式与电开水器进行了比较。经计算,在长春地区按7月份平均的太阳辐射强度确定出的集热器面积使太阳能开水器年费用最小,与开水供应量相同的电开水器相比,其回收年限为4．1年。从经济性方面来看,这种开水供应形式在长春地区使用是可行的,经济效益比较可观,在全国大部分地区都有推广价值。     

太阳能电热水系统集热器阵列布置优化

综合考虑集热器倾角、方位角、间距等因素,确立了安装在水平面上有限面积内太阳能集热器阵列得热量与地理位置及集热器布置方式之间的关系,基于上述关系又建立了太阳能电热水系统全年辅助加热量计算模型及系统全年用电成本计算模型。最后,文中以太阳能电热水系统用电成本最低、辅助加热量最小为目标确定太阳能集热器阵列的最优布置。研究结果表明:当阵列得热量最大时,系统年辅助电加热量最小,系统的耗电成本也最低。以某高校男生宿舍楼为例,在宿舍楼楼顶平面500m2的区域按照集热器阵列最小维护间距为0.5m的规范布置集热器,最优设计方案为:阵列排数为8排,阵列倾角为、阵列方位角为,此时系统全年辅助加热量为128943MJ,全年系统辅助加热电耗成本为2.45万元。     

典型太阳能集热器热性能研究

以当今市场保有量最高的两种典型太阳能集热器——全玻璃真空管型太阳能集热器和平板型太阳能集热器为研究对象,从能量传递角度,构建了太阳能集热器在理想状态下的热效率模型,并依据模型计算了极限热效率;最后对两种太阳能集热器做了热性能测试实验,并使用最小二乘法拟合出太阳能集热器瞬时热效率与归一化温差的关系,对比两种太阳能集热器在同一实验条件下的极限热效率和热损失系数,并验证了该模型的正确性。     

新疆地区水果冷藏太阳能水蒸汽喷射CO2制冷系统

针对新疆地域和生产水果的特点,设计了太阳能热源、水和CO2为工质的水果冷藏制冷系统。通过计算分析得出,CO2循环蒸发温度提高,外界环境温度升高,太阳能辐射强度增加,喷射器引射率提高,系统的耗能减小。外界环境温度每增加1℃,太阳能集热器的面积减小0.5m2,太阳能辐射强度每增加10W/m2,太阳能集热器的面积减小1.2m2,喷射器的引射率每提高0.01,太阳能集热器的面积减小0.8m2。与发生器的热源全部来自电能的系统运行情况相比,吐鲁番地区葡萄冷藏2个月节约运行费用达96.2%,哈密地区哈密瓜冷藏15天节约运行费用约94.4%,库尔勒地区香梨冷藏6个月节约运行费用约41.1%,库车地区白杏冷藏21天节约运行费用约74.2%。设计时应针对使用场所,优化选取设计参数,减少设备初投资。     

泰安地区利用太阳能采暖的技术经济分析

从泰安地区气候条件、可采用的采暖系统形式、集热器选择及面积计算、蓄热水箱容量计算等几个方面对太阳能采暖系统的技术性分析,又通过对几种方案的年计算费用的比较对系统的经济性分析,论证了太阳能采暖在泰安地区是切实可行的。为泰安地区今后在建筑中推广利用太阳能采暖工作提供参考。     

住宅太阳热水器的技术经济性分析

以福州地区典型气象年逐时气象数据为基础,对平板型太阳热水器的热性能进行逐时模拟。利用综合能源价格法,分析集热器面积对太阳热水器经济性的影响,并比较各类热水器的技术经济性。在当前能源价格体系下,集热器面积为8.5m~2时,系统的年平均太阳能保证率最大(为67.72%);集热器面积为4m~2时,综合能源价格现值最小(为0.283$/kWh),此时系统的年平均太阳能保证率为62.65%。     

Determination of design space and optimization of solar water heating systems

In this paper, a methodology is proposed to determine the design space for synthesis, analysis, and optimization of solar water heating systems. The proposed methodology incorporates different design constraints to identify all possible designs or a design space on a collector area vs. storage volume diagram. The design space is represented by tracing constant solar fraction lines on a collector area vs. storage volume diagram. It has been observed that there exists a minimum as well as a maximum storage volume for a given solar fraction and collector area. Similarly existence of a minimum and a maximum collector area is also observed for a fixed solar fraction and storage volume. For multi-objective optimization, a Pareto optimal region is also identified. Based on the identified design space, the solar water heating system is optimized by minimizing annual life cycle cost. Due to uncertainty in solar insolation, system parameters and cost data, global optimization may not be utilized to represent a meaningful design. To overcome this, a region of possible design configurations is also identified in this paper.     

