Title: A numerical investigation on how to efficiently utilise carbon dioxide in convection-based energy systems

Authors: Yuhui Cao; Xin-Rong Zhang

Addresses: College of Physics, University of Chinese Academy of Sciences, Room N606, Teaching Building, No. 3 Zhongguancun-Nanyitiao Road, Haidian District, Beijing 100094, China ' Department of Energy and Resources Engineering, College of Engineering, Peking University, No. 5 Yiheyuan Road, Haidian District, Beijing, 100871, China

Abstract: Owing to the environmentally benign nature and the special property variation at supercritical pressure, greenhouse gas carbon dioxide is regarded as the best retrofit to meet the future demand on long-term environmental-friendly working fluids. However, how to efficiently utilise carbon dioxide to reduce energy consumption and mitigate global warming is still an unsolved problem. In this paper, the natural convection heat transfer of carbon dioxide under supercritical pressure condition in a small cavity is studied for the first time. The potential of carbon dioxide as working fluid is quantitatively estimated in terms of enhancing heat transfer and reducing the cost of heat exchangers. It is found that the operating conditions including the temperature, temperature difference and pressure all have significant effects on heat transfer rate due to the special property variations of the CO₂ fluid. Furthermore, a heat transfer correlation is proposed for the first time to quantitatively describe the natural convection heat transfer of CO₂ at supercritical pressure in a small cavity.

Keywords: carbon dioxide; CO2 fluids; natural convection; heat transfer; global warming; environmentally-friendly working fluids; energy consumption; supercritical pressure; heat exchangers; temperature; small cavities.

DOI: 10.1504/IJGW.2016.079773

International Journal of Global Warming, 2016 Vol.10 No.4, pp.404 - 422

Received: 04 Sep 2014
Accepted: 06 Feb 2015
Published online: 14 Oct 2016 *

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