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 = {Simpson, M and Rotolo, G and Sapin, P and De, Palma P and White, AJ and Markides, CN},
publisher = {ICHMT},
title = {Thermodynamic performance maps of reciprocating-piston expanders for operation at off-design and part-load conditions},
url = {},
year = {2017}

RIS format (EndNote, RefMan)

AB - Renewable energy sources, such as solar-thermal or geothermal heat, and low-/medium-grade industrial waste-heat can be converted into useful power and/or heating with a variety of technologies, including organic Rankine cycle (ORC) and vapour-compression heat-pump systems. The thermodynamic performance and cost of these technologies depends crucially on the efficiency of key components, including the compressor or expander used. Reciprocating-piston machines can be advantageous over turbomachines and other positive-displacement machines at intermediate scales (~10s-100s of kW) thanks to their ability to operate with relatively high isentropic efficiencies at large expansion ratios. However, modelling the thermodynamic losses in reciprocating-piston expanders, with a view towards designing high-performance machines, is a complex undertaking. The aim of this paper is to develop a spatially-lumped, yet dynamic model of a piston expander suitable for early-stage engineering design, that can provide simplification without sacrificing accuracy. The unsteady heat transfer between the gas and the cylinder walls, and the mass leakage are predicted independently with correlations available in the literature and simplified one-dimensional models, respectively. However, the turbulence induced by the mass intake through the piston rings can affect the gas-to-wall heat transfer. In order to address this dependency two complementary approaches are used. Compression and expansion processes are simulated in a gas spring configuration (i.e. without valve systems) using a computational fluid dynamics (CFD) model developed using the open-source code OpenFOAM, where the loss mechanisms are solved directly. The results are then compared with predictions from the heuristic lumped model based on heat tr
AU - Simpson,M
AU - Rotolo,G
AU - Sapin,P
AU - De,Palma P
AU - White,AJ
AU - Markides,CN
PY - 2017///
TI - Thermodynamic performance maps of reciprocating-piston expanders for operation at off-design and part-load conditions
UR -
ER -