Comparison between blended mode and fumigation mode on combustion,performance and emissions of a diesel engine fueled with ternary fuel (diesel-biodiesel-ethanol) based on engine speed

According to the literature, there is in lack of a comprehensive study to compare the combustion, performance and emissions of a diesel engine using diesel, biodiesel and ethanol fuels (DBE) in the blended mode and fumigation mode under various engine speeds. This study was conducted to fill this knowledge gap by comparing the effect of blended, fumigation and combined fumigation + blended (F + B) modes on the combustion, performance and emissions of a diesel engine under a constant engine load (50% of full torque) with five engine speeds ranging from 1400 rpm to 2200 rpm. A constant overall fuel composition of 80% diesel, 5% biodiesel and 15% ethanol, by volume % (D80B5E15), was utilized to provide the same fuel for comparing the three fueling modes.According to the average results of five engine speeds, the blended mode has higher peak heat release rate (HRR), ignition delay (ID), brake thermal efficiency (BTE), brake specific nitrogen monoxide (BSNO) and brake specific nitrogen oxides (BSNO_X), but lower duration of combustion (DOC), brake specific fuel consumption (BSFC), brake specific carbon dioxide (BSCO₂), brake specific carbon monoxide (BSCO), brake specific hydrocarbon (BSHC), brake specific nitrogen dioxide (BSNO₂), brake specific particulate matter (BSPM), total number concentration (TNC) and geometric mean diameter (GMD), and similar peak in-cylinder pressure compared to the fumigation mode. In addition, for almost all the parameters, results obtained in the F + B mode are in between those of the blended and fumigation modes. In regard to the effect of engine speed, the results reveal that the increase in engine speed causes reduction in peak in-cylinder pressure, BTE, BSHC, BSNO_X, BSNO and BSNO₂, but increase in peak HRR, ID, DOC, BSFC, BSCO₂, BSPM and TNC, and similar BSCO and GMD for almost all the tested fueling modes. It can be inferred that the blended mode is the suitable fueling mode, compared with the fumigation mode, under the operating conditions investigated in this study.     

Risk constrained self-scheduling of hydro/wind units for short term electricity markets considering intermittency and uncertainty

In view of the intermittency and uncertainty associated with both the electricity production sector of restructured power system and their competitive markets, it is necessary to develop an appropriate risk managing scheme. So that it is desirable to trade-off between optimum utilization of intermittent generation resources (i.e. renewable energy resources), uncertain market prices and related risks in order to maximize participants' benefits and minimize the corresponding risks in the multi-product market environment. The main goal of this paper is to investigate risk management by introducing a novel multi-risk index to quantify expected downside risk (EDR) which is caused by both the wind power and market price uncertainties. Value-at-Risk (VaR) method is used to assess the mentioned risk issue by the proposed weighted EDR, so that an optimal trade-off between the profit and risk is made for the system operations. Also, the roulette wheel mechanism is employed for random market price scenario generation wherein the stochastic procedure is converted into its respective deterministic equivalents. Moreover, the autoregressive integrated moving average (ARIMA) model is employed to characterize the stochastic wind farm (WF) generation by predetermined mean level and standard deviation of wind behavior as well as temporal correlation. The problem is formulated as a mixed-integer stochastic framework for a hydro-wind power system scheduling and tested on a generation company (GENCO).     

Solar photovoltaic cells performance improvement by cooling technology: An overall review

This paper presents, a precise review on cooling of Solar Photovoltaic (PV) Cells has been examined. The critical analysis aims to improve electrical efficiency, life span of PV cells. The paper discusses the impact of previous research, technical details for optimization to provides supporting information to enhance the quality of future research. As well, some of the strengths and weaknesses of different cooling techniques are discussed. The analysis of some studies on passive and active cooling techniques show that the flow rate in the water cooling method has a direct relation with the reduction in temperature and increase in efficiency of cells. The cooling rate of PV cells and total energy generation by jet impingement cooling method in a hybrid PV-wind system is more efficient compared to conventional PV systems. Phase Change Material (PCM) cooling of PV cells is one of the efficient techniques. It can be used to store large amount of heat energy at small temperature difference of coolant fluid and PV cell. It is helpful to support PV cells cooling in hot as well as cold environment conditions. An appropriate PCM suitable for PV cell cooling application according to local temperature variation would be required.     

Extension of the VIKOR method for group decision making with extended hesitant fuzzy linguistic information

Group decision-making approaches are very important due to the complexity and uncertainty of many real-world decision-making problems. Some of the decision-making problems are defined in qualitative frameworks. Extended hesitant fuzzy linguistic term set (EHFLTS) is proposed as a new and powerful tool for elicitation of hesitant qualitative information in group decision-making process. In this paper, we first introduced the comparison laws and a family of distance and similarity measures for extended hesitant fuzzy linguistic terms (EHFLTs) and EHFLTSs, respectively. Next, we developed the extended hesitant fuzzy linguistic (EHFL)-VIKOR method as a qualitative multi-attributes group decision-making approach based on the EHFLTS distance measures to deal with the qualitative hesitancy in group decision making. Finally, we presented an application example about selection of suitable telecommunications service provider of small- and medium-sized enterprises to verify applicability and validation of proposed method in the process of qualitative group decision making.