Multiple-Flow Heat Exchanger Thermal Decoupling Between Channels
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Solution Overview
Problem
Existing multiple-flow heat exchangers, such as gas coolers, experience undesirable heat losses due to heat transmission between channels with different fluid temperatures, leading to reduced efficiency, especially in HVAC systems using CO2 as the refrigerant fluid.
Innovation Solution
A multiple-flow heat exchanger design that thermally decouples adjacent channels with different fluid temperatures by using a deflecting pocket, fluid distributor, and fluid collector, and employing thermal insulators, slotted lamellae, or blind channels to prevent heat transfer between channels, thereby reducing heat losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If lamellae are positioned between channels and brazed to the channels to form a compact heat exchanger structure, then the heat exchanger achieves high heat transfer efficiency and compact design, but heat loss occurs due to heat conduction through the lamellae from warmer to colder channels
Solution Approach 1:
The heat exchanger is divided into thermally independent zones using thermal barrier elements (insulating walls or gaps) that segment the channel structure. This segmentation prevents heat conduction through the lamellae between adjacent channels with different fluid temperatures, thereby reducing heat loss while maintaining the compact sandwich-type design.
Solution Approach 2:
Thermal barrier elements are introduced as intermediary components between adjacent channels. These barriers act as mediators that block the heat conduction path through the lamellae, preventing thermal coupling between channels carrying fluids at different temperatures while allowing the structural integrity of the heat exchanger to be maintained.
2Productivity
If thermal decoupling measures are implemented to prevent heat transmission between channels with different temperatures, then heat loss is reduced and efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The thermal barrier elements are integrated into the existing manufacturing process by combining them with the channel structure fabrication. The insulating walls or gaps are incorporated during the forming of the channel blocks, allowing thermal decoupling to be achieved without requiring separate assembly steps or additional complex manufacturing operations.
Solution Approach 2:
The design utilizes parameter changes in the structural configuration (such as varying wall thicknesses, introducing gaps, or modifying lamella arrangements) to achieve thermal decoupling. These parameter adjustments can be implemented through standard manufacturing tolerances and design modifications rather than requiring entirely new manufacturing processes.
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 thermal decoupling design effectively reduces heat losses between channels with different fluid temperatures, enhancing the efficiency of the heat exchanger and minimizing heat retention in the refrigerant fluid, resulting in improved performance, particularly in CO2-based HVAC systems.
Implementation Method 1
a thermal insulator (9) instead of the lamella (5) is provided between the adjacent channels (4.1), each with a different fluid temperature, for the adjacent flows (2, 3)
Implementation Method 2
the lamella (5) positioned in between has in its longitudinal extension at least partially a slot (10), whereby two lamella halves separated to each other by an air gap form
Implementation Method 3
the temperature minimum—e.g. in case of condenser, gas cooler, and radiator—is the center of the lamella, the heat flowing toward the center of the lamella while being dissipated by convection to the air flow at the same time
Data Source
AI summary
The invention relates to a multiple flow heat exchanger (1), especially a gas cooler, comprising at least two flows (2, 3) passable by a fluid (13) in opposite directions and which respectively comprise a group of parallel channels (4) provided with lamellae (5) positioned between the channels (4) in a sandwich-type manner. A deflecting pocket (6) is positioned on a first front side (1.1) of the heat exchanger (1), for reversing the direction of the fluid (13), and a fluid distributor (7) for a first flow (2) and a fluid collector (8) for a second flow (3) are arranged on a second opposing front side (1.2) of the heat exchanger (1). According to the invention, the adjacent channels (4.1), each with a different fluid temperature, for the adjacent flows (2, 3), are thermally decoupled from each other.