title: Optimisation Of Inter- Seasonal Ground Source Heat Pumps With Predictive Behavioural Control
Creators: name: Yebiyo, M
Publisher: name: London South Bank University
Year: 2016

description: In practice, heat pumps (HP) often do not perform as expected. This is due to many factors
such as how well the system and the ground loop are designed, installed and subsequently
maintained and how well they are operated and controlled in the field. Improving overall
system design and demonstrating increased HP performance and higher reliability are core
objectives for this research. Performance instability and variations in ground source heat
pump (GSHP) system output has been observed previously and this indicates that detailed
research is required for example (i) to identify the relationship between dynamic performance
and seasonal ground temperature patterns, (ii) to address the operation, installation and
control opportunities that arise from (i). This project investigates all of these issues.
This thesis focuses on the monitoring of the long-term operation of a 500 kW installed GSHP
system with the aim of understanding and establishing the current trend performance
characteristics of the installation. The research involved combination of experimental
measurements and analysis, mathematical simulation and the development of an empirical
transient model that could be generally applied.
Despite the importance of the effect of ground temperatures on performance, relatively little
data has been published on the effect of disturbed underground temperature distributions. The
author has therefore developed a novel mathematical model for the analysis of disturbed
ground temperatures over time. The novel mathematical model developed has been used to
predict the disturbed seasonal underground temperatures based on daily fluid and air
temperature data and has been validated against real historical data.
It was concluded from the critical literature review that the dynamic long term performance
investigation of GSHP systems using transient models is not well understood. Therefore the
work described in this thesis has focused on the development of a generic empirical transient
system model of a GSHP system. This model has been developed using TRNSYS 17 software. This has permitted investigation of the effects of different control strategies using a
dry air cooler (DAC) for heat rejection, energy consumption of the HP, the overall
performance of the system and ground temperature variations.
The main novelty and contributions to science from this work is:
 The better understanding of the effect of ground temperature variation over time and
its effect on the system’s performance.
 The development of new measurement methods for assessing system performance.
 The use of ground temperature in the prediction and control of system performance,
together with an analysis of the effects of specific interventions or control
methodologies.
 The development of a novel mathematical model for predicting disturbed ground
temperature.
 The development of a novel GSHP model using TRNSYS.
 The development and investigation of novel control strategies using DAC.