Temperature control of refrigeration cavities in low ambient temperature conditions
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Solution Overview
Problem
In refrigeration appliances, low ambient temperatures can cause the freezer compartment to warm up and the fresh-food compartment to cool down excessively due to inadequate temperature control, leading to undesired thawing or freezing, which existing solutions address with complex and costly external heating elements, sensors, and electronic dampers.
Innovation Solution
A method that monitors the compressor duty cycle and evaporator temperature to activate the refrigeration circuit when necessary, using a low ambient control algorithm to manage temperature in both compartments without external heating, sensors, or electronic dampers, by controlling the compressor, evaporator fan, and potentially heating the fresh-food compartment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the cooling system is controlled based on fresh-food compartment temperature in low ambient conditions, then the fresh-food compartment temperature is maintained, but the freezer compartment warms up to ambient temperature causing undesired thaw
Solution Approach 1:
The system dynamically adjusts the control strategy based on ambient temperature conditions. When low ambient temperature is detected, the system switches from fresh-food compartment-based control to freezer compartment-based control, ensuring the freezer maintains proper temperature while the fresh-food compartment is protected from over-cooling through controlled air flow.
Solution Approach 2:
The control parameters are changed based on ambient conditions. In low ambient temperature conditions, the system modifies the temperature thresholds and control logic for the compressor and air flow dampers to prevent freezer thaw while avoiding fresh-food compartment freezing.
2Measurement precision
If external heating elements and electronic dampers are used to control temperature in low ambient conditions, then temperature control precision is improved, but device complexity and cost increase
Solution Approach 1:
The system uses the existing refrigeration components (compressor, evaporator, air flow paths) to achieve temperature control without requiring external heating elements. The control logic self-adjusts based on temperature sensor feedback, and the existing air flow dampers are utilized to manage air distribution, eliminating the need for additional complex heating systems.
Solution Approach 2:
The existing air flow dampers and compressor are made multi-functional by implementing intelligent control logic. The same components used for normal cooling operations are also used to prevent freezer thaw and control fresh-food compartment temperature in low ambient conditions, eliminating the need for dedicated heating elements or additional control devices.
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
Effectively prevents freezer thaw and fresh-food compartment freezing, maintaining optimal temperatures without external heating elements, ambient sensors, or electronic dampers, simplifying the control system and reducing costs.
Implementation Method 1
A refrigeration appliance includes a refrigeration circuit and a controller. The controller is configured to monitor a duty cycle of the compressor and monitor a temperature of the evaporator.
Implementation Method 2
monitoring the duty cycle of the compressor
Implementation Method 3
monitoring a temperature of the evaporator
Data Source
AI summary
A method of controlling the temperature in cavities of a refrigerator (10) cooled by a refrigeration circuit having a compressor (18) and an evaporator (32) includes the steps of: monitoring the duty cycle of the compressor (18); determining whether the duty cycle is below a threshold; determining whether the temperature of the evaporator (32) is above a threshold; and if the duty cycle is below the threshold and if the evaporator temperature is above a threshold, activating the refrigeration circuit to start cooling of at least one of the refrigerator cavities. A refrigeration appliance (10) with a controller that activates the refrigeration circuit based on the monitored duty cycle of the compressor (18) and the evaporator temperature is also provided.