Refrigerator with a variable speed compressor and a method for controlling the compressor speed
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Solution Overview
Problem
Domestic refrigerators face challenges in efficiently controlling refrigerant flow and temperature settings across multiple compartments, leading to imbalanced cooling loads and energy inefficiency, particularly when compartments have different temperature requirements.
Innovation Solution
A control system that adjusts the compressor speed based on minimum and required speed calculations, using elapsed time and temperature settings to optimize refrigerant flow, eliminating the need for external inputs and simplifying the control method, thereby improving energy efficiency and balancing cooling loads between compartments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the compressor is activated based on temperature sensor signals from the fresh food compartment, then the fresh food compartment temperature is maintained, but the freezer compartment may receive excessive cooling regardless of its actual needs
Solution Approach 1:
The control system continuously receives temperature feedback from both the fresh food compartment and freezer compartment temperature sensors. Based on this feedback, the microcontroller dynamically adjusts the compressor operation and refrigerant flow distribution to maintain appropriate temperatures in both compartments while avoiding excessive cooling and energy consumption.
Solution Approach 2:
The system dynamically adjusts the refrigerant flow distribution between compartments using controllable valves or variable restrictors. The refrigerant flow to each evaporator is continuously modified based on real-time temperature conditions and cooling demands of both compartments, allowing the system to adapt to changing conditions and prevent energy waste.
2Adaptability or versatility
If different temperature settings are applied to different compartments, then each compartment can store appropriate food types, but the refrigerant flow control becomes complex
Solution Approach 1:
The control system serves multiple functions through a single integrated microcontroller that manages compressor operation, refrigerant flow distribution, and temperature monitoring for both compartments. The electronic expansion valves or variable restrictors simultaneously control refrigerant flow to both evaporators based on unified control logic, reducing the need for separate mechanical control systems for each compartment.
Solution Approach 2:
The microcontroller acts as an intermediary that processes temperature signals from both compartments and coordinates the operation of compressors, valves, and restrictors. This electronic mediator simplifies the control architecture by replacing complex mechanical linkages and separate control mechanisms with a centralized digital control system that can handle multiple temperature settings efficiently.
3Loss of energy
If a variable speed compressor is used to control refrigerant flow, then energy efficiency is improved, but the control system complexity increases
Solution Approach 1:
The variable speed compressor allows continuous adjustment of the refrigerant compression rate and flow volume by changing the motor speed parameter. The electronic expansion valves adjust the refrigerant expansion ratio and flow rate by modifying valve opening degrees. These parameter changes enable precise control of refrigerant distribution to match the actual cooling demands of different compartments, improving energy efficiency while the integrated control system manages the complexity.
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 control system ensures efficient refrigerant flow and temperature management across compartments, reducing energy consumption and enhancing the ability to maintain user-set temperatures, especially in refrigerators with compartments at different temperatures.
Implementation Method 1
the refrigerant flow path from the freezer compartment to the fresh food compartment the rich refrigerant is initially delivered in the freezer, evaporating and absorbing heat from the freezer compartment
Implementation Method 2
the rich refrigerant is initially delivered in the freezer, evaporating and absorbing heat from the freezer compartment
Data Source
AI summary
Refrigerator (200, 210) comprising a compartment (13a) for storing foodstuff; a cooling system (200, 210) comprising an evaporator (12a), a condenser (14) and a variable speed compressor (10), the cooling system (200, 210) being adapted to go through a refrigeration cycle at certain intervals. A control system (11) is configured to control the variable speed compressor (10) during the refrigeration cycle, the control system (11) being based on a minimum speed (36) and a required speed (22), whereby the control system (11) is configured to set the compressor speed (35) to the highest speed of both the minimum speed (36) and the required speed (22). Such control system (11) provides an improved performance of the cooling system (200, 210), maintaining a balance of different temperatures inside the refrigerator (100, 110).