Feasibility study of a solar water pumping system

Solar photovoltaic (SPV) water pumping systems have the potential to provide clean drinking water to millions of unserved people around the world. The abundant solar energy resource and groundwater availability in the Pacific Island Countries (PICs) can be combined to make much needed potable water available to remote island communities in these countries. This paper looks at the feasibility of using a SPV pumping system in one of the villages in the Fiji Islands.     

Dynamic modeling and simulation of a solar direct steam‐generating system

A dynamic model of solar parabolic trough collectors has been developed and solved by explicit Euler's method to predigest partial differential equations to ordinary differentials in this paper. Different working conditions of the collector structure and thermal parameters have been considered in the model. The simulated results are validated using the selected real test data on typical summer and winter days, and the steam‐generating process from unsaturated water to superheated steam has been studied in the startup simulation. The disturbance analysis validates the model's dynamic responses and confirms the relations between output steam characters and solar radiation, inlet water temperature, flow rate and collectors' area. The results indicate the possible demarcation point of superheated steam generating in different working conditions. Therefore, the model can be used to analyze the performance of the solar direct steam‐generating system. Copyright © 2010 John Wiley & Sons, Ltd.     

Dynamic simulation and parametric sensitivity studies on a central solar domestic hot water system

A computer simulation program for a central solar domestic heat water (DHW) system has been developed and validated by comparing it with the actual performance data obtained from a real-life system. A computer simulation language, CSMP, was used for the simultaneous solution of the differential equations describing the system. The program was developed from basic principles and defined parameters. It was utilized to study the dynamic behavior of the system and to perform parametric studies to determine the effects of various system parameters on its performance.Parametric sensitivity studies were carried out to determine the response of the central solar DHW system performance to the following parameters: flow rate of heat-exchange fluid in the solar collector loop, consumption rate in the consumer loop, start-up time (i.e., activation of the collector loop circulation pump), and storage tank capacity.The concept of consumption management is analyzed and discussed in order to emphasize the fact that solar loop productivity, both qualitative and quantitative, is not independent of load. As a corollary, we show that it is possible, when the situation allows, to maximize solar loop productivity by controlling the consumer loop consumption schedule.     

太阳能户用供水供电系统

介绍了太阳能户用供水供电系统的构成、原理和特点；将此系统与常规的太阳能视听照明系统进行了比较分析；论述了其资源利用效果、功能收益和经济效益。     

Modelling and simulation of a solar absorption cooling system

A detailed numerical simulation model is developed for a commercially available solar absorption chiller. The model incorporates the performance data of a Yazaki-manufactured water-cooled system. We take into consideration the variation of the COP and cooling water temperature. Using a summer season's meteorological data for an arid location in the Sahara desert, the system performance is computed for different collector types, areas and storage volumes. The results show that an optimum storage volume/collector area ratio exists. Also a high solar fraction can be obtained with relatively small areas of collectors, even when the collectors are of the inexpensive type. The interesting feature was that the system operated at design load conditions with generator temperatures as low as 80°C owing to the fact that very low cooling water temperatures are available in the dry conditions of the Sahara. The study establishes the high potential of solar operated, water-cooled absorption coolers especially for arid conditions.     

Dynamic simulation and parametric sensitivity studies on a flat-plate solar collector

A dynamic simulation program for a flat-plate solar collector has been developed and used for a parametric sensitivity study of the collector. A computer simulation language, C.S.M.P., was used for the simultaneous solution of the differential equations describing the system. The program is developed from basic principles and defined parameters, so that the effect of each element of the collector on its efficiency and outlet fluid temperature can be analyzed. The dynamic simulation program was validated by comparing calculated with actual test results on a commercial flat-plate solar collector; the agreement between the results was found to be very good.Sensitivity studies were carried out to determine the effect of the following parameters on the performance of a single-glazed solar collector: heat transfer coefficient between absorber plate and fluid transport tubes; fluid flow rate through the collector; plate absorptivity; plate emissivity and insulation thickness. Sensitivity studies were also performed on a double-glazed solar collector but for only the last three of the above listed parameters. The results of these sensitivity studies are analyzed in the text.The transient behavior of the solar collector, viz. the response of the outlet fluid temperature to a step change in insolation rate, has also been studied.     

Dynamic analysis and control of a solar power plant—II. Control system design and simulation

The paper (splitted in two parts) describes the main results of the study concerning dynamic analysis and control of the EEC solar power plant, coupled to the grind for the first time in April 1981.High temperature solar energy systems require quite sophisticated receivers, able to work with considerable radiation flux, and well designed and controlled steam generators, to meet the severe constraints imposed by the turbine on the produced steam quality.In the case of the EEC solar power plant using a water cooled solar receiver, receiver and steam generator are, actually, the same component, which indeed is subject to a number of stringent somewhat conflicting requirements, concerning, in particular, its transient behavior.This latter aspect plays a fundamental role in view of the environmental conditions, i.e. of the irregularity of the power source due, for instance, to passing of clouds.In this Part I of the work, it is shown how a carefull dynamic analysis of the process is necessary for the verification and the assessment of the receiver design, the precise formulation of the plant operation procedures and safety conditions, the specification of the control system requirements. In particular, it is recognized that such kinds of processes can be adequately simulately by means of accurate partial derivatives models, based on suitable simulation codes.     

