Model Of Solar Collector Research Articles

Experimental and computational fluid dynamics investigations of tracking CPC solar collectors

The aim of the paper was to investigate thermal performance of two newly developed 15.4 m2 compound parabolic concentrator (CPC) solar collectors both theoretically and experimentally. The two collectors are identical except that one collector is equipped with a transparent Ethylene tetrafluoroethylene (ETFE) foil and the other collector is not. Experimentally the solar collectors were tested in an outdoor test facility at different temperatures. Collector efficiencies were determined. Theoretically simplified CFD models of the CPC solar collectors were developed and validated against the measurements. A ray tracing tool Tonatiuh was used to calculate distribution of solar irradiance on the receiver. The influence of the ETFE foil on collector heat loss coefficient and efficiency was investigated. The results show that the CFD model predicts satisfactorily temperature rises of the collectors in the temperature range between 20 °C and 81 °C. The deviations between the measured and the calculated temperature rises were limited to ±0.3 K with a relative error less than 3.7%. By installation of the ETFE foil, the first order collector heat loss coefficient decreased from 1.42 to 0.82 W/m2/K. Efficiency of the collector with the ETFE foil was measured to be 63%, 55% and 54% for a mean collector fluid temperature of 27 °C, 63 °C and 81 °C respectively. For a solar irradiance of 895 W/m2 and a mean collector temperature of 133 °C, collector efficiency is predicted to increase from 36% to 41% by installation of the ETFE foil. Another 5% increase of collector efficiency is expected if installation of the foil is made airtight.

Comparative and performative investigation of various data-based and conventional theoretical methods for modelling heat pipe solar collectors

Solar collector, as the key component of any solar system, has always been the focal point of research in the field of solar energy. Based on the literature, data-based methods, which have been proven to be promising in accurate modelling of solar collectors, have not been used for modelling heat pipe solar collectors (HPSCs). At the same time, accurate equations relating the thermal efficiency of solar collectors to the operational and climatic conditions have not been obtained for HPSCs. Therefore, in this study, various data-based and energy balance-based modelling methods were proposed, and based on different accuracy criteria, their precisions were compared in predicting the performance of HPSCs. First, an experimental rig was manufactured and the operational data of the system was recorded throughout a year. The recorded experimental data was used to train and validate various modelling approaches. Then, the accuracies of the proposed models were analysed and assessed. The evaluated models included Artificial Neural Network (ANN), Thermal Resistance Network (TRN), Artificial Neuro Fuzzy Inference System (ANFIS), and Fuzzy methods. Among different modelling approaches, ANN had the best performance which was followed by the ANFIS and TRN methods. The Fuzzy method was not recommended due to its poor accuracy. In addition, the optimum equations relating the outlet temperature of HPSCs to the operational conditions of the solar water heating systems as well as the climatic conditions were obtained and verified.

Performance evaluation of solar flat plate collector using different working fluids through computational fluid dynamics

The aim of this study involves establishing a three-dimensional computational fluid dynamic (3D-CFD) model of solar flat plate collector (SFPC) in order to investigate the effect of operating and geometric parameters on thermal efficiency. In this research work, commercial CFD code ANSYS FLUENT®14.0 version was used for the development of a model of solar plate collector. The single circular tube geometry was created using ANSYS DesignModeler®14.0. The general continuity equation along with Navied–Stokes equations was solved for tracking motion of the working fluid. The general k–e turbulence modeling approach was used for solving the turbulence in the flow. Solar ray tracing was activated for calculating solar load in the model. The latitude and longitude of the Hyderabad region were inserted in the solar ray-tracing model for calculating solar intensity as per local conditions. Two fluids i.e., water and air were circulated with different flow rates in the developed model of SFPC. It was observed that water gave higher efficiency due to high density and thermal conductivity. The simulation results gathered revealed that the temperature of water and air was raised by almost 79 °C and 73 °C respectively.

ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ РОБОТИ ГЕЛІОУСТАНОВКИ В УМОВАХ ХМАРНОСТІ

Purpose. The main objective of the research is to increase the solar efficiency by improving the design of the solar collector through the use of terrestrial radiation. Methodology. Studies are based on physical modeling of heat and mass transfer in the solar collector. Results. The design of the solar thermal collector has been improved, which allows reducing the negative impact of cloudiness on the solar installation due to the additional use of terrestrial radiation, which is taken from the battery. The battery is exposed to the sun and its substance is heated to a temperature higher than the ambient temperature. The application of the proposed design makes it possible to stabilize the operation of the installation by installing a collector above the battery after the Sun has closed with clouds. The results of physical modeling proved the effectiveness of the method of combining types of thermal radiation, the efficiency increased by 3 times. The results of the experiments are analyzed and the effectiveness of the improved design of the solar collector is revealed. It is promising to use this type of solar thermal collector in solar heating systems and hot water supply in conditions of variable solar radiation. The proposed method of using a solar collector with a battery is able to provide hot water supply, and significantly reduce the consumption of traditional fuel and energy resources, which in turn can reduce the negative impact on the environment. Scientific novelty. For the first time, earth energy was used in conjunction with solar energy. Existing models of solar collectors have a common drawback, this is a limited and unstable heat production, which is affected by the duration and intensity of solar irradiation. The proposed design solves the problem of reducing productivity in cloud cover. Practical relevance. Many years of experience in operating solar collectors prove that using solar energy can save about 70% of traditional natural resources. It is promising to use this type of solar thermal collector in solar heating systems and hot water for domestic purposes

Development of a solar colleсtor based on aluminum construction heat pipes

The object of research is the thermal efficiency of solar collectors based on aluminum structural heat pipes. Solar collectors with heat pipes have a structurally similar design. The heat-absorbing panel secures the heat pipes to the evaporation zone, and the condensation zones are located in the battery tank. The differences are only in the designs of the absorption panels, the areas of the condensation zones and the heat carriers of the heat pipes. One of the most problematic places of research is the justification and development of a new design of a heat-absorbing solar collector panel based on heat pipes.A review of the publications showed that a solar collector based on aluminum structural heat pipes operating in the two-phase thermosyphon mode has a heat loss when transmitting radiation heat exchange in the long-wavelength range between the absorbing flat panel and the heat pipe. The project of a solar collector with a new, absorbing solar rays panel is proposed. To analyze the efficiency of the solar collector based on aluminum structural heat pipes with a new absorption panel, two models of solar collectors were created – with a flat absorber panel and a cylindrical absorber panel.The models of solar collectors based on one aluminum structural heat pipe fixed on aluminum flat and aluminum cylindrical absorption surfaces are investigated by the method of thermophysical experiment.The results of studies of the efficiency of solar collector models are presented. The thermal efficiency of a new solar collector based on an aluminum structural heat pipe with a cylindrical absorbing panel in the initial period of heating water is up to 1 5 % higher than that of a solar collector with a flat absorbing panel, and at the end of heating up to 4 %. The cylindrical surface of the panel plays the role of a concentrator of the reflected part of the radiation and the own radiation of the panel in the region of the heat pipe.Further studies are planned to be conducted in the direction of optimization of the geometric parameters of the heat-absorbing surfaces of solar collectors.

Mathematical Modelling of Solar Thermal Collectors and Storages

Abstract Block-oriented modelling is a powerful tool in system design. The models developed this way can be used to study various systems, such as solar thermal systems. In the work presented, main goal is to compare different mathematical models of solar thermal devices. The difference in accuracy of such models in respect to the possibilities of a hardware-in-the-loop simulation will be discussed. Two models of solar thermal collectors will be compared and used in a system containing two different heat storages in order to study the behaviour of these models. The tests were carried out in a Simulink based block-oriented environment called SimSolar.

Influence of the Solarus AB reflector geometry and position of receiver on the output of the concentrating photovoltaic thermal collector

The main goal of the paper is to study, model and characterize suitable designs for a concentrating PVT collector at different locations on the globe to optimise the power at the receiver without cost penalties of the overall system. The power output and the number of photons collected in the receiver of the solar collector is analysed in details with respect to the time of the year, the inclination angle of the collector and also the hourly variation of the day. With standard MaReCo simulations are performed at Lisbon, Gavle and Delhi. It has been found that with a little orientation change in the system for lower latitude places, the performance of MaReCo improved further. Four new solar collector models, modified MaReCo with receiver at the focus, parabolic collector with receiver at side edge, parabolic collectors with vertical receiver at the middle, parabolic collector with horizontal receiver at the focus are introduced, and simulations are performed at Nairobi and Lisbon. The parabolic collector with side edge receiver is found to be the best suitable collector at the equatorial region for all the season.

