Search

Copyright of Environmental & Social Management Journal / Revista de Gestão Social e Ambiental is the property of Environmental & Social Management Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper addresses the potential of integrating a concentrating photovoltaic thermal (CPV/T) system with an absorption chiller for the purpose of space cooling in residential buildings in the United Arab Emirates (UAE). The proposed system consists of a low concentrating photovoltaic thermal (CPV/T) collector that utilizes mono-crystalline silicon photovoltaic (PV) cells integrated with a single-effect absorption chiller. The integrated system was modeled using the Transient System Simulation (TRNSYS v17) software. The obtained model was implemented in a case study represented by a villa situated in Abu Dhabi having a peak cooling load of 366 kW. The hybrid system was proposed to have a contribution of 60% renewable energy and 40% conventional nonrenewable energy. A feasibility study was carried out that demonstrated that the system could save approximately 670,700 kWh annually and reduce carbon dioxide emissions by 461 tons per year. The reduction in carbon dioxide emissions is equivalent of removing approximately 98 cars off the road. The payback period for the system was estimated to be 3.12 years. [ABSTRACT FROM AUTHOR]

Passive radiative cooling materials can efficiently reflect solar radiation and spontaneously dissipate heat through the long‐wave infrared (LWIR) transmission window to the coldouter space. They are highly attractive for application in walls and roofs of sustainable energy‐efficient buildings, but it is a challenging task to develop switchable radiative coolers for transparent windows. Herein, free‐standing bacterial cellulose‐templated radiative cooling liquid crystal films with high LWIR emissivity and self‐adaptive solar transmittance are reported. Biosynthetic silanized bacterial cellulose with 3D interconnected porous nanostructure is harnessed as a robust template for confining novel liquid crystals with smectic A to chiral nematic phase transition, thereby endowing the film with high solar transmittance modulation ability. The resulting film is found to not only exhibit a remarkable LWIR emissivity, but also adaptively change its solar transmittance between a transparent state and an opaque state according to environmental temperature variation. Outdoor radiative cooling experiments are performed, and the energy‐saving performance is evaluated through a simulation of a 12‐story reference office building with the films applied as radiative cooling windows. This research can shine light on the development of advanced radiative cooling materials with switchable transmittance and their widespread applications in buildings, vehicles, and transparent photovoltaics. [ABSTRACT FROM AUTHOR]

During solar cell operation, most light energy converts to heat, raising the battery temperature and reducing photoelectric conversion efficiency. Thus, lowering the temperature of solar cells is essential. Nanofluids, with their superior heat transfer capabilities, present a potential solution to this issue. This study investigates the mechanism of enhanced heat transfer by nanofluids in two-dimensional rectangular microchannels using the two-phase lattice Boltzmann method. The results indicate a 3.53% to 22.40% increase in nanofluid heat transfer, with 0.67% to 6.24% attributed to nanoparticle–fluid interactions. As volume fraction (φ) increases and particle radius (R) decreases, the heat transfer capability of the nanofluid improves, while the frictional resistance is almost unaffected. Therefore, the performance evaluation criterion (PEC) of the nanofluid increases, reaching a maximum value of 1.225 at φ = 3% and R = 10 nm. This paper quantitatively analyzes the interaction forces and thermal physical parameters of nanofluids, providing insights into their heat transfer mechanisms. Additionally, the economic feasibility of nanofluids is examined, facilitating their practical application, particularly in solar cell cooling. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) can be classified as smart materials having its applications in varied fields like domestic and commercial refrigerators, solar absorption chillers, air conditioning, free and radiative cooling, solar air heaters, solar stills, solar absorption cooling, electric and electronic devices for cooling purposes and in textiles. Here, in this review, the various polymer‐based and encapsulated PCMs used for fulfilling the above applications are discussed along with their varied synthesis/fabrication methods. Furthermore, chemical characterization is discussed by FTIR for understanding the chemical structure along with functional groups present in the materials. The thermogravimetric analysis (TGA) is also critically discussed for understanding the thermal stability of the Polymer PCM or the phase change composites and the latent heat of PCM melting was also explored by differential scanning calorimetry (DSC) for various PCM which gives insight into the thermal energy storage capability and property. The inbuilt surface structure of the polymer PCM was also tried to be investigated by scanning electron microscopy (SEM) which when understood gives a clear picture about the structure–property relationship. Highlights: Polymeric supporting materials and polymer encapsulation on PCM were reviewed.The materials used and the synthesis of polymeric PCM were studied in depth.Chemical characterization was reviewed for chemical structure.Thermal stability checks by TGA and latent heat prediction was done by DSC.Morphology was reviewed using SEM for the structure–property relationship. [ABSTRACT FROM AUTHOR]

In recent years, research communities have shown significant interest in solar energy systems and their cooling. While using cells to generate power, cooling systems are often used for solar cells (SCs) to enhance their efficiency and lifespan. However, during this conversion process, they can generate heat. This heat can affect the performance of solar cells in both advantageous and detrimental ways. Cooling cells and coordinating their use are vital to energy efficiency and longevity, which can help save energy, reduce energy costs, and achieve global emission targets. The primary objective of this review is to provide a thorough and comparative analysis of recent developments in solar cell cooling. In addition, the research discussed here reviews and compares various cooling systems that can be used to improve cell performance, including active cooling and passive cooling. The outcomes reveal that phase-change materials (PCMs) help address critical economic goals, such as reducing the cost of PV degradation, while enhancing the lifespan of solar cells and improving their efficiency, reliability, and quality. Active PCMs offer precise control, while passive PCMs are simpler and more efficient in terms of energy use, but they offer less control over temperature. Moreover, an innovative review of advanced cooling methods is presented, highlighting their potential to improve the efficiency of solar cells. [ABSTRACT FROM AUTHOR]

