G. Venkatarathnam, Ph.D.,

Venkataraman and Sita Srinivasan Chair in Innovation
Professor of Mechanical Engineering

Office: Room No 205, Refrigeration and Air Conditioning Laboratory
Telephone: +91 44 2257 5720 | 4685
URL: https://tinyurl.com/yc4nt3tu


The broad mission of our group is to develop innovative refrigeration systems, heat exchangers and design/thermodynamic tools. Another mission is to help the Indian refrigeration and heat exchanger industry improve their products and services, and introduce new world class products.


Our vision is to be one of the most happening labs in the areas of Refrigeration, Air conditioning, Cryogenic Engineering, and additive manufacturing of heat exchangers.

Research interests

  • Development of new innovative refrigeration systems
  • Development of Low GWP Refrigerant mixtures
  • Improvement of efficiency of Refrigeration and Air conditioning Systems
  • New refrigeration and liquefaction processes operating with mixtures
  • Heat exchangers – Modelling, additive manufacturing, testing
  • Thermodynamics of mixtures
  • Cooling of Microscopes to cryogenic temperatures (Centre for Correlative Microscopy, IIT Madras)

Current projects

  • New low GWP refrigerant mixtures
  • Mixed refrigerant processes for hydrogen liquefaction
  • Knowledge graphs and development of Ontologies for  Mechanical Engineering systems
  • Manufacturing technology eco-platform for Atmanirbhar Bharat (see https://beta.mykite.in )
  • Cooling of a Field Ion Microscope to 30 K (Centre for Correlative Microscopy)
  • Development of high efficiency -80 °C single stage refrigerator for storage of vaccines
  • AI and ML studies on heat transfer coefficients in complex heat exchanger geometries
  • Additive manufacturing of compact heat exchangers for combusition applications
  • Additive manufacturing of compact heat exchangers for low temperature applications
  • Innovative header designs for additively manufactured heat exchangers
  • New optimization methods for optimizing flow circuits of cross-flow heat exchangers
  • Development of micro heat exchangers for low temperature applications
  • Development of a cryocooler for space application
  • New processes for Liquid air energy storage systems
  • Next generation low cost mixed refrigerant based nitrogen liquefier
  • Improved methods for thermodynamic flash calculations
  • Improved methods for calculating phase envelopes (Isopleths, P-xy, T-xy, global phase diagrams)
  • Fault detection and diagnosis of HVAC systems in large buildings
  • Fault detection and diagnosis of large chillers
  • Development of a refrigerated vending cart
  • Thermal compensation of milling machines
  • Thermodynamics of Aqueous Biphasic Systems
  • Passive Recirculation System a for a cryogenic rocket stage

Courses taught

  • ME1100 Thermodynamics (Undergraduate)
  • ME3250 Refrigeration and Air Conditioning (Undergraduate)
  • ME4100 Design Project (Undergraduate)
  • ME5132 Refrigeration and Cryogenics (Graduate)
  • ME5134  Process Simulation (Graduate)

Patents Granted

  • Venkatarathnam, G., System and method for the liquefaction of feed fluid operating at high ambient temperature, Indian Patent No. 352407 (2020)
  • Venkatarathnam, G., Refrigerant composition and process for preparation thereof, US Patent No. 7722780 (2010)
  • Venkatarathnam, G., Refrigerant composition for refrigeration systems, US Patent No. 7582223 (2010)
  • Venkatarathnam, G., A refrigerant composition for refrigeration systems, India Patent No. 211627 (2007)
  • Venkatarathnam, G., A refrigerant composition for a single stage refrigeration system, India Patent No. 205644 (2007)
  • Venkatarathnam, G., A refrigerant composition for refrigeration systems, India Patent No. 197997 (2006)

Patents Applications Pending


Technologies developed and available for commercialisation

  1. Battery coolers
  2. Perforated plate matrix heat exchangers
  3. Freezers operating between -50 °C and -100 °C and operating with single compressor
  4. Mixed refrigerant cycle refrigerator operating between -40 °C and -100 °C and operating with a single compressor
  5. Thermostat (constant temperature bath) operating between -50 °C and -100 °C and operating with a single compressor
  6. Mixed refrigerant cycle refrigerator operating between 70 and 150 K Thermostat  and operating with a single compressor
  7. Mixed refrigerant cycle nitrogen liquefier with a liquefaction rate of 0.7-0.9 l/hr and a power input of about 1.5 kW
  8. Mixed refrigerant cycle water traps (in place of liquid nitrogen) for use with diffusion vacuum pumps, vacuum chambers, etc.

