Refrigerator Evaporator Bonding to Prevent Air Pockets
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Solution Overview
Problem
Existing evaporator production methods face inefficiencies in heat exchange due to air pockets and material wastage, and adhesive materials like thermosetting plastic and double-sided tape impede heat transfer or are costly.
Innovation Solution
A method using a butyl rubber adhesive bead, applied to the coolant pipe and compressed between the pipe and a blank, ensuring large-area contact and optimal heat transfer, with butyl rubber's low water absorption and high thermal conductivity providing a strong, efficient bond.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If expanded PU foam or pourable thermosetting plastic is used as adhesive to fill intermediate spaces, then the evaporator can be installed as a cold-wall evaporator with heat exchange via the blank surface, but the expenditure of material is considerable and production is costly
Solution Approach 1:
The adhesive is applied in segmented form as discrete beads at specific locations between the coolant pipe and blank, rather than as continuous foam or pourable material that would fill all intermediate spaces. This segmentation reduces material consumption while maintaining the cold-wall evaporator configuration and heat exchange functionality through the blank surface.
Solution Approach 2:
The adhesive beads are placed at specific local positions between the coolant pipe meanders and the blank, providing localized bonding and heat transfer paths. This local application of adhesive eliminates the need for extensive material filling while achieving the required thermal and mechanical performance for cold-wall evaporator installation.
2Ease of manufacture
If double-sided adhesive tape is used to secure the coolant pipe on the blank, then the pipe is easily attached, but the adhesive tape impedes heat exchange between the coolant pipe and blank and thus impairs the efficiency of the evaporator
Solution Approach 1:
The harmful intermediate layer (adhesive tape) that impedes heat exchange is completely removed from the contact area between the coolant pipe and blank. Instead, adhesive beads are positioned such that they bond the pipe to the blank while leaving the immediate contact area free for direct thermal contact, thus extracting the heat transfer impediment while retaining the ease of attachment.
Solution Approach 2:
The adhesive beads serve as a mediator that provides mechanical bonding between the coolant pipe and blank while being positioned to minimize thermal resistance. The beads are located at specific points rather than forming a continuous layer, allowing them to fulfill the bonding function without creating a heat transfer barrier across the entire contact surface.
3Strength
If bitumen film is heated and pressed to penetrate into the gusset for large-area adhesive bond, then strong bonding is achieved, but it is difficult to ensure that air is completely expelled from the gussets so that remaining air pockets impair the heat exchange
Solution Approach 1:
The adhesive bonding is segmented into discrete beads rather than a continuous film, which eliminates the formation of large gussets where air pockets can become trapped. The beads are positioned to provide bonding while allowing air to be easily expelled, thus maintaining strong adhesion without creating heat transfer barriers from trapped air.
Solution Approach 2:
The adhesive is applied in a different dimensional configuration - as discrete beads at specific locations rather than as a continuous two-dimensional film. This dimensional change from film to beads eliminates the gusset formation problem and associated air trapping, while still providing sufficient bonding area and strength through strategic placement.
4Loss of substance
If a bead of adhesive is placed between the coolant pipe and blank, then large-area contact can be produced with a small amount of adhesive, but the adhesive must be positioned precisely to ensure optimal heat transfer
Solution Approach 1:
The adhesive beads are applied to the coolant pipe or blank at predetermined positions before the assembly is compressed. This preliminary positioning ensures that the beads are correctly located to provide both bonding and optimal heat transfer paths, eliminating the need for high-precision positioning during the compression step while still achieving the desired contact area with minimal adhesive.
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 method enables reproducible and efficient heat exchange with minimal adhesive usage, preventing air pockets and ensuring high mechanical loading and food safety, suitable for various evaporator designs.
Implementation Method 1
by using butyl rubber with its good heat conduction properties compared to other adhesives, good heat transfer is produced between the blank and the coolant-carrying pipe
Implementation Method 2
This material is distinguished by an extremely low water absorption and permeability and thus prevents moisture from collecting at the interfaces between the adhesive and the pipe or the blank and impairing the coherence and therefore the thermal conductivity of the evaporator by freezing
Data Source
AI summary
A method for producing a heat exchanger, a) a coolant pipe and a blank are provided; b) a bead that is made of a plastic adhesive is placed between the coolant pipe and the blank so as to extend in a manner that is adapted to the shape of the coolant pipe; and c) the bead located between the coolant pipe and the blank is compressed.