Solar Water Collector Research Articles

The effect of the variation of glass thickness and angle tilt on the performance of the double cover solar water collector

The energy crisis occurs because of the high level of dependence on fossil energy sources. The solution to overcome this problem is by utilizing alternative energy. One of the uses of solar energy is the use of solar collectors to heat water. The purpose of this study was to determine the performance of the solar water heater collector. This study used a double cover collector, with variations in glass thickness of 3 mm and 5 mm and a tilt angle of 20° and 30°. The study was conducted from 10:00 Banjarmasin Time to 16:00 Banjarmasin time. In this study, the best results were produced by solar collectors with a variation of glass thickness of 5 mm and an angle of 30°obtained average energy of 129.3 Watt and average efficiency of 48.1% at an average intensity of solar radiation of 497.6 W m−2. The performance results of 5 mm thickness glass are better than 3 mm thickness glass. In this study, glass with a thickness of 5 mm is more optimal for transmitting received solar radiation and isolating the heat coming out of the collector into the environment.

Experimental analysis of thermal performance for flat plate solar water collector in the climate conditions of Yekaterinburg, Russia

Abstract Current experimental work studies the thermal performance of a flat plate solar water collector according to the weather conditions of the city of Ekaterinburg in Russia. All tests were carried within four months and four typical clear days were chosen for each month. Thermal efficiency, useful energy, and water temperatures at the inlet and outlet of the flat plate solar collector have been investigated in this study. The results were collected during summer and autumn have been analyzed to find out the effect of different weather conditions on the performance of the proposed flat solar water collector. The highest efficiency of the solar collector was recorded during midday when the collector receives the highest solar energy intensity and thus the highest rate of useful heat gained. The maximum efficiency observed by 66% in July compared to the other months included in the current study. The results showed good agreement between the previous studies and the current proposed solar water collector in terms of thermal efficiency.

Experimental Study of Electrical and Thermal Efficiencies of a Photovoltaic Thermal (PVT) Hybrid Solar Water Collector with and Without Glass Cover

Investigating the thermal and electrical gains and efficiencies influence the designed photovoltaic thermal hybrid collector (PVT) under different weather conditions. The designed system was manufactured by attaching a fabricated cooling system made of serpentine tubes to a single PV panel and connecting it to an automatic controlling system for measuring, monitoring, and simultaneously collecting the required data. A removable glass cover had been used to study the effects of glazed and unglazed PVT panel situations. The research was conducted in February (winter) and July (summer), and March for daily solar radiation effects on efficiencies. The results indicated that electrical and thermal gains increased by the increase in solar radiation. The average rise in PVT water collectors' thermal energy efficiency with a glass cover for three cases was 5% compared with the unglazed PVT water collector. While the maximum total efficiencies of 79 % and 69.5 % for glazed and unglazed collectors were recorded under maximum solar radiation of 1100 W/m2 and maximum water flow rate in the tubes system for July. The recorded result seemed promising and significant, indicating that the manufactured system is useful for adjusting PVT thermal and electrical efficiencies for cold and hot weather conditions.

Energy Production in Solar Collectors in a University Building Used to Improve the Internal Thermal Conditions in Winter Conditions

In this numerical study the energy production in solar collectors in a University building used to improve the internal thermal conditions is made. Passive and active solutions, using external solar collector and internal thermo-convectors, are used. The numerical simulation, in transient conditions, is done for a winter typical day with clean sky. This numerical study was carried out using a software that simulates the Building Dynamic Response with complex topology in transient conditions. The software evaluates the human thermal comfort and indoor air quality levels that the occupants are subjected, Heated Ventilation and Air Conditioned energy consumption, indoor thermal variables and other parameters. The university building has 107 compartments and is located in a Mediterranean-type environment. External solar water collectors, placed above the building’s roof, and internal thermo-convectors of water/air type, using mixing ventilation, are used as passive and active strategies, respectively. The thermal comfort level, using the Predicted Mean Vote index, and the indoor air quality, using the carbon dioxide concentration, are evaluated. The results show that in winter conditions the solar collectors improve the thermal comfort conditions of the occupants. The indoor air quality, in all ventilated spaces, is also guaranteed.