Thermodynamic Methods and Routines

Our phase identification parameter is actively used in the fitting of Helmholtz energy equations of state of a number of fluids at NIST and elsewhere. Similarly, our Density marching methods for phase envelope calculations are used in a number of process simulation and thermodynamic programs. Here are some of the well known software that use our methods and routines:

  • NIST Refprop property program – Phase identification method, phase envelope routine, true mixture critical point routine
  • Aspen Plus Process simulation software – Two and Three Phase envelope calculation methods
  • Aspen Hysys Process simulation software – Phase identification method
  • Coolprop property program – Phase identification method, Phase envelope calculation method

Software developed by us

  • MyPROPS – Program for the estimation of thermodynamic properties of mixtures  (VLE, VLLE, VLSE), routines for drawing phase envelopes based on the density marching method for phase envelope (parts I, II, III), etc.
  • MyCOIL – Program for the simulation of different types of heat exchangers
  • MRC-OPTIM – Program for the optimisation of J-T refrigerators operating with mixtures
  • MHE-OPTIM – Program for the optimum design of perforated plate matrix heat exchangers
  • COILHX – Program for the design and simulation of wound coil heat exchangers
  • CRYOSIM – General purpose process simulation program
  • MyThermoloop – Program for analysis of passive recirculation loop of rockets


Selected Publications

Books & Handbook Chapters

  1. G. Venkatarathnam, Cryogenic Mixed Refrigerant Processes, Springer, NY, 2008
  2. G. Venkatarathnam, Cryogenic Heat Exchangers, Heat Exchanger Design Handbook, Begell House, 2016


