Valve with flow modulation device for heat exchanger
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Solution Overview
Problem
In air conditioning and refrigeration systems, achieving equal distribution of two-phase refrigerant flow to each fin passage in heat exchangers is challenging, leading to reduced heat transfer and inefficiency, as traditional expansion valves and distributors fail to maintain uniform gas-liquid mass fraction and flow, especially in plate-fin, mini-channel, and micro-channel evaporators.
Innovation Solution
An exdributor valve with a rotating or sliding distributor and flow modulation device that distributes single-phase liquid refrigerant equally to each cooling channel before flashing, eliminating the need for traditional expansion valves and two-phase distributors, and modulates the flow area to prevent hydraulic cross-talk and ensure constant mass fraction during expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional expansion valves and two-phase distributors are used, then refrigerant flow can be reduced to the evaporator, but uniform distribution of gas-liquid mixture to each fin passage cannot be achieved
Solution Approach 1:
The patent applies preliminary action by distributing single-phase liquid refrigerant uniformly through the distributor before it enters the evaporator channels where flashing occurs. The distributor is designed with specific flow paths and pressure drops to ensure equal liquid distribution to all channels upstream of the two-phase formation zone, preventing non-uniform gas-liquid mixture formation that plagues traditional two-phase distributors
Solution Approach 2:
The patent changes the physical state parameter of the refrigerant from two-phase to single-phase at the distribution point. By maintaining liquid-only flow through the distributor and only allowing flashing to occur downstream in the evaporator channels, the system achieves uniform distribution based on liquid flow characteristics rather than attempting to control two-phase flow, which is inherently unstable and difficult to distribute evenly
2Manufacturing precision
If tube-fin distributors with individual capillary tubes are used, then uniform distribution to each fin passage can be achieved, but labor and material cost increases significantly
Solution Approach 1:
The patent merges the distributor function with the evaporator inlet structure, eliminating the need for separate tube-fin distributors and individual capillary tubes. The distributor is integrated directly into the evaporator assembly with flow modulation devices built-in, combining multiple functions into a single compact unit that achieves uniform distribution without requiring extensive manual assembly of individual components
Solution Approach 2:
The distributor design incorporates universal flow modulation capabilities that can serve multiple functions: distributing liquid uniformly, modulating flow rates, and preventing hydraulic cross-talk between channels. This multi-functional design replaces the need for separate distribution and control components, reducing both material costs and assembly complexity
3Device complexity
If piccolo distributors are used in plate-fin evaporators, then device complexity is reduced, but two-phase separation in the distributor cavity causes non-homogeneous mixture entering distributor holes
Solution Approach 1:
The patent applies preliminary action by completing the distribution of single-phase liquid refrigerant before any two-phase flashing occurs. The distributor is positioned and designed to deliver uniform liquid flow to all evaporator channels upstream of the flashing zone, ensuring homogeneous distribution is established before gas formation begins, thereby avoiding the separation problems that occur in piccolo distributors where two-phase mixing happens inside the distributor cavity
4Manufacturing precision
If customized distributors are tuned for one operating condition, then distribution performance improves for that condition, but the distributor becomes ineffective for other operating conditions
Solution Approach 1:
The patent applies dynamics by incorporating flow modulation devices that can dynamically adjust the flow characteristics of the distributor. These modulation devices allow the system to adapt to varying operating conditions by changing flow rates and pressure drops as needed, transforming a static, condition-specific distributor into a dynamic system that maintains effective distribution across a wide range of operating conditions
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 solution enables uniform distribution of refrigerant, enhancing heat transfer efficiency by maintaining equal flow apportionment to each channel, reducing the need for larger evaporators or increased compressor power, and improving robustness across various operating conditions.
Implementation Method 1
modulates the flow area to prevent hydraulic cross-talk and ensure constant mass fraction during expansion
Implementation Method 2
The single phase refrigerant changes to a two-phase refrigerant when entering the plurality of cooling channels
Data Source
AI summary
An exdributor valve of a heat exchanger includes a distributor to distribute single phase liquid refrigerant to cooling channels of the heat exchanger and a flow modulation device. The flow modulation device is interposed between the distributor and the cooling channels and is modulates an area through which the single phase liquid refrigerant is permitted to flow.