Comparative Analysis of Small-Scale Organic Rankine Cycle Systems for Solar Energy Utilisation

Zhiwei Ma,Abigail Gonzalez-Diaz,Long Jiang,Yaodong Wang,Ruiqi Wang,Anthony Roskilly

doi:10.3390/en12050829

Zhiwei Ma, Abigail Gonzalez-Diaz + Show 4 more

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https://doi.org/10.3390/en12050829

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Journal: Energies	Publication Date: Mar 2, 2019
Citations: 28	License type: CC BY 4.0

Affiliation: Newcastle University

Abstract

Small-scale organic Rankine cycle (ORC) systems driven by solar energy are compared in this paper, which aims to explore the potential of power generation for domestic utilisation. A solar thermal collector was used as the heat source for a hot water storage tank. Thermal performance was then evaluated in terms of both the conventional ORC and an ORC using thermal driven pump (TDP). It is established that the solar ORC using TDP has a superior performance to the conventional ORC under most working conditions. Results demonstrate that power output of the ORC using TDP ranges from 72 W to 82 W with the increase of evaporating temperature, which shows an improvement of up to 3.3% at a 100 °C evaporating temperature when compared with the power output of the conventional ORC. Energy and exergy efficiencies of the ORC using TDP increase from 11.3% to 12.6% and from 45.8% to 51.3% when the evaporating temperature increases from 75 °C to 100 °C. The efficiency of the ORC using TDP is improved by up to 3.27%. Additionally, the exergy destruction using TDP can be reduced in the evaporator and condenser. The highest exergy efficiency in the evaporator is 96.9%, an improvement of 62% in comparison with that of the conventional ORC, i.e., 59.9%. Thus, the small-scale solar ORC system using TDP is more promising for household application.

Highlights

Solar thermal technology is gathering the momentum to meet household demands for both heating and electricity in the UK [1]
Considerable progress has been made in the development of solar organic Rankine cycle (ORC) systems for small-scale power generation [6,7]
Solar hot water with different temperatures ranging from 34 ◦ C to 122.6 ◦ C is adopted to drive the ORC system, and the evaporating temperature is fixed at 80 ◦ C

Summary

Introduction

Solar thermal technology is gathering the momentum to meet household demands for both heating and electricity in the UK [1]. Due to the relatively low annual yield of incident solar radiation, low-temperature heat source recovery technologies have become more significant, e.g., thermoelectric power and the organic Rankine cycle (ORC), when considering thermal efficiency and system compactness [2,3]. Compared with the poor efficiency of thermoelectric power at low solar radiation, the ORC could be a better candidate for distributed household applications, as it is able to operate efficiently and affordably at relatively low working temperatures [4,5]. Considerable progress has been made in the development of solar ORC systems for small-scale power generation [6,7].

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