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Photovoltaic (PV) solar cells are at the forefront of sustainable electricity generation technologies, yet they exhibit relatively low efficiency. Typically, less than 20 % of the solar energy absorbed is converted into electrical energy, with the remainder converts into heat. This heat increases the PV panel's operating temperature, negatively impacting its efficiency and life expectancy. To mitigate this, a novel approach using multi-layered phase change materials (PCMs) has been examined in this study. The approach involves integrating organic PCMs (OPCMs) with metallic PCMs (MPCMs), enhancing PV panel cooling efficiency by attaching the multi-layer PCM to the panel's rear. This study, employing ANSYS FLUENT software's solidification and melting model, explores the impact of multi PCM layers thickness and total multi layers thickness on PV cell temperature and electrical efficiency. The analysis reveals that a multi-layered PCMs configuration with a thickness ratio of 15:85 between MPCM (CERROLOW-117® alloy) and OPCM (RT44) significantly decreases temperature rise in PV cells, resulting in a temperature drop of 59.6 °C. This improvement boosts PV panel performance by an average of 35.8 % compared to panels lacking cooling systems during peak sun hours under hot climate conditions characterized by ambient temperatures of 40 °C and high solar radiation exceeding 1000 W/m². This suggests that a carefully optimized PCM layering approach could markedly improve PV system efficiency, offering a practical solution to the overheating problem and extending the operational life of PV installations.

Achieving the global electricity demand and meeting the United Nations sustainable development target on reliable and sustainable energy supply by 2050 are crucial. Portable energy storage (PES) units, powered by solid-state battery cells, can offer a sustainable and cost-effective solution for regions with limited power-grid access. However, operating in high-dust and high-temperature environments presents challenges that require effective thermal management solutions. This paper is a comprehensive review of thermal management systems for PES units, with a specific focus on addressing the challenge of overheating in airtight designs. The review of various active and passive cooling systems is conducted through extensive study of the relevant literature, which is significant in providing insights into the operation, performance parameters, and design options for different cooling system technologies. The findings from this review show heat pipe (HP) technologies as key cooling-system solutions for airtight PES units. Specifically, loop and oscillating HPs, as well as the vapour chamber, offer desirable features such as compactness, low cost, and high thermal conductivity that make them superior to other alternatives for the cooling systems in PES. The insights and knowledge generated via this review will help facilitate the design and development of innovative, efficient, and reliable PES units, thereby contributing to the advancement of off-grid renewable energy applications and enabling sustainable power solutions worldwide. Furthermore, an appropriate design of PES units can help in reducing capital and maintenance costs. [ABSTRACT FROM AUTHOR]

THE PURPOSE. Consider the problems of the heat transfer process in the structural elements of the LED light source. Describe the cooling system of an LED light source using an equivalent circuit and thermal resistances. Conduct a comparative analysis of cooling systems for LED lighting devices. Perform thermodynamic calculations of the light device radiator using computer programs of automatic design systems. Suggest a way to improve the heat transfer properties of the radiator of the LED light source.METHODS. When solving the tasks set, the method of retrospective-prospective meta-analysis was used, computer programs of automatic design systems and direct determination of technical parameters using measuring instruments were used.RESULTS. The article describes the relevance of the topic, discusses the features of the heat transfer process in the structural elements of the LED light source. Thermodynamic calculations of the radiator of the lighting device were made using computer programs of automatic design systems KOMPAS and SolidWorks. The article proposes a method for improving the heat transfer properties of the radiator of an LED light source.CONCLUSION. There are many different cooling systems with their own advantages and disadvantages. The most efficient cooling systems are forced cooling systems, however, their use entails an increase in the final cost of the lighting device and a decrease in its light output due to an increase in energy consumption. Passive cooling systems are relatively cheap, but to provide effective cooling of LEDs, they must have a sufficient area of contact with the heat source, have good thermal conductivity and heat dissipation. In this case, the best way to improve the heat transfer properties of the radiator is to apply a special coating with a high heat transfer. This will increase the cooling efficiency with minimal cost without resorting to a significant change in the design features of an existing system.

