•Extreme Learning Machine (ELM) in modeling residential natural gas consumption.•To generate residential demand including heating and domestic hot water.•District Heating System (DHS) as one of the ...efficient technologies.
In this study, the residential heating demand of a case study (Baharestan town, Karaj) in Iran was forecasted based on the monthly natural gas consumption data and monthly average of the ambient temperature. Three various methods containing Extreme Learning Machine (ELM), artificial neural networks (ANNs) and genetic programming (GP) were employed to forecast residential heating demand of the case study and the results of these methods were compared after validating via real data. Actually, the main goal of the current study is to obtain the most accurate technique among these 3 common methods in this context. Validation of the forecasting results reveals that the important progress can be achieved in terms of accuracy by the ELM method in comparison with ANN and GP. Moreover, obtained results indicate that developed ELM models can be used with confidence for further work on formulating novel model predictive strategy for residential heating demand for the DHS. The outputs reveal that the new procedure can have a suitable performance in major cases and can be learned more rapid compare with other common learning algorithms.
Today, photovoltaic panels are used in various applications, and increasing their efficiency is of interest to many researchers. In this research, we try to increase the radiation density by ...increasing direct radiation to finally increase the energy production in photovoltaic power plants. The direct radiation amplification system is used to improve the photovoltaic efficiency. In this proposed system, energy and economics are analyzed by MATLAB software. Also, prototype testing and photovoltaic power plant testing are examined. The results show that by implementing this system in photovoltaic power plants, annual energy production can be increased. By adding this system to a photovoltaic power plant, the price of electricity produced in photovoltaic power plants will be increased from 13 ¢/kWh to 9 ¢/kWh, which shows a 31% reduction in the price of electricity per kilowatt-hour.
In this paper, the potential of combined injection of CNG and gasoline is studied on a 1.7 L turbocharged, port-injected SI engine and the best engine performance point for the best conversion ...efficiency of the catalytic converters has been investigated. Compressed natural gas (CNG) as an alternative fuel is used in spark ignition engines to improve fuel consumption and exhaust emissions. The improvements gave more advantage in emission but it lowered the performance of the engine. As a substitute, CNG has a higher octane number and knocking resistance than gasoline and hence CNG-dedicated engines can have higher compression ratios and therefore higher indicated efficiencies. Turbocharged bi-fuel, combined CNG and gasoline, injection engine of is a new concept which offers direct benefits with regards to gas or gasoline powered vehicles running separately on each fuels. It also opens very interesting perspectives for meeting future emission regulations using only a three-way catalyst, since the stoichiometry condition of combustion is maintained over the whole engine operating range. Results show that the combined injection of gasoline and CNG is much better than gasoline mode in terms of fuel consumption and raw HC and CO emissions. However, as expected the NO
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emission will increase. According to the obtained results at 16.2 bar BMEP, 3000 rpm full load condition with 30% CNG mass fraction, the BSFC, CO and HC emissions are improved by 16, 66 and 50%, respectively, compared to gasoline single mode. It was found that a fuel mixture of 30% CNG mass fraction was the best trade-off point between engine performance and emission production. Also, significant reductions of fuel consumption were observed. Full-load tests carried out with a turbocharged engine enhanced the synergy effect between the two fuels at full-load condition.
► An innovative point of view to analyze a double façades building with energy consideration. ► Techno-economical approach and feasibility study on double skin façades building. ► Simple payback ...estimated 3 years and 5 months. ► Total net profit value (NPV) would be equal to 657,883.94 ($). ► Its internal rate of return (IRR) is approximately 29.87%.
Double skin façade (DSF) building is one of the available energy conservation opportunities through recent intelligent buildings. In this research, an innovative point of view to analyze a DSF with energy consideration is appointed, at a glance. To propose this subject, absorbed solar energy plus contributed critical scenarios have been formulated. Continually, the wind energy and temperature and relative humidity effects, and dew formation for condensate appearance on the surface have been technically investigated to complete the simulation. Introducing differential equations is the main part of this study which indicates heat transfer characteristics through the trapped air at skins spacing. In order to cover that, empirical equations plus energy, continuity and momentum differential equations, related to natural convection on vertical thermal shield have been developed. The analytical solution method, with extracted velocity vector and temperature profile, is the other advantage of this research. For a desired building, velocity and temperature variations are defined bounded to façades geometry and spacing. The temperature and velocity profiles have been illustrated by MATLAB software, by increasing grid nodes. Finally, results on techno-economical modeling by which acceptable range of indexes could be explained have been tabulated.