Experimental Study of Electrical and Thermal Efficiencies of a Photovoltaic Thermal (PVT) Hybrid Solar Water Collector with and Without Glass Cover

Investigating the thermal and electrical gains and efficiencies influence the designed photovoltaic thermal hybrid collector (PVT) under different weather conditions. The designed system was manufactured by attaching a fabricated cooling system made of serpentine tubes to a single PV panel and connecting it to an automatic controlling system for measuring, monitoring, and simultaneously collecting the required data. A removable glass cover had been used to study the effects of glazed and unglazed PVT panel situations. The research was conducted in February (winter) and July (summer), and March for daily solar radiation effects on efficiencies. The results indicated that electrical and thermal gains increased by the increase in solar radiation. The average rise in PVT water collectors' thermal energy efficiency with a glass cover for three cases was 5% compared with the unglazed PVT water collector. While the maximum total efficiencies of 79 % and 69.5 % for glazed and unglazed collectors were recorded under maximum solar radiation of 1100 W/m2 and maximum water flow rate in the tubes system for July. The recorded result seemed promising and significant, indicating that the manufactured system is useful for adjusting PVT thermal and electrical efficiencies for cold and hot weather conditions.

AUGMENTATION OF SOLAR WATER DISTILLER PERFORMANCE WITH PV/T

Recently, due to global warming and urbanization, there are many major cities that may face the challenge of day zero next decades. Obviously, water is an indispensable component for maintaining life on the earth. Although portable water is required of the hour, the quantity of available freshwater is impacted significantly by sea-level rise and pollution from industrialization. As a consequence of the global water crisis, different methods for clean water production from brackish water have been studied and developed in practice, however, the solar distillation of water is the most economical and desirable approach due to this method utilize solar energy that is the environmentally friendly and economical resource. Over the last 15 years, the impressive price drop of the photovoltaic solar collector (PV/T) makes them popular and easy to access. As a result, the employment of PV/T in solar stills is emerging as a potential device for water distillation. Therefore, in this paper, an active solar distiller combined with a photovoltaic panel has been reviewed for improvement of the distillate yield and effectiveness of solar photovoltaic. This review work presents a variety of studies on various types of solar still (for example conventional solar still (CSS), double slope solar still (DSSS), stepped solar distiller, and cascade solar still) couples with different solar water collectors (such as flat plate collector (FPC) and evacuated tubes collector (ETC)) and solar photovoltaic modules. It is obtained that the hybrid PV/T active solar still improves the distillate yield, energy efficiency, and exergy efficiency as compared to passive mode. The cooling method enhances the performance of the photovoltaic solar collector as well as the productivity of solar still. Moreover, the environmental economic estimation reveals that the solar still coupled with the PV/T mitigated considerably the amount of CO2. It can be stated that it is suitable to commercialize the hybrid PV/T active solar still for supplying not only electricity but drinking water also. Finally, this review paper also suggests the scope for the research in the future.

Dynamic heat transfer model of flat plate solar water collectors with consideration of variable flow rate

The dynamic thermal model of the collector could serve as a useful tool for the thermal prediction. Normally, collectors’ thermal prediction models are developed based on the dynamic thermal process, and then the thermal output or the mean temperature of the fluid would be obtained from the mathematical derivation. The critical parameters in the equations are fitted from the test data. In which, the heat loss coefficient F′UL has a close relationship with the flow rate, and thus the fitting formula could only be used for a given flow rate. In this paper, a dynamic heat transfer model of the normal flat plate solar collector is introduced, with consideration of the mass flow rate variations. Matrix is employed for solving the heat transfer equations. The analytical solution of the model indicates that the temperatures at timeτ are determined by the initial value and the accumulated effect of the ambient environment. The model is validated by the on-site experiment carried out in Zhangjiakou, Hebei Province, in the north part of China. The main trend of the simulation and measurement was in accordance continually in the initialization, operation, and halt phase for around 24 h. While, the thermal mass of the duct connected to the collector is not included in the model, leading to the accuracy reduction of the model prediction. The modification with consideration of the pipeline’s thermal mass will be conducted in future work.

Mathematical modelling and analysis of solar water collector with flat and V-groove absorber plate with helical and plain water flow path tubes

A mathematical model for Solar Flat Plate Collector (SFPC) has been developed to compare the thermal performance between different geometrical profiles of the collector like Flat plate, V-groove absorber plate and with plain and helical strip inserted in the absorber tube. Water, used as working fluid, is passed through the tubes to investigate the thermal performance. Different geometry of the absorber plate and tube are used to increase the heat gain by the collector. The temperatures at inlet and outlet are measured and analysis of collector recovery factor, heat gain, losses like bottom loss, edge loss and efficiency of collector has been done. The comparative study on the thermal performance shows 4% higher collector efficiency for helical strip absorber tube than the other geometric profiles. Also, the results of mathematical analysis closely agree with the experimental results.

