The internal working processes in pulse tube cryocooler (PTC) are quite complex due to the unsteady, oscillating compressible gas flow in the pulse tube. Although considerable theoretical studies have been carried out as of date phenomena occurring in a pulse tube cryocooler are still to be understood. The present research work is carried out in order to understand the cooling mechanism and to ...

Chemical Vapor Deposition (CVD) is one of the most important methods for producing Carbon Nanotubes (CNTs). In this research, a numerical model, based on finite volume method, is investigated. The applied method solves the conservation of mass, momentum, energy and species transport equations with aid of ideal gas law. Using this model, the growth rate and thickness uniformity of produced CNTs,...

This work presents development of an oxygen-based diode laser absorption sensor designed to be used in a supersonic combustion ramjet engine inlet. The sensor uses free-space propagation of light from a vertical-cavity surface-emitting laser (VCSEL) to determine the temperature, velocity and angle of attack of an engine inlet in hypersonic flow. The report outlines the method of calculating the...

Biological waste gas cleaning is gaining more and more importance for the removal of the volatile organic compounds from air polluted streams. In order to investigate the performance of this technology a biofiltration pilot unit was operated for a continuous period of 14 months. The biofilter was packed with newly developed compost pellets and a mixture of compost and peat. At start-up, the bio...

Most of gas sources are located in long distances from consumption centers. Gas is sent to final consumption points sometimes thousands kilometers far from their sources after extraction. So according to gas industries development and improvement of its transmission industries, technical developments are necessary in order to analyze the gas transmission system. In this study for the first time...

The present study investigated the effect of operating parameters of a laboratory spray dryer on powder characteristics, in order to optimise the production of trehalose and raffinose powders, intended to be used as carriers of biomolecules for inhalation. The sugars were spray dried from 80:20 methanol:n-butyl acetate (v/v) solutions using a Büchi Mini Spray dryer B-290. A 2(4) factorial desig...

Abundant availability and potential for lower CO2 emissions are drivers for increased utilization of natural gas in automotive engines for transportation applications. However scarce refueling resources for on-road vehicles impose an infrastructure limited barrier on natural gas use in transportation. A novel ‘bimodal’ engine which can operate in a compressor mode has been developed that allows...

A Large Eddy Simulation of a bluff body flame has been carried out using an unstructured grid. The flame, burning a methane-hydrogen fuel with detailed combustion chemistry (based on a mechanism of 18 species) is simulated using STAR-CD. The mixture fraction is used as a conserved scalar, and a subsequently temperature, density and species mass fraction are calculated using a probability densit...

Gas mixture of H2S and NH3 in this study has been the focus in the research area concerning gases generated from the animal husbandry and the anaerobic wastewater lagoons used for their treatment. A specific microflora (mixture of Thiobacillus thioparus CH11 for H2S and Nitrosomonas europaea for NH3) was immobilized with Ca-alginate and packed inside a glass column to decompose H2S and NH3. The...

in this study, the effect of the levels of hydrogen addition to methane-air premixed flame in a micro-stepped reactor has been studied numerically. in addition, the effects of mixture velocity and walls’ thermal conductivity (kw) on the flame’s location, temperature, and species distribution in a micro reactor were calculated using a 2d numerical laminar steady code. the results showed that an ...