Mustafa Atmaca

Energy and Exergy Analyses Applied to a CI Engine Fueled with Diesel and Natural Gas

In this study, energy and exergy analysis of a direct injection compression ignition engine converted into dual fuel systems using different composition of mixed fuel formed from natural gas and diesel were performed. Effects of parameters, such as composition of mixed fuel, engine load, and speed, on various energetic and exergetic performance parameters of the engine were evaluated and compared with each other. The irreversibilities of mixed fuel and diesel were comparable at high engine speed but at low engine speed the irreversibility of mixed fuel was higher than that of diesel fuel.

Efficiency Analysis of Combined Cogeneration Systems with Steam and Gas Turbines

Abstract Increasing demand of energy and adverse environmental impact of the use of fossil fuels emphasized the need of using renewable energy. At this stage, cogeneration has come into question. Cogeneration, also called combined heat and power, is a consecutive generation of electrical power and heat energy. It is an efficient and cost-effective means to save energy and reduce emissions of human origin. In this study, a combined cogeneration system has been investigated. This cogeneration system uses a combined gas/steam turbine and draws gap steam from the steam turbine for heat production. Thermodynamic analysis of the system has been done and effects of some design parameters on performance values have been examined.

Investigation of the effects of fabric parameters on air permeability of woolen fabrics

Permeability and porosity of woolen fabrics are investigated experimentally in this paper. Permeability experiments are conducted in a wind tunnel to the TS 391-EN ISO 9237 standard. Woolen fabric is placed in the test section of the wind tunnel to measure permeability to airproofing . Velocity measurements are made used a hot wire anemometer in the front and rear of the wool. Air permeability is closely related to pore size and distribution. So, it is important to study porosity, in order to classify and determine the right use of woolen fabrics. Many methods are used to estimate porosity. In this study, the theoretical model is used for determination of porosity values, and the influence on porosity of various fabric parameters was investigated. Depending on the permeability, weft and warp density, weight, fabric thickness and porosity relationship are investigated. The results are presented as graphs.

Power and Efficiency Analysis of Brayton Cycles with Internal Irreversibility

Abstract In this article, power and efficiency analysis of irreversible Brayton cycle, which is one of the well-known heat engine cycles by the undergraduates, are carried out based on alternative criteria. Power, power density, and efficient power optimizations are also realized and the thermal efficiencies of the cycle are determined at maximum power and efficiency outputs. The efficient power is relatively new criterion and defined as the multiplication of power by efficiency. Therefore, this criterion considers not only the power output but also the cycle efficiency. Maximizing the efficient power function gives a compromise between power and efficiency. The effects of the external irreversibilities on the performances are investigated for various cycle parameters.

Thermal Comfort of Woolen Fabrics Depending on Physical Properties

ABSTRACT In this study, thermal comfort properties of woolen fabrics depending on the physical properties have been investigated. Thermal and water vapor resistance of fabrics have been measured by the PERMETEST instrument and air permeability has been investigated in a wind tunnel. The air permeability depends on the shape and value of the pores and inter thread channels, which are dependent on the structural parameters of the fabric. Theoretical model has been used in order to determine the porosity values. Experimental data and regression statistics proved that porosity and other fabric parameters have a very strong influence on thermal comfort property.