A numerical study was carried out to assess the practicality of running inverter air conditioner directly on photovoltaic cells in the climatic conditions of Iraq. The research aims to assess the energy consumption and efficiency Regarding the solar air conditioning system in various weather conditions and operational situations. The study employs a computational model to replicate the system's behavior and enhance its performance. Where solar panels with a capacity of 570 watts the number of solar panels4 were used, the number of batteries 2, and inverter capacity 3.5 kw , the number of panels, and the amount of energy consumed during different time periods and for different air conditioner loads were used, such as one ton, one quarter ton, one half ton, and two tons. Solar panels' lifespan is determined by the extremes in temperature they are exposed to, whereas their output capacity is determined by the amount of light radiation they receive. The amount of batteries, the number of panels, and the kind of inverter required are all determined numerically in this study. The aim of the study was to estimate the efficiency of the air conditioning system, which It runs on solar energy. [ABSTRACT FROM AUTHOR]

In this study, a comprehensive thermodynamic analysis was performed to evaluate and optimize the performance of a solar-powered single-effect lithium bromide-water absorption chiller system. A computational model was developed to systematically investigate various design parameters, including the impact of inlet generator, absorber/condenser, and evaporator temperatures on the system's energy and exergy efficiency. Additionally, the study evaluated the influence of solution heat exchanger effectiveness and hot source temperatures. Key performance indicators such as cooling production capacity, coefficient of performance, exergy efficiency, and overall solar cooling system efficiency were considered. The results indicated that a condenser/absorber temperature of 30 ℃ improved the coefficient of performance to 0.8, and the cooling capacity to 30.05 kW while varying the evaporation temperature between 4.5 to 10.5 ℃ improves the coefficient of performance by approximately 10.38%. Increasing the solution heat exchanger effectiveness resulted in a 16.77 and 16.076% enhancement for both the coefficient of performance and exergy efficiency, with generator temperatures of 74 and 90 ℃. The system achieves its highest performance within a hot source temperature range of 70–75/ ℃. Proper selection of heat exchanger temperatures significantly improved the performance of the absorption subsystem. The intensity of solar irradiance and ambient conditions influenced the system's efficiency. [ABSTRACT FROM AUTHOR]

The need for refrigeration and air conditioning plays a crucial role in energy consumption. It is one of the important aspects which plays a crucial role in the food, human comfort, and energy problems of any country. Rapid consumption of energy and fossil fuels depletion results in the onset of energy crises thus, the research on absorption refrigeration systems has been widely promoted because the input energy supply for the systems can be a low-grade heat available from solar, geothermal, and/or waste heat from Industries. Solar refrigeration and air conditioning is an attractive and promising applications of solar energy because the cooling demand and the availability of solar energy are in phase and solar cooling can be made cost-effective. The present work includes the solar energy option and the potential for cooling with various range of parameters such as availability of solar radiation, environmental effects, types of collectors, types of solar cooling systems in general, and closed/open/continuous/multistage/hybrid and advanced absorption refrigeration cycles in particular. A literature survey has been carried out for possible improvements in the performance of solar absorption cooling systems and different solar collection and storage options. The most suitable solar cooling option viz. absorption refrigeration with the solar operation, historical developments, and commercial products. Advanced absorption cycles and novel cooling systems have also been presented and discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] Outdoor radiative cooling is a passive method of cooling a surface that faces the sky. During the past decade, numbers of successful demonstrations of daytime radiative coolers have been reported. Because a daytime radiative cooler can be radiatively cooled both during the day and at night, it is always cooled and a temperature difference against the surroundings is generated. This temperature difference can be used to generate thermoelectric power throughout the day by placing a daytime radiative cooler on a thermoelectric module. However, such a device cannot harvest solar heat because sunlight is reflected by the daytime radiative cooler. In this study, a thermoelectric device that simultaneously harvests both radiative cooling and solar heating is presented. The essential component is a vertically placed thermoelectric module made of transparent thermoelectric thin films which allows radiatively cooled and solar heated surfaces to be co-planar. The outdoor and indoor measurements confirm that the device can harvest both radiative cooling and solar heating simultaneously during the day without offsetting each other, and can harvest radiative cooling at night. The co-planar design is an efficient method for simultaneously harvesting solar heating and radiative cooling, which could facilitate efficient energy harvesting and can be applied to a standalone power supply for off-grid sensor modules. [ABSTRACT FROM AUTHOR]

Solar distillation has gained more importance as a practical and environmentally friendly solution for converting non-potable water into clean water using solar energy, in response to the increasing concern about the scarcity of clean water. In the city of Kirkuk, Iraq, located at 35.4666° N, 44.3799° E, we conducted an experiment to enhance the efficiency of a conventional solar distiller with a surface area of 1 m². To enhance evaporation, we incorporated 8 vacuum tubes. For improved condensation, we conducted experiments using two different cooling methods to cool the glass cover: pulse cooling (1min/15min), (1min/10min) and continuous cooling. Based on the trial findings, the productivity reached 2653 ml/day, representing a 237.5% increase in production. When vacuum tubes were attached to the solar still, the productivity increased compared to a conventional distiller. With a cooling time of (1min/15min), the productivity reached 3510 ml/day. With a cooling(1min/10min), the productivity reached 3587ml/day. When constantly cooling, the productivity reached 4980 ml/day. The productivity experienced respective increases of 332%, 386%, and 656.8% in comparison to the conventional distiller. The modified still's thermal efficiency was 21.6%, 24.6%, and 37.7%, compared to 17% for the conventional system and 18.8% for the improved system without glass cover cooling. [ABSTRACT FROM AUTHOR]

