Flooded Evaporator Drainage Mechanism for Liquid Carryover
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Solution Overview
Problem
Existing evaporator systems face challenges in effectively removing liquid refrigerant carryover, which can damage compressors and reduce system efficiency, with current solutions being costly or inefficient, such as large shells, liquid/vapor separators, mist eliminators, and baffles that either require additional space or cause pressure drops.
Innovation Solution
A drainage system comprising a baffle with a mesh pad and a tapered drainage pipe is used to trap and collect liquid refrigerant, allowing it to flow back to a refrigerant pool, reducing carryover and enhancing system efficiency without the need for large or costly components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a liquid/vapor separator is provided to remove liquid refrigerant, then liquid carryover is reduced, but system cost increases substantially
Solution Approach 1:
The separator is divided into an upper separator portion and a lower separator portion with distinct functions. The upper portion removes large liquid droplets through gravitational separation, while the lower portion captures finer liquid carryover through a mesh pad and drainage system. This segmentation allows effective liquid removal without requiring a complete complex separator system.
Solution Approach 2:
The drainage mechanism extracts and removes the liquid separation function from the traditional complex liquid/vapor separator. By providing a dedicated drainage system with mesh pad and drainage pipes that return liquid to the refrigerant pool, the system achieves effective liquid carryover control without the substantial cost and complexity of conventional separators.
2Reliability
If vertical space is increased between tube bank and suction nozzle to allow gravity drainage, then liquid carryover is reduced, but shell size and cost increase
Solution Approach 1:
Instead of increasing vertical space (one dimension), the solution introduces a horizontal drainage mechanism with mesh pad and drainage pipes that extend across the evaporator shell. This dimensional shift allows liquid removal without requiring additional vertical clearance, maintaining compact shell dimensions while achieving effective liquid carryover control.
3Reliability
If a mist eliminator is provided to trap liquid droplets, then liquid carryover is reduced, but pressure drop increases and performance degrades
Solution Approach 1:
The mesh pad is positioned specifically in the lower separator portion where liquid carryover is most problematic, rather than placing a comprehensive mist eliminator throughout the entire vapor flow path. This localized approach provides effective liquid trapping at the critical location while minimizing interference with the main vapor flow, thus reducing pressure drop and maintaining system performance.
4Reliability
If a baffle is provided to collect liquid refrigerant, then liquid carryover is reduced, but drainage effectiveness is insufficient
Solution Approach 1:
The solution merges the baffle's liquid collection function with a dedicated drainage system comprising mesh pad and drainage pipes. The baffle collects liquid refrigerant, the mesh pad traps liquid droplets, and the drainage pipes provide effective drainage back to the refrigerant pool. This combination of multiple functions into an integrated system ensures both effective liquid collection and drainage, resolving the insufficiency of standalone baffles.
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 effectively reduces liquid carryover into the compressor, decreases power consumption, and improves system efficiency by eliminating costly devices, while ensuring effective drainage of collected liquid refrigerant.
Implementation Method 1
a mesh pad disposed adjacent to the inside surface of the baffle and configured to trap liquid refrigerant
Implementation Method 2
any liquid droplets will be caused to flow downwardly by the force of gravity before they reach the suction nozzle
Data Source
AI summary
A liquid refrigerant drainage mechanism is described for use in a flooded evaporator to mitigate liquid carryover. The drainage mechanism can trap liquid refrigerant droplets, create a liquid column to overcome a pressure difference across the mechanism and drain liquid back to the pool in the evaporator. The drainage mechanism is disposed in a suction baffle, and has a mesh pad and a tapered pipe secured to the bottom of the baffle. The pipe has a drainage aperture at one end to allow the accumulated liquid refrigerant to return to the refrigerant pool below. The mesh pad helps to separate liquid droplets that coalesce and fall into the tapered pipe. By using this liquid drainage mechanism in conjunction with a suction baffle, liquid carryover can be reduced and chiller performance improved.