Ducted Shelf Airflow Layout for Open Refrigerated Displays
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Solution Overview
Problem
Conventional refrigerated display cabinets with doors fail to effectively retain cold air, leading to energy wastage, temperature control issues, and contamination from ambient air, which affects food quality and safety due to high entrainment rates of ambient air and moisture, causing condensation and microbial activity.
Innovation Solution
A ducted shelf design with a forwardly extending duct and guide walls that divide the duct into pathways with varying widths and lengths, ensuring balanced airflow and pressure drops across the shelf, combined with airflow guide bodies that distribute air evenly, reducing ambient air entrainment and maintaining temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If doors are fitted to refrigerated display cabinets to retain cold air, then cold air retention should improve, but in practice doors are opened frequently causing cold air spillage and energy wastage
Solution Approach 1:
The invention removes the door barrier entirely from the refrigerated display cabinet, extracting the obstruction that prevented easy access while implementing an air curtain system to maintain cold air retention without requiring physical doors
Solution Approach 2:
The invention uses a pneumatic air curtain system where high-velocity cold air is projected horizontally across the cabinet opening to create a barrier that retains cold air without requiring physical doors, thus maintaining both energy efficiency and easy access
2Loss of energy
If high velocity air curtain is used to seal the access opening, then cold air retention improves, but ambient air entrainment increases
Solution Approach 1:
The invention changes the velocity parameter of the air curtain from high to low, using low-velocity air that still effectively seals the opening while minimizing ambient air entrainment, thus reducing both energy loss and contamination
3Speed
If additional cooling air is supplied via back panel to support air curtain, then air curtain velocity can be reduced, but ambient air entrainment rates remain as high as 80%
Solution Approach 1:
The invention transitions from vertical air curtain flow to horizontal air curtain flow, projecting cold air horizontally across the cabinet opening rather than vertically, which fundamentally changes the flow dynamics and reduces ambient air entrainment while maintaining effective sealing
4Illumination intensity
If doors are equipped with heating to reduce fogging, then visibility improves, but energy consumption increases
Solution Approach 1:
The invention removes the door structure entirely, eliminating the source of fogging and misting problems, thus no heating is required and visibility is maintained through the open front design with air curtain protection
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 solution significantly reduces ambient air entrainment, maintains consistent temperature across the display space, and minimizes energy consumption while preventing condensation and microbial growth, thereby enhancing food safety and shelf life.
Implementation Method 1
refrigerated multi-deck display cases or cabinets that are used in retail premises for cold-storage
Implementation Method 2
employ a large downwardly-projected refrigerated air curtain extending between discharge and return air terminals from top to bottom over an access opening
Implementation Method 3
guide walls that extend along the duct to divide the duct into a group of pathways disposed successively side-by-side in the widthwise direction, each pathway comprising a respective channel having respective forward and rearward ends, the guide walls splaying forwardly such that the channels are wider in the widthwise direction at their forward ends than at their rearward ends
Implementation Method 4
The moisture that the air carries causes condensation, which may also lead to icing. Condensation is unsightly, off-putting and unpleasant for shoppers
Data Source
AI summary
A ducted shelf for an open-fronted display unit employing air curtains comprises a duct extending forwardly or rearwardly through the shelf and communicating at a forward end with a discharge or return opening, the duct being wider in the widthwise direction at the forward end than at a rearward end of the duct. Guide walls divide the duct into a group of channels disposed successively side-by-side in the widthwise direction. Each channel has a respective length reflecting a degree of widthwise offset between the rearward end and the forward end of that channel. A longer channel of the group has a greater width in the widthwise direction at its rearward and forward ends than a shorter channel of the group.