Renewable Energy Resources and Technologies
Setare Peirow; Fatemeh Razi Astaraei; Amir Ali Saifoddin; Hossein Yousefi
Abstract
The issue of power supply in hospitals is of special importance because of its direct effect on people's health conditions and vital treatment and care measures. Hospitals are among buildings with high energy consumption. The possibility of using renewable sources in their energy supply is one of the ...
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The issue of power supply in hospitals is of special importance because of its direct effect on people's health conditions and vital treatment and care measures. Hospitals are among buildings with high energy consumption. The possibility of using renewable sources in their energy supply is one of the issues and challenges that specialists encounter. This paper discusses the possibility of installing a small solar power generation unit on a hospital rooftop to improve the quality of power supply systems. The case study is a hospital located in Tehran, Iran. For this purpose, the hospital energy system was modeled with the Design-Builder software. The obtained results were validated based on the actual consumption of the model specified in the hospital energy bills. According to the modeling step results, the annual consumption of the current energy system was 3.08 GWh of electricity and 4.23 GWh of gas. In the second step, a renewable power generation unit consisting of photovoltaic panels and battery was designed for the hospital's roof using PVsyst software. The designed power generation unit could produce 132 MWh of solar energy per year, of which 85 MWh may be sold to the main grid. The techno-economic and environmental feasibility study for the proposed system was performed using HOMER Pro software. The evaluation results revealed that considering the 20-year lifetime of the project, the proposed system achieved a lower energy cost and lower net present cost than the current system. Environmental assessment of the model by considering emission penalty indicated that the proposed system emitted fewer pollutant gases into the environment than the current system. Sensitivity analysis was also applied to investigate the effect of discounting and diesel fuel price variation on the system’s energy cost. According to the results, a 4 % increase in the discount rate leads to a 14 % growth in the cost of energy for the project. Also, there was a direct relation between enhancement of the expected inflation rate and raising the net present cost of the project.
Renewable Energy Resources and Technologies
Hemad Zareiforoush; Adel Bakhshipour; Iraj Bagheri
Abstract
Drying process is an important post-harvest stage of food crops production which accounts for about 20 % of the world’s energy consumption in the industrial sector. One of the effective ways to reduce the share of fossil fuel consumption in the food drying process is to develop new drying systems ...
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Drying process is an important post-harvest stage of food crops production which accounts for about 20 % of the world’s energy consumption in the industrial sector. One of the effective ways to reduce the share of fossil fuel consumption in the food drying process is to develop new drying systems based on the use of renewable energy sources. In this research, a novel solar-assisted multi-belt conveyor dryer was developed and its performance was analysed. The required thermal energy for drying process was supplied by the combination of solar-gas water heaters and four solar-powered infrared (IR) lamps. The experimental factors included the speed and temperature of the drying air and the power of IR lamps. The performance characteristics were drying time, Overall Specific Energy (OSE), Non-Solar Specific Energy (NSE), Overall Energy Efficiency (OEE), and Solar-Assisted Energy Efficiency (SEE). The optimization process of the drying system was carried out using Response Surface Methodology (RSM) by defining two general modes for the energy sources of the drying system, namely overall mode and solar-assisted mode. Based on the results, the lowest OSE (17.30 MJ/kg water evaporated) was obtained when the speed and temperature of the drying air were equal to 7 m/s and 40 °C, respectively, without using IR power. The lowest NSE (2.71 MJ/kg water evaporated) was achieved by applying the treatment of 7 m/s * 40 °C * 300 W. The maximum OEE was equal to 13.92 % whilst the maximum SEE was obtained as 88.71 %. Both of the mentioned maximum values were obtained at the speed and temperature combination of 7 m/s and 40 °C and their difference was applying 300 W IR power to gain maximum SEE and no IR utilization for the maximum OEE. According to RSM analysis, the optimum working conditions for the drying system included the treatment of 7 m/s * 39.96 ºC * 300 W. Under this condition, the drying time, NSE, and SEE values were equal to 180.95 min, 1.062 MJ/kg water evaporated, and 84.63 %, respectively.
Renewable Energy Resources and Technologies
Amin Habibzadeh; Samad Jafarmadar
Abstract
A considerable amount of waste heat is produced by internal combustion engines. Bottoming cycle application of Organic Rankine Cycles (ORC) is one of the promising technologies that recuperates the waste heat of engines. A lot of engine waste heat is released into the environment. There are a lot of ...
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A considerable amount of waste heat is produced by internal combustion engines. Bottoming cycle application of Organic Rankine Cycles (ORC) is one of the promising technologies that recuperates the waste heat of engines. A lot of engine waste heat is released into the environment. There are a lot of working fluids that can be applied in these cycles. As the engine waste heat temperature is extremely high, finding a suitable working fluid, which operates properly in the combined cycle, is challenging. In this paper, the thermodynamic analysis of ten working fluids including cyclohexane, HFE7000, HFE7100, n-hexane, n-pentane, R11, R123, R134a, R141b, and R245fa is conducted to observe the influence of different parameters on the system performance and introduce the most appropriate working fluid. Results indicated that, in the studied ranges, R134a had the best performances since (a) its thermal and exergy efficiencies were 17.39 % and 17.34 %, respectively; (b) the thermal efficiency of the engine increased by 9 %, and the net power of the system reached 7.5 kW. Furthermore, there was about 9 % reduction in fuel consumption. On the other hand, among the studied working fluids, cyclohexane operates as the least suitable one by possessing the minimum amounts.