Vacuum Insulation for Refrigerator Suction Lines and Capillary Tubes
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Solution Overview
Problem
Current insulation methods, such as foam insulation, are imperfect and can be compromised by condensation, leading to reduced thermal efficiency and increased operating costs in refrigerator appliances, particularly in the refrigeration cycle components like the suction line and capillary tube.
Innovation Solution
A vacuum insulator is introduced, comprising an outer and inner conduit with an annular space evacuated to create a vacuum, which significantly reduces heat transfer and enhances thermal efficiency by encasing the suction line, capillary tube, or their heat exchanger within an outer conduit sealed at both ends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foam insulation is used to insulate the suction line and capillary tube, then the insulation provides a certain level of thermal protection, but the insulation ability decreases when the foam becomes wet due to condensation
Solution Approach 1:
The patent removes the air/gas from the annular space between the inner and outer conduits to create a vacuum environment. This extraction of the gas phase eliminates the medium through which heat can conduct, and simultaneously prevents condensation from forming on the inner conduit surface, thereby maintaining insulation ability even when exposed to cold temperatures and moisture-prone environments.
Solution Approach 2:
The patent creates an inert vacuum environment within the annular space between the inner and outer conduits. This vacuum acts as an inert atmosphere that prevents heat transfer through conduction and convection, and also prevents condensation from forming on the refrigerant lines, thereby maintaining reliable insulation performance.
2Temperature
If foam insulation is used around the refrigeration cycle components, then thermal protection is provided, but heat transfer from the environment still occurs reducing the capacity to cool the refrigerant
Solution Approach 1:
The patent replaces the foam insulation system with a vacuum-based insulation system. Instead of relying on the mechanical/chemical structure of foam to resist heat transfer, the system uses the physical principle of vacuum to eliminate conductive and convective heat transfer pathways, thereby significantly reducing heat gain and maintaining lower refrigerant temperatures.
Solution Approach 2:
The patent creates an inert vacuum environment within the annular space that eliminates the atmosphere through which heat can transfer. This vacuum barrier prevents environmental heat from warming the refrigerant in the inner conduit, thereby maintaining the refrigerant's cooling capacity more effectively than foam insulation.
3Reliability
If the suction line is insulated with foam, then some thermal protection is achieved, but the insulation effectiveness is compromised when the foam is cooled below the dew point
Solution Approach 1:
The patent extracts the gas phase from the annular space to create a vacuum, thereby removing the medium that would otherwise allow condensation to form on the inner conduit surface. This prevents the insulation effectiveness from being compromised by condensation, even when the refrigerant line is cooled below the dew point temperature.
Solution Approach 2:
The patent creates an inert vacuum environment that prevents condensation from forming on the inner conduit surface, even when temperatures drop below the dew point. This maintains the insulation effectiveness by eliminating the harmful condensation that would otherwise degrade foam insulation performance.
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 vacuum insulator effectively maintains the cooler temperature of refrigerant vapor and liquid, improving the thermal efficiency of the refrigeration cycle by minimizing heat transfer from the environment and reducing condensation-related insulation degradation.
Implementation Method 1
The annular space is evacuated so as to create a vacuum enclosed within the pair of seals, the outer conduit, and the inner conduit
Data Source
AI summary
A vacuum insulator for portions of the refrigeration cycle of a refrigerator appliance is provided. The vacuum insulator can be applied to the suction line leading to the refrigerant compressor, the capillary tube leading to the evaporator inlet, and/or the capillary tube—suction line heat exchanger. An outer insulating layer is used to create a vacuum that serves to insulate the intended portion of the refrigeration cycle.