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• Assistant Professor, ME Department, NIT Agartala, Agartala, Tripura, India
  (July, 2014-June, 2015)
• Assistant Professor, ME Department, NIT Meghalaya, Shillong, Meghalaya, India
  (July, 2015-Present)
  

At UG(B.Tech) Level: Core Courses
Applied Thermodynamics ME206 (3-0-0:3)

Fluid Machines ME 220 (3-0-0:3)   

Engineering

Thermodynamics ME102 (2-0-0: 2)

Heat and Mass Transfer, ME 303/ 301 (3-1-0:4) 

At UG(B.Tech) Level: Elective Courses

Refrigeration and Air-Conditioning ME 411/435 (3-0-0:3)

Power plant Engg. And Energy Audit. ME 371 (2-0-0:2)

At PG Level: 

Experimental Methods in Mechanical Systems ME 553 (3-0-0:3)

Seminar-I ME 550 (0-0-2:1) 

At Doctoral Level:

Measurement Systems in Mechanical Engineering ME 701 (3-0-0:3)

Sponsored Research Projects

Consultancy Projects

Abdullah Ansari, Solar-Assisted Liquid Desiccant, 2023.

Vishal Kumar Bhaskar, Solar Air Heating Systems. 2023

International Journals

1. Pradhan M, Das K, Das RS. Performance improvement of a solar-assisted liquid desiccant regenerator: An experimental study and system-level transient modelling. Applied Thermal Engineering (Accepted)

2. Khelkar AB, Das RS. Performance enhancement of a solar air heating device featuring wavy absorbing plate with cylindrical fins: An experimental and CFD study. Heat Transfer Engineering (Accepted)

3. Khelkar AB, Patwari K, Das RS. Heat transport and flow characteristics in triangular finned solar air heating duct with wavy absorber. Journal of the Brazilian Society of Mechanical Sciences and Engineering. 2025 Dec;47(12):637.

4. Marwein D, Debnath BK, Das RS. Energetic and Exergetic Evaluation of Secondary Heating in Double Slope Solar Still. Journal of Thermophysics and Heat Transfer. 2025 Apr:1-0.

5. Patwari K, Khelkar AB, Das RS. Analysing the thermal characteristics of a two-pass solar air heater featuring triangular grooves. Journal of Thermal Analysis and Calorimetry. 2025 Jun 24:1-6.

6. Bhaskar VK, Khelkar AB, Patwari K, Das RS, Meshram GS. Performance improvement of a single-pass solar air heater by introducing cuboidal-shaped vortex generators on absorbing plate. International Journal of Fluid Mechanics Research. 2025;52(6). 

7. Das A., Das R.S., Das K., Numerical analysis of liquid desiccant dehumidification system with novel trapezoidal baffled surface, International Journal of Refrigeration 145, 457-466, 2023.

8. Das A., Das R.S., Das K., Performance analysis of aqueous LiCl and CaCl2 based falling film dehumidifier with surface modification, Applied Thermal Engineering, 200, 117704, 2022.

9. Das A., Das R.S., Das K., Performance enhancement of a liquid desiccant absorber with triangular corrugated structured packing, Journal of Building Engineering, 45, 103677, 2022.

10. Das S., Debnath B.K., Das R.S., Analyzing the Combustion Behavior of different Ceramic Porous Media in the Piston Bowl of a Diesel Engine, Journal of The Institution of Engineers (India): Series C, 1-15, 2022.

11. Bezbaruah P.J., Das R.S., Sarkar B.K., Experimental and numerical analysis of solar air heater accoutered with modified conical vortex generators in a staggered fashion, Renewable Energy,  180, 109-131, 2021.

12. Bezbaruah P.J., Das R.S., Sarkar B.K., Experimentally validated 3D simulation and performance optimization of a solar air duct with modified conical vortex generators, Solar Energy, 224, 1040-1062, 2021.

13. Das S., Debnath B.K., Das R.S., Experimental investigation of porous media combustion applied on the piston bowl of diesel engine, Journal of the Brazilian Society of Mechanical Sciences and Engineering, 43(3), 1-14, 2021.