Experimental study for the performance of an integrated solar collector water heater based on helical fins heat pipes using phase changing material

One of the most promising solar heaters is the evacuated tube solar collector (ETSC). Enhancing the performance of ETSCs using latent heat energy storage system has been widely investigated. Accordingly, paraffin wax as phase changing material (PCM) has taken a large portion of research work. Although paraffin wax has a significant disadvantage of having low thermal conductivity, using fins to enhance the overall heat transfer coefficient has been studied to overcome such drawback. The present work compares experimentally the performance of twoevacuated tubes systems having two novel fins systems. Namely; an ETSC with copper helical fins of 20 mm pitch and an ETSC with copper helical fins of 40 mm pitch. The experimental work was done under four different flow rates to investigate the effect of the thermal load on the systems performance. These flow rates are; 0.165 L/min, 0.335 L/min, 0.5 L/min and 0.665 L/min with normal water as the heat transfer fluid (HTF). In addition, the PCM temperature inside the evacuated tubes are measured along the tube axis to investigate the fins effect on PCM temperature homogeneity and thermal storage. The systems performances and daily efficiencies are also compared to emphasis the effect of fins configurations. The experimental results have shown that both systems provided a proper PCM temperature homogeneity ant peak temperatures. However, both systems have shown different trends for PCM temperature distribution along the tubes axis. A peak HTF temperature of 53 ˚C was achieved in the system with 40 mm helical pitch fins. Both systems have successfully supplied hot HTF throughout the night for the four different flow rates. However, regarding daily efficiency, the 20 mm pitch system provide an enhancement of 11.85% with maximum efficiency of 68.66% at 0.665 L/min flow rate.

Optimization of PV/T Solar Water Collector based on Fuzzy Logic Control

Hybrid solar collector (PV/T) is designed to produce electricity, hot water, or hot air at the same time as they operate solar cells and solar heaters in one system. This system is designed to increase the electrical efficiency of solar cells by absorbing heat from these cells. The fuzzy logic (FL) is a tool usually used to optimize the operation of the systems. In this paper, the FL is to monitor and correct the mainsystem parameters to remain optimization efficiency at a better level. Three affected variables were studied: Effect of reflective mirrors, the effect of the glass cover, and the effect of the lower reflector angle on the performance of the PV / T hybrid solar system. These three parameters are traveled to be inputs for the FL, and the PV temperature in addition to system efficiency is the output for it. The effect of solar radiation was found to have a great effect on the efficiency of the hybrid solar collector. The thermal efficiency was 82% for the given value of the PV and mirrors, while the efficiency down to 50 for another angle. By using the artificial intelligent the system behavior depends on its output, which called feedback close loop control, at a real-time process that optimizes the system efficiency and its output.

Preliminary studies of the water solar collector

Preliminary studies of the water solar collector

Solar-LP gas hybrid plant for dehydration of food

This paper presents the thermal and energy analysis of a Solar-LP gas hybrid drying plant built in Zacatecas, Mexico. It is focused on the dehydration of agricultural products. The drying system is a forced convection hot air type with a drying chamber. For the air heating required in the drying process, there are two solar thermal systems: a direct air heating system (48 solar air heaters with an area of 111.1 m2) and an indirect air heating system (40 solar water collectors with an area of 92.4 m2 and 6000 L of thermal storage). Also, there is a backup system of conventional energy (LP gas burner). Two hybrid tests were carried out to dry Nopal (Opuntia ficus-indica) initially operating with the direct system, after that with the indirect system and complementing the energy demand of drying with the conventional system. The effective drying time was 14.3 and 11.7 h, removing a total of 179 and 183 kg of water, respectively. The air temperature at the entrance of the drying chamber was around 59 °C. The solar fraction obtained for this hybrid mode of operation was around 80%. The thermal analysis of the direct and indirect air heating system, together with the conventional system, are presented and discussed. The performance of the solar systems is finally compared with a conventional LP gas drying system via a cost and return on investment analysis.

