IRANIAN JOURNAL OF MECHANICAL ENGINEERING (ENGLISH)
Year:2017 | Volume:18 | Issue:4 |Papers Count:6

The review, analysis, design, construction and operation of a digester biogas digester is a combination of Indian and Chinese models is investigated. The digester has a low production, which is one of the reasons, there is an outdoor outlet tank of gas that is wasted. Design and construction of digesters in combination to increase production, mechanical agitator to homogenize the feed gas and the caps were used to collect biogas tank outlet. All calculations for the design of the digester, EES V9.430 is done by software. In analyzing the issue, to identify performance improvements, three types of digester 1.simple, 2.equipped with a stirrer and 3.equipped with a stirrer and lid made and tested. Digester volume of 9, 600 liters, feed, including cow dung and water that has been mixed with a ratio of one to one. Two cubic meters of gas to cover its output volume and the volume of 350 liters respectively. It has the ability to produce an average of more than one cubic meter biogas digester with reinforced concrete in the country's northwest border (city of Khoy-city Firuraq) is constructed. decreases. Experimental results based on test days 1 to 117 days, for software modeling has been done over the years.

In this study, the laminar forced convection heat transfer of water-coper nanofluid is numerically investigated within a parallel plate channel. Fixed temperature heat sources with the specified sizes and distances are embedded on the walls of the channel. The entry and exit sections of the channel as well as the sections between the heat sources are thermally insulated. The fluid flow with uniform velocity and temperature enters the channel. The channel length is considered large enough, so the flow in the channel output is assumed fully developed. The aim of this research is the numerical investigation of the effects of the Reynolds number, the solid volume fraction and the number of the heat sources on the flow field and heat transfer rate. For this purpose, the governing equations are discretized by finite difference method based on the control volume formulation and are solved using the SIMPLE algorithm. In order to validate the computer program, the results of this study have been compared with the results of the previous numerical studies. This comparison has confirmed the accuracy of the performance of the computer program. The results show that the rate of heat transfer increases by increasing the solid volume fraction and Reynolds number. The results also show that, heat transfer rate increases when the heat sourse is divided into smaller sections and these sections are distributed on the channel wall.

In this paper investigations performed on dual fueled constant speed diesel engine. At first; performance and emission of diesel engine investigated and after converting to dual fuel mode experimental tests performed on performance and emissions in different injection timing (at 14, 17, 20 degree before TDC) and loads (100%, 75%, 50%, 25%, 10% of full loads). Results show that in different loads and injections timing, amount of Nox and particle materials (PM) in dual fueled engine are lower than diesel engine. Amount of CO2 in dual fuelled mode have a little difference with diesel mode, although, it is lower than diesel engine. In loads lower than 75% load, amount of CO in diesel engine was lower than dual fuelled engine but in full load this term was inverse and have significant difference. Amount of HC in dual fuel mode was higher than diesel mode in all injections timing and loads.

In this study, a novel method for prediction of lean blowout in turbine engines based on combination of numerical simulation and semi-empirical relations has been presented. In recent years empirical tests have shown that in addition to the parameters used in Lefebvre’s relation, two parameters of flame volume and fraction of dome air have a major impact on lean blowout. These two parameters have been obtained from numerical simulation for a special combustion chamber by using fluent software. Two ways was presented to calculate these parameters which is in first method, fuel was used in gas form and in the second method in liquid form. Finally, these two parameters were placed in a semi-empirical correlation and provide a novel combine method. The error of first and second combine method were obtained respectively 6.15 and 2.2 percent. Finally, these two parameters were placed in a semi-empirical correlation and provide a novel combine method. The error of first and second combine method were obtained respectively 6.15 and 2.2 percent.

Improvement of existing vehicles to reduce fuel consumption and emissions due to factors such as the completion of fossil fuels, increasing fuel consumption, global warming and environmental issues for governments and industry is essential, For this reason, direct injection diesel engines are widely used in automotive and industrial applications. With tightening emissions standards and a desire to build an engine with higher efficiency, better understanding of combustion engines is essential to the next step in order to optimize engine design to reduce emissions and improve engine performance picked up. One of the parameters that are important role in the treatment of combustion engine is fuel injection pressure and injection timing. This study examines a number of changes on emissions and performance of diesel engine with fuel injection pressure changing using AVL-FIRE numerical simulation software. In this study, keeping the fuel consumption and engine speed for main injection of 5 to 12 degrees crankshaft was changed and for these changes, engine emissions were evaluated. The results showed that by reducing fuel injection time the amount of pollutants nitrogen dioxide increased and soot emissions reduced.