14. Bezbaruah PJ, Das RS, Sarkar BK. Overall performance analysis and GRA optimization of solar air heater with truncated half conical vortex generators, Solar Energy, 2020, 196, 637-652.

15. Bezbaruah P.J., Das R.S., Sarkar B.K., Solar Air Heater with Finned Absorber Plate and Helical Flow Path: A CFD Analysis, Applied Solar Energy, 56, 35-41, 2020.

16. S Das, BK Debnath, RS Das, A Stagni, T Faravelli, Numerical investigation of a porous media combustor in a small-scale diesel engine, Energy 186, 115785, 2019.

17. Bezbaruah PJ, Das RS, Sarkar BK. Thermal and Fluid Flow Analysis of Miller Teeth Shaped Ribbed Solar Air Heater-A CFD Approach, Journal of Scientific & Industrial Research, 2019, 78, 694-698.

18. Bezbaruah PJ, Das RS, Sarkar BK. Thermo-hydraulic performance augmentation of solar air duct using modified forms of conical vortex generators, Heat and Mass Transfer, 2019, 55, 1387-1403.

19. Das RS, Jain S. Performance characteristics of cross-flow membrane contactors for liquid desiccant systems Experimental investigations on a solar assisted liquid desiccant cooling system with indirect contact dehumidifier, Solar Energy, 2017, 153, 289-300.

20. Das RS, Jain S. Performance characteristics of cross-flow membrane contactors for liquid desiccant systems, Applied Energy, 2015, 141, 1-11.

21. Das RS, Jain S. Simulation of potential standalone liquid desiccant cooling cycles, Energy, 2015, 81, 652-661.

22. Das RS, Jain S. Experimental performance of indirect air–liquid membrane contactors for liquid desiccant cooling systems, Energy 57, 319-325, 2013.

23. Jain S. Tripathi S, Das RS, Experimental performance of a liquid desiccant dehumidification system under tropical climates, Energy Conversion and Management 52 (6), 2461-2466, 2011.

International Conferences

1. Ashish B. Khelkar and Rajat Subhra Das. “Evaluating the performance of a medium-scale solar air heating system roughened with longitudinal fins and transverse circular ribs,” Proceedings of the ASME 2025, International Mechanical Engineering Congress and Exposition, IMECE-2025, September 10-13, 2025, Hyderabad, India.

2. Ashish B. Khelkar, Debashish Behera and Rajat Subhra Das, “Investigation of thermo-hydraulic performance of a solar air heater with elliptical ribs,” 2nd International Conference on Recent Innovations and Developments in Mechanica Engineering (ICRIDME 2024) November 14 - 16, 2024, NIT Meghalaya, Shillong, India.

3. Krittika Patwari, Ashish B. Khelkar and Rajat Subhra Das. “Effect of triangular grooves on the performance of a double-pass solar air heater: A technical study” 2nd International Conference on Recent Innovations and Developments in Mechanical Engineering (ICRIDME 2024) November 14 - 16, 2024, NIT Meghalaya, Shillong, India.

4. Mrinal Pradhan, Koushik Das, Rajat Subhra Das. “Comparative Analysis of Predictive Models for Regeneration Capability of a Liquid Desiccant Regenerator: Regression Tree vs Artificial Neural Network” 2nd International Conference on Recent Innovations and Developments in Mechanical Engineering (ICRIDME 2024) November 14 - 16, 2024, NIT Meghalaya, Shillong, India.

5. Ashish B. Khelkar, Mrinal Pradhan and Rajat Subhra Das. “Experimental Analysis of a Liquid Desiccant Regenerator Cum Solar Air Heater with Undulated Absorber Plate” 5 th International Conference on Recent Advances in Mechanical Infrastructure (ICRAM 2025) held on 10-12 January 2025 at IITRAM Ahmedabad.

6. D. Marwein, P. Yadav, B. K. Debnath, R. S. Das, Effect of variation of water depth on the performance of a double slope solar still for Shillong weather condition? a CFD study, In Proceedings of the 27th National and 5th International ISHMT-ASTFE Heat and Mass Transfer Conference, IIT Patna, Patna-801106, Bihar, India, December 14-17, 2023, pp. 987-992. https://ishmtdigitallibrary.com/conferences/1654896405e56590,4869f8107409fb40,3f1b122a5325c3df. HTML.

