Evaporator with redirected process fluid flow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In shell-and-tube flooded type refrigerant evaporators, high performance tubes generate more vapor near the process fluid inlet, leading to higher vapor velocities and potential liquid carry-over into the compressor, causing undesirable losses and unbalanced heat exchange, which reduces heat transfer efficiency and wetting of tubes.
Innovation Solution
The use of low pressure drop redirect pipes and high performance heat exchange tubes within the evaporator to separate and redirect process fluid flow, creating areas of high heat flux and balancing vapor generation at both ends, while reducing liquid carry-over and enhancing refrigerant wetting throughout the tube bundle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high performance tubes are used to increase heat transfer rates, then heat exchange efficiency is improved, but liquid refrigerant carry-over into the compressor increases causing harmful effects
Solution Approach 1:
The evaporator shell is divided into multiple zones with separate inlets and outlets for different process fluid streams. This segmentation allows independent control of vapor generation zones, preventing excessive vapor velocity and liquid carry-over while maintaining high heat transfer rates in each zone.
Solution Approach 2:
Different sections of the evaporator are designed with locally optimized characteristics - some zones use high performance tubes for maximum heat transfer while others use redirect pipes to control flow patterns and prevent liquid carry-over. Each zone's properties are tailored to its specific function.
2Stress or pressure
If process fluid flows through tubes from inlet to outlet in a single direction, then pressure drop is reduced, but heat exchange becomes unbalanced with poor wetting at certain locations
Solution Approach 1:
The process fluid flow is segmented into multiple parallel streams with separate inlets and outlets. Each stream flows through dedicated tubes in a single direction, maintaining low pressure drop while the overall system achieves balanced heat exchange through multiple zones generating vapor at different locations.
Solution Approach 2:
The invention transitions from a single linear flow path to a multi-dimensional flow network with multiple inlets and outlets distributed throughout the shell. This allows heat exchange to occur balanced across multiple locations simultaneously, preventing poor wetting at any single location.
3Productivity
If vapor velocities are increased to improve heat transfer, then heat exchange efficiency is improved, but liquid refrigerant is carried over into the compressor causing losses
Solution Approach 1:
Vapor generation is segmented into multiple zones with separate process fluid inlets and outlets. Each zone generates vapor at controlled velocities, preventing excessive vapor speed that would cause liquid carry-over while maintaining efficient heat transfer in each zone.
Solution Approach 2:
Each evaporator zone is designed with locally optimized vapor velocity characteristics. Zones are positioned and sized to generate vapor at appropriate velocities for their specific locations, ensuring efficient heat transfer without creating conditions for liquid carry-over into the compressor.
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 configuration balances heat transfer rates, reduces liquid carry-over into the compressor, and facilitates better refrigerant wetting, resulting in a more efficient and compact evaporator design with reduced refrigerant charge and copper usage.
Implementation Method 1
A group of tubes are used to carry process fluid which passes through the shell from a process fluid inlet to a process fluid outlet. Refrigerant, as the working fluid, enters the shell of the evaporator from a refrigerant inlet, for example, near the bottom of the shell, exchanges heat with the process fluid and is vaporized.
Implementation Method 2
Refrigerant, as the working fluid, enters the shell of the evaporator from a refrigerant inlet, for example, near the bottom of the shell, exchanges heat with the process fluid and is vaporized.
Implementation Method 3
A portion of the process fluid is carried from the process fluid inlet to one location of the evaporator shell via heat exchange tubes for heat exchange, and then is redirected from that location to the process fluid outlet via redirect pipe(s).
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
An apparatus, system, and method of separating and directing process fluid flow via the use of both low pressure drop pipes and high performance tubes within a refrigerant evaporator are disclosed. The evaporator includes a shell; the shell includes a process fluid inlet and a process fluid outlet. The evaporator also includes a plurality of tubes disposed within the shell and carrying a process fluid; the plurality of tubes includes a first plurality of tubes and a second plurality of tubes. The evaporator further includes a plurality of redirect pipes disposed within the shell and carrying the process fluid; the plurality of redirect pipes includes a first redirect pipe and a second redirect pipe. The evaporator functions by separating and directing process fluid flow into two portions via the use of both tubes and redirect pipes.