Journals & Conferences

  1. Rahul Kumar, Shankar Krishnapillai, G Venkatarathnam, Optimisation of flow paths of air-cooled heat exchangers, International Journal of Energy for a Clean Environment, Special issue (2022, Accepted for publication)
  2. Vineed Narayanan, G Venkatarathnam, Theoretical analysis of Rankine cycle operating with zeotropic mixtures of carbon dioxide and hydrocarbons, ASME Journal of Energy Resources Technology, 144 (6), 062103 (2022)
  3. G. Venkatarathnam, MyCOIL – A program for the rating and optimisation of the flow path of air-cooled heat exchangers, Paper No. 384, Proceedings of the ISHMT-ASTFE Heat and Mass Transfer conference (IHMTC 2021) 17-20th December, 2021
  4. T. Barath Adhithya and G. Venkatarathnam, New pressure and density based methods for isothermal-isobaric flash calculations, Fluid Phase Equilibria, 537, 112980 (2021)
  5. H. Kruthiventi and G. Venkatarathnam, Performance of J-T refrigerators operating with mixtures and coiled wire finned heat exchangers, Journal of Thermal Analysis and Calorimetry, 141, 2169–2175 (2020)
  6. Vineed Narayanan and G. Venkatarathnam, Prediction of vapour-liquid equilibria of binary mixtures of neon-nitrogen, neon-oxygen and neon-argon used in J-T refrigerators, Cryogenics, 106, 103039 (2020)
  7. Sunil Jerome and G. Venkatarathnam, Performance of a Linde-Hampson refrigerator operating from –120 °C to –60 °C with optimised R14-hydrocarbon mixtures exhibiting vapour-liquid-liquid equilibria, Heat Mass Transfer,  doi:10.1007/s00231-019-02801-z (2019)
  8. T. Barath Adithya and G. Venkatarathnam, A review of second-order isobaric-isothermal flash calculations, paper no. NCCS_TP_1029, National  conference on Cryogenics for Space, Thiruvanathapuram, 12-14, December 2019
  9. V. Chaitanya, S. Narasimhan and G. Venkatarathnam, Effect of assumption of common stream temperature in the simulation of multistream heat exchangers on the overall process efficiency, paper no. NCCS_TP_1015, National  conference on Cryogenics for Space, Thiruvanathapuram, 12-14, December 2019
  10. G. Venkatarathnam, Some exciting developments in cryogenic engineering applications, Invited paper, National  conference on Cryogenics for Space, Thiruvanathapuram, 12-14, December 2019
  11. G. Venkatarathnam, Alternatives for low GWP refrigerants for India, Invited paper, International conference on Recent advancements in Air conditioning and Refrigeration, RAAR-2019, Bhubaneswar, 28-30, November 2019
  12. G. Venkatarathnam, Performance of A Small Nitrogen Liquefier, 27th “National Symposium on Cryogenics and Superconductivity, Mumbai, January 16-18, 2019
  13. G. Venkatarathnam, Three-phase routines for the NIST Refprop program, 27th “National Symposium on Cryogenics and Superconductivity, Mumbai, January 16-18, 2019
  14. H. Gurudath Nayak and  G. Venkatarathnam, Performance of an auto refrigerant cascade refrigerator operating in gas refrigerant supply mode with optimized nitrogen- hydrocarbon refrigerant mixtures, Paper No. PA-C-001,the sixth International Conference on Cryogenics and Refrigeration, April 12–14, 2018 at Shanghai Jiao Tong University, Shanghai, China
  15. R. Satya Maher and G. Venkatarathnam, Estimation of performance of a J-T Refrigerators Operating With Nitrogen-Hydrocarbon Mixtures and a Coiled tubes-in-tube heat exchanger, Cryogenics, 92, 27-35 (2018)
  16. I.Sujatha and G. Venkatarathnam, Comparison of performance of a vapor absorption refrigeration system operating with some hydrofluorocarbons and hydrofluoroolefins as refrigerants along with ionic liquid [hmim][TF2N] as the absorbent, Int. J. Refrigeration, 88,370-382 (2018)
  17. V. Narayanan and G. Venkatarathnam, Prediction of Vapour-Liquid and Vapour-Liquid-Liquid equilibria of nitrogen-hydrocarbon mixtures used in J-T refrigerators, Cryogenics, 90, 70-85 (2018)
  18. G. Venkatarathnam, density marching method for drawing phase envelopes: 3. P-xy diagrams of binary mixtures, Ind. Eng. Chem. Res., 56 (46),  13894–13904  (2017)
  19. I. Sujatha and G. Venkatarathnam, Performance of a vapor absorption heat transformer operating with ionic liquids and ammonia, Energy, 141, 924-936  (2017)
  20. S.S. Harish Kruthiventia and G. Venkatarathnam, Studies on capillary tube expansion device used in J-T refrigerators operating with nitrogen-hydrocarbon mixtures, Cryogenics, 87, October 2017, 76-84 (2017)
  21. H. Gurudath Nayak and G. Venkatarathnam, Occurrence of Dry out Phenomenon in an Auto Refrigerant Cascade Refrigerator operating with zeotropic mixtures, ASME J. Thermal Sci. Eng., 9(3):031012-031012-6. doi:10.1115/1.4035940 (2017).
  22. B. Sreenivas, H. Gurudath Nayak and G. Venkatarathnam, Relationship between composition of mixture charged and that in circulation in an auto refrigerant cascade and a J-T refrigerator operating in liquid refrigerant supply mode, Cryogenics 81, 42-46, (2017)
  23. Padmanabhan, C.S. Gurudath, Thota Srikanth, A Ambirajan, S.A. Basavaraj, Kumar Dinesh, and G. Venkatarathnam,  Studies on Phase Shifting Mechanism in PulseTube Cryocooler, IOP Conf. Ser.: Mater. Sci. Eng. 171 012082 (2017)
  24. Vineed Narayanan, G VenkatarathnamExperimental investigation on mixed refrigerant cryocooler operating at 70 K for cooling high temperature superconductors, IOP Conference Series: Materials Science and Engineering 171 (1), 012073 (2017)
  25. V. Narayanan and G. Venkatarathnam, Performance of two mixed refrigerant processes providing refrigeration at 70K, Cryogenics, 78, 66-73 (2016)
  26. P.C. Jayanti, and G. Venkatarathnam, Identification of the phase of a substance from the derivatives of pressure, volume and temperature, without prior knowledge of saturation properties: Extension to solid phase, Fluid Phase Equilibria, 425, 269-277 (2016)
  27. G. Sharma, R.L. Gardas, A. Coronas and G. Venkatarathnam, Effect of anion chain length on physicochemical properties of N, N-dimethylethanolammonium based protic ionic liquids, Fluid Phase Equilibria, 415, 1-7 (2016)
  28. Harish Kruthiventi SS, Venkatarathnam GG. Comparison of the Straight Adiabatic Capillary Tube Expansion Devices Used in Refrigeration Systems Operating With Refrigerants R134a and R1234yf. ASME. J. Thermal Sci. Eng. Appl., 8, 021015-1–021015-7 (2016)
  29. G. Venkatarathnam, Thermodynamics of refrigerant mixtures used in J-T refrigerators, Presented at the 26th International Cryogenic Engineering Conference, March 7-11, 2016, New Delhi
  30. G.S.C. Prasad, C.S. Kumar, S.S. Murthy and G. Venkatarathnam, Performance of an organic Rankine cycle with multicomponent mixtures,Energy, 88, 690-696 (2015)
  31. B. Sreenivas, D.R. Patel, S.S. Murthy, and G. Venkatarathnam, Performance of mixed refrigerant cascade refrigerator for cooling a space simulation chamber, Indian Journal of Cryogenics 39 (1), 81-85 (2014)
  32. G. Venkatarathnam, Density Marching Method for Calculating Phase Envelopes, Ind. Eng. Chem. Res. 53, 3723−3730 (2014)
  33. G. Venkatarathnam, Density marching method for calculating phase envelopes: Part II – Three-phase envelopes, Ind. Eng. Chem. Res. Vol. 53, 12122-12128 (2014)
  34. Sumit K. Swarnkar, S. Srinivasa Murthy, Ramesh Gardas and G. Venkatarathnam, Performance of a vapour absorption refrigeration system operating with ionic liquid-ammonia combination with water as cosolvent, Applied Thermal Eng. Vol. 72, 249-256 (2014)
  35. G. Venkatarathnam, Thermodynamics of refrigerant mixtures used in Cryogenic Mixed Refrigerant Processes, National Symposium on Cryogenics, Hyderabad, December 8-10, 2014, Hyderabad, India
  36. Sunil Jerome and G. Venkatarathnam, Comparatative study of Helmholtz, Peng-Robinson and PC-SAFT equation of state applied to a J-T Cryocooler, National Symposium on Cryogenics, Hyderabad, December 8-10, 2014, Hyderabad, India
  37. Vineed Narayanan and G. Venkatarathnam, A mixed refirgerant cycle for providing refrigeration below 70 K for superconducting application, National Symposium on Cryogenics, Hyderabad, December 8-10, 2014, Hyderabad, India