Due to the shortage of electricity with abundant solar radiation in Iraq especially in summer, increasing temperatures with higher cooling demand. This concerns the all-life sector, especially agriculture, industrial, medical, and air purification. By utilizing solar radiation as the primary energy source, adsorption chillers are a potential technology to reduce the strain on the demand for renewable power. The kinetics of the adsorbent, the refrigerant selected, the adsorber's design, and the temperatures chosen all affect how well they work. The primary objective of this work is to optimize the cylindrical bed dimensions with specific cooling power (SCP) and performance (COP) of adsorbent bed reactors by optimizing the geometrical design parameters and the influencing cooling time. These geometric design criteria included the reactor bed's mass, shape, and thickness. This study explores the design and operational parameters' impact factors' effects upon COP & SCP of an adsorptive refrigerator machine, as well as the influence of the thickness of the activated carbon bed at bed's heat transfer performance. Using ethanol and 16 kg of activated carbon as the working pair, a transient one-dimensional modeling simulation was used to build and examine the performance of the cylindrical two-bed adsorber chiller, measuring 0.048 m in thickness and 0.5 kW in cooling power. By investigating the connections between cooling efficiency, ethanol adsorption, bed thicknesses, and desorption temperature. The (EES) program was used to carry out the simulation technique. The results of this investigation demonstrated that the ideal layer thickness for refrigeration power of 359 W, COP of around 0.702, SCP of 11.22 W/kg, and ideal chilling time of roughly (50) min was found to be 0.048 m. The conclusion is that although a greater input temperature would result in a comparatively longer cycle time, it may also provide a higher cooling power. SCP will, however, drop for cylindrical bed thicknesses greater than (0.048) m. SCP is 9.6 W/kg at thickness (0.0625) m; this value decreases by approximately 15% as thickness increases from (0.048-0.0625) m, and this increase is progressive. The cylindrical bed designs were discovered to have thickness and cooling time optimization superior to the flat plane with the same specifications. 95° was the generating temperature at the 5 °C evaporator, and the cooling time was around 40 minutes less than with the flat plate design. In contrast, the cooling period in this instance, 0.048 meter long cylindrical bed was (58) minutes. SCP = 9 W/kg for the flatbed design, a 20% decrease from the existing research design. [ABSTRACT FROM AUTHOR]

Photovoltaic systems, a clean and renewable energy source, face challenges in optimizing efficiency due to temperature-induced performance loss. This research explores passive cooling strategies using phase change materials, which collect excess heat during peak solar irradiance, store it, and release it during less sunshine or high temperatures. This method efficiently controls panel temperature, enhancing performance and extending lifetime. The choice of cooling technique should be based on the specific requirements and constraints of the photovoltaic system. Solar panels receive 780 W/m2 of incoming solar radiation in summer and peak at noon. Convective heat transfer and air temperature of 25 degrees Celsius allow heat to escape. The stiff material, aluminum fins, and PCM have specific heat of 2000 J/kg.K and thermal conductivity of 0.2 W/m.K, respectively. Temperature distribution reveals significant reduction in surface temperatures with increasing Al2O3 concentrations. The best case was at 0.5wt%, achieving 49.896℃. Electrical efficiency increases with concentration. The distribution of temperatures at different CuO concentrations reveals lower surface temperatures due to increasing concentrations. The optimal concentration was 0.5 wt percent, where temperatures fell to 49.870℃. Increasing electrical efficiency is crucial for temperature improvement, with a peak at 9.26% at 0.5 weight percent mm. Temperature distribution decreases with ZnO concentration, with optimal 0.5wt% concentration, enhancing electrical efficiency with increasing concentrations. [ABSTRACT FROM AUTHOR]

While technical optimization focuses on maximizing the annual energy yield of utility-scale PV parks, the ultimate goal for power plant owners is to maximize investment profit. This paper aims to bridge the gap between technical and economic approaches by using simulation data from a real-case utility-scale PV park. It analyzes how changes in configuration parameters such as the DC–AC ratio and string length and PV technologies like solar tracking systems and bifacial modules impact the economic metrics of the project, i.e., net present value (NPV) and internal rate of return (IRR). PVSyst software was utilized as a simulation tool, while in-house developed software implementing appropriate technical and economic models served as a comparison platform and was used to validate the outputs generated through PVSyst. Results indicate that the commonly used horizontal single-axis tracking configuration may economically underperform compared with fixed-tilt setups. The optimal DC–AC ratio fell within the range of 1.30 to 1.35. Extending the string length from 25 to 28 modules improved economic indexes. Additionally, fixed-tilt bifacial modules can enhance project economics if a 10% cost premium compared with standard monofacial PV modules is considered. [ABSTRACT FROM AUTHOR]

Plasma-assisted nitrogen fixation has emerged as a promising alternative to conventional nitrogen fixation methods. In this study, we investigate the feasibility of plasma-assisted nitrogen fixation using an AC-driven dielectric barrier discharge generated from the micro-tips of a specially designed fast-modulated pyramid-shaped electrode. The obtained result is compared with the conventional flat electrode. Our results demonstrate that pyramid-shaped micro-tip electrodes can excite more nitrogen molecules than flat electrodes. Thus, pyramid electrodes have 58% more nitrogen oxides yield efficiency at 32% less energy cost. The highest nitrogen fixation is attained at 60% to 70% of oxygen concentration in nitrogen-feeding gas. These findings suggest that discharge through microtip is a promising and viable technology that could play a significant role in reducing the energy cost of the plasma-assisted nitrogen fixation method to meet the growing demand for sustainable nitrogen-based fertilizers. [ABSTRACT FROM AUTHOR]

Reductions of carbon dioxide emissions from the building sector are mandatory for climate protection. This calls for both a reduction of the construction material and energy as well as a reduction of the operational energy. Against this background, a novel facade-integrated adsorption system for solar cooling of lightweight buildings is proposed and theoretically investigated in this work. For this purpose, a detailed simulation model is developed to analyze both the processes in the single components as well as the overall system behavior. The proposed system consists of the three components adsorber, condenser and evaporator, which are connected vacuum-tight and are coupled by vapor transfer. The simulation results of a defined reference case yield cooling rates of 54   W per installed square meter of adsorber facade. The cooling power can be maintained for 12 h, confirming the applicability of the proposed system. Furthermore, a comprehensive parametric study is carried out in order to identify an optimum set of parameter values for maximum cooling rate under the assumed conditions. The results reveal that controlled constant cooling rates of 105   W per square meter of adsorber facade can be reached and a maximum peak power of 145   W per square meter of adsorber facade is possible. [ABSTRACT FROM AUTHOR]