Economic feasibility of solar pumping

Two major questions concerning the economic feasibility of solar pumping are addressed. The first of these is concerned with finding a least-cost solar system by considering the alternative use of either thermal or water storage. The second involves the determination of areas where solar energy would be economically competitive with electricity or fuel as a power source for pumping installations.A linear programming solution is developed to find the optimal combination of thermal and water storage for a solar installation. The formulation is then extended to determine a least-cost system when hybrid systems are considered. A hybrid system may incorporate a combination of solar, electric and fuel power inputs. The concept of a breakeven “critical” distance from existing infastructure for solar installations is developed, and an example problem is provided to illustrate typical values of this distance and to show its sensitivity to the base energy costs and rate of inflation for those costs. It appears that electrical pumping is probably the most economical alternative provided that electric infrastructure is located nearby. Fuel power will also be more economical than solar if there is a source of fuel near the proposed pumping site. However, solar systems may be economically competitive when considered for installation at realistic distances from existing infrastructure.     

Dynamic modeling of a solar hydrogen system under leakage conditions

Dynamic behaviors of an integrated solar hydrogen system have been modeled mathematically, which is based on a combination of fundamental theories of thermodynamics, mass transfer, fluid dynamics, and empirical electrochemical relationships. The model considers solar hydrogen system to be composed of three subsystems, i.e., solar cells, an electrolyzer, and a hydrogen tank. An additional pressure switch model is presented to visualize the hydrogen storage dynamics under a leakage condition. Validation of the solar hydrogen model system is evaluated according to the measured data from the manufacturer's data. Then, the overall was simulated by using solar irradiation as the primary energy input and hydrogen as energy storage for one-day operation. Finally, electrical characteristics and efficiencies of each subsystem as well as the entire system are presented and discussed.     

Design and simulation of a new energy-conscious system (CFD and solar simulation)

This paper presents the use of a validated CFD programme (FLUENT) and a solar simulator, for designing a solar water-heater. The water-heater is part of a new passive cooling and heating system introduced for buildings in North Africa. CFD transient simulations were carried out using a small time-step of 10 s and a set of fine body-fitted computational grids (1770–4740 nodes). FLUENT results were then verified against indoor testing employing a solar simulator. Good agreement was achieved.     

Dynamic modelling and simulation of a new air conditioning prototype by solar energy

This work presents a new design of an air conditioning prototype by solar energy developed at the Laboratory of Electromechanical Systems of the National Engineering School of Sfax, Tunisia. The new conception permits to produce heat or cold by using solar energy without polluting the environment. The installation, composed of four compartments, consists of three functioning modes according to the season of the year and according to the climatic conditions.A numerical model is developed to study the behaviour of the unit. This model uses real meteorological data to predict the performance of a thermal solar driven system. The dynamic modelling and simulation of only two modes of functioning (winter mode and summer mode without pre-cooling of air) are presented in this paper. This theoretical model is expected to help in predicting the behaviour of the installation in various climatic conditions. Besides, it would enhance the performance of such installation.     

Design of a hybrid polygeneration system with solar collectors and a Solid Oxide Fuel Cell: Dynamic simulation and economic assessment

Solid Oxide Fuel Cells (SOFC) are very promising energy conversion devices, producing electricity and heat from a fuel directly via electrochemical reactions. The electrical efficiency of SOFCs is particularly high, so that such systems are very attractive for integration in complex polygeneration systems. In this paper, the integration of SOFC systems with solar thermal collector is investigated seeking to design a novel polygeneration system producing: electricity, space heating and cooling and domestic hot water, for a university building located in Naples (Italy), assumed as case study. The polygeneration system is based on the following main components: concentrating parabolic through solar collectors, a double-stage LiBr-H₂O absorption chiller and an ambient pressure SOFC fuel cell. The system also includes a number of additional components required for the balance of plant, such as: storage tanks, heat exchangers, pumps, controllers, cooling tower, etc. The SOFC operates at full load, producing electric energy that is in part self-consumed for powering building lights and equipments, and in part is used for operating the system itself; the electric energy in excess is eventually released to the grid and sold to the public Company that operates the grid itself. The system was designed and then simulated by means of a zero-dimensional transient simulation model, developed using the TRNSYS software; the investigation of the dynamic behavior of the building is also included. The results of the case study were analyzed for different time bases, from both energetic and economic points of view. Finally, a thermoeconomic optimization is also presented aiming at determining the optimal set of system design parameters. The economic results show that the system under investigation may be profitable, provided that it is properly funded. However, the overall energetic and economic results are more encouraging than those claimed for other similar polygeneration systems in the recent literature.     

