Two-Block Evaporator Layout for Uniform Refrigerant Distribution
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Solution Overview
Problem
Existing heat exchangers in heating and air-conditioning systems for motor vehicles face issues with non-uniform refrigerant distribution, leading to increased pressure losses and reduced evaporator power due to demixture of the two-phase refrigerant mixture and complex structural designs.
Innovation Solution
A heat exchanger design with a distribution unit that ensures uniform refrigerant distribution across the entire evaporator width through a single diversion, maintaining a pressure difference ratio greater than 3 between the distribution and evaporator units, minimizing intermediate mixing and pressure losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If refrigerant is distributed only over a small portion of flat pipes in multiple blocks, then uniform distribution is achieved, but pressure loss increases significantly
Solution Approach 1:
The evaporator is divided into multiple blocks with flat pipes arranged in segments, allowing the refrigerant to be distributed uniformly across all blocks through a single diversion rather than requiring multiple intermediate mixing installations. This segmentation approach maintains uniform distribution while reducing pressure loss by eliminating redundant diversion points.
Solution Approach 2:
A distributor unit acts as an intermediary component that receives the two-phase refrigerant mixture and distributes it uniformly to all flat pipes across the entire evaporator width. The distributor unit includes distribution channels that ensure even refrigerant distribution without requiring intermediate mixing installations between blocks, thereby reducing pressure loss while maintaining uniformity.
2Manufacturing precision
If intermediate mixing installations are added to distribute refrigerant uniformly, then distribution uniformity improves, but device complexity increases
Solution Approach 1:
The distributor unit combines multiple distribution channels into a single integrated component that serves all flat pipes across the evaporator. This merging of distribution functions into one unit eliminates the need for separate intermediate mixing installations between blocks, reducing device complexity while maintaining uniform refrigerant distribution.
Solution Approach 2:
The distributor unit performs multiple functions: it distributes refrigerant to all blocks, maintains two-phase mixture homogeneity, and provides pressure regulation. This multi-functional design replaces what would otherwise require multiple separate components, thereby reducing overall device complexity while achieving uniform distribution.
3Power
If two-phase refrigerant mixture is allowed to flow through the evaporator, then evaporator power is maintained, but demixture occurs leading to non-uniform distribution
Solution Approach 1:
The distributor unit is designed with distribution channels that create equipotential flow conditions, ensuring that the two-phase refrigerant mixture is distributed uniformly to all flat pipes. The channel geometry and positioning are optimized to maintain pressure equilibrium across all distribution points, preventing demixture and ensuring uniform two-phase flow throughout the evaporator.
Solution Approach 2:
The distributor unit modifies flow parameters such as velocity distribution and pressure gradient to maintain two-phase mixture homogeneity. By carefully controlling these parameters in the distribution channels, the system prevents demixture of the refrigerant while ensuring uniform distribution across all flat pipes, thereby maintaining evaporator power.
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 reduced pressure losses and enhanced refrigerant power by maintaining a uniform temperature profile and efficient distribution of refrigerant across all flat pipes, improving the overall performance of the evaporator unit.
Implementation Method 1
owing to the uniform provision of the refrigerant to all the flat pipes intermediate mixing does not occur in the diversion. A configuration of the distribution unit with a ratio V of the pressure difference between the pressure difference in the distribution unit, on the one hand, and the pressure difference in the evaporator unit, on the other, can be provided which is larger than 3
Implementation Method 2
Evaporators are known in which the two-phase refrigerant is distributed from an inflow duct to a through-flow device, preferably pipes
Implementation Method 3
a heat exchanger having an evaporator unit to which a refrigerant medium can be supplied via a distribution unit and through which said refrigerant medium flows
Data Source
AI summary
A heat exchanger, in particular for a heating or air-conditioning system in a motor vehicle, having an evaporator unit to which a refrigerant medium can be supplied via a distribution unit and through which said refrigerant medium flows and around which said refrigerant medium flows after only one diversion (two-block design) at the bottom in a diversion unit, wherein the distribution unit is designed to effect a uniform distribution of the refrigerant medium over the full width of the evaporator.