EFFICIENCY PARAMETER ESTIMATION OF SOLAR COLLECTOR DESIGN UNDER ACTION OF EXTERNAL FACTORS

The stress-strain state and natural vibrations of the solar collector were investigated in this work. The most common types of solar collectors and their relevance are analyzed at present. The resulted description and analysis of applied software products are given for the purpose of revealing their conformity to perform this work. The spatial model of the disk solar collector was constructed, on the basis of which the analysis of the design was carried out. As a result, the values of displacements, tensions and internal fluctuations of the design for different angles of inclination to the horizon are obtained. The design weaknesses for further modernization are revealed. The ways of elimination of identified structural defects are proposed

Performance modeling of PVT collectors: Implementation, validation and parameter identification approach using TRNSYS

Photovoltaic-thermal (PVT) collectors are hybrid solutions for the conversion of solar energy into electrical and thermal energy. The development of validated and standardized PVT collector models is important for the comparison of products, informed decision making based on energetic and economic performance, and to promote the market diffusion of PVT technology. This contribution presents a novel PVT performance model, compares different parameter identification approaches, and validates the model and its implementation in a common simulation software (TRNSYS) for system simulations.For the thermal performance model, a two-node model with either one or two thermal capacities is compared. The two-node approach with one thermal capacity represents an extension of the quasi-dynamic solar thermal collector model with the added functionality of the electrical performance. This modeling approach has also proven to be the recommended modeling approach for the investigated PVT collectors in this work. Furthermore, the parameter identification procedure is described in detail and different approaches are compared. It is shown that a combined identification of thermal and electrical model parameters with determination of all thermal and electrical model parameters is the most suitable approach regarding accuracy and processing effort.To sum up, the presented PVT performance model and the proposed parameter identification procedure achieve a good agreement of simulated and measured thermal and electrical power output for the analyzed PVT collector types and operating conditions. Hence, the model is suitable for dynamic simulation studies and is proposed as standardized performance model for PVT collectors.

Comparative study of two types of mini chicanes concentrators implanted in solar collector

Saving energy and protecting the environment are the cornerstones of the modern concept of energy consumption. Following the Algerian program on renewable energies and energy consumption, dictated by Algeria's new energy transition policy, 40% of electricity production should come from renewable energies by the year 2030. The present article accompanies this policy and makes an attempt to improve the energy efficiency. This work presents a comparative experimental study of two models of flat plate air solar collectors, namely a solar collector with black mini solar concentrators (BMSC) and another model, similar to the first one, with the same geometry and dimensions, and supplied with mini solar concentrators and mirrors (MSCMR) instead of black mini solar concentrators. A comparison of the temperature profiles for these two models of solar collectors is performed in this work, in the two cases of free convection and forced convection. Comments on this innovative design are presented and the results obtained are found encouraging.

Cogeneration of energy in solar systems - a study case, Kosovo

<p>Nowadays the main goal of sustainable energy supply is the use of renewable energy sources and, in addition, the increased efficiency of the energy used. One possibility of using renewable energies is the use of solar energy through photovoltaic panels. Taking into account the meteorological characteristics of the country in which the study takes place, it appears that the use of photovoltaic panels will be available most of the time during the year. We applied a model of hybrid solar collectors for maintaining the cell temperature near 25°C by introducing a flat plate cover integrated with solar cells. This method represents a way to increase the efficiency of the solar collector. This will enable the production of electricity from the part of the photovoltaic panel incorporated into the solar collector, in which the water temperature will increase, and this heat from the water is due to the effect of sunlight and as a result of cooling the part of the photovoltaic panel. This represents an increase in the efficiency of the system and the main purpose of our analysis.</p>

