Cryogenics in India

Introduction of various processes of welding and its technology in early 30s, followed, the manufacture of gases and electrodes. During 1990s several Air Separation Plants of large size were set up in various parts of the country. At present the total tonnage capacity of Air Separation Plants is over 15000 TPD. Prior to 1990, Cryogenics was confined to the scientific laboratories and industries for experimental investigations. However, there is a quantum jump in these activities and successful development of technology has been witnessed. This paper provides a summary of the major cryogenics activities in India

Exergy analysis of stirling cycle cryogenerator

Exergy or the available work energy function is a useful concept for analysing various systems. This paper attempts to present exergy analysis for Stirling cycle cryogenerator. The cycle deviates from the ideal cycle due to (1) finite temperature difference (Delta t) during heat transfer processes and (2) loss of refrigerating effect due to regenerator ineffectiveness. The analysis shows that at lower temperature ratios the influence of Delta t on exergetic efficiency is marginal. However, the influence of regenerator effectiveness on the exergetic efficiency even at lower temperature ratios is considerable. The combined effect of Delta t and regenerator effectiveness leads to the practical case and the same also has been analysed

Design and development of an orifice/inertance pulse tube cryocooler using a linear compressor

The design of an Orifice Pulse Tube (OPT) Cryocooler has been validated and applied for the design of Inertance Pulse Tube (IPT) Cryocooler with 15 W at 70 K. Parametric analysis based on cyclic simulation model has been used as a design tool. This model begins with the estimates of the ideal refrigerating effect and ideal power requirement. Different losses in refrigerating effect and power are later incorporated to arrive at the net refrigeration effect and gross power requirements. Based on this information, the IPT cryocooler has been developed. A matching moving coil type opposed piston linear compressor has been designed and developed to meet the requirements of this IPT cryocooler. The system comprising IPT cryocooler and linear compressor has been installed and commissioned. To validate the design, detailed experimental investigations on the IPT are planned. Some of the experimental results are reported in this paper

Performance prediction and parametric analysis of 2-stage stirling cycle cryocooler

The lowest temperature that can be achieved in Stirling cycle cryocooler is governed by various losses. This paper presents performance prediction of Two Stage Stirling Cryocooler (for 20K as the second stage temperature) by using second order analysis which calculates the ideal refrigerating effect at intermediate and final stage temperatures and the ideal power input. The losses are found out for both the stages to determine the actual refrigerating effects and power input. The results obtained are in good agreement with reported values. The performance of the cryocooler is governed by various operating and geometric parameters. Parametric analysis is carried

Experimental investigation on Mixed Refrigerant Joule Thomson (MR J-T) cryocooler

Mixed Refrigerant Joule Thomson (MR J-T) cryocoolers have obvious advantages, such as low cost, high reliability, higher cooling effect at 80 K, low vibrations and simplicity in design layout. As a result of this, their use for different applications has become a major threat to conventional cryocoolers such as Stirling coolers. The performance of the MR J-T cryocooler, in terms of cooling power at low temperatures, depends significantly on the components of the gas mixture and their concentration. An experimental set up has been developed in our laboratory to analyse various gas mixtures. An efficient Hampson type counter flow heat exchanger has been fabricated and tested in the set up. The present paper gives experimental results for various gas mixtures so as to get maximum cooling effect for a given temperature. The paper also presents the effect of working pressure of the optimized gas mixture on the performance of the cooler

OPTIMIZATION OF DESIGN PARAMETERS OF STIRLING CYCLE MACHINE

The performance of a Stirling cryocooler is governed by six principal design parameters, namely speed, pressure limits, the temperature of the working fluid in the compression and expansion spaces, the ratio of the compression and expansion space swept volumes, the ratio of total dead volume and expansion space swept volume and the phase angle between the volume variations of the expansion space and compression space. For optimizing the performance of a cryocooler, its cyclic analysis should be considered along with a loss analysis. The present paper attempts to find out the optimum combination of these design parameters for machines PLN-106 and PLN-108s, for which design data are known. The objective functions of optimization can be based on COP maximization or any design constraints such as the total volume or space taken up by the machine, maximum pressure generation, etc. This paper first applies the optimization routine to the Philips machine and identifies the optimization function for which the machines are designed. The routine is then further extended to develop a generalized procedure for designing a cryocooler of any capacity. The procedure is applied to determine the different dimensions of machines with a liquid nitrogen producing capacity of 8 dm3 h-1. The design developed using this procedure is then compared with the actual existing design