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In hot climates, excessive heat gain through building roofs significantly increases cooling loads and energy consumption. This study aims to reduce roof heat gain by developing an innovative hybrid active slab with phase change material (PCM) panels and a geothermal well (HASP-GW). The HASP-GW system incorporates PCM panels and an active concrete slab embedded with water pipes as heat exchangers. Water at a constant temperature of 22 °C, sourced from a geothermal well, flows through these pipes to stabilize indoor temperatures. This research investigates the thermal performance of the HASP-GW with varying PCM transition temperatures and water flow rates using numerical simulations, validated against experimental results. The experimental setup involved two well-insulated test rooms (each 0.85 m × 0.85 m × 1 m); one equipped with the HASP-GW system and the other as a conventional comparison. Results showed that using the HASP-GW with a PCM transition temperature of 38–41 °C and a water flow rate of 1 L/min reduced the heat flux on inner surface of the roof, decrement factor, and inner surface temperature by 90.13 %, 0.127, and 16.24 °C, respectively, compared to a traditional roof. These findings indicate the potential of HASP-GW for energy-efficient roof cooling in hot climates.

In this manuscript, we present a unique cogeneration system that combines diesel power generators with thermoelectric generators (TEGs), using the comparatively cool water in an integrated tank and hot exhaust gases to produce additional heat and power. By connecting a series of TEGs and a cold water tank to the diesel generator, the design enables the water to gradually warm up and become appropriate for usage in both domestic and commercial settings. We did a parametric study and created detailed thermal models to verify the viability of our idea. The findings indicate that the temperature differential across each TEG module and the total power output increase roughly linearly, based on the ratio of the diesel generator's power to the thickness of TEG to thermal conductivity. Additionally, the total power output increases linearly with the length of the TEG plate and declines exponentially with the height of the exhaust gas duct. The system may produce up to 3,223 W more electricity under certain circumstances, such as an exhaust gas duct height of 0.05 m, a TEG plate length of 1 m, and a generator output of 150 kW. This improvement could result in a 2.58 % reduction in fuel consumption and an equivalent increase in total power production when compared to conventional systems. The heater system recovers up to 22.4 kW/m² and can heat 100 liters of water in 0.2 h. According to these results, diesel generators and eventually diesel power plants might use less fuel and have more energy efficiency thanks to the suggested cogeneration technology.

This paper presents a numerical investigation of the performance of a rectangular storage solar collector with three different absorber plate shapes: smooth, parabolic, and triangular. The research employs three-dimensional, unsteady modeling using COMSOL software version 5.5 to simulate a solar storage collector system in Kufa-Najaf's climatic conditions. Two days in November and July were selected to evaluate the system's performance under various atmospheric conditions. The results showed that the highest water temperature for a no-load condition was 36.2 °C in November and 51.7 °C in July. For a triangular corrugation absorber storage collector under load, the largest temperature difference between the outflow and inflow temperatures was 14.9 °C at 1 p.m. and 11.9 °C at sunset in November, while the maximum temperature difference was 13.4 °C at 4 p.m. in July. The study also found that the total efficiency of the triangular corrugation absorber storage collector was higher than that of the other designs, and generally, the total efficiency under no-load conditions was lower than the load. The present work offers a novel solar storage collector configuration with a parabolic or triangular roughened integrated plate absorber, which enhances heat transfer, promoting energy efficiency and improving outlet water temperature.

Solar energy is one of the most efficient forms of renewable energy. Solar air collectors are promising utilization of solar energy. The present study used unsteady three-dimensional Computational Fluid Dynamic (CFD) analysis to investigate the heat transfer and fluid friction in solar air collectors with smooth and v-corrugation absorber plates. The studied parameters are Reynolds number, v-corrugation height, and pitch. Three Reynolds number (500, 1000, 1500) values were used with three arrangements configuration of the v-corrugation of relative heights of 0.10, 0.16, and 0.23. Roughness pitches varied between 1.33, 1.66, and 2. By comparing the simulated thermal efficiency with the currently known experimental values, great agreement can be approved. Results show the superiority of the performance of v-corrugated collector against the traditional or smooth type. The outlet temperature obtained in case of relative roughness height = 0.23 and relative roughness pitch = 2 is 61 °C, while it is 53 °C for a smooth type. Also, a higher thermal efficiency of 46.7 % can be obtained compared to 33.01% for smooth type.