Photovoltaic Thermal Air Collector Research Articles

Mathematical modeling and performance evaluations of a wood drying process using photovoltaic thermal and double-pass solar air collectors

This research conducts a novel and complete 4E assessments and introduces an innovative method for examining solar wood drying systems. The software TRNSYS and MATLAB programming are combined to simulate and create a numerical program. This novel combination allows for a thorough examination that goes beyond conventional assessments of wood drying. The aim is to evaluate the effectiveness of a solar wood dryer using two different collectors, a double-pass and a photovoltaic thermal collectors, in terms of four key aspects: energy, exergy, economic, and environmental. Further, the drying process was investigated under various climates in three African cities (Errachidia, Dakar, and Nouakchott). The moisture content of wood was reduced from 74% to 12% in the three cities. Elaborate simulations were performed and the results were confirmed by experimental validation, using methods including Mean Absolute Error, Mean Relative Error, and Root Mean Square Error.The primary findings of this study are the following: In the double-pass dryer, the drying time required in Errachidia, Dakar, and Nouakchott was 139h, 189h, and 170h, respectively. Whereas in the photovoltaic thermal dryer, it needed 192h in Errachidia, 210h in Dakar, and 189h in Nouakchott. Further, using photovoltaic thermal, the dryer exhibited superior exergy efficiency compared to the use of double pass collector. Photovoltaic thermal collector reduces yearly CO2 emissions by an average of 54.87, 66.2, and 44.11 tonnesCO2 in Errachidia, Dakar, and Nouakchott, respectively. In contrast, double pass collector reduces CO2 emissions by an average of 38.49, 57.9, and 38.56 tonnesCO2 in Errachidia, Dakar, and Nouakchott, respectively, throughout the year. Further, the solar dryer, using double pass collector, has a shorter payback time than using photovoltaic thermal collector, indicating a quicker economic return.

Impact of solar cell materials on the energy performance of SPVT air collector

The impact of roof-integrated semitransparent photovoltaic thermal (SPVT) air collectors connected in series for cold climates has been assessed using a new model established in this research. Numerical calculations have been performed using analytical formulae derived for the temperatures of the room air, roof, and solar cells. These findings have led to evaluations of the thermal, electrical, and overall exergy of various solar cell materials (Single-crystalline, Multi-crystalline silicon, Nanocrystalline -Silicon, Amorphous silicon, Cadmium Telluride and copper indium gallium selenide). According to the findings, amorphous silicon has the maximum peak solar cell electrical efficiency of 10.8% and single-crystalline has the minimum peak efficiency of 7.0% for the proposed system. Further, performance analysis has also been done based on different packing factor and mass flow rates.

Active heating of greenhouse integrated semitransparent photovoltaic thermal system with series connected semitransparent photovoltaic thermal air collectors

In order to fulfill the demand for energy and food security, an active heating of a controlled environment greenhouse integrated semitransparent photovoltaic thermal (GiSPVT) system with N-semitransparent photovoltaic thermal (SPVT) air collector for cold climatic conditions has been analyzed in this paper. The proposed SPVT air collectors are connected in series and integrated with GiSPVT. It is used to generate thermal as well as electrical energy to meet the daily requirements of users. Based on the energy balance equation which is a function of design and climatic parameters, an analytical expression for various variable parameters namely plant, room air, and solar cell temperatures have been derived. Numerical computation has been made in Matlab for computing the thermal, electrical, and overall exergy of the proposed system. Based on numerical computation, the following observations have been made: (i) From a thermal point of view, the packing factor (0.5, 0.8) of the semitransparent PV module plays an important role and it must be optimized for maximum thermal heating. (ii) The selection of a number of collector N is an important parameter to generate electrical energy as well as thermal heating of GiSPVT room air in an optimum way.

Photovoltaic-thermal systems applications as dryer for agriculture sector: A review

In this paper, the literature writing on the use of photovoltaic thermal air collectors (PV-T) and integrated greenhouse drying systems for PV-T air collectors as a mean to reduce fossil fuel consumption and reduce global warming is reviewed. Countries with limited electricity sources, solar drying is an effective way to preserve crops for long-term use. There has been evidence that PV-T air collectors are superior to individual PV modules for storing energy when it comes to controlling drying parameters. The review will offer valuable insights and data that can aid scientists and researchers in the creation and improvement of thermal models for combined solar systems. The review will present a detailed analysis of the current state of knowledge in the field of combined solar systems, including the latest advancements, trends, and challenges. It will also identify gaps in the existing research and suggest potential avenues for future investigation.

