TY - JOUR
T1 - Numeric study of geothermal borehole heat exchanger enhancement via phase change material macro encapsulation
AU - Conde, José Manuel Paixão
AU - Pássaro, João
AU - Rebola, A.
AU - Coelho, Luis
N1 - info:eu-repo/grantAgreement/EC/H2020/680555/EU#
Funding text
This article reflects only the authors’ view and the European Commission is not responsible for any use that may be made of the information it contains. This publication was supported by the Polytechnic Institute of Setúbal, Portugal .
PY - 2022/11
Y1 - 2022/11
N2 - This article addresses the theoretical effect of using geothermal boreholes enhanced with macro-encapsulated phase change materials (PCM) employed with a ground sourced heat pump (GSHP). The aim being the improvement of the heat pump performance through soil temperature stabilisation, taking advantage from the PCM inherent property of changing phase at a constant temperature, that can be matched with the temperature of the surrounding soil, contributing as well to increase the energy storage capacity underground. The numeric work studied different PCM thermal parameters with regards to their influence on the overall behaviour of the heat pump, with different operation modes (On/Off and Inverter) changing the solidus and liquidus temperatures and phase change enthalpy values. The CFD results showed that, while it underperformed having 0.15% difference in the best of cases (specifically the On/Off mode), it used in the best case scenario only 30% of the stored energy in the PCM. The application of macro-encapsulation did provide a stabilising effect to the soil and heap pump operation as it was originally intended to do, helping reduce energy expenditure by the system. Significant modifications are needed in order to improve, both concerning geometry and encapsulation techniques to overcome the PCM and other materials thermal limitations.
AB - This article addresses the theoretical effect of using geothermal boreholes enhanced with macro-encapsulated phase change materials (PCM) employed with a ground sourced heat pump (GSHP). The aim being the improvement of the heat pump performance through soil temperature stabilisation, taking advantage from the PCM inherent property of changing phase at a constant temperature, that can be matched with the temperature of the surrounding soil, contributing as well to increase the energy storage capacity underground. The numeric work studied different PCM thermal parameters with regards to their influence on the overall behaviour of the heat pump, with different operation modes (On/Off and Inverter) changing the solidus and liquidus temperatures and phase change enthalpy values. The CFD results showed that, while it underperformed having 0.15% difference in the best of cases (specifically the On/Off mode), it used in the best case scenario only 30% of the stored energy in the PCM. The application of macro-encapsulation did provide a stabilising effect to the soil and heap pump operation as it was originally intended to do, helping reduce energy expenditure by the system. Significant modifications are needed in order to improve, both concerning geometry and encapsulation techniques to overcome the PCM and other materials thermal limitations.
KW - CFD melting/solidification model
KW - Ground sourced heat pump
KW - Ground thermal stabilisation
KW - Latent heat storage system
KW - Macro-encapsulated phase change material
U2 - 10.1016/j.ijft.2022.100245
DO - 10.1016/j.ijft.2022.100245
M3 - Article
VL - 16
JO - International Journal of Thermofluids
JF - International Journal of Thermofluids
M1 - 100245
ER -