PCM Pack Surface Depressions for Airflow Heat Transfer
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Solution Overview
Problem
Existing phase change material (PCM) packs in air conditioning systems have limited heat transfer efficiency due to the lack of effective surface features that enhance thermal energy exchange with airflow.
Innovation Solution
A PCM pack design featuring thermally conductive layers with a plurality of depressions on at least one outer surface, which generate vortices to enhance heat transfer, is used in a stacked air conditioning system configuration to maximize heat transfer while minimizing pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a smooth flat surface is used for the PCM pack, then the manufacturing is simple and the structure is straightforward, but the heat transfer efficiency between the PCM pack and airflow is limited
Solution Approach 1:
The patent applies curvature by introducing depressions (dimples) on the PCM pack surface. These curved surface features generate vortices in the airflow, enhancing heat transfer between the air and PCM. The curved geometry disrupts the boundary layer and promotes turbulent mixing, directly improving thermal energy exchange while adding only moderate structural complexity
Solution Approach 2:
The patent applies local quality by creating localized depressions on specific regions of the PCM pack surface rather than changing the entire surface uniformly. This allows targeted enhancement of heat transfer in areas where airflow contact is most beneficial, while maintaining simpler geometry in other regions. The depressions are strategically positioned to maximize vortex generation and heat exchange efficiency
2Productivity
If depressions are added to enhance heat transfer, then the heat transfer coefficient increases by up to 90%, but the surface area is reduced and manufacturing complexity increases
Solution Approach 1:
The patent applies dimensionality change by transitioning from a two-dimensional flat surface to a three-dimensional textured surface with depressions. This adds vertical dimension (depth) to the surface geometry, creating volumetric vortex structures that enhance heat transfer. The depressions occupy space in the third dimension, allowing improved thermal performance while the projected footprint area remains similar to the original flat surface
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 depression-enhanced surface design increases heat transfer coefficients by up to 90% compared to smooth surfaces, improving the efficiency of the PCM packs in both laminar and turbulent flow regimes, and optimizes airflow for better thermal performance.
Implementation Method 1
It has been found that vortices are generated within the depressions that enhance heat flow
Implementation Method 2
The depressions in the outer surface of the PCM pack enhance the heat transfer between an air flow passing over the outer surface and the PCM
Implementation Method 3
The phase change materials use the latent heat property of material to store thermal energy so that the phase change material can be frozen using cool night time air and then used to cool daytime air
Implementation Method 4
The phase change materials use the latent heat property of material to store thermal energy
Data Source
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Figure 5~6
AI summary
A phase change material (PCM) pack (1) for an air conditioning system comprises phase change material sealed between a first thermally conductive layer (2) forming a first outer surface of the PCM pack and a second thermally conductive layer (2) forming a second outer surface of the PCM pack. At least the first or second outer surface of the PCM pack takes the form of a substantially planar surface having defined therein a plurality of depressions (4) deviating from the planar surface towards the interior of the PCM pack in a direction perpendicular to the planar surface. The depressions improve heat transfer between the pack and an airflow passing over the surface of the PCM pack.