Evaluation of isopentane, R-245fa and their mixtures as working fluids for organic Rankine cycles

Garg, Pardeep and Kumar, Pramod and Srinivasan, Kandadai and Dutta, Pradip (2013) Evaluation of isopentane, R-245fa and their mixtures as working fluids for organic Rankine cycles. In: APPLIED THERMAL ENGINEERING, 51 (1-2). pp. 292-300.

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Abstract

Low grade thermal energy from sources such as solar, geothermal and industrial waste heat in the temperature range of 380-425 K can be converted to electrical energy with reasonable efficiency using isopentane and R-245fa. While the former is flammable and the latter has considerable global warming potential, their mixture in 0.7/0.3 mole fraction is shown to obviate these disadvantages and yet retain dominant merits of each fluid. A realistic thermodynamic analysis is carried out wherein the possible sources of irreversibilities such as isentropic efficiencies of the expander and the pump and entropy generation in the regenerator, boiler and condenser are accounted for. The performance of the system in the chosen range of heat source temperatures is evaluated. A technique of identifying the required source temperature for a given output of the plant and the maximum operating temperature of the working fluid is developed. This is based on the pinch point occurrence in the boiler and entropy generation in the boiling and superheating regions of the boiler. It is shown that cycle efficiencies of 10-13% can be obtained in the range investigated at an optimal expansion ratio of 7-10. (C) 2012 Elsevier Ltd. All rights reserved.

Item Type:	Journal Article
Publication:	APPLIED THERMAL ENGINEERING
Publisher:	PERGAMON-ELSEVIER SCIENCE LTD
Additional Information:	Copyright for this article belongs to the PERGAMON-ELSEVIER SCIENCE LTD, ENGLAND.
Keywords:	Organic Rankine cycles; Hydrocarbons; Refrigerants; Mixtures; Irreversibility
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	17 Apr 2013 05:46
Last Modified:	17 Apr 2013 05:46
URI:	http://eprints.iisc.ac.in/id/eprint/46389

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