THERMODYNAMIC MODELING OF A PULSE TUBE REFRIGERATION SYSTEM

Abstract

Thermodynamic model of the pulse tube refrigeration (PTR) system has been developed based on the ideal gas behaviour to study the cooling effect at the cold end of the refrigerator. Compression and expansion processes of the gas column have been assumed to be isothermal. Mass flow in the regenerator has been evaluated through Ergun's law. Mass flow through the orifice and double inlet valve has been assumed a nozzle flow with a correction factor. Model predicted results have been validated with in-house experimental results as qualitative basis. Model predicted results in compression and expansion processes are also validated with that of the experimental data. Model predicted results are presented to understand the basic phenomenon for the refrigeration effect in various pulse tube refrigerators (BPTR, OPTR and DIPTR). Time duration for expansion process is more than the compression process in case of OPTR and DIPTR, which leads to lower pressure during the expansion and more cooling capacity obtained compared to the BPTR. A distinct comparison among three types of PTRs has been done based on the work done at the cold end . It has been clearly observed that a DIPTR shows better cooling capacity compared to OPTR or BPTR.