Subrata K. Ghosh

Mathematical Analysis for Off-Design Performance of Cryogenic Turboexpander

A study has been conducted to determine the off-design performance of cryogenic turboexpander. A theoretical model to predict the losses in the components of the turboexpander along the fluid flow path has been developed. The model uses a one-dimensional solution of flow conditions through the turbine along the mean streamline. In this analysis, the changes of fluid and flow properties between different components of turboexpander have been considered. Overall, turbine geometry, pressure ratio, and mass flow rate are input information. The output includes performance and velocity diagram parameters for any number of given speeds over a range of turbine pressure ratio. The procedure allows any arbitrary combination of fluid species, inlet conditions, and expansion ratio since the fluid properties are properly taken care of in the relevant equations. The computational process is illustrated with an example.

Development of bearings for a small high speed cryogenic turboexpander

Purpose – The purpose of this paper is to examine the development of aerodynamic thrust bearings and aerodynamic journal bearings applied to a small high speed cryogenic turboexpander in Indian conditions.Design/methodology/approach – As a part of indigenous programme in the process of development, some input parameter was taken from the available literature and then dimensions were optimized and computed while taking care to minimize fabrication constraints.Findings – A series of tests were conducted to confirm the findings. Detailed study of the effect of stability and vibration of bearings was taken up. The maximum rotational speed obtained was 200,000 rpm.Practical implications – The outcome may help the designers, researchers and manufacturers of these components.Originality/value – Although manufacturers design and develop the bearings of turboexpanders for their production, no academic literature has been available for this purpose until now.

Numerical analysis of stresses in mine excavator bucket

Excavator plays a vital role in mining industry and bucket is one of its most important components as failure of excavator bucket causes loss of production. In this paper, static analysis of excavator bucket (Tata JD 315SJ Model 2006) made of Hardox 400 alloy has been done. A solid model has been developed in CATIA V5 R18 Software by considering actual dimension of the bucket. The analysis of the model has been done by ANSYS WORKBENCH 14.0 Software. Static analysis of bucket has been done by assuming bush as a fixed component and load is applied on the teeth. Meshing of bucket is done with fine mesh with element size 0.15 to get more accurate result. Finite element analysis of bucket is done to find out equivalent von misses stress and equivalent von Mises strain acting on the bucket. Total deformation and directional deformation is also calculated by finite element method. Maximum stress developed and section prone to early failure is found out by this analysis. Results state that equivalent von Mises stress value is less than yield stress of material.

EFFECT OF AN AXIAL HOLE ON NATURAL CONVECTION HEAT TRANSFER FROM A CYLINDRICAL PIN FIN ATTACHED TO A HORIZONTAL PLATE

Heat transfer under laminar natural convection from a hollow cylindrical fin mounted on a horizontal base plate has been numerically The flow outside the fin is much stronger than that inside the hole and as a consequence the rate of heat transfer from a hollow fin is primarily due to the contribution by the outer surface of the Fortunately, the rate of heat transfer is not negatively affected by the presence of the hole at the fin On the contrary, when the Grashof number is higher or the hole diameter is bigger, the inside surface contributes marginally to the heat A hollow fin saves material and weighs less compared to a solid So, this feature may be exploited.