Energy and Exergy Analysis of an Ejector Expansion Transcritical Carbon Dioxide Air Conditioning System

Abstract

A carbon dioxide based transcritical air conditioning system integrated with an ejector is thermodynamically modeled and the system is simulated for different ambient conditions. Throughout the analysis, the isentropic efficiency of motive nozzle, suction nozzle and diffuser is assumed as 85% while the mixing takes place at constant pressure. A step-by-step iterative procedure is adopted to obtain the pressure lift and entrainment ratio. The present thermodynamic model is validated with the experimental results available in the open literature. Results were then compared to a conventional transcritical carbon dioxide system working between the same operating conditions. Results show a significant improvement of about 21% and more in system performance compared to a conventional system working under the same operating conditions. To justify the application of an ejector as an expansion work recovery device and to identify the component level exergy destruction rate, a comprehensive exergy analysis is implemented and the results show 20% reduction in total exergy destruction rate of the system, with an ejector.

Acknowledgements

The authors acknowledge the facilities and support provided by Vellore Institute of Technology-Vellore, for carrying out this research work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Jobel Jose

Jobel Jose is a full-time research scholar at Vellore Institute of Technology, Vellore, India. He received his MTech degree in 2019 in thermal engineering and Btech degree in 2017 in mechanical engineering from Karunya Institute of Technology and Sciences, Coimbatore, India. He has published an Indian Patent titled “Specnoscope”, one research article and one conference paper. His research interests are in the field of transcritical CO₂ refrigeration and air conditioning system, heat transfer studies and clean energy technologies.

Parthasarathy Rajesh Kanna

Parthasarathy Rajesh Kanna is a Professor in the CO₂ Research and Green Technologies Research Center, Vellore Institute of Technology Vellore, India. He received his PhD from Indian Institute of Technology Guwahati, India in 2006 and Masters from Bharathiar University, India (2000). He has coauthored more than 90 international publications which includes refereed journals and conferences. He received his D.Sc. degree from Cracow University of Technology, Poland (2015). His research interest includes fluid dynamics, heat transfer, CO₂ refrigeration and green energy technologies.

Senthil Kumar Arumugam

Senthil Kumar Arumugam obtained his doctoral degree from Indian Institute of Science, Bangalore in the field of Cryogenics. He carried out his post-doctoral research in the field of sub-millimeter gravitational force at Washington University in St. Louis, USA. He has more than 30 years of experience in teaching and research. His research interests include cryogenic heat pipes, CFD analysis of steam turbine exhaust-hood, transcritical CO₂ refrigeration, and solid hydrogen extrusion. He has successfully handled three funded research projects and six consultancy projects. He has published over fifty research papers in international journals and conferences. He is a fellow of Institution of Engineers, India.