Floating Refrigerant Line Restriction for Compressor Liquid Slugging
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Solution Overview
Problem
Existing refrigerant systems face issues with liquid refrigerant entering the compressor, particularly during startup or transient operation, which can damage the compressor, and existing float valves either restrict gaseous flow or allow liquid refrigerant to enter due to high flow rates or pressure differentials.
Innovation Solution
A float valve design with ample space around its floating element, a vertically long and narrow passageway to draw liquid refrigerant from the bottom, radial guides to maintain centering, and a streamlined shape to minimize pressure drop, along with a flow-restricting passageway to throttle refrigerant flow, ensuring the valve remains unresponsive to high gaseous flow rates and effectively inhibits liquid refrigerant entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a float valve is used to block liquid refrigerant, then liquid refrigerant entry is prevented, but gaseous refrigerant flow is restricted
Solution Approach 1:
The valve body is designed with different flow characteristics for different flow types: a restricted flow path for liquid refrigerant through the float mechanism, and an unrestricted flow path for gaseous refrigerant around the float. This local differentiation allows the valve to selectively restrict liquid while maintaining gas flow.
Solution Approach 2:
The float mechanism changes its position based on the density parameter of the refrigerant. When liquid refrigerant is present, the float rises to block the liquid flow path. When only gas is present, the float remains in a position that does not restrict gas flow, thus adapting to the fluid parameter changes.
2Reliability
If the float valve restricts flow to prevent liquid entry, then liquid refrigerant is blocked, but the compressor is starved of refrigerant
Solution Approach 1:
The valve is segmented into separate flow paths: one path for liquid refrigerant that can be blocked by the float, and another path for gaseous refrigerant that remains open. This segmentation ensures that blocking liquid does not automatically block gas, maintaining refrigerant supply to the compressor.
Solution Approach 2:
The float acts as an intermediary element that selectively interacts with liquid refrigerant based on density differences. It blocks liquid flow when liquid is present but allows gas flow to pass through, thus mediating between liquid prevention and gas supply requirements.
3Productivity
If high flow rate of gaseous refrigerant is allowed, then cooling capacity is maintained, but velocity pressure blows the float upward to block the outlet
Solution Approach 1:
The float is designed with a horizontal outlet passage rather than a vertical one. This dimensional change allows the float to block vertical liquid flow while permitting horizontal gas flow to pass around the float, eliminating the problem of gas velocity pressure blowing the float upward.
Solution Approach 2:
The float geometry and outlet configuration are asymmetrically designed to create different flow resistance characteristics for liquid versus gas. The float presents a blocking surface to vertical liquid flow while allowing horizontal gas flow to bypass it, creating asymmetric flow behavior that stabilizes float position.
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 solution prevents liquid refrigerant from entering the compressor while maintaining adequate gaseous flow, ensuring the compressor is not starved of refrigerant and maintaining the cooling capacity of the system by effectively vaporizing liquid refrigerant before it reaches the suction port.
Implementation Method 1
a float valve between the evaporator and the compressor. The proposed valve includes a ball that is free to float loosely within a housing. When the housing is flooded with liquid refrigerant, the ball floats to block off a primary refrigerant outlet of the valve.
Implementation Method 2
Another object of some embodiments is to provide a float with a streamlined shape that minimizes the gaseous pressure drop across the float.
Data Source
AI summary
A flow device for a refrigerant/compressor system is installed between the outlet of an evaporator and the suction port of a compressor. The device includes a floating element that helps inhibit liquid refrigerant from entering the compressor. Under certain conditions where liquid refrigerant discharges from the evaporator, the floating element floats in the discharged liquid. Upon doing so, the float rises to a generally closed position where the float obstructs a main fluid outlet that leads to the compressor. In the closed position, refrigerant can still pass through the flow device, but through a more restricted outlet. To prevent the float from undesirably rising under the impetus of refrigerant vapor flowing at high flow rates, the floating element itself includes a flow-restricting passageway, radial guides, and/or a streamlined shape. The float can be incorporated within a manifold of a multi-coil or multi-circuited heat exchanger.