Refrigerant Charge Monitoring Using Pressure and Current Sensing
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Solution Overview
Problem
The accuracy of determining refrigerant levels in refrigeration systems using sight glasses is unreliable due to operating conditions, leading to potential overcharging or undercharging issues.
Innovation Solution
Incorporating current sensors to measure the system's current draw and pressure sensors to determine refrigerant pressure, with a controller comparing these readings to acceptable ranges to calculate the refrigerant charge level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sight glasses are used to visually assess refrigerant charge level, then the method is simple and inexpensive, but the accuracy and reliability of determination is poor due to dependence on operating conditions
Solution Approach 1:
The patent replaces the mechanical/visual sight glass method with an electrical/electronic measurement system. Current sensors measure electrical current draw and pressure sensors measure refrigerant pressure, substituting the visual assessment mechanism with instrumental measurement that provides objective, condition-independent data for determining refrigerant charge level.
Solution Approach 2:
The patent introduces intermediate measurement parameters (current draw and pressure) that serve as mediators between the refrigerant charge state and the determination process. These intermediaries provide indirect but reliable information about refrigerant levels without being directly affected by the visual limitations of sight glasses under various operating conditions.
2Reliability
If sight glasses are used to monitor refrigerant levels, then no additional sensors are required, but the reliability of the monitoring is poor under certain operating conditions
Solution Approach 1:
The patent replaces the mechanical/visual sight glass method with an electrical/electronic measurement system. Current sensors measure electrical current draw and pressure sensors measure refrigerant pressure, substituting the visual assessment mechanism with instrumental measurement that provides objective, condition-independent data for determining refrigerant charge level.
Solution Approach 2:
The patent implements a feedback mechanism where the controller continuously receives data from current and pressure sensors, compares measurements against stored reference information, and provides ongoing assessment of refrigerant charge status. This closed-loop feedback system maintains reliable monitoring across varying operating conditions by continuously adjusting assessments based on actual system state.
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
Provides a reliable and accurate method for determining the refrigerant charge, reducing the likelihood of overcharging or undercharging the system by continuously monitoring and comparing current draw and pressure to predefined ranges.
Implementation Method 1
one or more current sensors to determine a total system current draw
Implementation Method 2
One or more pressure sensors are positioned to determine a refrigerant pressure in the refrigerant vapor compression unit
Implementation Method 3
a compressor, a condenser, an expansion device and an evaporator serially connected by refrigerant lines in a closed refrigerant circuit in accord with known refrigerant vapor compression cycles
Data Source
AI summary
A refrigeration system includes a refrigerant vapor compression unit including a compressor and one or more current sensors to determine a total system current draw. One or more pressure sensors are positioned to determine a refrigerant pressure in the refrigerant vapor compression unit. A controller compares the current draw on the system and the refrigerant pressure to selected acceptable ranges and determines a level of refrigerant charge in the refrigerant vapor compression unit. A method of determining a level of refrigerant charge in a refrigeration system includes measuring a refrigerant pressure in the refrigeration system and sensing a current draw of the refrigeration system. A level of refrigerant charge in the refrigeration system is calculated from the refrigerant pressure and the current draw.