Despite the fact that there are wastewater treatment plants (WWTPs) currently operational across Iran and great advances have been made in this area, there are still problems in the design, ...construction, and operation of WWTPs with large nonlinear systems, varying flow rates, and pollution charges. The objective of this study was to investigate the effect of operating parameters including the return activated sludge (RAS) ratio, internal recycle (IR) ratio and dissolved oxygen (DO) concentration in an activated sludge system for the Modules 5&6 of the Southern Tehran WWTP. This study designed and simulated a plant based on the activated sludge model No.1 (ASM1) to determine the factors affecting wastewater treatment systems; then, the kinetic parameters were measured. The kinetic parameters such as the yield coefficient (Y), decay coefficient (Kd), maximum specific growth rate (K), and saturation constant (Ks) were in the range of 0.303-0.331g/g, 0.030-0.033d-1, 1.65-1.93d-1 and 37.6-44.92mg/l, respectively. The RAS ratios, IR ratios, and DO concentration varied from 0.2 to 2, 1 to 3.5, and 0.27 to 3.54 mg/l, respectively. The amount of RAS had the greatest impact on the effluent. The amounts of IR and DO concentration had no significant effect on the concentration of the five-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), and total suspended solids (TSS) in the effluent. After the RAS, the amount of IR had the most direct effect on reducing the effluent total nitrogen (TN) concentration. As a result, the overall removal efficiency increased up to 75% when the IR rate was 200% of the influent flow rate, the RAS rate was 90% of the influent flow rate, and the DO concentration in the first aeration unit was 2 mg/l considering the aeration cost. Therefore, proper operating parameters can provide the best quality of effluent that meets environmental standards.
In order to obtain the best performance of the solar air heaters, it is necessary to find optimum performance conditions. The aim of this research paper is to achieve optimum conditions, by comparing ...single and double pass solar air heaters. Also, a brief review study of various related research works of all scenarios for a single and double pass and packed bed (including particle technologies) solar air heaters was carried out to observe the challenges of the mentioned systems. Energy modeling and simulation with EES and MATLAB open source code software indicated significant results in efficiency. According to the obtained results, it can be explained that double pass duct not necessarily always increases the overall system energy efficiency. Results of this work indicate, higher ambient air temperature (inlet air temperature) and lower solar irradiation can increase overall energy efficiency of solar double pass systems. More precisely at solar irradiation of 916 W/m2 and inlet air temperature of 302 οK, the system achieves the targeted optimum value in energy efficiency, approximately 90%, which is considerably more than the 65% as an average value.
The environmental aspects of PSOFC/GT hybrid systems, has been less attention from researchers. In this research, increasing efficiency approaches and environmental aspects is considered on a novel ...considerable hybrid cycle capacity is determined with 1.7 MW which used biomass fuel as a part of system fuel requirement, for small scale industrial factories end users. In this research, the suggested PSOFC/GT combined system has been modelled with Cycle-Tempo software and calculated total cycle energy and mass balance. The main outputs of the model, are the system electrical energy and exergy and total cycle efficiencies and the amount of solid and gaseous emissions those values and their improvement conditions of each approach is obtained. The survey results showed that in order to increase efficiency and reduce emissions in these systems, wood chips and bagasse can be used as an alternative fuels. Also, by adding an air cooling system, it was found that reducing emissions does not lead to increased efficiency. Finally, with inlet air humidifying of the gasifier system, the total cycle efficiency increases 7.7%. This approach thereby will be reducing carbon emissions and toxic gases like COS and H2S, equal to 6.66% and 9.61×10-3 tons per year respectively and increase annually of NH3 5.82×10-2 tons.
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