Dissimilar Multichannel Tubes for Phase-Specific Heat Exchange
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Solution Overview
Problem
Multichannel heat exchangers face inefficiencies due to phase changes of refrigerant, as vapor and liquid phases have different heat transfer properties, leading to varying flow velocities and pressure drops, which affect overall system efficiency.
Innovation Solution
A heat exchanger system with two sets of multichannel tubes having different configurations to optimize heat transfer for vapor and liquid phases, including manifolds connected by multichannel tubes with varying flow path configurations to enhance heat exchange efficiency and minimize pressure drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single uniform tube configuration is used for all multichannel tubes, then the device complexity is reduced and manufacturing is simplified, but heat exchange efficiency deteriorates because different refrigerant phases (vapor and liquid) have different heat transfer properties and flow characteristics
Solution Approach 1:
The patent applies local quality by configuring different multichannel tubes with different internal flow path configurations based on their specific function. Tubes containing vapor phase refrigerant have configurations optimized for vapor heat transfer, while tubes containing liquid phase refrigerant have configurations optimized for liquid heat transfer. This allows each tube to have the appropriate local structure for its specific refrigerant phase, improving overall heat exchange efficiency without requiring a completely uniform design across all tubes.
Solution Approach 2:
The patent segments the heat exchanger into different functional zones with different tube configurations. By dividing the multichannel tubes into groups based on refrigerant phase and flow characteristics, each segment can be optimized independently. This segmentation allows the system to handle different phases (vapor and liquid) with appropriately configured tubes, resolving the contradiction between manufacturing simplicity and heat exchange efficiency.
2Stress or pressure
If the flow area is increased to minimize pressure drop, then pressure drop is reduced and system efficiency improves, but the heat transfer surface area is reduced which may decrease heat exchange efficiency
Solution Approach 1:
The patent applies parameter changes by varying the flow path configuration parameters (such as channel width, channel depth, number of channels, and bend radius) in different multichannel tubes based on their specific function. Tubes with vapor phase refrigerant may have different flow path parameters compared to tubes with liquid phase refrigerant. This allows optimization of pressure drop and heat transfer surface area for each specific application, resolving the contradiction between minimizing pressure drop and maintaining heat exchange efficiency.
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 system improves heat exchange efficiency by tailoring tube configurations for de-superheating vapor and subcooling liquid phases, reducing pressure drops and enhancing overall system performance.
Implementation Method 1
Each multichannel tube may contain several individual flow channels. Fins may be positioned between the tubes to facilitate heat transfer between refrigerant contained within the tube flow channels and external air passing over the tubes.
Implementation Method 2
heat exchangers transfer heat by circulating a refrigerant through a cycle of evaporation and condensation
Implementation Method 3
the refrigerant may enter an evaporator heat exchanger as a liquid and exit as a vapor
Implementation Method 4
the refrigerant may enter a condenser heat exchanger as a vapor and exit as a liquid
Data Source
AI summary
Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems and heat exchangers are provided which include dissimilar internal configurations. The heat exchangers include multiple sets of multichannel tubes in fluid communication with each other. One set of multichannel tubes contains flow channels of one shape and size while the another set of multichannel tubes contains flow channels of a different shape and/or size. The dissimilar flow channels within the multichannel tube sets allow each set of tubes to be configured to the properties of the refrigerant flowing within the tubes.