Cost of house heating with solar energy

There has long been a need for a practical method of predicting the true cost of heating a house with solar energy and designing the heating system (solar and auxiliary) to achieve the minimum total annual heating cost possible under the particular climatic, geographic, and residential characteristics involved. Rough approximations based on various types of averaged values of weather and seasonal variables have previously been developed, but the reliability of such methods and results is open to question. The authors have therefore made a rigorous analysis of projected solar heating costs in eight U.S. cities and have optimized the heating system design in each location.The analysis involved the use of a high speed computer and approximately 400,000 hourly observations in eight cities of radiation, temperature, wind, solar altitude, cloud cover, and humidity. Equations for performance of flat plate solar collectors and sensible heat storage systems were developed and programmed with the above weather variables and with eight design parameters comprising house size, collector size, storage size, collector tilt, number of transparent surfaces in collector, hot water demand, insulation on storage unit, and thermal capacity of collector. Capital and operating costs were quantitatively related to heating system design parameters, and the values of all design variables which yielded lowest annual heating cost in each city were then selected.The findings are presented in the form of two tables and ten graphs, showing heating costs as functions of various design and location factors. The relative importance of each factor is discussed, and the overall costs of solar heating are compared with the costs of conventional heat supply in each location. The method for designing the least-cost combination of solar and conventional heat supplies is also shown, and an example of the use of the method is presented.     

An approximate model for sizing and costing a solar thermal collector-central receiver system

An approximate generalized theoretical model is presented for the geometry and energy transfer of a solar thermal collector-central receiver system. Equations permit sizing the receiver, tower, and heliostat field. Cost functions correlate data from Department of Energy studies. Based on a set of assumed conditions, simplified, optimized sizing equations yield the minimum capital cost. The costs of the tower and central receiver will change with plant and equipment cost indices, while heliostat costs are expected to diminish as annual production increases. The heliostat cost is the major cost component even at lowest projected unit cost; therefore optimization tends toward minimum heliostat area. The model permits order-of-magnitude cost estimates to be made very quickly, compared to detailed simulation.     

A feasibility study of solar heating in Iran

A single-glass, flat-plate solar collector for air heating is analyzed for an optimum tilt angle of 45° for Shiraz (29° 36′ N latitude, 52° 32′ E longitude, and elevation of 4500 ft). The absorbed and utilized solar energy, as well as the collector outlet air temperature, the glazing, and the blackened plate temperatures, are determined with respect to the incident solar energy, parametric with collector inlet air temperatures and flow rates and outside air temperature.A 10 ft² collector and an 8 ft³ rock storage are built to experimentally verify the analysis and obtain cost estimates. A 5000 ft² single-story building is considered for solar heating and economic evaluations. Based on an annual interest rate of 8 per cent amortization of the solar heating equipment over 15 yr, electrical energy costs of 3c/kWh, and fuel costs of $1·10 per 10⁶ B.t.u., the optimum collector area which results in minimum annual operating costs (of the solar heating system and the auxiliary heating unit) is determined. A net saving results because solar heating is employed. The feasibility study is extended to eleven other Iranian cities. It is found profitable to employ solar heating in cities with low annual rainfall and relatively cold winters. An effective evaporative cooling is obtained by spraying water over the rock storage during the summer.     

Cost analysis of different solar still configurations

The enhancement of the productivity of the solar desalination system, in a certain location, could be attained by a proper modification in the system design. Therefore, different design configurations could be found in literatures. However, the increase in the system productivity with high system cost may increase also the average annual cost of the distillate. Cost analysis of different design configurations of solar desalination units is essential to evaluate the benefit of modification from the economical point of view. The main objective of this work is to estimate the water production cost for different types of solar stills. In this paper 17 design configurations are considered. Systems with higher and lower values of productivity are considered in this investigation. A simplified model for cost analysis is applied in this study. The results show that, the best average and maximum daily productivity are obtained from solar stills of single-slope and pyramid-shaped. The higher average annual productivity for a solar still is about 1533 l/m² using pyramid-shaped while the lower average annual productivity is about of 250 l/m² using modified solar stills with sun tracking. The lowest cost of distilled water obtained from the pyramid-shaped solar still is estimated as 0.0135 $/l while highest cost from the modified solar stills with sun tracking is estimated as 0.23 $/l.     

Solar multiple optimization for a solar-only thermal power plant, using oil as heat transfer fluid in the parabolic trough collectors

Usual size of parabolic trough solar thermal plants being built at present is approximately 50 MW_e. Most of these plants do not have a thermal storage system for maintaining the power block performance at nominal conditions during long non-insolation periods. Because of that, a proper solar field size, with respect to the electric nominal power, is a fundamental choice. A too large field will be partially useless under high solar irradiance values whereas a small field will mainly make the power block to work at part-load conditions.This paper presents an economic optimization of the solar multiple for a solar-only parabolic trough plant, using neither hybridization nor thermal storage. Five parabolic trough plants have been considered, with the same parameters in the power block but different solar field sizes. Thermal performance for each solar power plant has been featured, both at nominal and part-load conditions. This characterization has been applied to perform a simulation in order to calculate the annual electricity produced by each of these plants. Once annual electric energy generation is known, levelized cost of energy (LCOE) for each plant is calculated, yielding a minimum LCOE value for a certain solar multiple value within the range considered.     