Innovative heat dissipation design incorporated into a solar photovoltaic thermal (PV/T) air collector: An optimization approach based on 9E analysis

Innovative heat dissipation design incorporated into a solar photovoltaic thermal (PV/T) air collector: An optimization approach based on 9E analysis

Performance Analysis and Identification of an Indirect Photovoltaic Thermal Dryer with Aluminum Oxide Nano-Embedded Thermal Energy Storage Modification

In the current paper, different thermal energy storage unit-integrated photovoltaic thermal (PVT) air collectors with and without nanoparticles have been designed, fabricated and tested. Aluminum oxide nanoparticles have been integrated into the thermal storage unit to increase the performance of the PVT collector. The developed collectors have been tested in a drying application at two different mass flow rates. The major goals of this work are upgrading the performance of the PVT air collector by employing a nano-embedded thermal energy storage unit and analyzing the impacts of using nanoparticles in the latent heat storage unit in the PVT collector on the drying performance of the system. The drying time was reduced by approximately 15–22% by employing nanoparticles in the thermal storage unit. Moreover, overall exergy efficiency values were obtained in ranges of 12.49–14.67% and 13.64–16.06%, respectively, for modified and unmodified PVT air collectors. It should be indicated that the overall energy and exergy efficiencies of the PVT air collectors were improved in the ranges of 6.91–6.97% and 9.20–9.47%, respectively, by using nanoparticles in the thermal energy storage unit. The combination of increasing the flow rate and integrating nanoparticles into the storage unit improved the overall exergetic efficiency of the PVT air collector by 28.58%. The mean exergetic efficiency of the drying room was between 48.33 and 54.26%. In addition to the experimental analysis, dynamic models for thermal and exergy efficiencies of developed collectors were constructed by employing the system identification method.

Experimental and numerical study of the PVT design impact on the electrical and thermal performances

In terms of energy efficiency, photovoltaic thermal (PVT) systems have great potential to produce simultaneously heat and electricity. PVT solar air collectors are often used in various applications due to their simple structure and low installation cost. While the overall performance of PVT is closely correlated with its design. In this paper, one proposes to design a novel prototype of PVT air collector, in order to improve the electrical and thermal performances. The presented numerical and Experimental studies are carried out to evaluate the impact of the designed prototype on the PVT efficiency. The essential goal of this work is to identify the optimal geometrical and operational PVT air collector parameters with square tube channel. To achieve this goal, numerical simulation using COMSOL Multiphysics is combined with experimental validation of the PVT system. The objective of the optimization consists on improving the output temperature suitable for drying applications firstly, and cooling PV modules by reducing their temperature in order to improve the electrical characteristics such as power and voltage and thereby the efficiency of the photovoltaic modules. Therfore, the PV panel temperature dropped from 53.37 °C to 42.5 °C when the design varies from PVT-1 to PVT-6. Nevertheless, PVT-5 was retained because it has the most appropriate design which gives the best overall efficiency 58.48%. Finally, it should be remembered that the tests were carried out under the same operating conditions namely, the mass flow rate Qm = 0.0235 kg/s at the inlet of the PVT, the inlet temperature (Tint), the ambient temperature (Ta) and the solar irradiation (G).

Thermal and exergy analysis of N-semi-transparent photovoltaic thermal air collectors connected in series/parallel

Thermal and exergy analysis of N-semi-transparent photovoltaic thermal air collectors connected in series/parallel