CFD modeling and performance evaluation of multipass solar air heaters

This article investigates the impacts of flow configurations on the thermal performance of a solar heater system. Recycled aluminum cans (RACs) have been utilized as turbulators with a double pass single duct solar air collector. The CFD software of COMSOL Multiphysics V5.3a is used to model three designs: Cocurrent (model A), countercurrent (model B), and U-shape (model C). The numerical results reveal that the U-shape design offers a greater thermal performance of 5.4% and 6.5%, respectively, compared with the cocurrent and countercurrent flow models. Furthermore, an outdoor experiment is performed based on the numerical modeling of flow configurations. The experimental setup is examined for three configurations of model C, namely, solar air heater (SAH) without RAC model C-I (plain model), SAH with in-line RAC layout (model C-II), and SAH with staggered RAC layout (model C-III). We found the double pass single duct solar air collector (model C) design is in a good agreement with the experimental data, and model C-III has a better thermal efficiency of 60.2%, compared to those of model C-II, 53.1%, and model C-I, 49.4%.

Modelling of a flat-plate solar collector using artificial neural networks for different working fluid (water) flow rates

The operation of a flat-plate solar collector using three different working fluid flows (water, i.e. 1, 1.6, 2 L/min) has been modelled using the artificial neural networks (ANNs) of computational intelligence technique. The ANNs model has been built at the entrance to predict the outlet temperature in the flat-plate solar collector using measured data of solar irradiance, ambient temperature, inlet temperature and working fluid flow. The results obtained conclude the method is accurate with the three flow rates of the working fluid (water) (e.g. RMSE = 0.1781 °C and R2 = 0.9991 for an ANN prediction of the outlet temperature of the working fluid with 2 L/min test and RMSE = 0.0090 [0,1] and R2 = 0.7443 as a performance prediction test of 1 L/min), flexible when choosing the variables used and easy to apply to any solar collector. The Hottel-Whillier-Bliss (HWB) and the international standard ISO 9806 solar collector models are also described and applied using the data obtained in the tests performed on the flat-plate solar collector. The deviation that occurs with the three different flows of the working fluid (water) used, have been verified and also their repercussion when they are applied in the f-chart method.

Simplified heat transfer model for parabolic trough solar collectors using supercritical CO2

The main Concentrated Solar Power (CSP) plants type installed worldwide corresponds to parabolic trough (PT) technology transforming solar energy into thermal energy on the receiver tubes. The use of alternative Heat Transfer Fluids (HTF) in order to increase the solar-to-electric efficiency by means of either higher HTF temperatures or the use of supercritical cycles have opened a new line of research. In this framework, super-critical carbon dioxide (sCO2) seems to be a good candidate to replace current HTFs in PTs. This work implements a one-dimensional heat transfer model for a PT solar collector considering different HTFs such as synthetic oil, sub-critical carbon dioxide, and sCO2. The numerical results of the outlet fluid temperature are compared to experimental data and numerical results published in the literature, obtaining maximum temperature deviations of 0.9%, 2.9% and 2.7% respectively. Finally, a sensitivity analysis was conducted to evaluate the influence of the solar irradiation, mass flow rate and HTF inlet temperature on the thermal performance of a PT working with sCO2 showing that the solar irradiation produces the greatest variations.

Mathematical modelling and experimental investigation of solar air collectors with corrugated absorbers

This paper presents mathematical modelling and performance evaluation of solar air collectors (SACs) with corrugated absorbers for indoor space heating. Experimental tests were first conducted based on a SAC system to understand its real-time performance. A mathematical model was then developed and validated against the experimental data. A sensitivity study was further implemented to identify the key design factors and investigate their influence on the performance of the SAC. The results showed that the modelling results agreed with the experimental data. The surface absorptance and opening angle of the corrugated absorber were the most significant design variables governing the thermal efficiency of SACs. The other significant variables included the temperature setting for the outlet air from the SAC, the depth ratio of the upper air channel to the overall size of the air space, the slope and length of the SAC, the air flow rate, and the unit area mass of the absorber. Using the opening angle of 60° and surface absorptance of 0.8 can result in an average effective thermal efficiency of 27.14%, which was comparable to that using the opening angle of 120° and the surface absorptance of 0.96. The results obtained can be used to facilitate optimal design of SACs.

