PCM Heat Exchanger for Neonatal Incubator Thermal Autonomy
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Solution Overview
Problem
Existing neonatal incubators face challenges in maintaining a stable body temperature for premature infants in developing countries due to unreliable electrical grids and lack of access to spare parts and trained personnel, necessitating a solution that ensures thermal autonomy and is affordable, robust, and easy to use.
Innovation Solution
A PCM-based heat exchanger with a modular design, comprising a case with insulated walls and PCM-containing modules arranged to define a fluidic path, connected to a fan for air flow and a system to regulate temperature, allowing for efficient heat storage and release, even during power outages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional electrically-driven heater is used to maintain temperature, then temperature control is reliable when power is available, but the incubator cannot maintain temperature during power outages
Solution Approach 1:
The PCM is pre-charged to a liquid state during normal operation with electrical power available, storing thermal energy in advance. When power fails, the pre-stored latent heat in the PCM melts and solidifies to maintain temperature, enabling the incubator to operate autonomously during outages
Solution Approach 2:
The patent utilizes the phase change (melting and solidification) of paraffin-based PCM at approximately 25°C. During phase transition, the PCM absorbs and releases large amounts of latent heat at constant temperature, providing thermal buffering that maintains the incubator temperature within the required range during power interruptions
2Duration of action of stationary object
If a large PCM mass is used to extend thermal autonomy duration, then thermal autonomy duration increases, but the device volume and weight increase
Solution Approach 1:
The patent exploits the high latent heat of fusion of paraffin-based PCM (approximately 200-250 kJ/kg), which is significantly higher than sensible heat storage materials. This allows a compact PCM mass to store sufficient thermal energy for extended thermal autonomy (at least 4 hours) without requiring large volume, as the phase transition releases concentrated thermal energy
3Volume of stationary object
If PCM modules are placed close together to maximize space utilization, then space utilization improves, but heat transfer efficiency decreases due to insufficient fluidic path access
Solution Approach 1:
The patent creates localized high-heat-transfer zones at the interfaces between PCM modules and the hollow metallic walls/tubular elements, where the fluidic path ensures direct contact. Each PCM module has optimized local geometry (flat surfaces facing walls, curved surfaces facing tubular elements) to maximize thermal contact area in critical heat transfer regions while maintaining compact overall configuration
4Loss of energy
If a complex heat exchanger structure is used to improve heat transfer, then heat transfer efficiency improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent employs a composite heat exchanger structure combining different metallic materials (aluminum or stainless steel) for the hollow walls and tubular elements, each selected for specific properties (thermal conductivity, corrosion resistance). The modular assembly of standardized PCM modules with simple geometric features enables efficient heat transfer while maintaining ease of manufacturing and assembly
Solution Approach 2:
The heat exchanger is divided into multiple standardized PCM modules that can be independently manufactured and assembled. Each module has simple geometric features (flat surfaces, curved surfaces) that facilitate mass production and simplify assembly, while the collective arrangement of modules achieves the required heat transfer efficiency through increased surface area
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 solution provides thermal autonomy for at least four hours, minimizing heat losses, ensuring oxygen renewal, and maintaining a stable temperature, making it suitable for developing countries and resource-poor settings.
Implementation Method 1
A PCM is usually (but not exclusively) a substance that undergoes a solid-liquid phase transition with a high latent heat of fusion. In other words, by melting and solidifying at a certain temperature, the PCM is capable of storing and releasing large amounts of energy.
Implementation Method 2
A PCM is usually (but not exclusively) a substance that undergoes a solid-liquid phase transition with a high latent heat of fusion. Heat is absorbed or released when the material changes from solid to liquid and vice versa; thus, PCMs are classified as latent heat storage units.
Implementation Method 3
a case having insulated walls comprising an inlet and an outlet
Data Source
Figure 1
Figure 2a)~2b)
Figure 3
AI summary
A PCM-based heat exchanger is disclosed, said phase change material (PCM)-based heat exchanger comprising: a) a case having insulated walls comprising an inlet and an outlet; and b) a plurality of modules comprising a support structure containing a phase change material, wherein said modules are arranged within said case in a way as to define a fluidic path connecting said inlet with said outlet. Another object relates to an apparatus, wherein said apparatus is an incubator, such as an infant incubator or a chicken/eggs incubator, or a glove box, characterized in that it comprises the PCM-based heat exchanger operatively connected with a hood defining an insulating compartment, a fan adapted for injecting an air flow into said PCM-based heat exchanger and a system to regulate the air temperature inside the hood.