7. Pradhan M, Das K, Das RS. Numerical analysis of liquid desiccant regenerator with corrugated surface. InProceedings of the 27th National and 5th International ISHMT-ASTFE Heat and Mass Transfer Conference December 14-17, 2023, IIT Patna, Patna-801106, Bihar, India 2024. Begel House Inc..

8. Khelkar A, Patwari K, Das RS, Improving the Heat Transfer Performance of a Solar Air Heating Duct with Semicircular Grooves on a Wavy Absorber Plate, 1st International Conference on Mechanical Engineering: Researches and Evolutionary Challenges (ICMECH-REC 23), June 23-25, 2023, National Institute of Technology Warangal.

9. Khelkar A, Patwari K, Das RS, Analysis of a Solar Air Heater with Triangular Fins on Wavy Absorber Plate, Proceedings of the 9th International and 49th National Conference on Fluid Mechanics and Fluid Power (FMFP), December 14-16, 2022, IIT Roorkee.

10. Khelkar A.B., Syrti K., Das R.S., Sarkar B.K., Augmenting the thermal performance of solar air heater with absorber plate roughened with pin-fins. 7th International Conference on Mechanical Engineering and Robotics Research; December 9-11, 2022, Krakow, Poland.

11. Rajive N.M., Khelkar A.B., Das R.S., Simulation of a single zone building in Meghalaya using solar air heater in TRNSYS software. Proceedings of the 1st International Conference in Fluid Thermal and Energy Systems, June 9-11, 2022, NIT Calicut, Kerala, India.

12. Behara D., Das R.S., Thermohydraulic Performance of a Novel Solar-Based Air Heating System, 24th September 2021in the 2nd National and 1st International Conference on Advances in Fluid Flow and Thermal Sciences (ICAFFTS-2021).  September 24- 25, 2021, SVNIT Surat, Surat, India.

13. Das, A., Das, R.S. and Das, K., 2020. Performance evaluation of LiCl and CaCl2 based falling film dehumidifier with surface modification. In Proceedings of the 1st International Conference on Thermal Engineering and Management Advances (ICTEMA 2020).

14. Das, A., Das, R.S. and Das, K., 2019. Performance evaluation and enhancement of LiCl-H2O based falling film dehumidifier using surface modification. In Proceedings of the International Mechanical Engineering Congress (IMEC-2019).

15. Das, A., Das, R.S. and Das, K., 2019. Investigation on Fluid Flow, Heat and Mass transfer Characteristics in a LiCl-H2O Falling Film Absorber. In Proceedings of the 25th National and 3rd International ISHMT-ASTFE Heat and Mass Transfer Conference (IHMTC-2019). Begel House Inc. December 28-31, 2019, IIT Roorkee.

16. Das S, Debnath B.K., Das R.S., Effect on Combustion Behaviour in the Presence of Ceramic Porous Materials on the Piston Bowl of a Diesel Engine. In Proceedings of the 25th National and 3rd International ISHMT-ASTFE Heat and Mass Transfer Conference (IHMTC-2019). Begel House Inc. December 28-31, 2019, IIT Roorkee.

17. Bhandarkar A.C., Bezbaruah P.J., Sarkar B.K., Das R.S., “Solar air heater system control for space heating application in Shillong” 8th International and 47th National Conference on Fluid Mechanics and Fluid Power (FMFP 2020), IIT Guwahati. Paper ID: 154”

18. Bezbaruah P.J., Gupta A. K., Das R.S., Sarkar B.K., “CFD analysis of solar collector with truncated hemispherical vortex generators” Proceedings of 14th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics (HEFAT 2019), pp. 265-270. Paper ID: 348, July 21-24, 2019, Wicklow, Ireland.

