Investigation of the effect of physical factors on exergy efficiency of a photovoltaic thermal (PV/T) with air cooling

Thermal photovoltaic systems are used to harness solar energy to generate electricity and thermal at the same time. In this technology, electrical efficiency is very low compared to thermal efficiency; as the cell surface temperature rises, the electrical efficiency decreases, so one of the ways to achieve high efficiency is exergy analysis. Exergy analysis of a process or system shows how much of the ability to perform the work or input exergy has been consumed by that process or system. In this research, an ordinary thermal photovoltaic panel with air cooling has been examined for exergy. To do this, it has identified the effective performance variables from a mechanical point of view, which are inlet air temperature, inlet air flow, and length (number of modules that are connected in series). The effect of changing each of the variables based on Saveh weather conditions has been simulated using MATLAB software. The results show that the exergy efficiency of the panel decreases with the inlet air temperature increasing. It was also observed that the optimal airflow is 0012 (kg/s) and will have the highest efficiency per 8.8 m length.http://www.hindawi.com/journals/ijpMechanical and Aeronautical Engineerin

Enhancing energy efficiency in zero energy buildings: Analyzing the impacts of phase change material-filled enclosures and outlet air distance on solar wall performance

This paper presents a study on solar walls integrated with phase change material (PCM) to enhance energy efficiency in zero-energy buildings. The research focuses on expanding the surface area with PCM-filled compartments to improve thermal performance. The effects of different expanded surface shapes and outlet air distances on the solar wall's temperature and PCM solidification process are investigated through numerical simulations. The findings show that semicircular surfaces with a 30 cm outlet air distance have the highest temperatures, while rectangular surfaces with the same distance have the lowest temperatures. Semicircular surfaces take the longest time to freeze PCM completely, whereas rectangular surfaces with a 30 cm gap achieve the fastest solidification. These insights provide valuable guidance for optimizing solar wall design and energy efficiency in zero-energy buildings. Finally, it was seen that by changing the shape of the extended surfaces and the air gap, the outlet air temperature changes up to 1.15° and the wall temperature changes up to 1.21°

Numerical study and optimization of thermal efficiency for a pin fin heatsink with nanofluid flow by modifying heatsink geometry

This paper presents a numerical study on the thermal efficiency of a pin fin heatsink (HEK). The working fluid used is an alumina/water nanofluid, which enters the HEK in a laminar flow regime and exits from its surroundings. This study involves varying the distance between circular pin fins, their height, and their diameter. By altering these parameters, we determine the values of thermal resistance (THR) and temperature uniformity (Teta) on the HEK, along with the heat transfer coefficient (HTC). We further optimize the obtained results using artificial intelligence techniques to minimize the THR of the HEK, maximize the HTC, and achieve the best Teta on the HEK. This numerical investigation employs a two-phase approach to model nanofluid flow within the HEK. The optimization process yields predictions with an accuracy of less than 4%. The findings reveal that increasing the height of the pin fins reduces the HTC and the heat capacity of the HEK, while simultaneously improving the Teta on the HEK. Expanding the distance between pin fins enhances the HTC, decreases the THR of the HEK, and further improves the Teta on the HEK. Similarly, augmenting the diameter of the pin fins amplifies the HTC, reduces the THR, and enhances the Teta on the HEK

A detailed review on the performance of photovoltaic/thermal system using various cooling methods

As an emerging technology, photovoltaic (PV) panels have made a vital energy source to meet increased energy consumption demand and to replace the associated scarcity of traditional energy resources. PV modules have electrical efficiency from 4 to 26%, depending on their materials. The PV panel transforms about 50–60% of total solar radiation into heat, leading to high temperatures during the operation of the PV panel. Due to high temperature, there is a decrease in electrical conversion efficiency and thermal stress in PV panels continue for a more extended period. In this context, a photovoltaic/thermal (PV/T) system is suggested to decrease the thermal stress of the PV panel by removal of heat and make it useful at high PV module temperature. This comprehensive literature review reports PV cooling techniques, research gaps and difficulties encountered by various researchers in this technology. To counter this drawback, active and passive methods of cooling have been studied, including jet impingement, airflow cooling, immersion cooling using liquids, thermoelectric based cooling, microchannel cooling, phase change materials (PCM) based cooling, water/liquid cooling and heat pipe cooling. This research study intends to present a modern, systematic review of PV/T cooling techniques and challenges associated with these methods. Furthermore, techno-economic analysis and the role of artificial intelligence in PV/T systems are also summarized.http://www.elsevier.com/locate/seta2023-12-30hj2023Mechanical and Aeronautical Engineerin

Enhancing thermal performance of cylindrical Li-ion battery packs: A 3D simulation with strategic phase change material integration and airflow control

This study conducts a three-dimensional simulation of the temperature of a cylindrical Li-ion battery (LIB) pack with nine cells. The cells are arranged in the pack in square and diamond configurations, and the pack is filled with phase-change materials (PCMs). The airflow enters the channel from two inlets at 90° with respect to the pack and is guided by two blades at the sides of the inlet toward the pack. Arc-shaped and linear blades were used for this study, which was carried out for 2500 s. The results indicate that the square arrangement of batteries, combined with the use of curved blades, has been more effective in reducing temperature. In this configuration, a more uniform distribution of air flow and better efficiency of the PCM in absorbing heat were observed, leading to a significant decrease in the overall temperature of the battery pack. Specifically, compared to the diamond arrangement, the temperature of the batteries in the square arrangement was up to 10 °C lower. This reduction in temperature plays an important role in enhancing the lifespan and safety of the batteries. By using machine learning and providing the optimal model for the maximum temperature of the battery surface, it was shown that this parameter was designed with the model and comparing it with the numerical results had an error of 2.01 %

