Applied Mechanics and Materials Vols. 592-594

Abstract: In the present paper some results obtained from the thermodynamic analysis of a CO₂ based transcritical refrigeration system are presented. The system studied uses an ejector as an expansion device in place of the conventional throttle valve. Results are obtained considering constant pressure mixing process in the mixing chamber of the ejector. The compressor discharge pressure and ejector entrainment ratio are optimized for maximum COP. The required compressor displacement rate per ton of refrigeration (specific piston displacement rate, PD) is calculated at the optimum conditions. A correlation is obtained for PD in terms of the evaporator, gas cooler exit and ejector efficiencies. From the sensitivity analysis it is seen that of all the parameters, the PD is most sensitive to evaporator temperature.

Abstract: The objective of this paper is to study thermodynamic analysis of R134a-DMAC and R134a-DMAC/CNT vapour absorption system and compare this both system performance. This investigation for R134a-DMAC is carried out based on the correlations available in the literature. The change of thermophysical properties for R134a-DMAC/CNT is predicted and is incorporated in the pure R134a-DMAC correlations. The analysis is carried for 1 kW evaporator capacity and effectiveness of solution heat exchanger is taken as 0.8. Variations in the performance parameters of the system with and without nano fluids are studied against various operating temperatures of generator, absorber and different volume concentration. The result of this theoretical study shows that co-efficient of performance (COP) of system with CNT nano fluid is improved as well as the absorber capacity also increased due to enhanced heat transfer of nano fluids. It also observed that the performance achieved by the pure R134a-DMAC at the elevated generator temperature could be achieved at low generator temperature using R134a-DMAC/CNT.

Abstract: This study focuses on the analysis of Tetrafluoroethane-Dimethylacetamide (R134a-DMAC) VAR system based on both thermodynamic and economic point of view and optimal operating parameter are proposed. In thermodynamic analysis mass flow rates, temperature, pressure, enthalpy, mass fraction and exergy of various state points are determined and based on the above state point properties the system COP and exergetic efficiency are calculated. Simplified cost minimization methodology is applied to evaluate the economic costs of all the internal flows and products of the system by formulating exergoeconomic cost equations. Thermoeconomic comparisons are made between this system and H₂O-LiBr and NH₃-H₂O. It is found that thermodynamic performance of H₂O-LiBr is better than NH₃-H₂O and R134a-DMAC systems whereas thermoeconomic performance of R134a-DMAC is better than the other two systems. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}

Abstract: An experimental investigation is conducted for studying the effect of the oxygenates blended with Jatropha biodiesel in a single cylinder Direct Injection diesel engine by using AVL 444 Di-gas analyzer for measuring level of pollutants at engine exhaust and AVL 437 smoke meter for measuring smoke opacity. Two oxygenated additives namely Ethylene Glycol (C₂H₆O₂) and Propylene Glycol (C₃H₈O₂) are added equally to neat biodiesel at geometric sequence (1, 2 and 4 %) forming the blends EGPG1 (Biodiesel + 0.5 % Ethylene Glycol + 0.5 % Propylene Glycol), EGPG2 (Biodiesel + 1 % Ethylene Glycol + 1 % Propylene Glycol) and EGPG4 (Biodiesel + 2 % Ethylene Glycol + 2 % Propylene Glycol). This paper highlights the effect of two oxygenates added as additive in biodiesel, that affecting the performance and emission characteristics of the engine. Marginal improvement in the performance of the engine and reduced level of pollutant such as Carbon monoxide (CO) and Smoke opacity for the test fuels are observed with slight increase in NO ( Nitrogen oxide ) and Unburned Hydro carbon (UHC) emission.

Abstract: The present experimental investigation is carried out to establish the stability, compatibility and feasibility of working characteristics of DICI engine by using Jatropha biodiesel, Pongamia biodiesel and related water emulsion biodiesels. Experiments are carried out in two phases on a DICI engine test rig which includes CI engine, electric loading device, exhaust gas analysers, and a data-acquisition system. The performance and emission characteristics of the engine are studied by using neat diesel, Jatropha and Pongamia biodiesel in the first phase, and similar experiments are conducted by water – biodiesel emulsion fuels in the second phase. The water–biodiesel emulsion fuels are prepared with the aid of a mechanical homogenizer in the proportion of 10% water, 88 % biodiesel, and 2 % surfactants (by volume). Sequentially, the stability characteristics of water–biodiesel emulsion fuels are analyzed. The results indicated that slight improvement in BTE and BSFC for water – biodiesel emulsion fuels compared to biodiesel fuels. The exhaust emissions of NO_x and smoke opacity were decreased for the water biodiesel emulsion fuels as compared to respective neat biodiesel and neat diesel. CO & unburned HC emissions were slightly increased for the water biodiesel emulsion fuels compared to respective neat biodiesels and less than of neat diesel.