19. Bezbaruah, P.J., Kumar, R., Das, R.S., “Thermohydraulic performance analysis of solar air heater with helical roughness,” Proceedings of the 25th National and 3rd International ISHMT-ASTFE Heat and Mass Transfer conference (IHMTC-2019), pp. 233-237, 2019

20. Bezbaruah, P.J., Das, R.S. & Sarkar, B.K., "Numerical Analysis of Solar Triangular Air Duct with Conical Turbulators," 2nd International Conference on Power, Energy and Environment: Towards Smart Technology (ICEPE), Shillong, India, pp. 1-5, 2018.

21. Gupta, A.K., Bezbaruah, P.J., Das, R.S. & Sarkar, B.K., “Numerical Investigation on Solar Air Heater with Hemispherical Roughness," 2nd International Conference on Power, Energy and Environment: Towards Smart Technology (ICEPE), Shillong, India, pp. 1-6, 2018.

22. Kushwaha A.K.S., Das R.S., A simplified ANN model to assess the performance of a liquid desiccant air-conditioning system, International Conference on Renewable and Sustainable Energy, April 12-13, 2017, Coimbatore.

23. Das R.S., Saha P.K., Jain S. Investigations on solar energy driven liquid desiccant cooling systems for tropical climates; 50 th Annual Australian Solar Energy Society (AuSES) Solar 2012 Conference, December, 6-7, 2012, Melbourne, Australia.

24. Das R.S., Tripathi S., Jain S. Experimental performance of a liquid desiccant dehumidification system using an indirect contact heat and mass exchanger; Proc. of 5th International sorption heat pump conference, April, 6-8, 2011, Padua, Italy; pp. 725-732.

National Conferences                              

1. Vivek Gaba, Vaibhav Agrawal, Rajat Subhra Das, Sanjeev Jain. Development of solar driven liquid desiccant cooling system; National conference on Advances in Refrigeration and Air-Conditioning (NCARAC-2014), January 27-28, 2014, Bhopal India.

2. Rajat Subhra Das, Sanjeev Jain. Performance of a solar liquid desiccant cooling system with indirect contact dehumidifier, National conference on refrigeration and air-conditioning, Dec, 12-14, 2013, IIT Chennai, India.

3. Rajat Subhra Das, Sanjeev Jain. Solar desiccant cooling technologies: Prospects and challenges, National conference on refrigeration and air-conditioning, July, 7-9, 2011, IIT Chennai, India.

 Book Chapters

1. Patwari, K., Khelkar, A.B., Das, R.S. (2024). Assessing the Impact of Integrating Triangular Grooves on the Performance of a Double Pass Solar Air Heater. In: Tatiparti, S.S.V., Seethamraju, S. (eds) Advances in Clean Energy and Sustainability, Volume 2. ICAER 2023. Green Energy and Technology. Springer, Singapore. https://doi.org/10.1007/978-981-97-5419-9_32 (Published: 27 September 2024)

2. Ansari A, Pradhan M, Das RS. Implementation of Artificial Neural Network to Forecast Liquid Desiccant Regenerator Performance. In: De, S., Roy, P.C. (eds) Advances in Energy and Sustainability. INCOM 2024. Lecture Notes in Mechanical Engineering. Springer, Singapore. https://doi.org/10.1007/978-981-97-7308-4_9 (Published:24 December 2024)

3. PJ Bezbaruah, A Das, RS Das, BK Sarkar; Advances in Energy Research; 2020; Numerical Investigation on Triangular Fin-Based Solar Air Heater 341- 350; (ISBN/ISSN No.  978-981-15-2661-9) Springer Nature

4. PJ Bezbaruah, RS Das, Bikash Kumar Sarkar; Advances in Mechanical Engineering; CFD-Based Study on Thermal and Fluid Flow Dynamics Due to Miller Teeth Shaped Ribs Over Absorber Plate of Solar Air Collector; 1045-1053; (ISBN/ISSN No.978-981-15-0126-5); Springer; 2020

5. H Barman, RS Das; Advances in Mechanical Engineering; Simultaneous Heat and Mass Transfer Analysis in Falling Film Absorber; 1001-1011; (ISBN/ISSN No.978-981-15-0126-5);Springer; 2020

• Covenor, Hostel Management Committee, from 04.08.025 to present

• Member Secretary/ Convenor, Anti-Ragging Committee, from 28.08.2025 to present

• Member Secretary/ Convenor, Hostel Patrolling Committee, from 28.08.2025 to present

• Warden, 1st Year Boy's Hostel from 01.07.2025 to present

• Prof-in-Charge, Centre for Career Development from 17.01.2019 to 06.07.2025.

