Informatics Publishing Limited

B. Jayaraman ¹, P. Senthil Kumar ²

Affiliations
1 Dept. of Mechanical Engineering, Sathyabama University, Chennai – 600 119, IN
2 Dept. of Mechanical Engineering, KSR College of Engg., Tiruchengode - 637209, TN, IN

Abstract

Pulse Tube Refrigerator (PTR), a regenerative cryocooler is used in cryogenic cooling applications. Thermodynamic and numerical models help in estimating the operation parameters, analysing and thereby predicting the performance of a PTR. A one dimensional simulation model for analytical studies, design and optimization of the regenerator geometry for improving the performance of the PTR is developed. The simulation program is based on the equations obtained from applying the ideal gas laws, energy and mass balances in the Orifice PTR (OPTR). Predictions by the simulation program of the thermodynamic performance are compared with published experimental results (Kral et al, 1992) to validate the program. At 274 K, the refrigerating effect predicted by the program is 12.689 W, whereas the experimental value is 11.57 W, a difference of around 9%. Conflicting requirements for regeneration are satisfied by selecting appropriate material and size of wire screen mesh type regenerator. Based on empirical understanding hybrid regenerators have been used instead of single mesh, showing improved performances. A mathematical model simulating the regenerator is developed and solved numerically. Unconstrained optimisation technique with univariate search method is adopted to design optimal hybrid regenerators and is integrated with the simulation program. Using a hybrid regenerator, instead of single mesh regenerator used in Kral's experiments, the regenerator effectiveness increases by 0.16% and pressure drop decreases by 29.2% when compared to single mesh regenerators. Hybrid regenerators improve the refrigeration capacity of the OPTR system by as much as 40%. The validated simulation program can be used for the design and development of high performance OPTR.

Keywords

Cryocooler, Orifice Pulse Tube Refrigerator, Regenerator, Simulation, Refrigeration

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R. Kalidas , P. Senthil Kumar , S. Vinoth Sarun

Abstract

This paper presents an optimum concept to design passenger-friendly vehicle suspension system with the help of Taguchi approach. A full car suspension is considered as an illustrative example of vehicle model to demonstrate the concept and process of optimization. The experimental have been conducted by varying the stiffness of four shock absorbers (A), damping co-efficient of four shock absorbers (B), stiffness of seat (c) and damping co-efficient of seat (D) is taken as input parameters. The values of suspension parameters have been obtained by using the Taguchi design of experimental method. The implication of input parameters on seat displacement (DS) and settling time (ST) has been investigated by using analysis of variation. The optimum system parameters are predicted using Taguchi analysis and verified by the confirmation analysis carried out using MSC ADAMS. In addition mathematical model using regression model is done for both seat displacement (DS) and settling time (ST). The results show that stiffness of shock absorber and stiffness of seat spring are there most significant parameters which affect the seat displacement, while damping coefficient of. The concept proposed in this paper is applicable to generic cases, where more complex vehicle model and pavement surface condition apply.

Keywords

Full Car Model, Mathematical Modeling for Full Car Suspension, Taguchi Method, Optimization of Passive Suspension System

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