There has been an increasing interest in solar-driven combined energy supply systems for low-temperate applications, particularly those based on the Organic Rankine Cycle (ORC), Kalina Cycle (KC), or Trilateral Cycle (TLC). However, systems based on these thermodynamic cycles usually employ large area collectors that stand alone or are placed on the roof, without considering integration with the building facade. This research presents a solution to large-scale photothermal utilization integrated with facades for co-generated systems. The current study is the first to conduct performance and economic assessment for four novel solar cooling and power (SCP) co-generated systems driven by evacuated tube solar collectors (ETCs) or semi-transparent photovoltaic (STPV) integrated into the building facades. The suggested systems were simulated using TRNSYS to forecast their performance metrics when used in four Chinese cities with various climate zones. As indicators, a solar fraction (SF) and unit energy cost (UEC) were used to evaluate the technical and financial aspects of each system. The STPV-vapor compression cycle (VCC) system had the highest SF (100%, except Haikou), as well as the lowest UEC (0.211$/kWh on average) among the four cities, according to the results. Among the three solar-thermal co-generation systems, ETC-ORC-VCC had the best performance (SF,37.9%; UEC,0.597$/kWh on average). [ABSTRACT FROM AUTHOR]

Drylands are highly vulnerable to climate change due to their fragile ecosystems and limited ability to adapt. In contrast to the global drying after tropical volcanic eruptions shown previously, we demonstrate that large tropical volcanic eruptions can induce significant two-year hydroclimatic wetting over drylands by employing the last millennium simulations. During this wetting period, which extends from the first to the third boreal winter after the eruption, several hydroclimatic indicators, such as self-calibrating Palmer Drought Severity Index based on the Penman-Monteith equation for potential evapotranspiration (scPDSIpm), standard precipitation evapotranspiration index (SPEI), aridity index (AI), top-10cm soil moisture (SM10cm), and leaf area index (LAI), show significant positive anomalies over most drylands. The primary contribution to the wetting response is the potential evapotranspiration (PET) reduction resulting from dryland surface cooling and reduced solar radiation, as well as a weak contribution from increased precipitation. The latter is due to the wind convergence into drylands caused by slower tropical cooling compared to drylands. The wetting response of drylands to volcanic eruptions also demonstrates some benefits over the global hydrological slowdown resulting from stratospheric aerosol injection, which replicates the cooling effects of volcanic eruptions to address global warming. [ABSTRACT FROM AUTHOR]

Renewable cooling via absorption chillers being supplied by various green heat technologies such as solar collectors has been widely studied in the literature, but it is still challenging to get positive economic outcomes from such systems due to the large expenses of solar thermal systems. This study offers the use of a new generation of solar collectors, so-called eccentric reflective solar collectors, for driving single-effect absorption chillers and thereby reducing the levelized cost of cooling. This article develops the most optimal design of this system (based on several different scenarios) using multi-objective optimization techniques and employs them for a case study in Brazil to assess its proficiency compared to conventional solar-driven cooling methods. For making the benchmarking analyses fair, the conventional system is also rigorously optimized in terms of design and operation features. The results show that the eccentric solar collector would enhance the cost-effectiveness by 29%. In addition, using optimally sized storage units would be necessary to get acceptable economic performance from the system, no matter which collector type is used. For the case study, at the optimal sizing and operating conditions, the levelized cost of cooling will be 124 USD/MWh and an emission level of 18.97 kgCO2/MWh. [ABSTRACT FROM AUTHOR]

Radiative thermal management technologies that utilize thermal radiation from nano/microstructure for cooling and heating have gained significant attention in sustainable energy research. Passive radiative cooling and solar heating operate continuously, which may lead to additional heating or cooling energy consumption due to undesired cooling or heating during cold nighttime/winters or hot daytime/summers. To overcome the limitation, recent studies have focused on developing radiative thermal management technologies that can toggle radiative cooling on and off or possess switchable dual cooling and heating modes to realize sustainable and efficient thermal management. This review will explore the fundamental concepts of radiative thermal management and its switching mechanisms, utilizing novel systems composed of various materials and nano/microstructures. Additionally, we will delve into the potential future research directions in radiative thermal management technologies. [ABSTRACT FROM AUTHOR]

This study investigates the impact of cooling methods on the performance of a basin solar still integrated with a condensation chamber wall. Two different cooling techniques of the condensation chamber, namely water cooling and radiative cooling, were tested in Algerian climatic conditions. The findings revealed that the type of cooling system significantly affects the temperature of different components of the solar still. Moreover, the output of Peltier‐cooled still was better on the basin side, while the water‐cooled still was better on the condensation chamber side. The solar stills equipped with Peltier and water cooling produced 2.95 and 2.44 kg/m2 day, respectively. Additionally, the use of radiative cooling increased the solar still production by 43% compared to water cooling. The cost analysis indicated that the radiative‐cooled solar still is more cost‐effective with a cost of $0.09237 per liter of freshwater produced, compared to $0.29320 per liter produced by the water‐cooled still over the 15‐year system lifespan. [ABSTRACT FROM AUTHOR]

In this work, sorbent was coupled with radiative cooling and solar heating to improve AWH performance and working conditions, providing a potential passive approach for future solar-driven AWH systems. [Display omitted] Atmospheric water harvesting (AWH) technology is a promising technology for addressing global water shortages and contributing to social development. Current AWH technologies, including fog collection, dew collection, and sorption-based AWH mostly focus on a single water harvesting mechanism, and this can limit their working conditions and overall performance. In this work, a composite hydrogel with a low phase change enthalpy of water (1695 kJ kg−1) was coupled with radiative cooling and solar heating to improve passive AWH performance and working conditions. High thermal emittance ε ¯ L W I R = 0.98 and solar absorptance α ¯ s o l a r = 0.93 were achieved for radiative cooling in the nighttime and solar heating in the daytime. During the night, radiative cooling could improve the water capture rate from 0.242 kg m-2h−1 (i.e., only sorbent) to 0.310 kg m-2h−1 (i.e., sorbent-coupled radiative cooling) in the outdoor experiment. In the daytime, solar interfacial evaporation improved the water release rate to 1.154 kg m-2h−1. Effects of meteorological parameters, such as relative humidity, ambient temperature, and solar intensity were also discussed theoretically and experimentally. It is indicated that the designed passive AWH device can work over a wide range of meteorological parameters. The outdoor all-day experiment indicated that the maximum water harvesting can be 2.04 kg m−2 in a cycle work. This demonstrates that sorbent-coupled radiative cooling and solar heating provide a potential approach for future solar-driven AWH systems. [ABSTRACT FROM AUTHOR]

