Display Case Door Defogging With Three-Speed Airflow Control
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Solution Overview
Problem
Transparent door display cases face issues with fog or condensation that hinder product visibility, leading to increased energy consumption and wear on refrigeration systems due to existing defogging methods, which either require complex ductwork, high-energy motors, or constant fan cycling.
Innovation Solution
A system with a multispeed electric motor and air moving device that operates at different speeds based on the door's position, providing nominal speed when closed, lower speed when open, and higher speed briefly after closure to clear fog, minimizing heat transfer and energy usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the evaporator fan motor is shut off when the door is open, then energy consumption is reduced, but additional wear occurs on the motor and electrical systems due to constant cycling
Solution Approach 1:
The evaporator fan motor operates dynamically at three different speeds depending on door position: low speed when door is open, nominal speed when door is closed, and high speed during defogging cycles. This dynamic operation eliminates constant on/off cycling, reducing motor wear while maintaining energy efficiency benefits.
Solution Approach 2:
The system implements periodic defogging cycles where the motor runs at high speed for predetermined intervals after door closure. This periodic action maintains reliability by preventing fog accumulation without requiring continuous high-speed operation, thus balancing energy consumption with motor durability.
2Loss of information
If the evaporator fan runs at high speed continuously to prevent fog, then product visibility is maintained, but energy consumption increases
Solution Approach 1:
Instead of continuous high-speed operation, the system uses periodic defogging cycles triggered by door closure. The motor runs at high speed only during these predetermined intervals to clear fog, then returns to nominal speed. This maintains product visibility when needed while significantly reducing overall energy consumption.
Solution Approach 2:
The system proactively initiates defogging cycles immediately upon door closure, preventing fog accumulation before it significantly impacts visibility. This preliminary action maintains clear viewing conditions without requiring sustained high-energy operation.
3Loss of information
If heat is applied to remove fog/condensate from glass, then visibility is improved, but the refrigeration system must work harder and consume more energy
Solution Approach 1:
The system replaces thermal defogging methods with mechanical air movement. The evaporator fan directs cold air across the glass surface to condense and remove moisture mechanically, eliminating the need for additional heating elements and the associated energy consumption and refrigeration system workload.
Solution Approach 2:
Cold air from the evaporator serves as an intermediary medium to remove fog. Instead of applying heat directly to the glass, the system uses the cold air stream to condense moisture on the glass surface, which then drains away, achieving defogging without adding thermal energy to the system.
4Use of energy by moving object
If an air curtain is used to prevent air exchange when door is open, then energy efficiency is improved, but complicated ductwork is required reducing merchandise space
Solution Approach 1:
The evaporator fan serves multiple functions: it cools the display case interior, prevents fog on the glass door, and creates an air curtain effect at the door opening. This multi-functionality eliminates the need for separate air curtain ductwork, preserving merchandise space while maintaining energy efficiency.
Solution Approach 2:
The system merges the air curtain function with the existing evaporator fan and ductwork. The same components that provide refrigeration also create the air barrier at the door, consolidating functions and eliminating the need for additional space-consuming ductwork.
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 improves energy efficiency, reduces wear on systems, and maintains product visibility by efficiently clearing fog without adding heat, thus optimizing the display case's energy consumption and merchandise visibility.
Implementation Method 1
Fog or condensation accumulated on a transparent door
Implementation Method 2
the refrigeration system must work harder to remove this heat and return the inside of the display case to the desired internal temperature
Data Source
AI summary
A system for defogging doors to a display case is described and includes an electric motor and an air moving device. The air moving device is operatively coupled to the electric motor and positioned to provide an output proximate to at least one door of the display case. The motor is configured to operate at a first speed under standard closed door conditions, at a second speed when the door of the display case is open, and at a third speed for a predetermined length of time after the door is moved from an open position to a closed position.