Abstract: India has a huge potential of solar energy as it is gifted with 300 sunny days in most part of the country. The simplest form of harvesting solar energy is to use it for water heating. Most of the solar heating systems developed before were big in size, uses more space, difficult to install and use it for domestic purpose. To make the installation of solar heating systems simple and compact with adequate improvement in performance, a novel sun point collector has been developed. In this paper reduced land use of solar water heating systems by using sun point collector is analysed. A new comparative test on two different types of conventional solar flat plate collector (FPC) and sun point collector (SPC) was also investigated by conducting experiments. A standard glazed flat plate collector and a novel sun point collector are installed in parallel and tested at same working conditions. Results are also presented in terms of daily efficiency versus daily average reduced temperature difference: this allows representing the comparative characteristics of the two collectors when operating under same conditions.

Abstract: In the present study, mathematical modelling of different chamber profile of the vacuum pump to evaluate the evacuation time is developed. The validity of the developed mathematical modelling is demonstrated by performing an experiment on the vacuum pump with elliptical profile. The performance of the elliptical profile is also compared with that of the circular profile chamber of vacuum pump. It is shown that the evacuation time of vacuum pump with an elliptical chamber is lower than with a circular profile. Various parametric studies are also performed to investigate the effect of rotor eccentricity, ratio of minor and major axes of the elliptical profiles, air tank capacity on evacuation time of the vacuum pump.

Abstract: The aim of this work is to design and fabricate solar assisted single effect absorption cooling system of 5.25 kW cooling capacity to cool a room having floor area of 15m². The design of the major components of the cooling system like generator, condenser, evaporator, absorber and solution heat exchanger are described in this paper.

Abstract: Bio-diesel manufactured from vegetable oils, animal fats and used cooking oils is an alternative fuel for diesel engines. It offers many advantages such as renewable, energy efficient, nontoxic, sulfur free and bio-degradable, and also offers cleaner combustion and reduces global warming gas emissions. Experiments are conducted by fuelling the diesel engine with bio-diesel with LPG blends. The engine is properly modified to operate under dual fuel operation using LPG as the mixed fuel along with Diesel and TME as ignition source. The brake thermal efficiency of TME with LPG (2LPM) blend is increased at an average of 5%.HC emissions of TME with LPG (2LPM) blend is reduced by about at an average 21%. CO emissions of TME with LPG (2LPM) blends are reduced at an average of 33.6%. NOx emissions of TME with LPG (2LPM) blend are reduced at an average of 4.4%. Smoke Opacity of TME with LPG (2LPM) blend is reduced at an average of 10%. Keywords Biodiesel, diesel engine, alternate fuels, tallow oil and methyl esters of tallow oil, LPG

Abstract: “Necessity is the Mother of Invention”- one of the most Important and Interesting Man Made Inventions is Mobile Phone. there is a Rapid Increase in the Number of Users of Mobile Phone in the Last Decade. Today, it's Hard to Find a Cell Phone that Doesn't Offer some Sort of "smart" Technology because it's in such a High Demand. the Use of Mobile Phone has Become an Integral Part of Human Lives. in this Paper, an Attempt is Made to Study the Optimization of 3-Dimensional Heat Transfer Phenomena in Mobile Phone Using ANSYS for Three Different Models and Different Companies such as HTC Desire C, Nokia Lumia 900 and Sony Xperia Tipo. the Actual Dimensions and Materials are Chosen for above Models. the Three Models are Modelled in Pro/E, then Meshed by 3D-10 Nodded Tetrahedral Thermal Solid Elements (SOLID87) and Analysed in ANSYS Software, by Applying Boundary Conditions. the Analysis is Carried-out to Find the Nodal Temperatures, Directional Thermal Fluxes. it is Found that the Optimum Heat Transfer Occurs at HTC Desire C and Validated with the References.