• Warden (Lapalang 3 and 4 Hostels) from 01.07.2016 to 01.06.2018
  GATE coordinator for TEQIP III 29.05.2019 to 31.03.2022 
  Convener, Invitation & reception sub-committee 10th Convocation of NIT Meghalaya 2023
  Convenor, Invitation Committee, Institution Foundation Day 2023
  Convenor, Invitation Committee, Institution Foundation Day 2024
  Lab in Charge, Computational Lab, 16/11/2022 to present
  Chairman, Industrial Visit Committee10.10.2022 to present
  Faculty Advisor, 17.12.2018 to present
  BTech-MTech Project Coordinator, 01.12.2015 to 01.01.2021
  Preparation of Institute Ranking, Member, from 2015-16
  Exploring International Collaboration and Cooperation, Member, from 2015-16
  Food Committee, Convocation, Member, from 2015-16
  Grade Evaluation Committee, ME, Member, from 2015-16
  Physical Verification of Departmental Stock, Member, from 2015-16
  Screening & Selection Committee for PhD Enrollment, Member, from 2015-16
  Committee for opening quotations for supply of consumables, Member, from 2015-16
  Mentor Faculty for 1st and 2nd year B.Tech Student, Mentor, from 2015-16
  Screening Committee for TA, ME, Chairman, from 2015-16
  Screening Committee for MTS (Fitter), Member, from 2015-16
  Advisory Committee, Member, from 2016
  Food Committee, Institute Day, Member, from 2016
  Food Committee, Convocation, 2016, Member, from 2016

Conferences:

Workshops:

·         Served as a resource person to conduct an interactive session on different aspects of higher studies/ research on 7th June 2022 from 1:00 pm at the Seminar Hall, Department of Energy, Tezpur University. Tezpur 784028, Assam.

·         Served as an expert in the Interview Board Committee for the interview for the Post of Placement Officer in St. Anthony's College, Shillong, held on 28th October 2022.

·         Expert lecture delivered on “Solar Based Heating, Cooling and Dehumidification Systems” in the Online self-financed Short-Term Course on 'Emerging Trends in Renewable Energy technologies (ETRET-2022)' organized by the Department of Mechanical Engineering, Motilal Nehru National Institute of Technology (M.N.N.I.T.) Allahabad, Prayagraj-211004, U.P., from 20th to 24th June, 2022.

·         A thematic talk delivered on “Thermohydraulic Performance of a Novel Solar-based Air Heating System” On 24^th September 2021 In1st International Conference on “Advances in Fluid Flow and Thermal Sciences (ICAFFTS-2021)” organized by Department of Mechanical Engineering, SVNIT Surat, Gujarat.

·         Served as Session Chair at the 4th ICEPE 2022 Organized by Department of Electrical Engineering, National Institute of Technology Meghalaya during 29th April – 01st May, 2022.

·         Served as an External Expert for Mr. Sandipan Roy (2021AMM019) on his MTech Thesis entitled “Aerodynamics of novel 3D printed biomimicking flapping wing” held on 06-07-2023 through online mode in the Department of Aerospace and Applied Mechanics, IIEST Shibpur, West Bengal, India.

·         Served as an External Expert for Mr. Ankit Kumar (2020AMM028) on his MTech Thesis entitled “Design, fabrication and testing of a 6-component platform balance for measuring aerodynamic forces and moments of a tube launched UAV” held on 11-08-2022 through online mode in the Department of Aerospace and Applied Mechanics, IIEST Shibpur, West Bengal, India.

·         Served as an external examiner for Practical Examination of EN566 Energy laboratory-I practical examinations of M.Tech in Energy Technology Programme, scheduled on 6-7 June, 2022, in the Department of Energy, Tezpur University, Tezpur, Assam, India.

Reviewed 04 nos. of DST SERB projects under CRG scheme.