Design and analysis of new solar‐powered sustainable dryers: Alfalfa crop

AbstractDecreasing carbon emissions is possible with the usage of renewable energy sources. Therefore, the usage of renewable energy has increased in the last decade. Due to the fact that the drying process of agricultural products consumes a significant amount of energy, fossil fuel consumption can be reduced by using the solar dryer. In this study, two novel solar drying systems were designed and tested for alfalfa drying. Experiments were carried out in two different drying systems double‐pass solar air collector (DPSAC) and photovoltaic thermal solar air collector (PVT). In order to increase the heat transfer surface area, unlike the literature, a drying chamber consisting of two intertwined cylinders was designed and manufactured. The aims of this study are to bring the drying kinetics of alfalfa and the performance, energy, and exergy analysis of the designed system to the literature. The effective moisture diffusivity values were found to be in the range of 9.13 × 10−14 to 1.06 × 10−9 and the value for the highest drying rate was determined as 2.53 × 10−2gwater/gdrymatter.min. The highest thermal efficiency was obtained from DPSAC experiment as 73.7%, while the highest COP value was obtained from the PVT experiment as 12.5. The DPSAC dryer has shown the best performance in drying the alfalfa. The outcomes of the present study demonstrate that the use of DPSAC dryer is suitable when only heat energy is required for the drying system and the use of PVT when both heat and electrical energy are required. It is recommended that these systems can be used together in off‐grid agricultural areas.Practical applicationsAlfalfa (Medicago sativa L.), a type of forage crop, is a delicious, high‐energy, and protein food source for dairy cattle. By drying the alfalfa with high nutritional value in a quality method, several beneficial minerals and vitamins are preserved. The drying process is used since ancient times for the protection of the food material and for storage without degradation. Alfalfa is dried in two new solar‐powered sustainable dryers making an important contribution to reducing carbon emissions as well as providing cleaner and more reliable drying methods compared to the conventional solar drying method. This study presents an alternative for the drying process with high energy efficiency for food drying processes, according to the necessity of using both heat and electrical energy. In addition, sustainable solar dryers in this study can be used for drying agricultural products, textile, industry and dewatering municipal waste.

Enhancement of output power of semitransparent photovoltaic thermal air collector using ANFIS model.

The paper aims to develop a model using adaptive neuro-fuzzy inference system (ANFIS) architecture for enhancing output power of semitransparent photovoltaic thermal (PV/T) air collector by predicting the failure of PV panels for different weather conditions and different climate zones. Increased temperature of the photovoltaic module is a big problem which reduces its working life. The working and hotspot temperatures of photovoltaic (PV) modules have been reduced using ANFIS-based thermal design with optimal placement of PV cells which increase their life and reduce the failure rate which in turn increase the output power. The overall analysis reveals that output power is enhanced using ANFIS-based model by minimizing absolute error to 1.4% in 100 epochs by predicting accurate parameters.

Performance analysis of direct solar dryer driven by photovoltaic thermal energy recovery and solar air collector for drying materials and electricity generation

AbstractThe direct‐type solar dryer is characterized by very simple construction, less maintenance, cost‐effectiveness, and is easy to handle. The present study aims to enhance the performance of a direct‐type solar dryer. To achieve this, the photovoltaic (PV) panels with thermal energy recovery and solar air collector were integrated with the direct‐type solar dryer. In this study, the PV panels with thermal energy recovery and solar air collector were utilized as preheating units to raise the air temperature before entering the direct solar dryer. Moreover, the PV panels were utilized to drive the air blower. In this study, three incorporated models are suggested to study the performance of the solar dryer integrated with PV panels with thermal energy recovery and solar air collector. The model of each component was validated by the previously recorded empirical data. The results confirmed that the dual utilization of the PV panels with thermal energy recovery and solar air collector as a preheating unit raised the air temperature entering the direct solar dryer by the rate varying between 29°C and 42°C within the period 9:00 a.m.–4:00 p.m. Also, the moisture content of banana samples inside the direct solar dryer reduced from the initial value of 72% (wb) to the value of 33.4% (wb) within 7 h (9:00 a.m.–4:00 p.m.). During this operating period, moisture removal from the banana samples varied between 110 and 400 g/h.

Thermal and exergy analysis of N-semi-transparent photovoltaic thermal air collectors connected in series/parallel

Thermal and exergy analysis of N-semi-transparent photovoltaic thermal air collectors connected in series/parallel

SEASONAL ENERGY-EXERGY ANALYSIS OF A NEW FOLDABLE PHOTOVOLTAIC-THERMAL AIR COLLECTOR: AN EXPERIMENTAL AND NUMERICAL STUDY

Simultaneous generation of electricity and thermal energy can be done employing photovoltaic-thermal (PVT) systems. A significant issue in access to reliable and continuous energy is the power shortage in some regions in the world and the problems that arise accordingly. In this survey, yearly performance of a novel foldable PVT collector to be used in regions with limited access to energy has been experimentally and numerically investigated. In the first step of this survey, the CFD approach has been utilized to select the most efficient absorber design for the PVT air collector. In the next stage of the work, the PVT collector has been fabricated considering the numerical results and tested at different working condition in various seasons. Both numerical and experimental outcomes of the present work indicated the successful design of the foldable PVT system. The mean thermal efficiency of the portable PVT collector was attained in the range of 51.11-67.05%. The overall exergetic efficiency of the PVT system varied between 5.18 and 6.14%.

