MRJT cryocoolers are known for their low cost and low vibrations at the cold end because of no moving parts in the cold section. The use of refrigerant mixture of nitrogen-hydrocarbons as a working medium in these cryocoolers enhances their efficiency. The overall performance of such MRJT cryocoolers greatly depends on the refrigerant mixture, heat exchanger and compressor. The proposed work involves:

• Experimentally and numerically analyse the performance of the recuperative heat exchanger in the MRJT cryocooler
• Examine the condensation and boiling phenomena that takes place in the heat exchanger
• Develop correlations of heat transfer coefficients for multi-component mixtures during two phase heat transfer

A two stage MRJT cryocooler is built by assembling two MRJT refrigerators in a cascade cycle configuration. The high temperature mixed refrigerant cooling stage precools the low temperature mixed refrigerant cooling stage. This would improve the efficiency of the low temperature cooling stage. Hence, a two stage MRJT cryocooler could be used to reach a lower temperature as compared to a single stage cryocooler. The proposed work involves:

• Numerical study of the performance of a two stage MRJT cryocooler
• Design a two stage MRJT cryocooler to reach a temperature below 80 K
• Fabricate the cryocooler and initiate trials
• Experimentally analyse the working of the cryocooler