Water and energy shortages are among the significant concerns of human life within the current century; thus, it is essential to save consumption of these resources everywhere, including in solar ...collectors. This study aims to numerically model the direct absorption parabolic trough collector (DAPTC) for low-temperature applications. In this paper, a comprehensive analysis of the energy, exergy, economic and environmental (4E) impacts of the collector at different geometric dimensions and operating conditions is conducted. The collector's embodied energy (EE), and the embodied water (EW) are investigated. The main finding of this study is that CuO + MWCNT/water hybrid nanofluid, MWCNT/water and CuO/water nanofluids can save about 40.44 GJ, 39.01 GJ, 30.8 GJ embodied energy as well as 59.03 KL, 56.95 KL, and 44.96 KL embodied water, respectively. Obtained results claim that a rise in the inlet temperature increases the exergy efficiency and relatively decreases the energy efficiency. Furthermore, lowering the inlet temperature results in a reduction of the cost of energy production. According to the numerical results, the highest accessible exergy and energy efficiencies are 36.63% and 65.47%, respectively, while the lowest energy production cost is 0.0195 $/kWh.
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•PTC modeling by consideration of direct absorption mechanism.•Comprehensive 4E analysis and calculation of PEC, embodied energy, and embodied water.•Different nanofluids in hybrid and single forms were investigated.•The highest accessible exergy and energy efficiencies were 36.6% and 65.5%, respectively.
•An innovative multi-generation system has been designed for liquid ammonia and hydrogen production.•Comparative examination of energy carriers (Hydrogen and Ammonia) is carried out.•Sensitivity ...analysis and Machine learning optimization are applied to the system.•Optimal liquid hydrogen and ammonia production rate and exergy efficiency are 0.026 kg/s, 0.151 and 41.24 %.•Steam Rankine cycle and the elecrolyzer have the highest exergy destructions.
Power-to-fuel energy systems have an essential need for decarbonizing energy carriers. This study proposes a solar and wind energy-based system for producing liquid hydrogen and ammonia as energy carriers. The proposed system caters to urban requirements encompassing electricity, cooling, heating, and freshwater. Three different scenarios, only liquid hydrogen, only ammonia, and dual production, are considered and compared. An artificial neural network is employed for prediction and computational time reduction, coupled with a genetic algorithm for system optimization. For a case in which 40 % of the net power is used in the electrolyzer, and the system simultaneously produces liquid hydrogen and ammonia, the overall energy and exergy performance of the system are 56.78 % and 44.69 %, respectively. In this case, the system has the capability of producing 13.2 MW of net power, 0.057 kg/s of liquid hydrogen, 0.162 kg/s of cold ammonia, 3.63 kg/s of freshwater, and 3.4 MW cooling load. The exergy analysis of the system reveals that the Rankine cycle and the electrolyzer have the highest exergy destruction, at 27 % and 21 %, respectively. Using the Technique for Order Preference by Similarity to Ideal Solution method, the optimal liquid hydrogen rate, ammonia production rate, overall exergy efficiency, and net power are determined as 0.026 kg/s, 0.151 kg/s, 51.38 %, and 16.52 MW respectively are recognized as optimal values for dual production scenario.
Energy supply and environmental protection by reducing pollutants are among the main challenges these days. As a clean and sustainable source, solar energy is capable of generating thermal and ...electrical power. In this regard, Iraq is one of the regions with high solar energy harvesting potential. A numerical model was developed and validated by experimental findings in MATLAB software. This model, which also included geometrical and optical characteristics, was developed using information from four cities representative of different climates in Iraq: Baghdad, Samawa, Mosul, and Al-Qa'im. This study examined the effects of climate on the performance of direct absorption parabolic solar collectors used for energy production in Iraq. According to the results, solar collectors in Samaveh provide the highest thermal energy efficiency (up to 66.5%). Even thoth, the highest exergy efficiency is found in Al-Qa'im (36.21%). From an environmental point of view, the collector in Al-Qa'im has the highest CO2 mitigation (2.73 kg per m2 of collector) every year. As compared to other cities, Al-Qa'im and Samawah have a high thermal efficiency and solar intensity, which can lead to more water and energy savings.
This study aimed to investigate the potential of supercritical carbon dioxide (sCO2), organic Rankine cycle (ORC), and thermoelectric generator (TEG) systems for application in automotive exhaust ...waste heat recovery (WHR) applications. More specifically, this paper focuses on heavy-duty diesel engines applications such as marine, trucks, and locomotives. The results of the simulations show that sCO2 systems are capable of recovering the highest amount of power from exhaust gases, followed by ORC systems. The sCO2 system recovered 19.5 kW at the point of maximum brake power and 10.1 kW at the point of maximum torque. Similarly, the ORC system recovered 14.7 kW at the point of maximum brake power and 7.9 kW at the point of maximum torque. Furthermore, at a point of low power and torque, the sCO2 system recovered 4.2 kW of power and the ORC system recovered 3.3 kW. The TEG system produced significantly less power (533 W at maximum brake power, 126 W at maximum torque, and 7 W at low power and torque) at all three points of interest due to the low system efficiency in comparison to sCO2 and ORC systems. From the results, it can be concluded that sCO2 and ORC systems have the biggest potential impact in exhaust WHR applications provided the availability of heat and that their level of complexity does not become prohibitive.
The charging and discharging process of batteries generates a significant amount of heat, which can adversely affect their lifespan and safety. This study aims to enhance the performance of a ...lithium-ion battery (LIB) pack with a high discharge rate (5C) by proposing a combined battery thermal management system (BTMS) consisting of improved phase change materials (paraffin/aluminum composite) and forced-air convection. Battery thermal performance is simulated using computational fluid dynamics (CFD) to study the effects of heat transfer and flow parameters. To evaluate the impact of essential parameters on the thermal performance of the battery module, temperature uniformity and maximum temperature in the cells are evaluated. For the proposed cooling system, an ambient temperature of 24.5 °C and the application of a 3 mm thick paraffin/aluminum composite showed the best cooling effect. In addition, a 2 m/s inlet velocity with 25 mm cell spacing provided the best cooling performance, thus reducing the maximum temperature. The paraffin can effectively manage thermal parameters maintaining battery temperature stability and uniformity. Simulation results demonstrated that the proposed cooling system combined with forced-air convection, paraffin, and metal foam effectively reduced the maximum temperature and temperature difference in the battery by 308 K and 2.0 K, respectively.
