Latent Heat Storage in Flexible Heating Devices
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Solution Overview
Problem
Conventional hot water bottles often result in burns due to excessive heat, as users typically fill them with freshly boiled water, leading to a continuous cooling rate that makes them either too hot or too cold for comfort, and existing solutions fail to adequately address this issue.
Innovation Solution
Incorporating a latent heat storage medium, such as sodium acetate or paraffin, which absorbs excess heat during an endothermic change of state and releases it during an exothermic change of state, maintaining a consistent temperature within an optimal range of 38°C to 48°C for an extended period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional hot water bottles are filled with freshly boiled water, then the initial heating effect is strong, but the temperature becomes too hot causing burns and then cools down too quickly becoming too cold
Solution Approach 1:
The patent utilizes phase change materials (paraffin or salt hydrates) that undergo phase transitions at specific temperatures. When the flowable material cools below the phase change temperature, the material transitions from liquid to solid, releasing latent heat to maintain temperature. This phase transition mechanism provides prolonged warmth at a stable temperature, preventing both burns from excessive heat and rapid cooling.
Solution Approach 2:
The patent changes the thermal parameters of the heating device by incorporating phase change materials with specific transition temperatures (20-50°C). This parameter change allows the system to maintain a relatively constant temperature output over an extended period, transforming the continuous cooling curve into a plateau temperature profile that provides sustained comfortable warmth.
2Object-affected harmful factors
If the wall thickness is increased to limit heat transfer and prevent burns, then safety is improved, but the heating effect is reduced
Solution Approach 1:
The phase change materials release latent heat during solidification, providing a sustained heating effect that compensates for the reduced heat transfer through thicker walls. The continuous release of latent heat maintains effective heating while allowing increased wall thickness for safety, as the temperature remains stable and predictable rather than experiencing rapid heat transfer.
3Duration of action of moving object
If users try to extend the duration of use by filling with very hot water, then the heating duration is extended, but the risk of burns increases
Solution Approach 1:
The phase change materials act as a temperature buffer, absorbing excess heat when the flowable material is very hot and releasing it gradually during cooling. The phase transition occurs at a controlled temperature range, ensuring that even if boiled water is used, the temperature released to the user remains within a safe and comfortable range while extending the useful duration of heating.
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 solution reduces the risk of burns by gradually releasing heat, providing more homogeneous and prolonged warmth, thus enhancing user comfort and safety by maintaining a stable temperature.
Implementation Method 1
the latent heat storage medium comprises a phase change material, in particular sodium acetate, wherein the phase change material absorbs energy during an endothermic change of state and releases energy in the form of heat during an exothermic change of state
Implementation Method 2
the phase change material absorbs energy during an endothermic change of state and releases energy in the form of heat during an exothermic change of state
Data Source
Figure 1
Figure 2a~2c
Figure 3a~3b
AI summary
The invention relates to a heat device (1), in particular a hot-water bottle or a heat cushion, for bringing in at least indirect contact with a living being. The heat device comprises at least one holding chamber (2) for holding a flowable material (4), wherein the holding chamber (2) is formed by a flexible wall (6) at least in some sections, wherein the flexible wall (6) can be brought in at least indirect contact with the living being. According to the invention, a latent-heat storage means (8) is provided, wherein the latent-heat storage means is arranged in such a way that temperature control of the flowable material (4) is effected by the latent-heat storage means (8) at least at times, wherein the latent-heat storage means (8) has a phase-change material, in particular sodium acetate, wherein the phase-change material absorbs energy during an endothermic change of state as a consequence of heating and outputs energy in the form heat during an exothermic change of state.