PCM Heat Storage Layout for Compact Hot Water Heating
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Solution Overview
Problem
Conventional heaters require large hot water storage tanks due to insufficient burner output for heating both buildings and hot water, leading to space inefficiencies as thermal insulation improves.
Innovation Solution
Incorporating a Phase Change Material (PCM) storage unit in the return line of the secondary heat exchanger to preheat the heat transfer medium, which is then heated to the final temperature by the primary heat exchanger, reducing the power required from the burner and allowing for a smaller hot water storage tank, with optional use of a condensation heat exchanger and solar heat exchanger for enhanced energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large hot water storage tank is used to cover hot water demand with low burner output, then sufficient hot water supply is achieved, but the device occupies a lot of space
Solution Approach 1:
The patent segments the heating function into two separate storage units: a hot water storage tank for domestic hot water and a PCM storage unit for heating circuit heat storage. This segmentation allows each unit to be optimized for its specific purpose, enabling the hot water tank to be smaller while still meeting overall heat demand through the combined system.
Solution Approach 2:
The patent utilizes phase change material (PCM) in a dedicated storage unit that undergoes phase transitions (melting/freezing) to store and release heat for the heating circuit. This phase transition mechanism provides high heat storage density, allowing the heating function to be separated from the hot water storage function, thereby reducing the required hot water tank volume.
2Loss of energy
If a low output burner is used for heating buildings with improved thermal insulation, then energy efficiency is improved, but the burner output is insufficient for heating hot water
Solution Approach 1:
The patent implements a PCM storage unit that is charged with heat from the burner during periods when heating demand is low or during hot water heating operations. This preliminary storage of heat energy allows the low-output burner to meet both heating and hot water demands over time, effectively decoupling the instantaneous power requirement from the total energy requirement.
Solution Approach 2:
The system changes the temporal distribution of heat delivery by storing heat in the PCM unit during off-peak periods and releasing it during peak demand periods. This parameter change in heat delivery timing allows a low-output burner to satisfy both heating and domestic hot water requirements without requiring high instantaneous power output.
3Power
If a PCM storage unit is added to preheat the heat transfer medium, then the primary heat exchanger and burner require less power, but the device complexity increases
Solution Approach 1:
The patent adds a PCM storage unit as a separate, modular component in the heating system. This segmentation allows the PCM unit to function as an independent heat buffer that preheats the heat transfer medium before it enters the primary heat exchanger, thereby reducing the burner's power requirement without significantly complicating the overall system architecture.
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
This configuration allows for a compact design that matches heating performance for both buildings and hot water, reducing energy expenditure and storage tank size while maintaining sufficient heat output.
Implementation Method 1
a phase change material (PCM) storage unit (10) in the return line (15) of the secondary heat exchanger (4) for heating the hot water tank (8) is provided, from which the cooled heat transfer medium flows in in order to be heated by the primary heat exchanger (3), in front of the primary heat exchanger (3)
Implementation Method 2
a primary heat exchanger (3) for transferring the heat from the burner (2) to a heat transfer medium
Implementation Method 3
a condensation heat exchanger is provided between the secondary heat exchanger and the PCM storage unit in the case of a condensing boiler. As a result, additional heat can be extracted from the exhaust gas of the burner
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a heating device (1) for alternating or parallel heating of water flowing through or stored in a hot water tank (8) or of a heating circuit (11) for heating a building. In order to cover the higher heat requirement when heating hot water, a PCM accumulator (10) is arranged according to the invention in the hydraulic system (5) downstream of the secondary heat exchanger (4) and upstream of the primary heat exchanger (3).