Evaporator Micro-Channel Design for Simplified Phase Separation
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Solution Overview
Problem
Existing evaporators in refrigerant circuits, particularly in vehicle air conditioning systems, face challenges with complex process technology and structurally complicated separator geometries when using centrifugal force for phase separation.
Innovation Solution
The evaporator design incorporates micro-channels divided into vapour and liquid phase micro-channels, with the liquid phase micro-channels positioned below and vapour phase micro-channels above the liquid level, and a distributor tube with a reduced cross section and offset discharge opening to enhance phase separation, reducing pressure loss and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If centrifugal force is used for phase separation in the evaporator inlet chamber, then phase separation can be achieved, but the process technology becomes complicated and the separator geometry becomes structurally complex
Solution Approach 1:
The micro-channels are divided into two distinct groups: vapor phase micro-channels positioned higher in the inlet chamber and liquid phase micro-channels positioned lower. This segmentation allows automatic phase separation based on gravity and density differences, eliminating the need for complex centrifugal separation mechanisms while maintaining reliable phase separation functionality
Solution Approach 2:
Instead of using complex active mechanisms (centrifugal force) to achieve phase separation, the invention inverts the approach by using passive gravitational separation combined with strategically positioned micro-channel orifices. The vapor channels are positioned to access the upper vapor region while liquid channels access the lower liquid region, achieving separation through inverted logic of simple geometric positioning rather than complex mechanical action
2Productivity
If micro-channels are divided into vapour and liquid phase micro-channels with different positions, then phase separation efficiency improves and pressure loss reduces, but the inlet chamber geometry becomes more specific
Solution Approach 1:
Different micro-channels are positioned at different local heights within the inlet chamber to match the local distribution of vapor and liquid phases. Vapor phase micro-channels are positioned in the upper region where vapor accumulates, while liquid phase micro-channels are positioned in the lower region where liquid collects. This local quality differentiation optimizes phase separation efficiency without requiring complex overall geometry
Solution Approach 2:
The system uses the natural density and phase separation properties of the refrigerant itself to achieve phase separation. The refrigerant's own gravitational settling and phase stratification in the inlet chamber automatically directs vapor to upper channels and liquid to lower channels, eliminating the need for external separation mechanisms or complex geometric constraints
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 simplifies the separator geometry, reduces pressure loss, and improves phase separation efficiency, allowing for a more straightforward and effective operation of the evaporator.
Implementation Method 1
The refrigerant liquid phase in the evaporator is therefore evaporated into the vapour phase with absorption of thermal energy from the air flow, while the air flow is cooled at the same time
Implementation Method 2
The refrigerant liquid phase in the evaporator is therefore evaporated into the vapour phase with absorption of thermal energy from the air flow
Implementation Method 3
the two-phase liquid/vapour mixture is introduced into the evaporator inlet chamber in a vortex flow along the inner wall of a distributor tube. As a result, the vapour phase collects radially within the vortex flow, and the said vapour phase is fed to a bypass line
Implementation Method 4
the two-phase liquid/vapour mixture is introduced into the evaporator inlet chamber in a vortex flow along the inner wall of a distributor tube
Data Source
AI summary
An evaporator in a refrigerant circuit, having a bottom-side inlet chamber which is connected in flow terms to an evaporator outlet side via evaporator tubes, a separator being integrated into the evaporator inlet chamber, in which separator a refrigerant which is expanded in an expansion member is divided as a two-phase liquid/vapour mixture into a vapour phase and into a liquid phase which is separate therefrom, the vapour phase being conducted via a bypass line to the evaporator outlet side, and the liquid phase being conducted counter to the direction of gravity into the evaporator tubes, wherein at least one evaporator tube being a flat tube with a plurality of micro-channels, through which the refrigerant is guided.