Refrigerator Compressor Control Using Excess Enthalpy
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Solution Overview
Problem
Conventional refrigeration appliances with single-speed compressors and non-linear control systems face inefficiencies in energy consumption due to over-cooling and require extensive tuning for each configuration, leading to increased energy usage and design time.
Innovation Solution
A control system utilizing a linear model that calculates the instantaneous cooling capacity required based on excess enthalpy to operate a variable speed compressor efficiently, minimizing power consumption and optimizing compressor speed for energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single-speed compressor with thermostatic control is used, then the system can achieve temperature control, but energy consumption increases due to over-cooling and compressor cycling
Solution Approach 1:
The patent applies dynamics by transitioning from a single-speed compressor to a variable-speed compressor that can dynamically adjust its operating speed. The controller modulates the compressor speed continuously based on real-time temperature feedback and enthalpy calculations, allowing the system to match cooling capacity with actual load requirements and avoid over-cooling, thereby reducing energy consumption.
Solution Approach 2:
The patent changes the operating parameters of the compressor from fixed single-speed operation to variable-speed operation. By calculating excess enthalpy and determining the precise cooling capacity needed, the system adjusts the compressor speed parameter to deliver exactly the required cooling, preventing energy waste from excessive cooling capacity.
2Measurement precision
If complex non-linear control models are used, then temperature control precision can be improved, but design time and tuning complexity increase significantly
Solution Approach 1:
The patent transforms the control approach by changing from complex non-linear temperature-based control to a linear enthalpy-based control model. This parameter transformation simplifies the control mathematics while maintaining precision, as enthalpy directly represents the thermal energy that needs to be removed, allowing for more straightforward calculation and reduced tuning complexity.
Solution Approach 2:
The patent substitutes complex non-linear control algorithms with a simpler linear control model based on enthalpy calculations. By using the fundamental thermodynamic relationship between enthalpy, temperature, and cooling capacity, the system replaces complicated iterative algorithms with direct calculations, reducing computational complexity and design time.
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 system effectively reduces excess enthalpy in refrigeration compartments while minimizing energy usage, allowing for precise temperature control and reduced design time across various configurations.
Implementation Method 1
The subject matter of the present disclosure relates generally to a control system for a refrigeration appliance... calculating an excess enthalpy Hi of the component... determining an instantaneous cooling capacity required Cap to reduce the excess enthalpy Hi substantially to zero...
Data Source
AI summary
A control system for a refrigeration appliance is provided. The control system uses a linear model that is designed to minimize or remove excess enthalpy from one or more compartments and/or features of the appliance. At least one variable speed compressor is operated at a speed that will remove excess enthalpy within a desired time period while also operating at an optimized speed for energy efficiency.