Artificial neural-network based model to forecast the electrical and thermal efficiencies of PVT air collector systems

In the recent decade, Machine Learning techniques have been widely deployed in solar systems due their high accuracy in predicting the performances without going through the physical modelling. In this work, the Artificial Neural Network (ANN) method is adopted to forecast the electrical and thermal efficiencies of a photovoltaic/thermal (PVT) air collector system. Indeed, two accurate modelling techniques have been used to generate the output results for training and validation. Both deployed electrical and thermal models have been validated experimentally and demonstrated high accuracy. Then, real climatic samples of one year with a 10 minute step of the Jordan valley location have been adopted to generate the electrical and thermal efficiencies. These latter are used in the training and validation of the developed ANN model under various combinations of the weather variables. The solar irradiance and the module temperature are the most important variables to consider as input in a NN-based model respectively. The developed ANN model shows MAE of 0.0078% and 3.3607% in predicting the electrical and thermal efficiency respectively. The electrical efficiency can be predicted with higher accuracy than the thermal efficiency. Further, the results demonstrate that the ANN outperforms the LS-SVM in forecasting the PVT air collector performances.

Experimental and model validation of photovoltaic-thermal (PVT) air collector: exergy analysis

Solar energy is a renewable energy that can produce heat via a thermal system and generate electricity via a photovoltaic (PV) module. A photovoltaic-thermal (PVT) collector is a system that has a PV module combined with a thermal collector system. The PVT collector is a popular technology for harvesting solar energy. A PVT collector can generate both electrical and thermal energies simultaneously. The study aims to validate the PV and outlet temperature for various mass flow rates and solar radiation. To develop a predictive model, a steady-state energy analysis of a PVT air collector was performed. An energy balance equation was solved using the matrix inversion method. The theoretical model was developed and validated against the experimental results, which have a similar trend and are consistent with the experimental results. On the other hand, the validated model was used to study the performances of PVT air collectors using exergy analysis for the mass flow rate ranging from 0.007 kg/s to 0.07 kg/s and solar radiation ranging from 385 W/m2 to 820 W/m2. The result from the mathematical model was found to be consistent with the experimental data with an accuracy of about 95 %. The average PVT exergy efficiency was found to be 12.7 % and 12.0 % for the theoretical and experimental studies, respectively.

Assessment of Electrical and Thermal Performance of Photovoltaic Thermal Air Collector in the Climate of Pantnagar, Uttarakhand

The photovoltaic thermal collector (PVT) produces electricity and extracts heat from a common area exposed to solar radiation. The present work provides a methodology to assess the potential of PVT at any location. The climate of Pantnagar (a town situated in the Terai belt of Uttarakhand) is selected for the study. An unglazed PVT air heating collector is modelled, taking account of both electrical and thermal aspects of design. The performance of the collector is then simulated on four days, representing average weather of four seasons observed in North Indian Plains, in correspondence with the typical meteorological year (TMY) data of 2006-2015 for the location. The diode parameters and characteristic curves of PV module selected for PVT are obtained for reference and operating conditions. The operating temperature of solar cell and heated air are plotted after convergence of numerical solution at available data points. Finally, electrical and thermal power output of the PVT with associated optical and thermal losses are obtained. The highest electrical power output of 223 W (136 W/m2) is observed at 12:20 hours (IST) on equinox of September while highest thermal power output of 411 W (251 W/m2) is obtained at 12:20 hours (IST) on summer solstice.

Thermal performance and environmental assessment of a hybrid solar-electrical wood dryer integrated with Photovoltaic/Thermal air collector and heat recovery system

Improving the energy efficiency of the drying industry is considered as one of the most efficient and promising ways for reducing carbon emissions from the industrial sector. In this context, the present work is aimed at investigating numerically the thermal performance and the environmental impact of a novel forced-air convection hybrid dryer for wood drying industry under realistic environmental conditions. The proposed dryer system consists mainly of a Photovoltaic/Thermal (PVT) solar air collector for thermal and electrical energy production, an insulated drying chamber, an air-to-air heat recovery system and fans. To simulate the functioning of the dryer system, a transient model based on energy and mass equations is developed and validated with experimental data. Annual dynamic simulations were carried out under weather conditions of the Ajaccio city and the effect of recovering waste heat from the dryer unit during both solar drying and hybrid drying processes was presented and analyzed. Results show that using the heat recovery system with an effectiveness of 0.8 leads to reduce the solar drying time by about 40% in summer and up to 32% in winter. For hybrid drying functioning, integrating of both heat recovery system and PVT air collector reduces the energy consumption of conventional dryer up to 86.5% during summer and up to 73.5% during winter. Finally, it was shown that the proposed hybrid wood dryer with PVT air collector and heat recovery system is suitable for wood drying industry and leads to improve the energy efficiency of conventional dryers and to reduce annually the amount of CO2 emissions up to 78.5%.

