Drain Pan Heater Layout for Better Refrigerator Defrosting
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Solution Overview
Problem
In refrigerator units, the dense disposition of drain pan heaters made from low heat transmitting resin materials leads to increased costs, hindered drainage, reduced defrosting performance, thermal deformation of the heat insulating wall, and prolonged defrosting times due to residual water and ice formation.
Innovation Solution
A thermal conductor, such as an aluminum or copper alloy plate, is laid on the surface of the drain pan through a heat insulating layer, allowing the drain pan heater to be disposed in contact with the thermal conductor, facilitating even heat transfer and reducing the need for a dense heater layout, which prevents residual water and ice formation and thermal deformation of the heat insulating wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drain pan heater is densely disposed on the surface of the drain pan to ensure even heat distribution, then the defrosting performance is improved, but the heater becomes lengthy and complicated, increasing its cost and complexity
Solution Approach 1:
A thermal conductor plate is introduced as an intermediary between the drain pan and the heater. The heater contacts only the thermal conductor plate, which then distributes heat evenly across the drain pan surface, eliminating the need for dense heater disposition and reducing heater complexity while maintaining defrosting performance.
2Temperature
If the drain pan heater is densely disposed on the surface of the drain pan, then heat distribution is improved, but the drain pan heater becomes a weir, hampering drainage of the drain water
Solution Approach 1:
The thermal conductor plate serves as a mediator that separates the heater from direct contact with the drain pan surface. This allows the heater to be sparsely disposed without creating drainage obstructions, while the thermal conductor plate itself provides even heat distribution across the drain pan, resolving the conflict between heating efficiency and drainage functionality.
3Reliability
If the temperature of the hot gas refrigerant becomes 100°C or more to ensure effective defrosting, then the defrosting performance is improved, but thermal contraction (thermal deformation) may occur at part of the drain pan contacting with the drain pan heater
Solution Approach 1:
The thermal conductor plate acts as a thermal buffer between the high-temperature heater and the drain pan. It conducts heat efficiently to provide effective defrosting while limiting the temperature transmitted to the drain pan, preventing thermal contraction and deformation of the resin material.
4Use of energy by stationary object
If the drain pan is made from low heat transmitting resin material to provide insulation, then the heat insulating performance is improved, but it is hard for the heat to evenly propagate on the surface of the drain pan
Solution Approach 1:
The system uses a composite structure combining the low heat transmitting resin material of the drain pan with a high thermal conductivity thermal conductor plate. This composite arrangement maintains the insulating performance of the resin while the thermal conductor plate ensures even heat propagation across the surface where needed.
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 configuration improves drainage, reduces heat loss, shortens defrosting time, and prevents thermal deformation of the heat insulating wall, enhancing overall defrosting performance while minimizing costs by optimizing the placement and material usage of the thermal conductor.
Implementation Method 1
a thermal conductor is laid on the surface of the drain pan through the intermediary of a heat insulating layer and the drain pan heater is disposed in contact with the surface of the thermal conductor
Implementation Method 2
guides high temperature and high pressure hot gas refrigerant discharged out of a compressor directly to the evaporator via a hot gas bypassing pipe to melt the frost by the heat of the hot gas refrigerant
Implementation Method 3
a thermal conductor is laid on the surface of the drain pan through the intermediary of a heat insulating layer
Data Source
Figure 1
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AI summary
A refrigerator unit is provided whose drainage is improved and which prevents ice from being produced by residual water, since a drain pan heater will not hamper the drainage of drain water. It can also improve a defrosting performance by reducing a loss of heat in the drain pan heater and can prevent a heat insulating wall from being thermally deformed. In the refrigerator unit (11) in which a drain pan (20) composed of the heat insulating wall (15) is provided under an evaporator (16), and the drain pan heater (28) is disposed in contact with the surface of the drain pan (20), a thermal conductor (22) is laid on the surface of the drain pan (20) through the intermediary of a heat insulating layer (27), and the drain pan heater (28) is disposed in contact with the surface of the thermal conductor (22).