Comparison of the performance of PV water pumping systems driven by fixed, tracking and V-trough generators

Photovoltaic pumping systems with solar tracking, coupled to low concentration cavities, have been proposed as a viable alternative to reduce the final cost of the pumped water volume. V-trough concentrators are particularly appropriate for photovoltaic applications since, for certain combinations of the concentration ratio (C) and vertex angle (Ψ), they provide uniform illumination on the region where the modules are located. Water pumping systems are only operational when the irradiance is larger than a minimum irradiance level (I_C). Solar tracking increases the average collected irradiance and, for a system operating with a given critical irradiance level (I_C), it is verified that the smaller the relationship , the larger the useful energy. Thus, the gain, in terms of pumped water volume, provided by solar tracking systems, can be larger than the gain in collected solar radiation. The combination of both devices, tracking and concentration provides an additional increase of the benefits resulting from the use of solar trackers. By means of the “Utilizability Method”, we estimate the long-term gains of pumped water volume, for tracking systems, with and without concentration, against fixed systems. The long-term water volume has been calculated using the characteristic curve of a tested PVP system with a tracking V-trough concentrator. Results show that, for the climate of the city of Recife (PE-Brazil), the annual pumped water volume of the tracking system is 1.41 times the value obtained with the fixed system. In that case, the gains observed for the collected solar energy were around 1.23. For the PVP system with tracking V-trough concentrator the annual benefits for pumped water volume are around 2.49, while for collected solar radiation we found 1.74. The annualized cost of the cubic meter of pumped water has been estimated for the three configurations. Results show a cost reduction of the order of 19% for the tracking system and of 48% for the concentrating system, when compared to the fixed configuration.     

Potential and viability of grid-connected solar PV system in Bangladesh

The potential of grid-connected solar PV system in Bangladesh was estimated utilizing GeoSpatial toolkit, NASA SSE solar radiation data and HOMER optimization software. Financial viability of solar photovoltaic as an electricity generation source for Bangladesh was also assessed utilizing a proposed 1-MW grid-connected solar PV system using RETScreen simulation software for 14 widespread locations in Bangladesh. The technical potential of gird-connected solar PV in Bangladesh was calculated as about 50174 MW. The annual electricity generation of the proposed system varied depending on the location between 1653 MWh and 1854 MWh, with a mean value of 1729 MWh. Several different economic and financial indicators were calculated, such as the internal rate of return, net present value, benefit-cost ratio, cost of energy production and simple payback. All indicators – for all sites – showed favorable condition for development of the proposed solar PV system in Bangladesh. The results also showed that a minimum of 1423 tons of greenhouse gas emissions can be avoided annually utilizing the proposed system at any part of the country.     

Technical and economical system comparison of photovoltaic and concentrating solar thermal power systems depending on annual global irradiation

Concentrating solar thermal power and photovoltaics are two major technologies for converting sunlight to electricity. Variations of the annual solar irradiation depending on the site influence their annual efficiency, specific output and electricity generation cost. Detailed technical and economical analyses performed with computer simulations point out differences of solar thermal parabolic trough power plants, non-tracked and two-axis-tracked PV systems. Therefore, 61 sites in Europe and North Africa covering a global annual irradiation range from 923 to 2438 kW h/m² a have been examined. Simulation results are usable irradiation by the systems, specific annual system output and levelled electricity cost. Cost assumptions are made for today's cost and expected cost in 10 years considering different progress ratios. This will lead to a cost reduction by 50% for PV systems and by 40% for solar thermal power plants. The simulation results show where are optimal regions for installing solar thermal trough and tracked PV systems in comparison to non-tracked PV. For low irradiation values the annual output of solar thermal systems is much lower than of PV systems. On the other hand, for high irradiations solar thermal systems provide the best-cost solution even when considering higher cost reduction factors for PV in the next decade. Electricity generation cost much below 10 Eurocents per kW h for solar thermal systems and about 12 Eurocents/kW h for PV can be expected in 10 years in North Africa.     

A reliable methodology based on mine blast optimization algorithm for optimal sizing of hybrid PV-wind-FC system for remote area in Egypt

In this paper, a reliable methodology incorporated mine blast algorithm (MBA) is applied to solve the optimal sizing of a hybrid system consisting of photovoltaic modules, wind turbines and fuel cells (PV/WT/FC) to meet a certain load of remote area in Egypt. The main objective of the optimal sizing process is to achieve the minimum annual cost of the system with load coverage. The sizing process is performed optimally based on real measured data for solar radiation, ambient temperature and wind velocity recorded by the solar radiation and meteorological station located at national research institute of astronomy and geophysics, Helwan city, Egypt. Three other meta-heuristic optimization techniques, particle swarm optimization, cuckoo search and artificial bee colony are applied to solve the problem and the results are compared with those obtained by the proposed methodology. A power management strategy that regulates the power flow between each system component is also presented. The obtained results show that; applying the proposed methodology will save about 24.8% in the annual total cost of the proposed system compared with PSO, 8.956% compared with CS and 11.5576% compared with ABC. The proposed algorithm based on MBA is candidate for solving the presented optimization problem of optimal sizing the hybrid PV/WT/FC system.