Canopy Heat Exchanger Layout for Low-Charge Falling Film Evaporation
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Solution Overview
Problem
Conventional vapor compression refrigeration systems face challenges in reducing refrigerant charge while maintaining performance, particularly with high-cost, low-global-warming-potential refrigerants, and suffer from oil accumulation and vapor refrigerant velocity issues in falling film evaporators.
Innovation Solution
A heat exchanger design that incorporates a canopy member and a trough part to reduce refrigerant charge, manage oil accumulation, and control vapor refrigerant velocity, featuring a distributing part, tube bundle, and a refrigerant recirculation system to ensure efficient heat transfer and minimize liquid droplet carryover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a flooded evaporator is used, then heat transfer performance is improved, but refrigerant charge increases
Solution Approach 1:
The evaporator is divided into multiple sections with different heat transfer modes. Some heat transfer tubes are arranged in a falling film section where refrigerant flows as a film, while other tubes are arranged in a flooded section. This segmentation allows the system to achieve high heat transfer performance through the flooded section while reducing overall refrigerant charge by using the falling film section that requires less refrigerant.
2Quantity of substance
If a falling film evaporator is used, then refrigerant charge is reduced, but heat transfer performance decreases
Solution Approach 1:
The patent combines two different heat transfer modes (falling film and flooded) into a single evaporator system. The falling film section reduces refrigerant charge while the flooded section maintains high heat transfer performance. By merging these two modes in one device, the system achieves both benefits: reduced refrigerant charge and maintained heat transfer performance.
3Productivity
If liquid refrigerant is recirculated in a falling film evaporator, then heat transfer efficiency is improved, but oil accumulation increases
Solution Approach 1:
The patent extracts and separates the oil from the recirculating refrigerant by providing a dedicated oil discharge port. The oil separator component removes oil from the liquid refrigerant before recirculation, and the separated oil is discharged through a separate port. This extraction of the harmful substance (oil) from the recirculation loop allows efficient heat transfer through recirculation while preventing oil accumulation that would otherwise degrade performance.
4Productivity
If vapor refrigerant velocity is increased, then heat transfer efficiency is improved, but liquid droplet carryover increases
Solution Approach 1:
The patent introduces an intermediary component (liquid separator or baffle structure) between the heat transfer section and the vapor outlet. This intermediary structure captures and separates liquid droplets from the high-velocity vapor stream before the vapor exits the evaporator. The intermediary allows the system to maintain high vapor velocity for efficient heat transfer while preventing harmful liquid droplet carryover that would reduce system efficiency and potentially damage 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
The design effectively reduces refrigerant charge, manages oil accumulation, and decreases vapor refrigerant velocity, ensuring high heat transfer efficiency and minimizing liquid droplets in the gas refrigerant pipe, thereby improving overall system performance.
Implementation Method 1
Heat from walls of the heat transfer tubes is transferred via convection and/or conduction through the liquid film to the vapor-liquid interface
Implementation Method 2
Heat from walls of the heat transfer tubes is transferred via convection and/or conduction through the liquid film
Implementation Method 3
the refrigerant to evaporate from liquid to vapor while absorbing heat from liquid to be cooled
Implementation Method 4
the refrigerant to evaporate from liquid to vapor while absorbing heat from liquid to be cooled
Implementation Method 5
The liquid refrigerant that does not evaporate falls vertically from the heat transfer tube at an upper position toward the heat transfer tube at a lower position by force of gravity
Data Source
Figure 1
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AI summary
A heat exchanger (1, 1A, 1B, 1C, 1D, 1E, 1F, 101, 201, 201A, 201B, 201C, 301, 401, 401 ', 501, 501 ', 601, 701, 701 ') includes a shell (10), a refrigerant distribution assembly (20, 420), a heat transferring unit (30, 30A, 30B, 30C, 30D, 30E, 30F, 230, 230A, 230B, 230C, 330, 430, 530, 630, 730) and a canopy member (452). The refrigerant distribution assembly (20, 420) receives a refrigerant that enters the shell ( 10) and discharges the refrigerant. The refrigerant distribution assembly (20, 420) has at least one outermost lateral end. The heat transferring unit (30, 30A, 30B, 30C, 30D, 30E, 30F, 230, 230A, 230B, 230C, 330, 430, 530, 630, 730) is disposed below the refrigerant distribution assembly (20, 420) so that the refrigerant discharged from the refrigerant distribution assembly (20, 420) is supplied to the heat transferring unit (30, 30A, 30B, 30C, 30D, 30E, 30F, 230, 230A, 230B, 230C, 330, 430, 530, 630, 730). The heat transferring unit (30, 30A, 30B, 30C, 30D, 30E, 30F, 230, 230A, 230B, 230C, 330, 430, 530, 630, 730) includes a plurality heat transfer tubes (31). The canopy member (452) includes at least one lateral side portion (482) extending laterally outwardly and downwardly from a position above the refrigerant distribution assembly (20, 420). The lateral side (482) portion has a free end disposed laterally further from a vertical plane (V) than the refrigerant distribution assembly (20), 420), and lower than an upper edge of the outermost lateral end of the refrigerant distribution assembly (20, 420).