Performance of an integrated greenhouse equipped with Light-Splitting material and an HDH desalination unit

Abstract The concept of a novel integrated greenhouse is introduced in which a spectral-splitting material is employed to reduce heat transfer to the greenhouse by utilizing part of the solar spectrum for heating a water solar collector. The irradiating solar spectrum is also shifted to wavelengths propitious for plant growth. The solar collector is part of an integrated humidification-dehumidification system that can produce freshwater for plant irrigation from a variety of compromised water sources. In order to evaluate the performance of the proposed integrated greenhouse, a multivariable thermal model is presented which includes the solar collector, the desalination system, and the greenhouse (accounting for the air, the soil, the plants, and the ground). A representative greenhouse is modeled and the results are used to estimate freshwater production and associated reduction in cooling or heating loads. The results of the model are used for evaluating the performance of the representative integrated greenhouse in various locations across the United States. Results suggest that the proposed greenhouse in Phoenix (Arizona, USA) can produce about 85% of required water for tomato growth, while reducing the cooling load by more than 25%.

Application of Generalized Regression Neural Network in Predicting the Performance of Solar Photovoltaic Thermal Water Collector

Solar photovoltaic thermal water collector (SPV/T-WC) is a hybrid device which converts power from the solar energy in to thermal and electrical simultaneously. The performance of such SPV/T-WC mainly depends on its electrical and thermal power output. Besides the performance of SPV/T-WC, is more sensitive to the transient nature of electrical and thermal power output. Thus a demand for predicting the performance variations in the SPV/T-WC is demand by users. Only limited performance prediction based research works are attempted in the performance prediction of the SPV/T-WC either numerically or by using cognitive models. In this study, two generalized regression neural network (GRNN) models are proposed to predict the transient performance variations in the SPV/T-WC. The two individual objectives of the first and second model include the prediction of overall power output and the overall efficiency delivered by an SPV/T-WC system. Both the GRNN models proposed in this study consist of two inputs and single output. In order to train this GRNN model, real time experiments are conducted with stand-alone SPV/T-WC for four continuous days. Then based on such experimental data sets, GRNN models are trained, tested, and validated. The results predicted by the both GRNN models are in good agreement with the real time experimental results. The overall accuracy of the proposed GRNN models in predicting the performance is 95.36% and 96.22% respectively.

High Pressure Water Solar Collector as Potential of Mini Steam Power Plant

High Pressure Water Solar Collector as Potential of Mini Steam Power Plant

Thermal performance improvement of the modified evacuated U-tube solar collector using hybrid storage materials and low-cost concentrators

Abstract This study aims to enhance the thermal performance of an evacuated tube solar water collector. To experimental investigate this idea, a modified evacuated U-tube solar water collector with hybrid storage materials and low-cost cylindrical parabolic concentrators were designed, constructed, and tested in Tanta city under the Egyptian weather conditions. To investigate the influences of the graphite powder mass concentration within hybrid energy storage material on thermal performance of the modified evacuated U-tube solar water collector with low cost cylindrical parabolic concentrators. Five different mass concentrations of graphite nanoparticles in hybrid storage materials (0.0, 2, 3, 4, and 5% by weight) was studied and compared to the case without hybrid energy storage material to obtain influences of hybrid storage materials with different mass concentrations on the thermal performance of the modified design. The results show that with increasing the rate of feed water from 14 to 22 LPH during the period 10:00 am-10:00 pm, the sum of the useful heat gain produced from the modified design with hybrid storage materials varying between 17,133 and 20,146, 17,458 and 20,378, 17,665 and 20,796, 17,783 and 20,954, 17,960 and 21,075 kJ/day at 0.0, 2, 3, 4, and 5% graphite mass concentration, respectively. But for the operating case without hybrid storage materials, the sum of useful heat gain varying between 10,605 and 12,255 kJ/day. The results of this study presented that, the average improvement in the sum of useful heat gain for the modified design with hybrid energy storage material reached 63.5, 65.8, 68.7, 69.9, and 71.1% at 0.0, 2, 3, 4, and 5% mass concentration, respectively compared to cases without storage material. Also, with increasing the mass concentration of graphite in hybrid storage material from 0.0 to 5%, the improvement in the daily thermal efficiency of the modified design reached to 69.4%, 72%, and 72.1% for the rate of feed water 14, 18, and 22 LPH, respectively as compared to the cases without hybrid storage material.

