For saline or wastewater, solar distillation is a suitable, environmentally friendly technique for purifying water. The problem is that there is no distillation process that produces salt water, and that salt water used on plants may cause plant death. The techniques described in this work aim to enhance the solar distillation process using solar stills with a steam generator and a condenser. The distilled water was heated between 11 am and 4 pm, with best output of 1200 ml at 80-90°C. One method used to achieve faster evaporation is to increase the heating rate so that the temperature changes rapidly, such as 100°C/min, which results in lower total yields due to overheating. The novelty of this work is that the heating rate to the steam generator is increased, thereby increasing the overall temperature and the surface water temperatures of the solar still and the water surface. The other advantage of the extended heating for three hours was that it also resulted in higher yields, and sunlight alone did not guarantee that high temperatures were equivalent to moisture-loss temperatures above 41°C.Various thermal enhancement techniques were used in the study, including sensible heat storage synthesis, warming in an aquatic basin, and altering surface absorptivity. Furthermore, external thermal support to increase heat supply and improve thermal conduction pathways to the basin was designed to keep high temperatures throughout the low-light availability period. This study examined the effect on system efficiency and the performance comparison of different approaches to increase the efficiency of the solar dehydration process under realistic operating conditions. This study provides a scalable, energy- efficient, and renewable-energy solution to locally produce freshwater for the benefit of global health and climate goals.
This study presents a platform that focuses on the improvement of the performance of trans-critical CO₂ refrigeration systems to face the big demand of economic and friendly cooling technologies, reduce environmental impact, and reduce operational costs. Four different refrigeration cycles were studied: abase cycle with 14 kW nominal capacity, a two-stage compression cycle, a cycle with R448a mechanical subcooling and a hybrid cycle that incorporates the two modifications. The Engineering Equation Solver (EES) software is used to analyze the different cycles under different operating parameters that includes gas cooling outlet temperature (35–50°C), evaporation temperatures (0–10 °C), compressor efficiencies (0.6–0.9), and gas cooler pressures (8,000–12,000 kPa). All modified cycles show more enhanced performance than base cycle. The hybrid cycle reached the highest coefficient of performance with an average enhancement of 55.3%, followed by mechanical sub-cooling cycle with (46.1%) average enhancement and two-stage compression cycle with (7%) average enhancement. The analysis showed that the hybrid cycle reduced power consumption by about 7.1% compared to mechanical sub-cooling cycle and by about 6% compared to the base cycle. Also, the mechanical sub-cooling showed an increase of power consumption of 13.2% over the base cycle. The increase in ambient temperature from 35 °C to 50 °C resulted in about 35.5% increase in power consumption and a 40.1% decrease in coefficient of performance (COP). This study is novel because it evaluates the combination of two-stage compression refrigeration system cycle and a mechanical sub-cooling cycle under the effect of Jordanian climate conditions, conditions, which resulted in achieving higher performance, lower environmental impact, shorter payback period, and higher return on investment (ROI).
This paper compares different studies to show how various fin shapes affect the thermal performance of heatsinks in both free and forced convection heat transfer modes, which are vital for heat dissipation in electronic and industrial systems. Numerical analysis was conducted to assess the cooling efficiency of various aluminum fin designs, including cylindrical, flat, trapezoidal, pin, annulus, elliptical, and tapered types. Some studies also explore the use of advanced materials, such as hybrid and quaternary nanomaterials, to improve thermal conductivity and reduce weight. Results show that elliptical fins with a side ratio between 2 and 2.65 offer the best heat transfer performance (exceeding 90%) under forced convection. Conversely, flat and cylindrical fins are most effective in natural convection. Importantly, the best fin shape and nanomaterial integration not only significantly enhances heat sink performance by decreasing thermal resistance compared to conventional designs but also promotes energy savings. These findings offer new insights into designing thermally efficient, compact, high-performance heat sinks, surpassing existing research and emphasizing the benefits of innovative shapes and materials for advanced cooling solutions.
The increasing global demand for high-quality greenhouse products, coupled with the heavy reliance on fossil fuels for climate control, has created an urgent need for sustainable, renewable-based solutions in agriculture. Conventional systems not only consume large amounts of energy but also contribute significantly to environmental pollution and greenhouse gas emissions. This study experimentally investigates a novel hybrid renewable energy system that integrates a windcatcher, photovoltaic-thermal chimney, and earth-to-air heat exchanger to provide passive heating and cooling for greenhouses. Experiments were conducted at Shahid Bahonar University of Kerman, Iran, using a lean-to greenhouse structure during peak summer (July-September 2024) and winter (January-March 2025) conditions. Vector linear regression was employed to develop robust predictive equations with broader applicability across different climates. Key performance parameters, including greenhouse temperature, ventilation rate, generated electricity, and the ratio of supplied electricity to consumed electricity (SECE), were measured and analyzed. Results proved a maximum temperature reduction of 21 °C in summer and successful maintenance of internal temperature between 19.5 °C and 22 °C in winter when outdoor temperature dropped to as low as 4.5 °C. The system achieved a ratio of supplied to consumed electricity exceeding 1, showing full self-sufficiency in meeting electricity demand, and delivered a higher coefficient of performance than most previously reported single- or dual-renewable systems. Energy and exergy analyses confirmed an energy-balance closure below 5% and second-law efficiencies of 0.32 in summer and 0.45 in winter. This study presents the first experimental demonstration of the configuration comprising a triple-hybrid windcatcher, a photovoltaic-thermal chimney, and an earth-to-air heat exchanger for greenhouse applications, addressing a critical research gap in integrated passive renewable systems and offering a practical pathway toward sustainable greenhouse thermal management in regions with high solar potential and extreme temperature variations.
The use of sustainable energy is of great importance in today’s world due to environmental issues and the lack of fossil fuels. Proton-exchange membrane fuel cells are a potential solution. The catalyst‐to‐ionomer ratio and the hot-press load are two important parameters that substantially affect the performance of the membrane electrode assembly. If the catalyst-to-ion-ion-ion-ion-ionomer ratio is too high, it can impair material bonding and cause uneven catalyst distribution; if it is too low, it can result in poor performance due to an insufficient catalyst amount. Likewise, too high a hot-press load can damage the porous catalyst layer, while too low a hot-press load increases the contact resistance between the catalyst-coated membrane and the gas diffusion layer. Optimization studies were performed on a 6.25 cm2 proton exchange membrane fuel cell with catalyst coated membrane-membrane electrode assembly at a loading of 0.15 mgPt cm-2. The best performance was achieved at a catalyst-ionomer ratio of 3:1 and a hot-press load of 160 kg. The statistical analysis with interaction plots and derived equations confirmed the correlation between the deviation value of 710 W m-2 (summed individual impact and integrated effect) and the traditional interaction effect value of 355 W m-2 (ratio of 2) and confirmed by the experimental results. The typical interaction effects are theoretically straightforward, and the deviation value provided here better depicts the influence of parameter interactions and provides a more reliable tool for performance measurement. The optimized catalyst-coated membrane electrode assembly showed a 5.8% improvement compared with a commercial membrane electrode assembly, mainly due to the optimized catalyst-to-ionomer ratio and hot-press load parameters. This work improves quantification and introduces a new evaluation metric, the deviation value, which can be extended to larger proton-exchange membrane fuel cell stacks, enabling a significant advance in the fundamental understanding of membrane electrode assembly design and in its practical application to sustainable energy systems.