Investigating the Index of Sustainable Development and Reduction in Greenhouse Gases of Renewable Energies

Considering the limited resources of fossil energy and the problems caused by the emission of greenhouse gases, it is necessary to pay more attention to renewable energies, because in this way, the goals of sustainable development can be achieved. The importance of renewable energies in sustainable development, reducing greenhouse gases and increasing energy security on the one hand, and the need for financial resources and large investments for renewable energy projects on the other hand, doubles the role and importance of financial development in the development of renewable energies. Considering the importance of this issue, the present study examines the impact of the development of modern facilities and renewable energy technology. In this study, dynamic interactions in the Sustainable-Energy-Energy Development Pattern of carbon dioxide are investigated using the Bayesian Vector Auto Regression (BVAR) method. One of the most important indicators for evaluating sustainable development is the modified pure arrangement (GS). For this purpose, this index was used as a sustainable development index. The results indicate that the effect of positive impulse on renewable and renewable energy consumption on sustainable development in Uganda is positive. In addition, the positive shock of renewable and renewable energy consumption increases the emissions of carbon dioxide pollutants to a different extent. In addition, the effect of the growth of sustainable development index on renewable energy consumption and renewal energy consumption is (CO2) negative. The research results show that based on the RMSE criterion, the former SSVS-Full function was used to investigate the impact of renewable energy consumption on sustainable development and the independent Normal-Wish art function was used. Therefore, in this research, the dynamic relationships between sustainable development, energy consumption (separately from renewable and non-renewable energy) and CO2 emissions are investigated

Investigating the Index of Sustainable Development and Reduction in Greenhouse Gases of Renewable Energies

Considering the limited resources of fossil energy and the problems caused by the emission of greenhouse gases, it is necessary to pay more attention to renewable energies, because in this way, the goals of sustainable development can be achieved. The importance of renewable energies in sustainable development, reducing greenhouse gases and increasing energy security on the one hand, and the need for financial resources and large investments for renewable energy projects on the other hand, doubles the role and importance of financial development in the development of renewable energies. Considering the importance of this issue, the present study examines the impact of the development of modern facilities and renewable energy technology. In this study, dynamic interactions in the Sustainable-Energy-Energy Development Pattern of carbon dioxide are investigated using the Bayesian Vector Auto Regression (BVAR) method. One of the most important indicators for evaluating sustainable development is the modified pure arrangement (GS). For this purpose, this index was used as a sustainable development index. The results indicate that the effect of positive impulse on renewable and renewable energy consumption on sustainable development in Uganda is positive. In addition, the positive shock of renewable and renewable energy consumption increases the emissions of carbon dioxide pollutants to a different extent. In addition, the effect of the growth of sustainable development index on renewable energy consumption and renewal energy consumption is (CO2) negative. The research results show that based on the RMSE criterion, the former SSVS-Full function was used to investigate the impact of renewable energy consumption on sustainable development and the independent Normal-Wish art function was used. Therefore, in this research, the dynamic relationships between sustainable development, energy consumption (separately from renewable and non-renewable energy) and CO2 emissions are investigated

Influence of artificial roughness parametric variation on thermal performance of solar thermal collector : an experimental study, response surface analysis and ANN modelling

Please read abstract in the article.The Deanship of Scientific Research at King Khalid University, Saudi Arabia.http://www.elsevier.com/locate/seta2024-02-21hj2023Mechanical and Aeronautical Engineerin

Thermal boundary condition analysis of cooling objects exposed to a free impinging jet using the heatline concept

Heat and flow pattern of a vertical free jet impinging on a hot disk were numerically investigated. A cylinder with various thicknesses and materials exposed simultaneously to uniform heat flux on one side and a free impinging jet on the other side is simulated by ANSYS Fluent 19.3. For simulations, the thermal boundary condition on the hot surface might differ due to the nature of the heat flow. The Volume of Fluid (VOF) approach is used to model the free jet heat transfer and fluid dynamics with the presence of air, while only the energy equation is solved in the cylinder. Heatline equation is solved to reveal the heat flow direction and effects of different geometry conditions. The maximum heat flux of 2.5MW/m2was obtained at the edge of stagnation region for hot target made of copper, while the value was 1.5 MW/m2 when the material was combined with stainless steel. However, the general thermal and hydrodynamic features of the jet flow were not influenced. It means that hot object condition may only affect the balance between heat flux and temperature, and the ideal uniform heat flux on the impinging wall may not be achieved in any experimental conditions.https://www.tandfonline.com/loi/tcfm20am2022Mechanical and Aeronautical Engineerin

A Review of Thermal Conductivity Models for Nanofluids

Nanofluids, as new heat transfer fluids, are at the center of attention of researchers, while their measured thermal conductivities are more than for conventional heat transfer fluids. Unfortunately, conventional theoretical and empirical models cannot explain the enhancement of the thermal conductivity of nanofluids. Therefore, it is important to understand the fundamental mechanisms as well as the important parameters that influence the heat transfer in nanofluids. Nanofluids’ thermal conductivity enhancement consists of four major mechanisms: Brownian motion of the nanoparticle, nanolayer, clustering, and the nature of heat transport in the nanoparticles. Important factors that affect the thermal conductivity modeling of nanofluids are particle volume fraction, temperature, particles size, pH, and the size and property of nanolayer. In this paper, each mechanism is explained and proposed models are critically reviewed. It is concluded that there is a lack of a reliable hybrid model that includes all mechanisms and influenced parameters for thermal conductivity of nanofluids. Furthermore, more work needs to be conducted on the nature of heat transfer in nanofluids. A reliable database and experimental data are also needed on the properties of nanoparticles.http://www.tandfonline.com/loi/uhte202016-09-30hb201