Advanced Power Reactor (APR-1400) is a Generation III + Pressurized Water Reactor (PWRs) and has gained popularity among energy mix community. APR-1400 features enhanced safety limits to prevent a “Fukushima-type” accident scenario for a duration up to 8 h. This work proposes a system that enhances APR 1400 passive cooling (Thermosyphon Cooling System, TCS) capabilities to guarantee at least double the coping time before core meltdown. TCS provides enough cooling to the reactor core in the case of loss of offsite power, known as Station Black-Out (SBO) accident. This work invites to use the In-containment Refueling Water Storage Tank (IRWST) to further extend the APR1400 capability to passively cool the reactor core after an SBO accident. This work is designed and tested by 3Keymaster simulator platform developed by Western Service Corporation. Simulation has modified the existing model of APR1400 in the simulator by adding pipes, valves and heat exchanger. Results show the system will cool the reactor core for almost 18 h after the SBO accident. The system works initially in parallel with steam generators then it continues cooling the reactor core for extra 18 h resulting in providing more time for restoring the on-site power sources and preventing core meltdown.

Today, earth-air heat exchangers (EAHEs) are important heat exchangers used in the air-conditioning of buildings and can be seen in different types and capacities. Thermal comfort is perceived as the comfort of human beings under given room conditions, namely average temperature and relative humidity. For example, the value of average comfort temperature in a room is between 294 and 296 K. The main objective of this analysis is not to obtain the lower air temperature of medium, rather to obtain comfort temperature interval of 294-296 K. This thermal comfort temperature has been achieved at nearly all channel outlets in 1 m depth. For the numerical analysis of EAHE, the maximum mean air temperature of July of the city of Elazığ was used. Computational fluid dynamics ANSYS FLUENT 12.1 program was chosen to examine the thermal comfort condition of a typical building. In the analysis of the thermal performance of the EAHE, examinations were made for different earth depths (H=1, 2, 3 m). PVC was chosen as the EAHE channel material. The numerical model was solved in three dimensions in the steady-state condition using different Reynolds number values (Re=5×103,104,15×103,2×104,4×104,6×104,105) in the turbulent flow. It was determined that the best thermal performance is at the smallest air inlet velocity. According to the numerical results, it was found that the cooling energy consumption required to provide thermal comfort condition for the typical building is reduced. [ABSTRACT FROM AUTHOR]

Wind towers or wind catchers, as passive cooling systems, can provide natural ventilation in buildings located in hot, arid regions. These natural cooling systems can provide thermal comfort for the building inhabitants throughout the warm months. In this paper, a modular design of a wind tower is introduced. The design, called a modular wind tower with wetted surfaces, was investigated experimentally and analytically. To determine the performance of the wind tower, air temperature, relative humidity (RH) and air velocity were measured at different points. Measurements were carried out when the wind speed was zero. The experimental results were compared with the analytical ones. The results illustrated that the modular wind tower can decrease the air temperature significantly and increase the relative humidity of airflow into the building. The average differences for air temperature and air relative humidity between ambient air and air exiting from the wind tower were approximately 10 °C and 40%, respectively. The main advantage of the proposed wind tower is that it is a modular design that can reduce the cost of wind tower construction. [ABSTRACT FROM AUTHOR]

The Kingdom of Saudi Arabia (KSA) generates the most electricity of any country in the Gulf region, and virtually all that electricity is produced by the burning of fossil fuels - natural gas and crude oil. The residential sector accounts for about 50% of the total electricity demand in the Kingdom, and around two-thirds of that electricity consumption is used for air conditioning. As the Kingdom transitions away from its reliance on fossil fuels, reducing air conditioning energy demand in dwellings becomes a key objective. Passive cooling systems can significantly reduce cooling energy loads for buildings while maintaining thermal comfort. This study investigated the potential of integrating a passive downdraught evaporative cooling (PDEC) tower into a typical Saudi Arabian villa. A computational model of a spray PDEC tower was developed in IES-VE software and calibrated against field data. Then, an actual Saudi villa was monitored, modelled, and validated before a PDEC tower was digitally integrated into the villa. Finally, the villa and its PDEC digital twin were used to conduct a series of parametric analyses to determine the PDEC performance in different rooms and cooling energy consumption in the villa as functions of wind speed and direction. The research found that, counterintuitively, higher wind speeds reduced the effectiveness of the PDEC system to cool rooms in the villa and that wind direction also played a role in the degree of cooling experienced in different villa spaces. In the summer season, the results indicated that the total villa energy consumption was approximately 32,415 kWh in the base case, with cooling energy representing 88% of the total energy used (28,337 kWh). The integration of the PDEC tower resulted in a reduction of approximately 22% in cooling energy consumption, from 28,337 kWh to 22,032 kWh, while the PDEC was operational continuously throughout the day. • Saudi house monitored in summer; data collected via site visits & data loggers for environmental data. • Villa & PDEC tower modelled in IES-VE software, validated using building details, monitoring data. • PDEC tower virtually incorporated into villa model to assess thermal performance, wind effect & energy use. • Research found high wind speeds reduced effectiveness of PDEC system to cool rooms, wind direction played a role as well. [ABSTRACT FROM AUTHOR]

