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 = {Kadivar, MR and Moghimi, MA and Sapin, P and Markides, CN},
doi = {10.1016/j.est.2019.101030},
journal = {Journal of Energy Storage},
title = {Annulus eccentricity optimisation of a phase-change material (PCM) horizontal double-pipe thermal energy store},
url = {},
volume = {26},
year = {2019}

RIS format (EndNote, RefMan)

AB - The application of phase-change materials (PCMs) has received significant interest for use in thermal energy storage (TES) systems that can adjust the mismatch between the energy availability and demand. In the building sector, for example, PCMs can be used to reduce air-conditioning energy consumption by increasing the thermal capacity of the walls. However, as promising this technology may be, the poor thermal conductivity of PCMs has acted as a barrier to its commercialization, with many heat-transfer enhancement solutions proposed in the literature, such as microencapsulation or metal foam inserts, being either too costly and/or complex. The present study focuses on a low-cost and highly practical solution, in which natural-convective heat transfer is enhanced by placing the PCM in an eccentric annulus within a horizontal double-pipe TES heat exchanger. This paper presents an annulus-eccentricity optimisation study, whereby the optimal radial and tangential eccentricities are determined to minimize the charging time of a PCM thermal energy store. The storage performance of several geometrical configurations is predicted using a computational fluid dynamics (CFD) model based on the enthalpy-porosity formulation. The optimal geometrical configuration is then determined with response surface methods. The horizontal double-pipe heat exchanger studied considered here is an annulus filled with N-eicosane as the PCM for initial studies. In presence of N-eicosane, for the concentric configuration (which is the baseline case), the charging is completed at Fo=0.64, while the charging of optimum eccentric geometries with the quickest and slowest charging is completed at Fo=0.09 and Fo=2.31, respectively. In addition, an investigation on the discharging performance of the studied configurations with N-eicosane shows the quickest discharge occurs with the concentric annulus case at Fo=0.99, while the discharge time of the proposed optimum annuli is about three times
AU - Kadivar,MR
AU - Moghimi,MA
AU - Sapin,P
AU - Markides,CN
DO - 10.1016/j.est.2019.101030
PY - 2019///
SN - 2352-152X
TI - Annulus eccentricity optimisation of a phase-change material (PCM) horizontal double-pipe thermal energy store
T2 - Journal of Energy Storage
UR -
UR -
UR -
VL - 26
ER -