Phase Change Material Thermal Store for Predictive Hot Water Supply
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Solution Overview
Problem
Heat pumps are unsuitable for replacing gas-fired boilers in smaller domestic and commercial premises due to their large size, high cost, complex installation, and inability to quickly respond to hot water demands, making them impractical for retrofitting and inefficient in providing instantaneous hot water.
Innovation Solution
A hot water supply system utilizing a thermal energy store with a phase change material (PCM) that receives energy from renewable sources, allowing for pre-charging based on predicted demand, reducing reliance on fossil fuels and improving energy efficiency by diverting heat from renewable sources to the PCM rather than using it for immediate heating needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If heat pumps are used to replace gas-fired boilers, then renewable energy usage is improved, but device size and installation complexity increase
Solution Approach 1:
The system is divided into separate functional modules: a heat pump unit for thermal energy generation, a thermal energy storage unit with phase change material for energy storage, and a hot water supply system. This segmentation allows each component to be optimized independently and installed in smaller domestic premises without requiring a single large complex unit.
Solution Approach 2:
The thermal energy storage unit with phase change material is integrated within or alongside the heat pump system, creating a compact nested arrangement. The PCM storage unit can be positioned within the heat pump housing or adjacent to it, maximizing space utilization in small premises while maintaining both renewable energy generation and storage capabilities.
2Use of energy by moving object
If heat pumps are used to provide instantaneous hot water, then fossil fuel reliance is reduced, but response time to hot water demand worsens
Solution Approach 1:
The thermal energy storage unit with phase change material pre-stores thermal energy generated by the heat pump or from other renewable sources. When hot water is demanded, the stored thermal energy is immediately released, providing instantaneous hot water without waiting for the heat pump to start up and heat the water, thus improving response time while maintaining reduced fossil fuel reliance.
3Loss of energy
If thermal energy storage with phase change material is implemented, then energy efficiency is improved, but device volume increases
Solution Approach 1:
The system utilizes phase change material that transitions between solid and liquid phases at specific temperatures to store and release thermal energy. This phase transition mechanism allows for high energy density storage in a compact volume, as the latent heat of fusion/condensation provides significant energy storage capacity without requiring large physical space, thus improving energy efficiency while minimizing volume increase.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides efficient and cost-effective hot water supply, reducing energy consumption and reliance on fossil fuels, while enabling the use of renewable energy sources, particularly in smaller dwellings where space and installation complexity are concerns.
Implementation Method 1
a thermal energy store, containing an energy storage medium comprising a phase change material to store energy as latent heat
Implementation Method 2
the hot water supply system being operable, under the control of the processor, to heat water that is to be supplied to the hot water outlet to a target system supply temperature using a selection of one or more of the renewable energy source, energy from the thermal energy store
Data Source
AI summary
There is provided a hot water supply system including: a controllable hot water supply outlet having when fully opened a given flowrate; a thermal energy store, containing an energy storage medium comprising a phase change material to store energy as latent heat, that is configured to receive energy from a source of renewable energy; a renewable energy source; the hot water supply system being operable, under the control of the processor, to heat water that is to be supplied to the hot water outlet to a target system supply temperature using a selection of one or more of the renewable energy source, energy from the thermal energy store, and optionally an auxiliary water heater intermediate the thermal energy store and the hot water supply outlet; wherein the thermal energy store has an energy storage capacity, when fully charged, that is sufficient to provide hot water to the hot water outlet, at the given flowrate, and at the target system supply temperature for a period of at least 8 minutes, and preferably at least 10 minutes; wherein the renewable energy source is also configured to provide building heating under control of the processor; the processor being configured to: monitor actual demand for hot water from the hot water supply system; predict future demand for hot water from the hot water supply system based on the monitored actual demand; pre-charge the thermal energy store so that sufficient energy will be stored in the thermal energy store to satisfy the predicted demand; and to temporarily divert heat from the renewable energy source to charge the phase change material rather than to provide building heating. A corresponding method is also provided.