Passive cooling systems, such as wind towers, can help to reduce energy consumption in buildings and at the same time reduce greenhouse gas (GHG) emissions. Wind towers can naturally ventilate buildings and also can create enhanced thermal comfort for occupants during the warm months. This study proposes a modern wind tower design with a moistened pad. The new design includes a fixed column, a rotating and movable head, an air opening with a screen, and two windows at the end of the column. The wind tower can be installed on roof-tops to take advantage of ambient airflow. The wind tower’s head can be controlled manually or automatically to capture optimum wind velocity based on desired thermal condition. To maximize its performance, a small pump was considered to circulate and spray water on an evaporative cooling pad. A computational fluid dynamics (CFD) simulation of airflow around and inside the proposed wind tower is conducted to analyze the ventilation performance of this new design of wind tower. Thereby, the velocity, total pressure, and pressure coefficient distributions around and within the wind tower for different wind velocities are examined. The simulation results illustrate that the new wind tower design with a moistened pad can be a reasonable solution to improve naturally the thermal comfort of buildings in hot and dry climates.

Counterbalancing climate change is one of the biggest challenges for engineers around the world. One of the areas in which optimization techniques can be used to reduce energy needs, and with that the pollution derived from its production, is building design. With this study of a generic office located both in a northern country and in a temperate/Mediterranean site, we want to introduce a coding approach to dynamic energy simulation, able to suggest, from the early-design phases when the main building forms are defined, optimal configurations considering the energy needs for heating, cooling and lighting. Generally, early-design considerations of energy need reduction focus on the winter season only, in line with the current regulations; nevertheless a more holistic approach is needed to include other high consumption voices, e.g., for space cooling and lighting. The main considered design parameter is the WWR (window-to-wall ratio), even if further variables are considered in a set of parallel analyses (level of insulation, orientation, activation of low-cooling strategies including shading devices and ventilative cooling). Finally, the effect of different levels of occupancy was included in the analysis to regress results and compare the WWR with corresponding heating and cooling needs. This approach is adapted to Passivhaus design optimization, working on energy need minimisation acting on envelope design choices. The results demonstrate that it is essential to include, from the early-design configurations, a larger set of variables in order to optimize the expected energy needs on the basis of different aspects (cooling, heating, lighting, design choices). Coding is performed using Python scripting, while dynamic energy simulations are based on EnergyPlus. [ABSTRACT FROM AUTHOR]

Passive cooling systems, such as wind towers, can help to reduce energy consumption in buildings and at the same time reduce greenhouse gas (GHG) emissions. Wind towers can naturally ventilate buildings and also can create enhanced thermal comfort for occupants during the warm months. This study proposes a modern wind tower design with a moistened pad. The new design includes a fixed column, a rotating and movable head, an air opening with a screen, and two windows at the end of the column. The wind tower can be installed on roof-tops to take advantage of ambient airflow. The wind tower's head can be controlled manually or automatically to capture optimum wind velocity based on desired thermal condition. To maximize its performance, a small pump was considered to circulate and spray water on an evaporative cooling pad. A computational fluid dynamics (CFD) simulation of airflow around and inside the proposed wind tower is conducted to analyze the ventilation performance of this new design of wind tower. Thereby, the velocity, total pressure, and pressure coefficient distributions around and within the wind tower for different wind velocities are examined. The simulation results illustrate that the new wind tower design with a moistened pad can be a reasonable solution to improve naturally the thermal comfort of buildings in hot and dry climates. [ABSTRACT FROM AUTHOR]