Effect of solar radiation correlations on system sizing: PV pumping case

The precise determination of solar radiation intensity is important for accurate system sizing. For PV pumping system case, the issue becomes more important since inaccurate solar radiation data nonlinearly reflected to the calculations. Inappropriate solar radiation model selection for a specific design site is a major cause for inaccurate system sizing. The differences in power output of a PV pumping system due to using some solar radiation correlations are examined here. The results are then compared with those of long-term solar radiation measurements. It is reported that the system sizing with the measurements and the most appropriate correlation for the application site significantly differ since the errors in predicting solar radiation data are nonlinearly propagated to the system power output.     

太阳能喷射式制冷系统的模拟

介绍了结构简单、工作可靠的太阳能喷射式制冷系统的原理和工作过程,给出了一个模拟计算。采用Ｒ１３４ａ为制冷剂,在发生器温度９０℃、冷凝器温度２０～３８℃和蒸发器温度 ６～１４℃时,对系统效率进行了模拟计算。结果表明,该系统具有一定的可行性。本文还对理想状况下水作为制冷剂的系统效率进行了讨论。     

Dynamic simulation of thermal energy storage system of Badaling 1 MW solar power tower plant

In this paper, the thermal energy storage system of Badaling 1 MW solar power tower plant is modelled from mathematical models for whole of the working conditions using the modular modelling method. This model can accurately simulate the recharge and discharge processes of thermal energy storage system. The dynamic and static characteristics of the thermal energy storage system are analyzed based on the model response curves of the system state parameters that are obtained from different steam flow disturbances. Conclusions of this paper are good references for the design, operating, and control strategy of solar thermal power plant.     

Small-scale solar pumping: The technology

The present work is concerned with the direct use of solar energy in water pumping. The available technologies of photovoltaic, thermal and other solar pumping systems are examined. It appears that the most suitable system for solar pumping is the one that satisfies several requirements such as: no movable mechanical parts, reasonable thermal efficiency, minimum manufacturing cost and compact in size.     

Dynamic modelling of a solar hydrogen system for power and ammonia production

A new configuration of solar energy-driven integrated system for ammonia synthesis and power generation is proposed in this study. A detailed dynamic analysis is conducted on the designed system to investigate its performance under different radiation intensities. The solar heliostat field is integrated to generate steam that is provided to the steam Rankine cycle for power generation. The significant amount of power produced is fed to the PEM electrolyser for hydrogen production after covering the system requirements. A pressure swing adsorption system is integrated with the system that separates nitrogen from the air. The produced hydrogen and nitrogen are employed to the cascaded ammonia production system to establish increased fractional conversions. Numerous parametric studies are conducted to investigate the significant parameters namely; incoming beam irradiance, power production using steam Rankine cycle, hydrogen and ammonia production and power production using TEGs and ORC. The maximum hydrogen and ammonia production flowrates are revealed in June for 17th hour as 5.85 mol/s and 1.38 mol/s and the maximum energetic and exergetic efficiencies are depicted by the month of November as 25.4% and 28.6% respectively. Moreover, the key findings using the comprehensive dynamic analysis are presented and discussed.     

Analytical simulation models for solar heating system design

Presented here is a method of simulating the performance of solar heating systems which can be incorporated into a microcomputer-based system design and sizing procedure. A general analytical solution to the storage energy balance is presented, and a scheme for varying the parameters of the general solution to represent changes in the operating mode and the driving forces is detailed. Three different simulation methods which employ the general solution are described. Two of these methods use hourly data and the third uses daily data. Measured results from an actual system are compared with simulated results to validate the models. Also, simulated results and computing speeds are compared with the general simulation model TRNSYS. Finally, an example of a microcomputer application is discussed.     

太阳能烟囱发电系统的CFD模拟研究

太阳能烟囱发电技术是一项综合应用温室效应技术、烟囱技术及风力涡轮发电技术于一体的太阳能发电新技术,是实现大规模开发和利用太阳能的一种新途径.采用计算流体动力学(CFD)方法对太阳能烟囱发电系统的速度场、压力场和温度场进行了数值模拟.结果表明:在其它条件不变的情况下,集热棚周边高度对系统的发电功率没有影响;太阳能烟囱直径存在一最佳值,使发电系统输出的发电功率最大.     

Characteristics of solar water pumping in Jordan

Remote underground water wells were investigated and 13 such wells were chosen for this study. Photovoltaic (PV) generators were used to power pumping the water up to the surface tanks to be used. A design method was established and illustrated depending on a pumping factor (F_p) which is a function of the solar characteristics. A laboratory solar water pumping unit was constructed and year round results were analyzed. Monthly F_p values were calculated by the experimental results.