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Abstract In this study, impingement/effusion cooling with cross-flow of in-line array of electronic components (ECs) is investigated numerically using RNG k-ɛ turbulence model. The cooling process is examined for two channel base configurations i.e., solid board (SB) and perforated board (PB). Effects of effusion perforation diameter (d/l) and its position (s/l) are considered on flow structure, temperature contours, heat transfer, and friction coefficient for different jet-to-cross Reynolds number ratios (ReR). Throughout the experiments, the jet position is kept at the third EC [1] . The results show that utilizing perforated board generates a new E vortex behind each component and the magnification of the wake vortex depends substantially on both perforation diameter and position. The ratio of average heat transfer coefficient ( h ¯ R ) on the rear faces of ECs decreases with increasing s/l; while, it increases with increasing d/l. As well, d/l has a significant effect on friction coefficient; while, ReR and s/l have inconsiderable effect. Furthermore, the highest value of performance evaluation criteria (PEC) that is accomplished at the largest perforation diameter for the closest one, equals to 1.36 at ReR of 0.5. Also, a proposed correlation is presented to estimate PEC for PB as a function of ReR, d/l, and s/l.

Abstract In the present study, the effect of the inclination angle (ɵ) of a shell and helically coiled tube heat exchanger (SHCT-HE) on its performance utilizing based water, Al2O3/water, and SiO2/water nanofluids is investigated experimentally. The hot based water as well as nanofluids with volume concentrations ( ϕ ) of 0.1 vol%, 0.2 vol%, and 0.3 vol% flow through the coiled tube with a coil Reynolds number (Rec) varied from 6000 to 15000. The inclination angle is measured from the horizontal axis of the SHCT-HE as 0°, 30°, 60°, and 90°. The results indicate that increasing the inclination angle enhances the coil Nusselt number (Nuc) and the effectiveness of SHCT-HE (e); while, it decreases the coil pressure drop (ΔPc). Where, at coil Reynolds number of 15000, changing the orientation of the SHCT-HE from the horizontal to the vertical orientation improves the coil Nusselt number by 11%, 8.3%, and 7.5% for based water, Al2O3/water, and SiO2/water nanofluids with 0.1 vol%, respectively. Furthermore, at vertical orientation of heat exchanger and coil Reynolds number of 6000, utilizing Al2O3/water nanofluid with 0.1 vol% intensifies significantly the coil Nusselt number and the effectiveness than those for the based water by 35.7% and 35.5%, respectively. In addition, increasing the inclination angle up to 30° keeping the performance evaluation criterion (PEC) almost constant and more elevating into the vertical orientation decreases the PEC. Using multiple regression analysis, empirical correlations are proposed to estimate the coil Nusselt number (Nuc) for based water, Al2O3/water, and SiO2/water nanofluids as a function of R e c , θ , a n d ϕ .

Fuel cells (FCs) have received huge attention for development from lab and pilot scales to full commercial scale. This is mainly due to their inherent advantage of direct conversion of chemical energy to electrical energy as a high-quality energy supply and, hence, higher conversion efficiency. Additionally, FCs have been produced at a wide range of capacities with high flexibility due to modularity characteristics. Using the right materials and efficient manufacturing processes is directly proportional to the total production cost. This work explored the different components of proton exchange membrane fuel cells (PEMFCs) and their manufacturing processes. The challenges associated with these manufacturing processes were critically analyzed, and possible mitigation strategies were proposed. The PEMFC is a relatively new and developing technology so there is a need for a thorough analysis to comprehend the current state of fuel cell operational characteristics and discover new areas for development. It is hoped that the view discussed in this paper will be a means for improved fuel cell development.

Numerical study of the effect of jet position (JP) on cooling process of an array of heated obstacles simulating electronic components has been investigated based on realizable k–ε model. Jet positions have been changed to impinge each row of obstacles consecutively. The experiments have been achieved at three different values of jet-to-channel Reynolds number ratio, Rej/Rec = 1, 2, and 4. In this study, a comparison between two different cooling processes, cross flow only (CF) and jet impingement with cross flow (JICF), has been achieved. The flow structure, heat transfer characteristics, and the pumping power have been investigated for different jet positions. The results show that the jet position affects significantly the flow structure, as well as the heat transfer characteristics. According to the results of average heat transfer coefficient and the pumping power, the more effective jet position for all values of jet-to-channel Reynolds number ratio (1, 2, and 4) is achieved when the jets impinge the third row of obstacles (JP3).

Unforeseeable growth in the global population needs growing technological advances in establishing power plants to overcome this critical issue by reducing greenhouse gases. In the present study, a thermodynamic analysis for a 626 MW supercritical oil-fired steam power plant under different operating loads of 50%, 75%, 100%, and 105% at a sliding-pressure operation is conducted. Based on the actual operation of the examined plant, the results show that the condenser has the highest energy loss. As well, at a 100% full load, 88.6% of the total exergy is destructed in the once-through steam generator, followed by the turbine, and then the condenser. Hence, a significant concern is introduced toward the steam generator since it has the largest exergy destruction percentage relative to other cycle components. The heat transfer sets inside a once-through steam generator are studied and analyzed. The exergy destruction in the combustion process represents 58.6% and 54% of the overall boiler exergy destruction at an operating load of 50% and 100%, respectively. In addition, the evaporator has higher exergy destruction in comparison with other heating surfaces in the furnace.

Advances in building-integrated photovoltaic (BIPV) systems for residential and commercial purposes are set to minimize overall energy requirements and associated greenhouse gas emissions. The BIPV design considerations entail energy infrastructure, pertinent renewable energy sources, and energy efficiency provisions. In this work, the performance of roof/façade-based BIPV systems and the affecting parameters on cooling/heating loads of buildings are reviewed. Moreover, this work provides an overview of different categories of BIPV, presenting the recent developments and sufficient references, and supporting more successful implementations of BIPV for various globe zones. A number of available technologies decide the best selections, and make easy configuration of the BIPV, avoiding any difficulties, and allowing flexibility of design in order to adapt to local environmental conditions, and are adequate to important considerations, such as building codes, building structures and loads, architectural components, replacement and maintenance, energy resources, and all associated expenditure. The passive and active effects of both air-based and water-based BIPV systems have great effects on the cooling and heating loads and thermal comfort and, hence, on the electricity consumption.