Some important projects undertaken for industrial clients

  1. Development of new refrigerant mixtures as replacement for R404A
  2.  -40 °C thermostatic bath
  3. Plant growth  chamber (simultaneous control of temperature and humidity)
  4. Very high COP air conditioner
  5. Improvement of performance of a -80 °C biofreezer
  6. Studies on low temperature container refrigeration system
  7. Program for the Diagnosis and detection of faults in large chillers
  8. Design of multistream Wound Coil heat exchangers
  9. Cooling of high Tc superconducting transformer
  10. Cooling of low Tc superconducting generator
  11. Studies on chill down of large pipelines
  12. Studies on stratification of cryogens in large tanks under different conditions
  13. Studies on chill down of turbopumps
  14. Very high effectiveness heat exchangers for a helium liquefier

In Press

  1. The Hindu article on low temperature refrigerator
  2. Times of India article on nitrogen liquefier

Also taught at

  • Indian Institute of Technology Kharagpur
  • Karlsruhe Institute of Technology, Germany

For prospective students and postdocs

Our mission is to develop innovative and next-generation refrigeration and heat exchanger products. Our work usually involves all aspects of design, fabrication and testing. While some of my students prefer to work only on theoretical aspects such as design optimization, machine learning, and process design, most prefer to build new equipment/systems and test them in the laboratory.

If you think you have a passion for developing next-generation technologies, software and design tools, send an email to me. 

All my students and I are very passionate about our work.  If you are interested in just completing the requirements for the award of your degree, then probably my group is the wrong one for you. On the other hand, if you want to be a future leader in any area we work in, our group is probably the right one for you.

Internship opportunity for students from other colleges (Sorry. Internships no longer available for 2022).

A few internships are available under online mode only due to the pandemic. Currently all the projects are on developing a web application.


B.Techs in any discipline with knowledge of JavaScript and a willingness to learn other software tools/concepts

ME4001 Design Project for III year B.Tech /DD students of IIT Madras

A few projects are available under the ME4001 Design project (9 credits). All the current projects involve programming in Fortran/C languages for an open source project that I’m developing. Email me if you are interested.


B.Techs/DD in ME/ChE/AE, with experience in Fortran/C languages and willingness to learn new concepts.

E-cell Project for II and III year B.Tech /DD students of IIT Madras

Please check Ecell website for the projects that I have announced