Falling Film Evaporator Distributor Baffles for Uniform Refrigerant Flow
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Solution Overview
Problem
Falling film evaporators in HVAC systems face challenges in maintaining a stable liquid level and uniform refrigerant distribution due to the requirement of gravity feed, which can lead to uneven flow and increased refrigerant volume, making them susceptible to installation issues and high refrigerant demands.
Innovation Solution
Incorporating a distributor box with a perforated distribution sheet and baffles to divide the distributor box into compartments, ensuring a homogeneous flow of liquid refrigerant over the evaporator tubes, thereby stabilizing the liquid level and reducing the refrigerant charge while allowing for unlevel installations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gravity feed is used to distribute refrigerant over evaporator tubes, then precise location of liquid film is achieved, but uniform flow distribution becomes difficult to maintain
Solution Approach 1:
The distributor box is segmented into multiple compartments by vertical baffles, with each compartment serving a specific zone of evaporator tubes. This segmentation isolates flow variations in different zones, preventing maldistribution caused by liquid level fluctuations in any single compartment while maintaining precise liquid film location through controlled orifice flow in each compartment.
2Stability of the object's composition
If liquid level is strictly controlled in distributor, then uniform refrigerant delivery through orifices is achieved, but system complexity and footprint increase
Solution Approach 1:
The distributor box is divided into multiple compartments by vertical baffles, with each compartment independently delivering refrigerant to a specific zone of evaporator tubes. This segmentation isolates liquid level fluctuations to individual compartments, allowing uniform refrigerant delivery through orifices in each compartment without requiring complex system-wide liquid level control mechanisms.
3Adaptability or versatility
If generous liquid level allowance is provided, then installation flexibility is improved, but flow through orifices becomes uneven
Solution Approach 1:
The distributor box is divided into multiple compartments by vertical baffles, creating isolated zones that can accommodate liquid level variations independently. Each compartment maintains relatively uniform orifice flow despite installation irregularities, while the overall system gains installation flexibility from the modular compartment structure that tolerates level differences between compartments.
4Stability of the object's composition
If more liquid refrigerant is stored in distribution system, then stable liquid level is maintained, but refrigerant volume requirement increases
Solution Approach 1:
The distributor box is divided into multiple compartments by vertical baffles, with each compartment containing a smaller volume of liquid refrigerant. This segmentation maintains liquid level stability within each compartment through controlled orifice flow, while the total refrigerant volume required in the distribution system is reduced compared to a single large-volume distributor.
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 solution enhances the uniformity of refrigerant distribution and reduces the refrigerant volume required, ensuring stable operation and efficient thermal energy transfer while accommodating potential installation irregularities without increasing the system's footprint or refrigerant storage.
Implementation Method 1
a falling film evaporator, the evaporator tubes are positioned typically below a distribution manifold from which refrigerant is urged, forming a 'falling film' on the evaporator tubes, utilizing gravity to drive the flow of refrigerant over the evaporator tubes
Implementation Method 2
HVAC systems, such as chillers, use an evaporator to facilitate a thermal energy exchange between a refrigerant in the evaporator and a medium flowing in a number of evaporator tubes positioned in the evaporator
Implementation Method 3
Evaporation is primarily accomplished through thin film evaporation on the surface of the evaporator tubes
Data Source
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AI summary
A heating, ventilation and air conditioning (HVAC) system includes a condenser (18) flowing a flow of refrigerant therethrough, and a falling film evaporator (12) in flow communication with the condenser. The falling film evaporator includes a plurality of evaporator tubes (38) through which a volume of thermal energy transfer medium is flowed and a distributor (42) to distribute a flow of liquid refrigerant over the plurality of evaporator tubes. The distributor includes a distributor box (46) and a distribution sheet (48) positioned at a bottom surface of the distributor box having a plurality of ports (56) therein to distribute the flow of liquid refrigerant downwardly over the plurality of evaporator tubes. A plurality of baffles (56) is positioned at the distribution sheet to divide the distributor box into a plurality of compartments to ensure a homogeneous flow of the liquid refrigerant is delivered through the plurality of ports.