Solar-powered thermoelectric air conditioning systems offer distinct advantages over traditional cooling methods, including thermal comfort, absence of moving parts, and eco-friendliness as they operate on solar energy. Despite these benefits, they exhibit a lower coefficient of performance (COP) compared to conventional systems. In this study, a solar-powered thermoelectric air conditioning system based on the Peltier effect was experimentally investigated in Baghdad during September (39 °C to 32 °C). The system was designed to cool a small 1 m² test room. The six Peltier modules were divided into groups, each powered by a different electrical source with varying ON/OFF intervals. The highest COP achieved was 0.649, with an optimal outlet air temperature of 22-23 °C and a 20 minute switching cycle. Notably, the inlet air velocity directly influenced COP and outgoing air temperature. The study also indicated improved performance at reduced air flow, making Peltier air coolers ideal for hot regions. [ABSTRACT FROM AUTHOR]

An exciting new class of heat transmission fluids, nanofluids, has been developed as an alternative to traditional fluids in manufacturing. Fuel cells, heat exchangers and pharmaceutical processes are just a few of the many uses for them. When compared to monofluids, the heat transmission properties of hybrid fluids are superior. These are findings used in an extensive diversity of fields, from solar energy to air conditioning. The objective of this paper is to examine how Lorentz force and chemical reaction parameters affect the characteristics of a couple stress hybrid nanofluid (Ethylene Glycol + Graphene + Copper) flow via an exponentially stretching surface. The heat transport phenomenon is studied using viscous dissipation, exponential heat source and thermal radiation parameters. Furthermore, irreversibility analysis is provided in this paper. Governing equations are transformed into a set of nonlinear ordinary differential equations using suitable similarity transformations. The bvp4c solver in MATLAB is used to solve the transformed system. Engineering parameters of interest, including skin friction coefficient, are described using bar diagrams. It has been noted that the magnetic field and volume fraction of graphene nanoparticles (ϕ1) reduce the skin friction coefficient. At 0≤ϕ1≤0.105$0 \le {\phi }_1 \le 0.105$, the skin friction coefficient decreases at a rate of 4.68187. It is observed that there is an increment in the fluid temperature with the rise in the exponential heat source parameter, and the velocity profile increases with the increase in the mixed convection parameter. It is detected that, while Eckert number (Eck$Eck$) was set to 0≤Eck≤0.7$0 \le Eck \le 0.7$, Nusselt number was reduced by 6.29239. It is noticed that, while the chemical reaction (Cr$Cr$) is set to 0≤Cr≤0.7$0 \le Cr \le 0.7$, the mass transfer rate rises at a Rate of 0.349644. It has been observed that as the Brinkmann number and magnetic field parameters increase, so does the rate of entropy production. It is also detected that as the porosity parameter increases, the fluid momentum decreases. Furthermore, increasing the couple stress parameter decreases the fluid velocity. [ABSTRACT FROM AUTHOR]

Over the last decade there has been a proliferation of glamping architecture. This study analyses the energy performance of geodesic domes for use in tourist glamping compared to more conventional prismatic architectural solutions. The energy analysis of geodesic domes applied to this type of singular construction project currently lacks detailed studies that provide conclusions about their relevance and suitability with respect to other types of architecture. The main objective of this research is to demonstrate the energy benefits of tourist accommodations that use geodesic structures compared to those with a simple geometry. A comparative study of a traditional and a geodesic geometry accommodation is carried out, considering that they share the same characteristics and they are built with the same construction solution. An energy simulation of both architectures is carried out by using DesignBuilder software. The most influential strategies, such as Direct Passive Solar Gain, Heating, Natural Ventilation Cooling, Fan-Forced Ventilation Cooling and Window Solar Shading are considered. After demonstrating the greater efficiency of geodesic domes, this study analyses the relevance of subdividing the accommodations into several geodesic dome spaces. The results quantify an energy benefit of 52% for cooling consumption using the geodesic dome solution compared to a traditional prismatic solution. [ABSTRACT FROM AUTHOR]

Hybrid configurations that combine two different solar thermal collector technologies are considered to improve the economic competitiveness of solar systems in district heating applications. However, the performance of these systems in the industrial sector has been scarcely studied. This study evaluates the energetic and economic potential of hybrid systems with flat plate and parabolic trough collectors under different industrial process temperatures and radiation levels. To enable this evaluation, a hybrid field sizing methodology was developed. The results showed that the hybrid system could achieve high solar fractions with a lower levelized cost of heat than parabolic trough collector individual systems and smaller solar field areas than flat plate collector individual systems. Furthermore, the hybrid system with approximately 50% flat plate collectors reached monthly solar fractions up to 91% higher than the individual flat plate collector alternative. The seasonal performance demonstrates that the hybrid configuration could have great potential for applications with higher demand in the summer months, such as solar cooling with absorption chillers and solar water desalination for crop irrigation. This study contributes to the understanding of the potential of hybrid systems in the industrial sector and presents tools and insights for future research of hybrid solar thermal configurations. • The performance of hybrid solar thermal systems in the industrial sector was evaluated and compared with individual schemes. • A pre-sizing methodology for the hybrid solar field was developed, and three hybrid configurations were modeled in TRNSYS. • A parametric analysis of the solar systems was carried out under different radiation levels and process temperature conditions. • The effect of collector and natural gas costs on the relative performance between hybrid and individual systems was analyzed. • Solar coverage, radiation levels, and demand characteristics with higher potential for the hybrid system were identified. [ABSTRACT FROM AUTHOR]

