Hot water supply
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Solution Overview
Problem
Heat pumps used for hot water supply in domestic and small commercial premises face delays and limitations in responsiveness compared to traditional gas boilers, with inefficiencies in energy usage and availability, particularly due to their inability to match the rapid response and frequent activation requirements of gas boilers.
Innovation Solution
A hot water supply system incorporating an energy storage arrangement with phase-change materials, a heat exchanger, and a supplementary heater, controlled by a controller that manages the use of both heat pump and supplementary heater to bridge delays and optimize energy usage, prioritizing 'green' energy sources and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a heat pump is used to heat water, then energy efficiency is improved (up to four or more times as efficient as electrical heater), but responsiveness deteriorates (delay of up to several minutes between power-up and supply of heated water)
Solution Approach 1:
The system pre-heats water using the heat pump during periods when hot water is not immediately needed, storing the heated water in a storage tank. This preliminary action allows the system to bypass the startup delay when hot water is demanded, as pre-heated water is already available for immediate delivery.
Solution Approach 2:
The hot water supply system is divided into two functional segments: a storage tank that holds pre-heated water for immediate delivery, and a heat pump system that performs the energy-efficient heating operation. This segmentation allows each component to perform its optimized function independently.
2Speed
If a heat pump is activated frequently to meet hot water demand, then responsiveness is improved, but reliability deteriorates (heat pumps have a limit on how often they can be activated and can be unavailable during defrost cycles)
Solution Approach 1:
The system maintains a reservoir of pre-heated water in the storage tank, allowing it to meet hot water demands without immediately activating the heat pump. This preliminary preparation ensures that the heat pump doesn't need to频繁 start and stop, preserving its reliability and avoiding defrost cycle interruptions.
Solution Approach 2:
The storage tank acts as an intermediary between the heat pump and the hot water demand. It buffers the system by storing thermal energy, allowing the heat pump to operate on its own schedule without being forced into frequent activation cycles that would compromise its reliability.
3Loss of time
If a traditional gas boiler is used, then responsiveness is improved (rapid response to hot water demand), but harmful factors increase (burning fossil fuels causing environmental damage)
Solution Approach 1:
The system replaces the combustion-based heating mechanism of traditional gas boilers with a heat pump-based thermal transfer mechanism. This substitution eliminates fossil fuel consumption and associated environmental harm while maintaining energy efficiency through the use of electricity-driven refrigeration technology.
Solution Approach 2:
The system changes the fundamental operating parameter from combustion temperature (high temperature direct heating) to refrigeration cycle temperature (lower temperature thermal transfer). This parameter change enables the use of electricity instead of fossil fuels, eliminating harmful emissions while achieving the desired hot water temperature through the heat pump and storage tank combination.
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 effectively reduces wait times for hot water, optimizes energy usage by preferentially using heat pump energy, and minimizes the reliance on fossil fuels by strategically activating the supplementary heater, thereby enhancing efficiency and reducing wear and tear on the heat pump.
Implementation Method 1
an energy storage arrangement, which contains a mass of phase-change material, for connection to a heat pump
Implementation Method 2
a heat exchanger associated with the energy storage arrangement
Data Source
AI summary
A hot water supply system 400 comprises a cold water inlet 402 coupled to a valve 404 which determines the degree of flow in a first path 406 and a second path 408. The first path comprises an Energy Storage Arrangement including a heat exchanger 410 which can heat the water from the inlet. The second path includes an electrical heater 422 which can also heat water from the inlet. The two paths each include a respective flow sensor 416, 428 and the paths re-join before providing an outlet 420 from the supply system via a temperature sensor 418. A controller 430 controls the valve 404 and the electrical heater 422 in response to the sensor signals to provide hot water at a desired temperature using a suitable proportion of stored energy and electrical energy. By charging the Energy Storage Arrangement using a heat pump, an economical and responsive hot water supply system is provided.