Kitchen Exhaust Hood Geometry for Low-Airflow Plume Capture
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Solution Overview
Problem
Existing kitchen exhaust hood systems require high exhaust airflow volumes to capture thermal plumes from commercial cooking equipment, leading to inefficient air management and increased energy consumption.
Innovation Solution
The exhaust system incorporates a hood structure with a downwardly facing inlet, a filter aperture angled at least 50 degrees, an exhaust flow infeed surface extending downward from the filter unit, and a bypass flow transition surface that aids in circulating bypass flow back toward the filter aperture, along with a front wall structure featuring a chamfered and/or curved transition portion to enhance airflow directionality and reduce air volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional hood systems use a filter aperture angled at 45 degrees or greater to vertical, then the structure is simple and easy to manufacture, but increased exhaust airflow rates are required to maintain capture and containment of thermal plume
Solution Approach 1:
The patent introduces a new spatial dimension by extending the filter aperture downward below the hood structure and providing an exhaust flow infeed surface that directs plume upward into the filter. This vertical dimensionality change allows the filter to capture rising thermal plume more effectively without requiring excessive exhaust airflow volume, resolving the contradiction between simple structure and reduced airflow requirements.
Solution Approach 2:
The exhaust flow infeed surface acts as an intermediary element between the cooking appliances and the filter aperture. It mediates the thermal plume flow by directing it upward into the extended filter aperture, enabling effective plume capture with reduced exhaust airflow rates while maintaining structural simplicity.
2Reliability
If conventional hood systems draw off large volumes of air to assure capture of thermal plume, then plume capture is effective, but energy consumption increases
Solution Approach 1:
The extended filter aperture and infeed surface perform preliminary action by pre-directing the thermal plume into the filter aperture before the main exhaust airflow acts on it. This preliminary organization of plume flow ensures effective capture with minimal exhaust airflow, thereby reducing energy consumption while maintaining reliable plume capture.
3Shape
If conventional hood systems use apron to force buoyancy driven exhaust flows to change direction, then lateral flows are created proximate filter aperture, but higher exhaust airflow rates are required
Solution Approach 1:
Instead of using an apron to force flows to change direction laterally, the patent inverts the approach by extending the filter aperture downward and using the infeed surface to naturally guide the buoyancy-driven upward flow into the filter. This inversion eliminates the need for high exhaust airflow rates to create lateral flows, reducing energy consumption while maintaining effective plume capture.
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 effectively captures thermal plumes with reduced exhaust airflow, improving efficiency and minimizing energy consumption by optimizing airflow patterns and reducing the volume of air drawn and expelled.
Implementation Method 1
the apron 10 of the hood 12 forces the buoyancy driven exhaust flows to change direction
Implementation Method 2
a bypass flow transition surface extending upward from the upper end of the filter unit and then forward to aid bypass flow in circulating back toward the filter aperture
Data Source
AI summary
An exhaust system includes a hood structure having one or more of (i) an exhaust flow infeed surface extending downward from a lower end of the filter unit that helps to feed the thermal plume toward the filter unit, (ii) a bypass flow transition surface extending upward from the upper end of the filter unit and then forward to aid bypass flow in circulating back toward the filter aperture and (iii) a front wall structure that includes a downwardly extending wall portion with a chamfered and/or curved transition portion at its lower end and a rearwardly extending wall portion.