Imperial College London


Faculty of EngineeringDepartment of Chemical Engineering

Professor of Clean Energy Technologies



+44 (0)20 7594 1601c.markides Website




404ACE ExtensionSouth Kensington Campus






BibTex format

author = {Unamba, CK and White, M and Sapin, P and Freeman, J and Lecompte, S and Oyewunmi, OA and Markides, CN},
doi = {10.1016/j.egypro.2017.09.211},
pages = {875--882},
publisher = {Elsevier Science BV},
title = {Experimental investigation of the operating point of a 1-kW ORC system},
url = {},
year = {2017}

RIS format (EndNote, RefMan)

AB - The organic Rankine cycle (ORC) is a promising technology for the conversion of waste heat from industrial processes as well as heat from renewable sources. Many efforts have been channeled towards maximizing the thermodynamic potential of ORC systems through the selection of working fluids and the optimal choice of operating parameters with the aim of improving overall system designs, and the selection and further development of key components. Nevertheless, experimental work has typically lagged behind modelling efforts. In this paper, we present results from tests on a small-scale (1 kWel) ORC engine consisting of a rotary-vane pump, a brazed-plate evaporator and a brazed-plate condenser, a scroll expander with a built-in volume ratio of 3.5, and using R245fa as the working fluid. An electric oil-heater acted as the heat source, providing hot oil at temperatures in the range 120-140 °C. The frequency of the expander was not imposed by an inverter or the electricity grid but depended directly on the attached generator load; both the electrical load on the generator and the pump rotational speed were varied in order to investigate the performance of the system. Based on the generated data, this paper explores the relationship between the operating conditions of the ORC engine and changes in the heat-source temperature, pump and expander speeds leading to working fluid flow rates between 0.0088 kg/s and 0.0337 kg/s, from which performance maps are derived. The experimental data is, in turn, used to assess the performance of both the individual components and of the system, with the help of an exergy analysis. In particular, the exergy analysis indicates that the expander accounts for the second highest loss in the system. Analysis of the results suggests that increased heat-source temperatures, working-fluid flow rates, higher pressure ratios and larger generator loads improve the overall cycle efficiency. Specifically, a 46% increase in pressure ratio from 2.4
AU - Unamba,CK
AU - White,M
AU - Sapin,P
AU - Freeman,J
AU - Lecompte,S
AU - Oyewunmi,OA
AU - Markides,CN
DO - 10.1016/j.egypro.2017.09.211
EP - 882
PB - Elsevier Science BV
PY - 2017///
SN - 1876-6102
SP - 875
TI - Experimental investigation of the operating point of a 1-kW ORC system
UR -
UR -
UR -
ER -