Extensive research has been conducted to address the issue of the reduced efficiency of solar photovoltaic (PV) cells at high temperatures. To address this problem, a hybrid cooling system has been developed. This system uses a thermal collector to convert waste heat into reusable heat. Selecting the best configuration and operational parameters for the collector is crucial for maximizing system performance. To achieve this, we conducted computational fluid dynamics (CFD) modeling using ANSYS. Various factors affecting the cooling of PV solar cells were analyzed, including the collector design, mass flow rate, and concentration of the Al2O3 nanofluids. Results showed that the 12S finned thermal collector system exhibits the lowest temperature for PV solar cells, at approximately 29.654 oC. The electrical efficiency of PV solar cells is influenced by the concentration of Al2O3 nanofluids. We found that the 12S finned collector system with 1% water/Al2O3 nanofluid achieved the highest efficiency (approximately 11.749%) at a flow rate of 0.09 kg/s. The addition of finned collectors affects efficiency and variations in fluid mass flow rates, and there is no relation between the connector type and different Al2O3 nanofluid concentrations. In other words, the cooling system can be optimized to enhance the efficiency of the PV solar cells under high-temperature conditions. [ABSTRACT FROM AUTHOR]

The primary focus of this study is on the energy, exergy, and environmental (3E) analysis of a dedicated mechanical subcooled vapor compression refrigeration (DMS-VCR) system for applications involving commercially available water chillers that employ R134a (in both subcooler and main cycle). For a cooling capacity of 100-kW water chillers, the mathematical model of the DMS-VCR system is built to determine the performance parameter of the system. The DMS-VCR system reduces electricity usage by 15.52% and increase in COP by 9.5%, which results in a significant reduction in CO2 emissions of about 15.55%. When compared to equivalent vapor compression refrigeration system (VCRS), the system's exergetic efficiency is also increased by 8%. Since the computer simulation results will undoubtedly give design engineers a better option, the subcooling and superheating of the vapor compression refrigeration system become alluring in this study. Consequently, the DMS-VCR system performs better as per the combined 3E study. [ABSTRACT FROM AUTHOR]

This paper presents the numerical study of a ground source heat pump with borehole free cooling in a solar greenhouse. The system is mainly composed of a solar greenhouse with a water-water heat pump, a ground heat exchanger, and several pipes for free cooling. Thermal performances of ground source heat pump with and without borehole free cooling are investigated. The cooling time of the solar greenhouse is divided into transitional seasons (May and September) and summer seasons (from June to August). The mixed mode, including the free cooling mode and the ground source heat pump cooling mode, runs in summer seasons. During the entire transition seasons, the free cooling mode consumes 33.6% of the electricity in the ground source heat pump cooling mode and the soil thermal storage in free cooling mode is 76.3% of that in ground source heat pump cooling mode. Throughout the summer seasons, the power consumption of the mixed mode is 4.3% lower than that of the ground source heat pump cooling mode, and mixed mode soil thermal storage is 19.5% lower than that of ground source heat pump cooling mode. The results indicate that borehole free cooling system has better energy-saving performance during whole cooling period. In addition, a borehole free cooling system can also reduce the thermal imbalance in the soil. [ABSTRACT FROM AUTHOR]

An ideal radiative cooler requires accurate spectral control capability to achieve efficient thermal emission in the atmospheric transparency window (8–13 μm), low solar absorption, good stability, scalability, and a simple structure for effective diurnal radiative cooling. Flexible cooling films made from polymer relying on polymer intrinsic absorbance represent a cost-effective solution but lack accuracy in spectral control. Here, we propose and demonstrate a metasurface concept enabled by periodically arranged three-dimensional (3D) trench-like structures in a thin layer of polymer for high-performance radiative cooling. The structured polymer metasurface radiative cooler is manufactured by a roll-to-roll printing method. It exhibits superior spectral breadth and selectivity, which offers outstanding omnidirectional absorption/emission (96.1%) in the atmospheric transparency window, low solar absorption (4.8%), and high stability. Impressive cooling power of 129.8 W m−2 and temperature deduction of 7 °C on a clear sky midday have been achieved, promising broad practical applications in energy saving and passive heat dispersion fields. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Advanced radiative cooling materials with both heating and cooling mode is of pivotal importance for all‐season energy‐saving in buildings. In this work, we report the design and fabrication of bacterial cellulose‐based Janus films (J‐BC) with radiative cooling and solar heating properties, which were developed by two‐step vacuum‐assisted filtration of modified MXene‐doped bacterial cellulose and modified silicon nitride (Si3N4)‐doped bacterial cellulose, followed by hot‐pressing and drying treatments. The as‐prepared J‐BC films show a unique Janus structure where modified MXene nanosheets and cellulose nanofibers are on the bottom surface, and modified silicon nitride (Si3N4) nanoparticles and cellulose nanofibers are on the top surface. The radiative cooling effect of J‐BC films is enabled by the Si3N4‐doped bacterial cellulose due to the high mid‐infrared emissivity of Si3N4 nanoparticles, which shows a high solar reflection of ~98.1% and high emissivity of ~93.6% in the atmospheric transparency window (8—13 μm). Thanks to the enhanced photothermal conversion of the modified MXene nanosheets, a reduced solar reflection (6.6%) and relatively low thermal emissivity in the atmospheric window (71.4%) are achieved, making sure the solar heating effect of J‐BC films. In the outdoor tests, J‐BC films achieve a sub‐ambient temperature drop of ~3.8 °C and an above‐ambient temperature rise of ~14.2 °C. Numerical prediction demonstrated that the J‐BC films with dual modes have great potential of all‐season energy saving for buildings and a corresponding energy‐saving map in China is also created. The work disclosed herein can provide an avenue for the shaping of advanced radiative cooling materials for emerging applications of personal thermal management, sustainable energy‐efficient buildings, and beyond. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Advanced radiative cooling materials with both heating and cooling mode is of pivotal importance for all‐season energy‐saving in buildings. In this work, we report the design and fabrication of bacterial cellulose‐based Janus films (J‐BC) with radiative cooling and solar heating properties, which were developed by two‐step vacuum‐assisted filtration of modified MXene‐doped bacterial cellulose and modified silicon nitride (Si3N4)‐doped bacterial cellulose, followed by hot‐pressing and drying treatments. The as‐prepared J‐BC films show a unique Janus structure where modified MXene nanosheets and cellulose nanofibers are on the bottom surface, and modified silicon nitride (Si3N4) nanoparticles and cellulose nanofibers are on the top surface. The radiative cooling effect of J‐BC films is enabled by the Si3N4‐doped bacterial cellulose due to the high mid‐infrared emissivity of Si3N4 nanoparticles, which shows a high solar reflection of ~98.1% and high emissivity of ~93.6% in the atmospheric transparency window (8—13 μm). Thanks to the enhanced photothermal conversion of the modified MXene nanosheets, a reduced solar reflection (6.6%) and relatively low thermal emissivity in the atmospheric window (71.4%) are achieved, making sure the solar heating effect of J‐BC films. In the outdoor tests, J‐BC films achieve a sub‐ambient temperature drop of ~3.8 °C and an above‐ambient temperature rise of ~14.2 °C. Numerical prediction demonstrated that the J‐BC films with dual modes have great potential of all‐season energy saving for buildings and a corresponding energy‐saving map in China is also created. The work disclosed herein can provide an avenue for the shaping of advanced radiative cooling materials for emerging applications of personal thermal management, sustainable energy‐efficient buildings, and beyond. [ABSTRACT FROM AUTHOR]

