Browsing by Author "N.K. Samria"

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Experimental Thermal Analysis of Diesel Engine Piston and Cylinder Wall
(Hindawi Limited, 2015) Subodh Kumar Sharma; P.K. Saini; N.K. Samria
Knowledge of piston and cylinder wall temperature is necessary to estimate the thermal stresses at different points; this gives an idea to the designer to take care of weaker cross section area. Along with that, this temperature also allows the calculation of heat losses through piston and cylinder wall. The proposed methodology has been successfully applied to a water-cooled four-stroke direct-injection diesel engine and it allows the estimation of the piston and cylinder wall temperature. The methodology described here combines numerical simulations based on FEM models and experimental procedures based on the use of thermocouples. Purposes of this investigation are to measure the distortion in the piston, temperature, and radial thermal stresses after thermal loading. To check the validity of the heat transfer model, measure the temperature through direct measurement using thermocouple wire at several points on the piston and cylinder wall. In order to prevent thermocouple wire entanglement, a suitable pathway was designed. Appropriate averaged thermal boundary conditions such as heat transfer coefficients were set on different surfaces for FE model. The study includes the effects of the thermal conductivity of the material of piston, piston rings, and combustion chamber wall. Results show variation of temperature, stresses, and deformation at various points on the piston. © 2015 Subodh Kumar Sharma et al.
Investigation of heat transfer in piston with and without ceramic insulation on crown face
(1989) R. Prasad; N.K. Samria
This paper describes the investigation of heat transfer in an aluminium piston of a diesel engine having 10 mm thick cast iron cylinder wall. The coating material used at the top face of piston is ceramic having a thickness of two mm. The problem has been solved by the method of finite difference approximations technique. The isothermic distributions in the piston body with and without insulation have been depicted for both the cases. The variation of temperatures of three characteristic points with resulting gas temperature (Tgr) for both the cases considered have been discussed in the paper. The comparison of heat flow rates to cooling water and air below the piston have been presented for varying Tgr for both the cases.
Thermal analysis of a cathode: temperature distribution and warm-up time
(1990) Anjan Sil; N.K. Samria; D.S. Venkateswarlu
This paper gives a theoretical estimate of the cathode temperature distribution at the surface and the warm-up time. Several cases of practical interest have been studied from the thermodynamic considerations using the software specially developed for this application. The software is in two parts, viz., the steady-state analysis which gives the cathode surface temperatures and the transient analysis which yields the warm-up time. Temperature-dependent thermal conductivity, specific heat, density, and emissivity have been used in the transient analysis which improves the accuracy. Scaling laws for the determination of cathode surface temperature have been devised to cater for various sizes of cathodes used in industry. Not reported so far, our results show that a pancake-heater configuration has a better thermal response but a non-uniform cathode surface temperature profile whereas the conventional helical-heater configuration has a relatively poor thermal response but a more uniform temperature profile on the cathode. This aspect gets amplified and is very revealing at larger cathode dimensions. © 1990.
Transient temperature analysis in a system of thin shells combined with convective and radiative cooling
(Kluwer Academic Publishers, 1989) Ravindra Prasad; N.K. Samria
The problem considered has applications in the transient thermal analysis and time for attaining the steady state of the cylinder wall and cylinder head of an air-cooled internal-combustion engine. Numerical calculations based on finite difference approximations are carried out to assess the thermal response in a system of thin cylindrical and spherical shells having hot gases inside with convective boundary conditions. The outside surface is exposed to cooling medium where it looses heat by natural convection and radiation. As a special case, when radius is large, the surface may be considered to be a plane wall. The cylinder cover and cylinder wall of an internal-combustion engine are considered to be a plane wall for a comparatively higher ratio of cylinder diameter to the thickness of the wall, i.e., when d/δ varies from 80 to 100. A plot of temperature-time history and heat flow rates have been obtained. © 1989 Kluwer Academic Publishers.
TRANSIENT TEMPERATURE DISTRIBUTION IN AN EXTERNALLY INSULATED CYLINDRICAL SHELL.
(ASME, 1986) N.K. Samria; R.K. Baidya; T.R. Roy
The paper presents the analytical solution for unsteady state temperature distribution in a cylindrical shell having thin external insulation coating. The formula has been derived assuming different initial temperatures of shell and insulation coating while the contact between them has also been assumed to be imperfect. The internal and external surfaces of the shell and coating are exposed to the non-uniform convective boundary conditions of third kind. The generalized formula obtained has been used to obtain the warming up period of the cylindrical wall of a Diesel engine coated externally by ceramic insulation material.