I. Al-Hinti

Effect of Piston Friction on the Performance of SI Engine: A New Thermodynamic Approach

This paper presents thermodynamic analysis of piston friction in spark-ignition internal combustion engines. The general effect of piston friction on engine performance was examined during cold starting and normal working conditions. Considerations were made using temperature-dependent specific heat model in order to make the analysis more realistic. A parametric study was performed covering wide range of dependent variables such as engine speed, taking into consideration piston friction combined with the variation of the specific heat with temperature, and heat loss from the cylinder. The results are presented for skirt friction only, and then for total piston friction (skirt and rings). The effect of oil viscosity is investigated over a wide range of engine speeds and oil temperatures. In general, it is found that oils with higher viscosities result in lower efficiency values. Using high viscosity oil can reduce the efficiency by more than 50% at cold oil temperatures. The efficiency maps for SAE 10, SAE 30, and SAE 50 are reported. The results of this model can be practically utilized to obtain optimized efficiency results either by selecting the optimum operating speed for a given oil type (viscosity) and temperature or by selecting the optimum oil type for a given operating speed and temperature. The effect of different piston ring configurations on the efficiency is also presented. Finally, the oil film thickness on the engine performance is studied in this paper.

Analysis of energy and exergy use in the Jordanian urban residential sector

This study presents an analysis of the energy and exergy utilisation of the Jordanian urban residential sector by considering the flows of energy and exergy through the main end uses and applications in Jordanian households. To achieve this purpose, a survey covering 200 households was conducted and energy consumption data were gathered. Exergy analysis of Jordanian urban residential sector utilisation indicates a less efficient picture than that obtained by the energy analysis. Energy and exergy efficiencies were found to be equal to 66.6% and 15.4%, respectively.

Heat Transfer and Fluid Flow Characteristics of Separated Flows Encountered in a Backward-Facing Step Under the Effect of Suction and Blowing

Numerical investigation of heat transfer and fluid flow over a backward-facing step (BFS), under the effect of suction and blowing, is presented. Here, suction/blowing is implemented on the bottom wall (adjacent to the step). The finite volume technique is used. The distribution of the modified coefficient of friction and Nusselt number at the top and bottom walls of the BFS are obtained. On the bottom wall, and inside the primary recirculation bubble, suction increases the modified coefficient of friction and blowing reduces it. However, after the point of reattachment, mass augmentation causes an increase in the modified coefficient of friction and mass reduction causes a decrease in modified coefficient of friction. On the top wall, suction decreases the modified coefficient of friction and blowing increases it. Local Nusselt number on the bottom wall is increased by suction and is decreased by blowing, and the contrary occurs on the top wall. The maximum local Nusselt number on the bottom wall coincides with the point of reattachment. High values of average Nusselt number on the bottom wall are identified at high Reynolds numbers and high suction bleed rates. However, the low values correspond to high blowing rates. The reattachment length and the length of the top secondary recirculation bubble are computed under the effect of suction and blowing. The reattachment length is increased by increasing blowing bleed rate and is decreased by increasing suction bleed rate. The spots of high Nusselt number, and low coefficient of friction, are identified by using contour maps.

Performance of a spark ignition engine under the effect of friction using a gas mixture model

AbstractThis paper presents the effect of friction on the performance of a spark ignition engine using a gas mixture as the working fluid. The results were compared to a frictionless engine. Engine parameters that were studied include equivalence ratio, engine speed, break mean effective pressure (BMEP), and cycle thermal efficiency. It was found for the frictionless engine operating at 6000 rev min−1 and stoichiometric air–fuel mixture that BMEP and efficiency were about 14 bar and 36% respectively. On the other hand, when friction is included under the same condition BMEP and efficiency were about 10 bar and 27% respectively. However, at lower engine speed and equivalence ratio, the deviations were much smaller. Therefore, it is more realistic to consider the effect of friction using the gas mixture model instead of air as the working fluid for the analysis of spark ignition engines, especially when running at high speeds and/or rich mixtures.

Decomposition analysis of electricity use in the Jordanian industrial sector

This paper is focused on the electricity demand of the industrial sector in Jordan, since it is responsible for about 24.15% of the total electricity consumption in the country. Analyses of the changes in energy demand for the years 2008–2013 and the factors affecting this demand are investigated in this study. The modified Laspeyers factor decomposition approach is used to give a more precise estimate of how changes in industrial production, structural, and efficiency effects contributed to the changes in electricity demand. The Jordanian industrial sector was disaggregated into twenty two sub-sectors according to International Standard Industrial Classification of All Economic Activities (ISIC). A major finding of this paper is that although increased industrial production caused energy demand to increase between 1998 and 2005, significant improvements in energy efficiency and structural shift have contributed to reducing the rate of this increase.

Performance of diesel engine using gas mixture with variable specific heats model

Abstract A thermodynamic, one-zone, zero-dimensional computational model for a diesel engine is established in which a working fluid consisting of various gas mixtures has been implemented. The results were compared to those which use air as the working fluid with variable specific heats. Most of the parameters that are important for compression ignition engines, such as equivalence ratio, engine speed, maximum temperature, gas pressure, brake mean effective pressure and cycle thermal efficiency, have been studied. Furthermore, the effect of boost pressure was studied using both the gas mixture and dependent temperature air models. It was found that the temperature dependent air model overestimates the maximum temperature and cylinder pressure. For example, for the air model, the maximum temperature and cylinder pressure were about 1775 K and 93·5 bar respectively at 2500 rev min−1, and the fuel/air equivalence ratio Φ = 0·6. On the other hand, when the gas mixture model is used under the same con...

Prediction of energy consumption of passenger transportation and GHG emissions in Jordan

In this paper, the structure of the Jordanian transport sector is analysed with focus on passenger cars, which represent 65% of total vehicles and responsible for almost all of the national gasoline fuel demand. In order to achieve the objectives of this study, an empirical model is developed based on multivariate linear regression analysis to identify key drivers that influence gasoline consumption. In addition, possible impacts of introducing diesel powered saloon cars, as an energy efficiency measure to the passenger cars market, on the future energy demand and associated reduction in GHG emissions are analysed and evaluated using different scenarios. Based on the conducted analysis, it was found that the number of cars, income level and unit gasoline price are the most important variables that affect present and future gasoline demand. The obtained results proved that the multivariate linear regression models can be used adequately to simulate gasoline consumption with very high coefficient of determi...

Potential CO2 reduction through restructuring the Jordanian utility sector

This study attempts to predict the potential CO2 reduction due to pre-proposed future restructuring scenarios toward clean generation technologies for the Jordanian utility sector. The calculation is based on CO2 emission for unit electricity generated and the changing type of fuel percentages for electricity generation in Jordan. It was found that such restructuring will significantly contribute to undermine the global greenhouse gases emissions. The potential CO2 reductions by gradually introducing energy sources substitutions for electricity generation in Jordan are in a range of 1413−12,170 million kg for different suggested scenarios by year 2028.