Thermal Engineering

A diffusion absorption refrigeration system is a thermal powered refrigeration system. Any low grade heat source can be used to run an absorption refrigeration system. In most of engine and industry large amount of heat is rejected as exhaust gas which is at low temperature. One of the efficient methods to utilize this energy is to convert it into cooling load by means of an absorption system. In this work exhaust gas of IC engine is used to power a commercial absorption system integrated with phase change material (PCM). PCM helps to control the generator temperature and also act as a constant temperature source whenever there is a fluctuation in the temperature. Experiment was conducted on single cylinder four stroke diesel engine exhausts coupled to a commercial 40L absorption system. PCM helps to increase the overall COP of the absorption system

The present work analyzes the influence of chemical reaction on free convective flow of a visco-elastic incompressible and electrically conducting fluid past an infinite vertical porous plate through porous medium with constant suction in presence of uniform transverse magnetic field. The necessity of the present analysis arises as the most industrial fluids exhibit the visco-elastic behavior. The coupled nonlinear partial differential equation are turned to ordinary by super imposing a solution with steady and time dependent transient part. Finally, the set of ordinary differential equations is solved with a perturbation scheme to meet the inadequacy of boundary condition. The solutions for the velocity, temperature and concentration are obtained and displayed graphically for pertinent parameters such as magnetic parameter, Grashof number, modified Grashof number, Prandtl number, Schmidt number, Eckert number and permeability parameter. It is observed that the magnetic parameter and the Schmidt number retard the velocity of the flow field while the Grashof number for heat and mass transfer, the porosity parameter have accelerating effect on the velocity of the flow field at all points. Further, the Prandtl number reduces the temperature and Schmidt number and chemical reaction parameter diminishes the concentration distribution of the flow field at all points.

Three-dimensional CFD simulations are carried out to evaluate the effect of baffle spacing on heat transfer and fluid flow characteristics of a single phase, single pass and 35% baffle cut, single segmental baffled Shell and Tube Heat Exchanger. Shell and tube heat exchanger is the most common type of heat exchanger and widely use in oil refinery and other large chemical processes because it is suitable for high pressure application. The processes in analyzing the simulation consist of modelling (SolidWorks 2012) and meshing (HyperMesh11). Then, the boundary condition will be set before been simulate in ANSYS Fluent version 6.3 based on the experimental parameters. The variation in Shell side Outlet temperature (K), Heat transfer coefficient (W/m2K), Shell side Pressure drop (Pa) and Total transfer rate (W) are measured for different Baffle spacing Bc and for different mass flow rate Kg/s. The sensitivity of the shell side heat transfer characteristics are analysed and concluded.

An exact analysis of unsteady radiative flow past a uniformly accelerated infinite vertical plate with variable temperature with uniform mass diffusion is presented here, taking in to account the homogeneous chemical reaction of first order. The plate temperature is raised linearly with time and the concentration level near the plate is also raised to . The dimensionless governing equations are solved using Laplace-transform technique. The velocity, temperature and concentration fields are studied for different physical parameters like thermal Grashof number, mass Grashof number, Schmidt number, Prandtl number, radiation parameter, chemical reaction parameter and time. It is observed that the velocity increases with increasing values of thermal Grashof number or mass Grashof number. But the trend is just reversed with respect to the thermal radiation parameter. It is also observed that the velocity increases with decreasing chemical reaction parameter.

Healthy and comfortable indoor air climates are essential for any type of building environment. Particularly, classroom air environment and thermal comfort has an important role in the teaching and learning process as it could be engaging students in activities that promote their performances, such as understanding of concepts, abilities of problem solving, and attitudes towards learning, and etc. In order to achieve such better indoor air environment and thermal comfort in classrooms, school buildings usually have been required to HVAC system operate with design norms.

This paper deals with the study of the potential substitution of Karanja methyl ester blends for diesel as fuel for automobiles and other industrial purposes. The objective of this study is the analysis of the performance, combustion and emission characteristics of the karanja methyl esters and comparing with petroleum diesel. The tests were carried out on a 4.4 KW, single cylinder, direct injection, Air-cooled diesel engine. The results of investigations carried out in studying the fuel properties of karanja methyl ester (KME) and its blend with diesel fuel from 20 to 100% by volume and in running a diesel engine with these fuels. Engine tests have been carried out with the aim of obtaining comparative measures of Brake power, specific fuel consumption and emissions such as CO2, CO, HC, smoke density and NOx to evaluate and compute the behavior of the diesel engine running on above mentioned fuels. The reduction in exhaust emissions together with increase in brake power, brake thermal efficiency and reduction in specific fuel consumption make the blends of karanja esterified oil (B20) a suitable alternative fuel for diesel and could help in controlling air pollution.

There is a growing interest in heating and cooling systems based on renewable energy. This is the property of earth ground the below about 2.5 to 3 m, the temperature of ground remains nearly constant throughout the year. This constant temperature is called undisturbed temperature of earth. However, a good visualize the undisturbed ground temperature, for a correct interpretation of the geothermal heat exchanger. The undisturbed temperature is very important yourself, which remains higher than the outside temperature in winter and lower than the outside temperature in summer. The EAHEs are considered as an effective passive heating/cooling medium for buildings. It is basically a series of metallic, plastic or concrete pipes buried underground at a particular depth through which the fresh atmospheric air flows and gets heated in winter and supplied to the building if at sufficiently high temperature and vice versa in summer. Until now, many researchers have conducted a series of studies in the development, modelling and testing of systems of the EAHE. This paper observe on earth air heat exchanger in summer cooling for various supply air conditions in summer climate in LNCT Energy Park Raisen Road Bhopal M.P.

Variety of vegetable oils are available as alternate fuels but due to their high viscosity and low volatility, they are blended with diesel. Aim of the present work is to evaluate performance of diesel engine fueled with blends of methyl ester of cotton seed oil and diesel. Filtered cotton seed oil is converted into its methyl ester using transesterification process. Engine used is four stroke, single cylinder, variable compression ratio water cooled engine. Results show higher brake thermal efficiency and lower brake specific fuel consumption for B10 as compared to other blends.

This work presents an experimental and numerical investigation of heat transfer characteristics for horizontal circular pipe of 500mm long fitted with ribs having middle arm with cross section of 5mm width ,5mm length, pitch=80mm, with air as the working fluid. Reynolds number ranged( Re=24253, 26119 and 27984). The steel pipe(ASM4120) was subjected to two constant surface temperatures (673Ko and 973Ko). The experimental data obtained were compared with plain (without ribs). Based on the same coolant flow, the pipe with ribs was found to possess the highest performance factors for turbulent flow. The results show a good agreement between theoretical and experimental bulk temperature by factor 0.9%, 1% for inner wall temperature and 0.8% for average Nusselt number. Using ribs improved the heat transfer in a circular tube. All studies where carried out using workbench program FlUENT14.5 by using K-? model.

This paper reviews the absorption enhancement of the aqua ammonia systems by various technologies like mechanical treatment, chemical treatment and nanotechnology. By using mechanical enhancement we can reduce size of the absorber by 48.7%, by using chemical treatment the absolute absorption can be increase by 8% than pure water. And the nano- solution is more effective than pure solution. However, the combined treatment with both surfactant and nanoparticles is recommended to improve the absorption performance for practical applications.