The validation of a novel lumped parameter model for photovoltaic thermal hybrid solar collectors: a new TRNSYS type

Decarbonisation is one of the most important challenges facing researchers, and solar-assisted systems represent an important solution to reduce the energy consumption at the household-scale. The current work contributes to existing research by proposing and validating a novel lumped parameter simulation model for photovoltaic thermal hybrid solar collectors using field measurements carried out at an experimental facility. The modelling approach, which also considers the effect of the thermal capacitances of the elements composing the photovoltaic thermal collector, used an electrical analogy method to solve the transient heat transfer problem. The results of the simulations were compared with the experimental data collected during different weather conditions; the effects of the thermal capacitances of the collector were also investigated. The results were compared in terms of both average daily performance and instantaneous values of the variables characterizing the system. Although the differences were negligible, the results of the simulation analyses matched the measurements more precisely when the thermal capacitances were taken into consideration. Finally, the simulation model was implemented as a TYPE of Transient System Simulation (TRNSYS) software, and it is made freely available to facilitate future integrated computer simulations.

Transient model and characteristics of parabolic-trough solar collectors: Molten salt vs. synthetic oil

Working media (typically, molten salt and synthetic oil) play a blood role in transporting solar energy for the concentrating solar power (CSP) technology. Yet, transient characteristics of both molten salt and synthetic oil are far less understood. Herein, a one-dimensional transient model associating with SIMPLE algorithm is developed to comparatively investigate the response characteristics of the parabolic-trough collector with molten salt (Solar Salt) and synthetic oil (Therminol VP-1). It has been demonstrated that although molten salt that takes advantages of high heat capacity, high thermal stability and high operation temperature is capable of building the higher-efficiency CSP plant, an intriguing finding shows that molten salt possesses much longer response delay than synthetic oil does. It is found that as DNI increases from 400 W m−2 to 1000 W m−2, the outlet temperature of loop with molten salt exhibits up to 3.4 times of response delay (from 811 s to 3285 s) than that with synthetic oil (from 300 s to 963 s). Likewise, when mass flowrate varies, the outlet temperature of loop with molten salt shows up to 4 times of response delay (from 546 s to 3373 s) than that with synthetic oil (from 187 s to 836 s). It is also found that the response delay is exponentially correlated to the variations of DNI and mass flowrate as y = A∙exp(−x/τ) + B for both molten salt and synthetic oil loops. These findings remind of a remarkable drawback of molten salt in the views of responsivity and controllability, which has been seldom pointed out before.

Analysis of models applied for modelling of adaptive control for thermal energy storage system. Part 1. Models of solar collector

Analysis of models applied for modelling of adaptive control for thermal energy storage system. Part 1. Models of solar collector

Seasonal solar thermal energy storage using thermochemical sorption in domestic dwellings in the UK

The present paper explored the potential of the seasonal solar thermal energy storage (SSTES) system using ammonia-based chemisorption for domestic application in the UK. The dynamic charging/discharging performance of the SSTES has been simulated using the real weather data with the solar thermal collector models, the domestic heating demand model and the chemisorption model. The selection of working salts has significantly influence on the system design and dynamic performance. The CaCl2-4/8NH3 chemisorption can satisfy almost 100% of space heating demand when using low temperature hating facility during discharging stage, however, due to its relatively higher desorption temperature and limited sunlight available in the Newcastle-upon-Tyne the required solar collectors area exceeds the commonly available space of dwelling roof. The NaBr-0/5.25NH3 chemisorption is only able to contribute 18.6% of heating demand because the temperature of the discharged heat cannot reach the required level for most of the time in the heating season. The best scenario studied was using BaCl2-0/8NH3 chemisorption SSTES (45.2 m3 storage volume) combined with low temperature heating facilities and a 30.5 m2 solar collector, which can cover about 57.4% of space heating for a dwelling with a heat loss coefficient at 150 W/K.

Analysis of models applied for modeling of adaptive control for thermal energy storage system. Part 1. Models of solar collector

Analysis of models applied for modeling of adaptive control for thermal energy storage system. Part 1. Models of solar collector