Ventilation unit for a refrigeration cabinet
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Solution Overview
Problem
Low temperature chambers, such as refrigerators and ultra-low freezers, experience air exchange and underpressure when the door is opened, causing the door to become stuck or damaged due to the contraction of cold air, which existing ventilation units fail to compensate quickly enough.
Innovation Solution
A ventilation unit with a tube-shaped base body featuring a heating element, offset inlet and outlet openings, and a mechanical valve that opens in response to pressure differences, allowing for rapid pressure compensation without additional power, and is designed to maintain a stable air layering to prevent frost formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heated piping with wire mesh is used to compensate pressure difference, then the pressure compensation function is achieved, but the required time to reopen the door increases to approximately 30 seconds
Solution Approach 1:
The ventilation unit is pre-installed in the door structure with inlet and outlet openings positioned to enable immediate pressure compensation upon activation, eliminating the need for external heating equipment and reducing response time
Solution Approach 2:
The heating element is extracted from the piping interior and repositioned to heat air before it enters the ventilation unit through the inlet opening, allowing faster thermal response and reduced pressure compensation time
2Use of energy by moving object
If the heating element is not permanently switched on to save energy, then energy consumption is reduced, but frost formation risk increases within the base body
Solution Approach 1:
The ventilation unit utilizes the temperature difference between inlet and outlet openings to create natural convection currents that prevent frost formation, eliminating the need for continuous heating while maintaining frost-free operation
Solution Approach 2:
The offset positioning of inlet and outlet openings creates a temperature gradient that drives air flow through the base body, dynamically adjusting the thermal parameters to prevent frost without continuous energy input
3Device complexity
If inlet and outlet openings are concentrically disposed, then the structure is simpler, but stable air layering cannot be established and frost formation is more likely
Solution Approach 1:
The inlet and outlet openings are positioned asymmetrically with an offset displacement, creating unequal flow paths that establish stable air layering and prevent frost formation through enhanced convective heat transfer
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
Enables the door to be reopened shortly after initial opening by efficiently compensating pressure differences, reducing the risk of ice formation and maintaining the valve's frost-free operation, even when the heating element is not continuously active.
Implementation Method 1
the base body comprises a heating element
Implementation Method 2
when a specified pressure difference between the inlet side end and the outlet side end is exceeded with an underpressure at the outlet side end, it opens under pressure induction
Implementation Method 3
Due to the height offset a stable air layering can be established in the base body
Implementation Method 4
Thereby that the base body tapers toward the outlet opening the flow rate of the mass flow increases toward the outlet opening which can entrain potentially forming condensation water
Data Source
AI summary
A ventilation unit for a low temperature chamber with a tube-shaped base body, having a heating element, an inlet side end with an inlet opening and an outlet side end with an outlet opening, wherein the base body has a tapered form such that the inlet opening has a greater area than the outlet opening. The inlet opening can be located in a first front side plane and the outlet opening can be located in a second front side plane, wherein the first front side plane and the second front side plane are substantially parallel offset with respect to one another, and wherein at perpendicular projection of the first front side plane onto the second front side plane, the inlet opening and the outlet opening are disposed offset with respect to one another. The base body can have a mechanical valve configured to open under pressure induction.