Variable Defrost Heater Control for Changing Evaporator Ice Load
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Solution Overview
Problem
Conventional defrosting arrangements for refrigeration appliances do not adequately account for varying ice accumulation on the evaporator between defrosting operations, leading to inefficient defrosting cycles.
Innovation Solution
A refrigeration appliance with a temperature-sensing system that adjusts the power level of the defrost heater based on the rate of evaporator temperature rise during a defrosting operation, allowing for dynamic power adjustments between heating intervals to ensure effective ice removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed power level is supplied to the defrost heater during all heating intervals, then the control system is simple, but the defrosting efficiency is insufficient due to varying ice accumulation conditions
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed power level to a variable power level system. The controller dynamically adjusts the defrost heater power between a first power level during initial heating intervals and a second power level during subsequent heating intervals based on real-time temperature sensor feedback, allowing the system to adapt to varying ice accumulation conditions and improve defrosting efficiency
Solution Approach 2:
The patent implements feedback control by using a temperature sensor to continuously monitor the evaporator temperature and provide feedback to the controller. The controller processes this feedback signal and adjusts the defrost heater power accordingly, creating a closed-loop control system that optimizes defrosting performance while managing complexity
2Reliability
If the defrost heater operates at high power continuously, then ice removal is effective, but energy consumption increases
Solution Approach 1:
The patent applies periodic action by dividing the defrosting process into distinct heating intervals with different power levels. The controller switches between a first power level during initial heating intervals and a second power level during subsequent intervals, creating a periodic variation in power delivery that maintains ice removal effectiveness while reducing overall energy consumption
Solution Approach 2:
The patent implements parameter changes by varying the power level parameter of the defrost heater throughout the defrosting cycle. The system changes from a first power level to a second power level based on the heating interval stage and temperature feedback, optimizing the balance between ice removal effectiveness and energy consumption
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 approach ensures more efficient and adaptive defrosting by optimizing power usage based on real-time evaporator conditions, improving the consistency and effectiveness of the defrosting process.
Implementation Method 1
A defrost heater is associated with the evaporator
Implementation Method 2
A temperature sensor senses an evaporator temperature and generates a temperature signal based on the evaporator temperature
Implementation Method 3
An evaporator cools the storage compartment
Data Source
AI summary
A refrigeration appliance includes a storage compartment. An evaporator cools the storage compartment. A defrost heater is associated with the evaporator. A temperature sensor senses an evaporator temperature and generates a temperature signal based on the evaporator temperature. A controller receives the temperature signal and generates a defrost heater power control signal. A power supply receives the defrost heater power control signal and controls a power level supplied to the defrost heater based on the defrost heater power control signal. A first power level is supplied to the defrost heater during a first heating interval of a defrosting operation, and, based on an evaporator temperature rise occurring during the first heating interval, the controller adjusts the defrost heater power control signal such that an adjusted power level is supplied to the defrost heater during a second heating interval of the defrosting operation.