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 = {Chatzopoulou, MA and Markides, C},
doi = {10.1016/j.apenergy.2018.06.022},
journal = {Applied Energy},
pages = {1229--1251},
title = {Thermodynamic optimisation of a high-electrical efficiency integrated internal combustion engine – organic Rankine cycle combined heat and power system},
url = {},
volume = {226},
year = {2018}

RIS format (EndNote, RefMan)

AB - Organic Rankine cycle (ORC) engines are suitable for heat recovery from internal combustion engines (ICE) in combined heat and power (CHP) systems. However, trade-offs must be considered between ICE andORC engine performance in such integrated solutions. The ICE design and operational characteristics influence its own performance along withthe exhaust-gas conditions available as heat source to the ORC engine, impacting ORC design and performance, while the heat-recovery heat exchanger (ORC evaporator) will affect the ICE operation. In this paper, an integrated ICE-ORC CHP whole-system optimisation framework is presented. This differs from other efforts in that we develop and apply a fully-integrated ICE-ORC CHP optimisation framework, considering the design and operation of both the ICE and ORC enginessimultaneously within the combined system, to optimise the overall system performance. A dynamic ICE model is developed and validated, along with a steady-state model of subcritical recuperative ORC engines. Both naturally aspirated and turbocharged ICEs are considered, of two different sizes/capacities. Nine substances (covering low-GWP refrigerants and hydrocarbons) are investigated as potential ORC working fluids. The integrated ICE-ORC CHP system isoptimised for eithermaximum total power output, or minimum fuel consumption. Resultshighlight that by optimising the complete integrated ICE-ORC CHP system simultaneously, the total power output increases by up to 30% in comparison to a nominal system design. In the integrated CHP system,the ICE power output is slightly lower than that obtained for optimal standalone ICE application, as the exhaust-gas temperature increases to promote the bottoming ORC engine performance, whose power increasesby 7%. The ORC power output achieved accounts for up to 15% of the total power generated by the integrated system, increasing the system efficiency by up to 11%. When only power optimisation is performed, the
AU - Chatzopoulou,MA
AU - Markides,C
DO - 10.1016/j.apenergy.2018.06.022
EP - 1251
PY - 2018///
SN - 0306-2619
SP - 1229
TI - Thermodynamic optimisation of a high-electrical efficiency integrated internal combustion engine – organic Rankine cycle combined heat and power system
T2 - Applied Energy
UR -
UR -
VL - 226
ER -