Over the past decade, the integration of desiccant technology with evaporative cooling methods has proven to be highly effective and efficient in providing comfortable indoor environments. The performance of desiccant-based direct evaporative cooling (DEC) systems is strongly influenced by environmental conditions, and their output behavior varies across multiple climatic zones. It is not easy to assess the system performance in numerous climatic zones as it is a time-consuming process. The current study focuses on determining the feasibility of a solid desiccant integrated with a direct evaporative cooler (SDI-DEC) for three different climatic zones of Pakistan: Lahore (hot and humid), Islamabad (hot and semi-humid) and Karachi (moderate and humid). To serve this purpose, a specially designed controlled climate chamber with an integrated air handling unit (AHU) was installed to create multiple environmental conditions artificially. It could also provide global climatic conditions under temperature and absolute humidity ranges of 10 °C to 50 °C and 10 g/kg to 20 g/kg, respectively. The weather conditions of the selected cities were artificially generated in the climate chamber. Based on different operating conditions, such as inlet air temperature, humidity and regeneration temperature, the performance of the system was estimated using performance indicators like COP, dehumidification effectiveness, solar fraction and supply air conditions. Results showed that the maximum temperature achieved from solar collectors was about 70 °C from collectors with an area of 9.5 m2. Moreover, the observations showed that when the regeneration temperature was increased from 60 °C to 80 °C, the COP of the system decreased about 41% in a moderate and humid climate, 28% in a hot and semi-humid environment and 23% in a hot and humid climate. The results revealed that an SDI-DEC system has the potential to overcome the humidity and cooling loads of the multiple climatic scenarios of Pakistan. [ABSTRACT FROM AUTHOR]

[Display omitted] Due to the huge energy consumption of traditional cooling- and heating-based electricity, passive radiative cooling and solar heating with a minimum carbon footprint using the outer space and Sun as natural thermodynamic resources have attracted much attention. However, most passive devices are static and monofunctional, and cannot meet the practical requirements of dynamic cooling and heating under various conditions. Here, we demonstrate a smart thermal-gated (STG) bilayer membrane that enables fully automatic and temperature-adaptive radiative cooling and solar heating. Specifically, this device can switch from reflective to absorptive (white to black) in the solar wavelength with the reduction in optical scattering upon ambient temperature, corresponding to a sunlight reflectivity change from 0.962 to 0.059 when the temperature drops below ∼30 °C, whereas its mid-infrared emissivity remains at ∼0.95. Consequently, this STG membrane achieves a temperature of ∼5 °C below ambient (a key signature of radiative cooling) under direct sunlight (peak solar irradiance >900 W m−2) in summer and a solar heating power of ∼550 W m−2 in winter. Theoretical analysis reveals the substantial advantage of this switchable cooling/heating device in potential energy saving compared with cooling-only and heating-only strategies when widely used in different climates. It is expected that this work will pave a new pathway for designing temperature-adaptive devices with zero energy consumption and provide an innovative way to achieve sustainable energy. [ABSTRACT FROM AUTHOR]

This paper presents the results of the activities related to the subtask "Building and process optimization" of the IEA SHC Task 65. The main topic of this activity was the integration of solar cooling in retrofitted HVAC systems. Based on the current conventional HVAC systems, the integration may present difficulties concerning cold distribution and refrigerants. Cold supply systems can also reduce airflow in air-based systems and enhance thermal comfort in buildings. The best technical actions for specific scenarios were mentioned considering both technical and economic aspects. Unfortunately, not all the analyses that were planned provide useful data. Results show that there are few recent projects that consider the application of solar cooling systems in buildings and most of them are based on simulation. Moreover, not much data about the characteristics of the buildings (envelope, other cooling systems, comfort conditions, etc.) are reported in the studies. This is because many of them are more focused on the plants' configurations, and the performance of the different plants is in general assessed by testing the prototype in a single room. Despite this, the information provided could be used as baseline cases in order to study the potential energy savings achievable by applying solar cooling systems. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Uncertain parameters and factors substantially impact the operational performances of combined cooling, heating, and power (CCHP) systems. This paper constructs a chance-constrained programming model for system design and energy dispatch management of a hybrid solar CCHP system under the uncertainties of solar energy and building loads. The uncertain scenarios with probability distributions are generated in the Latin hypercube sampling and clustering methods. The chance-constrained model transforms stochastic optimization into deterministic optimization based on these scenarios. Then, the multi-objective optimization model of CCHP system considering the performances of economic, energy, emission, and flexibility is established, and the modified ε -constraint method is employed to obtain Pareto solutions. A case study validates the proposed model. The capacities and operational strategies of components in the hybrid CCHP system are optimized, and the impacts of the confidence level of probability distributions of uncertain factors on the optimization results are discussed. The results indicate that the photovoltaic capacity in the hybrid CCHP system declines by 87.5% when the confidence level increases from 0.50 to 0.99. But other components' capacities are raised, and the gas turbine capacity as the key component rises by 10.49%. The energetic and environmental performances of the CCHP system rise with the confidence level, and the operation safety is improved. [ABSTRACT FROM AUTHOR]

