Thesis
A computational approach to the sizing of heat pump integrated thermal energy storage systems for wet central heating
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2025
- Thesis identifier
- T17301
- Person Identifier (Local)
- 201871275
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Integrating heat pumps with a TES system provides a suitable and efficient solution for replacing a gas-fired boiler within a wet central heating system for residential buildings. This approach addresses the growing demand for energy-efficient and low-carbon technologies. The system enhances the efficacy of residential heating by shifting energy consumption to off-peak periods and improving heat distribution during peak demand. This study assesses the feasibility of a phase change-based TES system for load-shifting capabilities in residential heating. The study explores the application of CFD and building simulation models to evaluate the performance of a heat pump-integrated TES system in meeting the full space heating needs of a detached dwelling. The engineering modelling method was employed to estimate the next-day heat demand for a dwelling using the ESP-r tool. This approach facilitates comprehensive simulations that considers the building's physical and thermal characteristics, construction materials, occupancy patterns and weather data to predict the next-day space heat demand of the dwelling. This predictive capability provides a robust foundation for sizing a TES system. A phase change TES model was developed using the enthalpy formulation method, with the thermal store modelled in the Fluent CFD tool. This involved a single shelland-tube heat exchanger, comprising PCM in the annular-gap and HTF flowing through the tube. The TES model was validated by comparing its simulated fluid outlet temperature and temperature profiles at different positions with the results reported by Longeon et al. [186]. The results showed that the simulated data closely agreed with the experimental and numerical findings. This demonstrated that the CFD model can reliably predict the heat transfer characteristics and thermal behaviour of the TES system during the charging and discharging phases. The TES system sizing was demonstrated by utilising the dwelling’s peak day heat demand profile to determine the maximum storage capacity. which is then sufficient to meet any daily heat demand throughout the heating season. The thermal behaviour and characteristics of the TES system were evaluated by simulating the charging process of the thermal store using mass flow rates and temperature conditions representative of a typical ASHP. The results indicate that system efficiency depends on the type of PCM used, the heat pump’s mass flow rate, and the charging strategies employed. A linkage between the dwelling and TES system model was established using a rudimentary model to determine radiator return temperatures during TES utilisation (discharge). Simulating the discharge of the TES system using the radiator fluid outlet temperature at variable inlet mass flow rates provides the heat output, necessary to fulfil the space heating needs of the dwelling. The results obtained from discharging the TES system indicate a total heat output of 37.44 kWh, with peak and average discharge rates of 1.73 kW and 1.56 kW respectively used to match the detached dwelling’s peak day heat demand profile. A statistical analysis using the Pearson correlation coefficient shows a 94% match rate between the TES discharge rate and the dwelling heat demand profiles, indicating that they are in close agreement. The TES system discharge achieved a fluid output temperature of 60–40˚C. The fluid output temperature obtained, can effectively meets the space heating needs of the dwelling when larger radiators are used. However, the result of the analysis further indicates that this fluid output temperature is well-suited for underfloor heating systems or radiators designed for low-output temperature applications, particularly when advanced control systems are employed to ensure thermal comfort in buildings. The study contributes to knowledge by developing a detailed procedure for sizing a heat pump-integrated TES system for wet central heating. The developed methodology was proved by assessing the load-shifting capability of the TES system in meeting the continuous full day space heating needs of the detached dwelling. The study further contributes to knowledge by developing the control procedure for charging and discharging the TES system.
- Advisor / supervisor
- Clarke, J. A. (Joe A.)
- Cóstola, Daniel
- Resource Type
- DOI
- Date Created
- 2024
Relations
Items
| Thumbnail | Title | Date Uploaded | Visibility | Actions |
|---|---|---|---|---|
|
|
PDF of thesis T17301 | 2025-04-22 | Public | Download |