Refrigerator Defrost Control Using Temperature Change Rate Feedback
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Solution Overview
Problem
Existing refrigerator defrosting systems inefficiently manage frost removal on evaporators, leading to improper defrosting and unnecessary power consumption, as they rely on predetermined time-based controls rather than actual frost amounts.
Innovation Solution
A refrigerator system that includes a controller managing a defrost operation mode with pre-defrost, heater, and post-defrost cooling modes, utilizing continuous and pulse operation modes for the defrost heater based on temperature changes, ensuring efficient frost removal and optimized power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the defrost heater is controlled based on predetermined time, then the control system is simple, but defrosting is not performed according to the actual amount of frost leading to improper defrosting or unnecessary power consumption
Solution Approach 1:
The patent implements feedback control by using a temperature sensor to detect the evaporator's ambient temperature and calculating the temperature change rate. This feedback mechanism allows the system to adjust the defrost heater operation based on actual frost conditions rather than predetermined time schedules, thereby reducing unnecessary power consumption while maintaining simple control logic through standardized response protocols.
Solution Approach 2:
The system transitions from static time-based control to dynamic condition-based control. The defrost heater operation is dynamically adjusted based on real-time temperature change rate detection, enabling the system to adapt its heating cycles to the actual frost accumulation rate and environmental conditions, optimizing energy usage.
2Reliability
If the defrost heater operates continuously, then defrosting is thorough, but power consumption increases unnecessarily when frost amount is small
Solution Approach 1:
The system applies partial action by operating the defrost heater intermittently rather than continuously. Based on the temperature change rate, the controller activates the heater only when frost accumulation reaches levels requiring intervention, avoiding excessive energy consumption during periods when frost is minimal or absent.
Solution Approach 2:
The defrost heater operates in periodic cycles determined by temperature change rate thresholds. When the rate exceeds a predetermined value, the heater is activated for a specific duration, then turned off. This periodic operation ensures thorough defrosting when needed while minimizing power consumption during lighter frost conditions.
3Use of energy by moving object
If the defrost heater is turned on and off frequently, then power consumption is reduced, but defrosting efficiency decreases when frost amount is large
Solution Approach 1:
The system dynamically adjusts the defrost heater operation strategy based on the magnitude of the temperature change rate. When the rate indicates heavy frost accumulation, the system extends heater operation duration or increases cycling frequency to maintain defrosting efficiency. When the rate is low, the system reduces operation to minimize power consumption, achieving adaptive optimization.
Solution Approach 2:
The controller modifies operational parameters such as heater duty cycle and activation threshold based on the detected temperature change rate. By changing these parameters dynamically, the system balances power consumption and defrosting efficiency across varying frost conditions.
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
Improves defrosting efficiency and reduces power consumption by adapting to actual frost amounts on the evaporator, extending the duration of effective defrosting while minimizing overheating and energy expenditure.
Implementation Method 1
a defrost heater configured to operate to remove frost formed on the evaporator
Implementation Method 2
an evaporator configured to perform heat exchange
Implementation Method 3
a temperature sensor configured to detect an ambient temperature of the evaporator
Data Source
AI summary
The present disclosure relates to a refrigerator. The refrigerator according to one embodiment of the present disclosure comprises: an evaporator; a defrosting heater; a temperature sensor; and a controller to control the defrosting heater. The controller is configured to: in response to a defrosting operation starting time arriving, perform a defrosting operation mode including a pre-defrosting cooling mode, a heater operation mode and a post-defrosting cooling mode; perform a continuous operation mode, in which the defrosting heater is continuously on; and when a temperature change rate sequentially increases, decreases and increases again, perform a pulse operation mode, in which the defrosting heater is repeatedly turned on and off. Accordingly, defrosting efficiency may be improved, and power consumption may be reduced.