A new method of acquiring perquisites of recirculation and vortex flow in sudden expansion solar water collector using vortex generator to augment heat transfer

The present study focuses on the heat transfer enhancement in sudden expansion channel (SEC) which is to be employed as solar water collector using vortex generator (VG) at different angles of attack. Expansion ratio (ER) of SEC is ascribed as 2:1. The analysis of heat transfer enhancement is carried out for various aspect ratios (AR) of ∞, 8 and 6 of SEC. The angle of attack (β) of VG is varied from 30° to 90° by an increment of 15° in each case. The results of this study are compared with that of simple rectangular channel (SRC) with VG. The flow is assumed to be laminar, steady and incompressible in the Reynolds (Re) number range investigated. Finite volume based commercial computational fluid dynamics (CFD) code FLUENT 16.2 has been used for solving three dimensional governing equations. The investigation shows that VGs are very effective in SEC than in SRC in enhancing the heat transfer against pressure drop at all angles of attack. Heat transfer rate increases with increase in AR of SEC while the change in friction factor with AR of SEC is negligible except at higher angle of attack. However with increasing angle of attack of VG, friction factor is on the rise. The results reveal that the enhancement of heat transfer rate is due to the combined effect of longitudinal vortex flow and flow separation. VG at β = 30° and 60° is found to have an optimal heat transfer and fluid flow characteristics in SEC.

The effect of the intermediate fluid-flow rate on the system performance in the closed circuit applications of the solar collector

Solar collector water heating system use solar thermal energy to provide hot water for domestic and industrial use. These systems are operated either as open-loop or closed-loop flow circuit. The former loop systems are not recommended for the cold climates having water freezing problem. Although previous studies on solar collectors have used closed-loop operation with water as the working fluid. However, it must have high boiling and low freezing points for the colder regions and thus arises the need for antifreeze mixtures of water. Another solution the same problem is the use of heat transfer oil as intermediate working fluids. In the present study, the energy and exergy analysis of a boiler supported vacuum tube solar collector system working with closed-loop in different working fluid-flow rates have been performed and evaluated. Heat transfer oil has been used as an intermediate working fluid in the closed loop system at different flow rates of 0.277 kg/s, 0.383 kg/s, and 0.494 kg/s. The results show that the collector temperature difference as well as the outlet temperature decrease. However, the collector inlet temperature increases by increasing the flow rate. Moreover, with the increase in flow rate, it was ascertained that the energy and exergy efficiency of the system and the collectors increase. The main finding of the present study is that the intermediate fluid used in the closed-circuit operation of the solar collectors has a direct effect on the energy and exergy efficiency of the system

Calorimetric investigation of magnesium nitrate hexahydrate and sodium thiosulphate pentahydrate as salt mixture encapsulated materials for thermal energy storage

The use of magnesium nitrate hexahydrate and sodium thiosulphate pentahydrate salt composite as an encapsulated phase change material in solar water heater storage unit for thermal energy storage was experimentally tested and investigated in this research study. A differential scanning calorimetry is performed to determine the properties such as melting temperature, specific heat capacity, and latent heat of the selected mixtures for the proportion 70:30 and 80:20 by weight. For the experimentation, these two samples are stored separately in the aluminum canisters and filled in storage tank to avoid the heat loss directly. The thermal performance of the solar water heater at different zones on collector with and without using encapsulated phase change material in storage tank was tested experimentally. Maximum temperature achieved in solar water collector was 50°C at midpoint and 46°C at outlet of the tank. It is found that even after late evenings 18.00 IST, the average storage tank temperature with phase change material was found to be nearly 2.6 to 3.2 times greater than conventional solar water heater and the average temperature of phase change material is 42°C. The test results shows that sample B 80:20 will produces higher amount of hot water and stores the maximum heat compared to sample A 70:30. The results demonstrate that this encapsulated phase change material cylinder stores higher latent heat of fusion and, it can also be used for indirect solar cooking and other low temperature application even at late evenings.

Verification and Validation of Solar Photovoltaic Thermal Water Collectors Performance Using Fuzzy Logic

AbstractThe performance of the solar photovoltaic (PV) module is more sensitive to its operating temperature. A PV module with a cooling system produces higher electrical power output than a PV module without a cooling system. In addition, the PV module with the integrated cooling system is capable of generating electrical and thermal energy simultaneously. Such an integrated (hybrid) system is termed as a solar photovoltaic thermal (PV/T) system. When two or more collectors connected in series as a mean to have higher output, then such a system is termed as series-connected PV/T water collectors. This study presents two fuzzy inference systems (FISs), namely, Mamdani and Sugeno, for predicting the performance of series-connected PV/T water collectors. The set of rules was framed individually for both models in a way to predict the power output of PV/T water collectors in an inaccurate manner. The predicted results by inference systems are compared with experimental values to check their prediction accuracies. The accuracy of such a proposed Mamdani and Sugeno FIS is 95.67% and 99.92%.