Variable Cross-Section Heat Exchanger Tubes
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Solution Overview
Problem
Existing vehicle air-conditioning heat exchangers fail to optimize the coolant's decreasing density effect on heat absorption capacity, leading to reduced efficiency and increased size and cost due to unnecessary space and tube connections.
Innovation Solution
The heat exchanger design features flat tubes with varying cross-section areas, allowing the coolant to flow through assemblies with progressively larger cross-sections as it evaporates, reducing pressure drop and enhancing heat absorption capacity without increasing the number of tubes or fins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the coolant flows through heat exchanger tubes, then heat absorption occurs, but the coolant density reduces on evaporation leading to reduced further heat absorption capacity
Solution Approach 1:
The patent applies parameter changes by varying the inner cross-section area of tubes along the coolant flow direction. Tubes adjacent to the coolant inlet have a larger inner cross-section area than tubes adjacent to the coolant outlet, optimizing the coolant flow velocity and heat absorption capacity at different positions in the heat exchanger.
Solution Approach 2:
The patent implements local quality by creating non-uniform tube cross-section areas in different regions of the heat exchanger. The tube cross-section area varies locally along the coolant flow path to match the local heat absorption requirements, with larger areas where more heat absorption is needed and smaller areas where the coolant is already partially evaporated.
2Productivity
If multiple heat exchanger assemblies are used to compensate for coolant density reduction, then heat absorption is improved, but the device size and cost increase due to additional space and tube connections
Solution Approach 1:
Instead of adding more assemblies, the patent changes the parameter of tube cross-section area within a single continuous assembly. This allows optimization of heat absorption capacity while avoiding the need for multiple separate assemblies and their associated connections.
Solution Approach 2:
The patent merges the function of multiple assemblies into a single continuous heat exchanger structure with variable tube cross-sections. This combines the heat absorption functions that would otherwise require separate assemblies, reducing the number of connections and simplifying the overall device structure.
3Productivity
If the number of tubes is increased to maintain heat absorption capacity, then productivity is improved, but the external dimensions of the heat exchanger increase
Solution Approach 1:
The patent changes the cross-section area parameter of existing tubes rather than increasing the number of tubes. This allows optimization of heat absorption capacity while maintaining the same external dimensions and footprint of the heat exchanger.
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 design achieves better air cooling, lower dew point, and reduced pressure drop, resulting in increased temperature differences and improved efficiency while maintaining the same external dimensions, thus meeting high vehicle air-conditioning system requirements.
Implementation Method 1
a coolant, cooled and liquefied by pressure reduction, evaporates in thin pipes, whereby it extracts heat from the air passing over the pipes containing the coolant and thus lowers the temperature of the air
Implementation Method 2
extracts heat from the air passing over the pipes containing the coolant
Implementation Method 3
the reduction in density of the coolant on evaporation leads to a reduction in the further heat absorption capacity
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention concerns a heat exchanger with an arrangement of parallel-guided flat tubes (1a, 1b) which are intended to conduct coolant which evaporates. Fins (2) are arranged between the tubes which form air guide slots in the direction perpendicular to the course of the tubes, and thus define the flow direction of air to be cooled. The tubes form at least two assemblies (11) which are arranged behind each other in the air flow direction (3). The assemblies (11, 12) differ in the free inner cross-section area (W1, W2) of the tubes (1a, 1b) for the coolant.