Performance analysis of stand‐alone solar photovoltaic thermal dryer for drying of green chili in hot‐humid weather conditions ofNorth‐EastIndia

AbstractIn the present study, an innovative stand‐alone solar photovoltaic thermal (PVT) dryer has been designed and tested in hot‐humid weather conditions of North‐East India for drying green chili. The electrical output of the hybrid PVT solar dryer has been utilized to operate the blower for the dryer making the system self‐sustained. A comparative analysis of the drying phenomena under the open sun and in the PVT based dryer is performed. Mathematical modeling is also done to investigate the drying kinetics of green chili for both drying conditions. Results indicate that the moisture content of 0.030 (d.b.) in the solar dryer and 0.035 (d.b.) in the open sun has been reduced for a span of 21 and 37 hr, respectively. Hybrid PVT solar dryer has achieved an average thermal efficiency of 31.37% and an average specific moisture extraction rate of 0.228 kg/kWh. The overall energy consumption for drying green chili is calculated to be 4.90 kWh/kg. Also, the overall thermal efficiency of 64.16%, thermal efficiency of 30.15%, and average electrical efficiency of 12.92% are secured. The results demonstrate the improved performance of the present PVT dryer for green chili drying in comparison to some of the conventional direct/indirect solar dryers.Practical ApplicationsThe present PVT solar dryer system can be utilized for drying the products using thermal energy produced by PVT air collector as well as generating electrical power in the decentralized off‐grid areas. Solar drying is not adequately popular in the North‐Eastern part of India due to the unavailability of solar drying systems for farmers. The agricultural products can be dried in the farming areas by installing this system. This PVT solar dryer provides a solution to the farmers for drying at zero energy cost and can be used as a source of income generation. This PVT solar drying system can be used to increase the storage life and reduce the spoilage and deterioration of agricultural commodities. Energy efficient solar drying process, high‐quality products, and faster drying rate compared to traditional drying method can be achieved with the help of using this system.

Energy analysis and economic feasibility of wood dryers integrated with heat recovery unit and solar air heaters in cold and hot climates

In this paper, the energy performance and economic feasibility of conventional wood dryer systems integrated with a heat recovery unit and solar air heaters are numerically investigated. Four different designs of wood dryers, composed of an insulated drying chamber, a heat recovery unit (HRU), a flat plate air collector (FPC), a photovoltaic/thermal air collector (PVT) and an auxiliary heater, are presented and compared. Annual dynamic simulations were carried out using a heat and mass transfer model with realistic meteorological data from two different climatic zones as boundary conditions. The effect of recovering waste heat and integrating each type of solar air heaters on the wood dryer energy consumption are presented and analyzed. Results show that recovering waste heat from conventional wood dryers in cold climate is more beneficial than in hot climate with an annual energy consumption reduction up to 41%. It is also shown that using a combined heat recovery unit and PVT collector improved significantly the energy efficiency of conventional dryers and reduced by about 67.5% and 49.5% the yearly energy consumption in hot and cold climates, respectively. Based on the economic analysis, the use of the HRU is beneficial in both climatic zones with a maximum payback period of 2 years. However, the use of the PVT collector is recommended only for wood dryers in hot climates where the payback period is about 3.5 years.

Design and Simulation of a semi-transparent photovoltaic thermal (PVT) indirect solar dryer integrated with kitchen chimney using ANN technique

In the proposed research, an effort has been made to develop a thermal model for a semi-transparent PVT solar dryer integrated with a kitchen chimney for faster drying of agricultural produce to enhance their shelf life. The thermal model is based on energy balance equations derived based on the design of the dryer and different climatic parameters for April month in New Delhi. It has been observed that there is an increase of 8oC in the drying chamber for the initial kitchen chimney outlet temperature of 72oC with a packing factor of 0.83 for the semi-transparent solar cells, which has also been validated by the ANN model. An exhaust fan placed between the PVT air collector and drying chamber is operated using electrical energy generated from the PVT air collector, making the entire set up self-sustainable.