Falling Film Evaporator Spray Layout for Uniform Refrigerant Distribution
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Solution Overview
Problem
Falling film evaporators face challenges in uniform refrigerant distribution onto heat exchange tubes, leading to uneven heat exchange performance and the occurrence of 'dry spots due to non-uniform refrigerant phases entering the refrigerant distributor.
Innovation Solution
A falling film evaporator design featuring a housing, heat exchange tube, perforated plate, spray tube, and liquid entry tube, where the spray tube is arranged perpendicular to the housing, with strategically positioned spray ports to ensure uniform refrigerant distribution across the heat exchange tube bundle, utilizing a perforated plate with distribution holes and a cover plate to guide refrigerant flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a refrigerant distributor is used to distribute refrigerant to heat exchange tubes, then the evaporator can achieve thin-film evaporation with high heat transfer efficiency, but the refrigerant distribution uniformity deteriorates leading to dry spots
Solution Approach 1:
The refrigerant distribution system is segmented into multiple spray tubes with multiple spray ports arranged along the length direction. Each spray port distributes refrigerant to a specific section of heat exchange tubes, ensuring uniform coverage across the entire bundle. The perforated plate is also segmented with multiple distribution holes to further divide and evenly distribute refrigerant flow.
Solution Approach 2:
The spray tube is arranged perpendicular to the housing length direction, creating a new spatial dimension for refrigerant distribution. This perpendicular arrangement allows refrigerant to be sprayed in a direction orthogonal to the heat exchange tube bundle, improving distribution uniformity by approaching the tubes from a different geometric perspective rather than parallel flow.
2Quantity of substance
If spray ports are arranged along the spray tube, then refrigerant can be distributed to multiple heat exchange tubes, but the refrigerant flow path is shortened reducing distribution effectiveness
Solution Approach 1:
The spray ports are asymmetrically arranged along the spray tube in the length direction, with varying spacing between adjacent ports. This asymmetric distribution optimizes the spray coverage pattern and extends the effective refrigerant flow path by preventing premature convergence of spray streams, allowing refrigerant to travel farther and distribute more uniformly across the heat exchange tube bundle.
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 ensures uniform refrigerant distribution, preventing 'dry spots and enhancing overall heat exchange performance by extending the refrigerant flow path and maintaining high refrigerant speed, thus improving the evaporator's efficiency.
Implementation Method 1
the spray tube having multiple spray ports, the spray ports being distributed at intervals in the length direction of the spray tube, and the spray ports being configured to be capable of spraying a refrigerant toward the perforated plate
Implementation Method 2
they exploit the mechanism of thin-film evaporation from heat exchange tube surfaces, have the advantages of high heat transfer efficiency
Data Source
AI summary
A falling film evaporator (100), a housing (101) thereof being accommodated with a heat exchange tube (304), a perforated plate (205) and a spraying tube (202), the perforated plate (205) being provided between the spraying tube (202) and the heat exchange tube (304), such that refrigerant sprayed from the spraying tube (202) is sprayed onto the surface of the heat exchange tube (304) by means of distribution of the perforated plate (205); spraying openings (301) on the spraying tube (202) have a strip shape, and the extension direction of the openings is perpendicular to the length direction of the spraying tube (202). By means of configuring the length direction of the spraying tube (202) to be substantially perpendicular to the length direction of the heat exchange tube (304), refrigerant sprayed from the spraying openings (301) flows substantially in the length direction of the housing (101), the flow path of the refrigerant being lengthened, avoiding uneven spraying on the surface of the heat exchange tube (304).