A theoretical investigation was carried out for determining the performances of NaX, LiX, NaA, NaY, SAPO-34 and FAPO-5 zeolites used as coatings in solar adsorption cooling systems. The regeneration temperatures of the zeolites varied in a broad range. The daily temperature variation of the zeolite adsorbent and the power of the solar adsorption cooling system were calculated for each zeolite by using different coating mass and wind speed values. It was determined that for the summer weather conditions investigated, the regeneration temperature of the zeolite had strong impact on the performance of the solar adsorption cooling system. The aluminophosphates, often considered as very suitable for adsorption heat pump and cooling systems due to their quite low regeneration temperatures, generally had lower performances while the aluminosilicates with higher regeneration temperatures performed much better. This was related to the relatively high minimum adsorbent temperature in the system using solar energy, resulting in quite lower amount of water circulation for the adsorbents with relatively low regeneration temperatures. It was also determined that using different amounts and types of zeolite affected the operating period of the solar cooling system, as well as the power along the daily cycle. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive exergetic analysis, facilitated by computational modeling, of a solar-powered air conditioning system directly linked to a photovoltaic generator. The system, designed without an energy storage component, aims at addressing the cooling requirements of a library by harnessing the natural regulation of solar energy, under two distinct solar irradiance profiles. Simulations revealed that the photovoltaic generator necessitates a minimum solar incidence of 240 W/m² to fulfill the basal cooling capacity of the system. The results indicated that only 25% of the library's operational period on a sunny day, and a mere 12.3% on a cloudy day, met the thermal comfort standards for occupants. Furthermore, the study discerned an increase in exergy destruction in the system components over the course of the day. The photovoltaic system exhibited the highest level of exergy destruction, followed by the compressor, condenser, evaporator, and expansion valve respectively. This exergy analysis offers a holistic evaluation of the system's overall efficiency. It transcends mere energy efficiencies and incorporates power quality losses that transpire during the conversion and transport processes. With this indepth assessment, the study not only identifies the areas of greatest energy losses but also offers insights that could enhance the system's design and operational efficiency. [ABSTRACT FROM AUTHOR]

Food production in arid countries like Qatar is strongly linked to water and energy resources to grow plants or rear cattle in a protected and controlled environment. The high energy demand for air conditioning in agro-industrial communities leads to significant CO2 emissions. In a case-study on buildings that are typical in the agro-industrial sector, the reduction potential for these emissions is investigated. Therefore, greenhouses and community buildings with an insulation according to the Passivhaus standard and solar cooling with photovoltaic driven compression chillers are compared to conventional buildings. An innovative solar cooling system is developed: Power is generated in hybrid photovoltaic / thermal collectors to enhance the electric efficiency of the photovoltaic cells and to deliver heat for food processing or other purposes at a high temperature level. A compression chiller model is designed, that is based on the experimentally determined performance of the refrigeration cycle for the harsh operating conditions in Qatar. Different refrigerants are compared regarding their cycle performance and Global Warming Potential. A result of the study at hand is that greenhouses are very well suited for solar cooling since their cooling load is nearly congruent to photovoltaic power generation due to their low thermal inertia and radiative cooling during the night. The case study reveals that an insulation according to the Passivhaus standard combined with the proposed solar cooling system reduces the CO2 emissions caused by the air conditioning of greenhouses by 98% and of residential buildings by 94.7% compared to conventional buildings and air conditioning systems. [ABSTRACT FROM AUTHOR]

In this research, analysis of a cogeneration system harnessing solar energy with the purpose of producing electricity and freshwater is carried out. A parabolic trough collector (PTC), a reverse osmosis (RO) desalination system and a steam Rankine cycle are considered as the primary modules of the system. Optimization is conducted on the basis of the Non-Dominated Sorting Genetic Algorithm II (NSGA-II), while the Engineering Equation Solver (EES) is used to cope with the presented thermodynamic model. Sensitivity analysis of different key parameters including pump and turbine efficiencies, pump and turbine inlet pressures, evaporator pinch point and inlet temperature and, finally, solar radiation are calculated. A location with high solar energy potential is selected to explore the feasibility of installing the designed system. The case study results show that the maximum level of freshwater production happens during June and July due to an increased sunlight and ambient temperature. Annual electricity and distilled water production of 260,847.6586 MW and 73,821.34 m3 are calculated, respectively. Furthermore, the optimum results regarding the cost rate and exergy efficiency were found to be 35.26 $/h and 12.02%, respectively. [ABSTRACT FROM AUTHOR]

• A novel natural vacuum desalination system integrated with solar absorption cooling. • The thermal performance of the hybrid NVD system is investigated. • The effect of the compressible flow is considered for the first time. • A validated desalination model with two optimizing approaches is developed. • Optimal COPs and the collector area for the temperature/pressure ratio are revealed. As the world's population and increasing urbanization continue to grow, freshwater needs have risen dramatically. A desalination process based on a natural vacuum and pipeline desalination method that can produce freshwater and transfer it simultaneously is designed and modeled comprehensively in this research. It has been demonstrated that the effect of compressibility is negligible for pressure and temperature ranges of the system, indicating that the first system model using incompressible flow assumption is valid. Solar thermal energy was also utilized to improve the system's efficiency. The results are investigated for three scenarios for Bandar-Abbas and the adjacent mountain, Genu. The first, second, and third scenarios are associated with the initial model based on pipeline desalination, the model utilizing solar cooling to reduce the temperature in the condensation section, and the model using solar energy to increase the temperature in the evaporation section, respectively. The results show that the highest freshwater production is estimated at 125,842,962 and 21,101,132 kg per year for a tube diameter of 2 and 1 m, respectively. Furthermore, the annual production rate of distilled water in scenarios #2 and #3 increased by 13.85% and 139.1% compared to scenario #1, with a tube diameter of 2 m. [ABSTRACT FROM AUTHOR]