S. Quoilin1*, M. Orosz2 and V. Lemort1

1 University of Liege, Thermodynamics Laboratory, Campus du Sart-Tilman, Liege, Belgium
Massachusetts Institute of Technology, Department of civil and environmental engineering, USA
* Corresponding Author, squoilin@ulg. ac. be

Abstract

This study aims at developing and optimizing an Organic Rankine Cycle (ORC) for a small scale, decentralized parabolic trough system.

A numerical model the Organic Rankine Cycle is developed and an experimental study is carried out on an ORC prototype working with refrigerant HCFC-123, and whose heat sources consist in two hot air flows. The ORC model is built by connecting different sub-models: the heat exchanger models, a volumetric pump model and a scroll expander model. Measured performances of the ORC prototype are presented and allow the validation of the ORC model.

Keywords: Organic Rankine Cycle, Concentrating solar power, Parabolic trough

1. Introduction

Currently 1.6 billion people worldwide lack access to electricity [4]. Many communities will continue to lack access to centralized grid infrastructure due to remoteness or to the poor rates of return on investment in grid extension. Small scale, decentralized concentrating solar power can constitute a cost effective energy solution for remote places with a high solar irradiation.

Organic Rankine cycles (ORC) are particularly suitable for small scale parabolic trough systems, since they can generate electricity at a lower temperature than the conventional steam Rankine cycle.

Simulation models of ORC are necessary to optimize the operating conditions and the components of the cycle. Previous studies have demonstrated the influence of the working fluid thermodynamic properties on ORC performance [1, 6, 8]. However, until now, relatively few papers present a detailed simulation model for an ORC [4, 10, 12].

This paper presents both a numerical simulation model of an ORC and the results of an experimental study used to validate the simulation model. Special attention is paid to the expander, since it is a key component for global cycle performance.