Refrigerant Charge Monitoring via Derived Condenser Temperature
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional compressor protection systems in refrigeration systems rely on discrete temperature and pressure sensors, which are costly, complex, and inaccurate in detecting refrigerant charge levels, especially under severe undercharge or overcharge conditions, due to variability in manufacturing and changes in refrigerant volume.
Innovation Solution
A diagnostic system that uses processing circuitry to derive condenser temperature from non-measured operating parameters, comparing detected temperatures to declared fault conditions, and validating sensor data to accurately determine refrigerant charge levels without additional sensors, thereby enhancing fault detection and system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple discrete temperature and pressure sensors are placed at numerous locations within the system and compressor, then accurate indication of pressure or temperature can be provided, but system complexity and cost increase
Solution Approach 1:
The patent replaces physical temperature and pressure sensors with a computational model that derives these parameters from electrical measurements (voltage, current, frequency) and operating conditions. The processing circuitry calculates equivalent temperature and pressure values based on compressor performance characteristics, eliminating the need for numerous physical sensors while maintaining diagnostic accuracy.
Solution Approach 2:
The compressor system uses its own electrical operating parameters (voltage, current, frequency) to self-diagnose temperature and pressure conditions. The processing circuitry leverages data already being collected for motor control to derive thermal and pressure states, making the system self-monitoring without additional hardware.
2Measurement precision
If discrete temperature and pressure sensors are used, then temperature and pressure parameters can be detected, but accuracy deteriorates under severe undercharge or overcharge conditions due to refrigerant volume changes
Solution Approach 1:
The patent changes the measurement parameters from direct physical sensing to electrical parameter-based derivation. By using voltage, current, and frequency measurements combined with compressor performance models, the system accurately determines equivalent temperature and pressure even when refrigerant charge varies, as electrical parameters reflect the actual operating state regardless of charge level.
Solution Approach 2:
The electrical measurements (voltage, current, frequency) serve multiple functions: motor control, performance monitoring, and thermal/pressure state determination. This multi-functional approach allows accurate diagnosis across all operating conditions including severe undercharge and overcharge scenarios without requiring condition-specific sensors.
3Reliability
If sensors are placed at numerous locations within the system, then comprehensive monitoring is achieved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the sensing function from physical sensors and relocates it to the electrical measurement and computational domain. By taking out the temperature and pressure sensing capability from hardware sensors and implementing it through processing circuitry that analyzes electrical parameters, the system achieves comprehensive monitoring at lower cost.
Solution Approach 2:
The patent merges the functions of temperature sensing, pressure sensing, and motor control into a single processing system. The same voltage, current, and frequency measurements used for motor control are simultaneously processed to derive temperature and pressure equivalents, consolidating multiple sensing functions into one integrated system.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A system is provided and may inclue a compressor (10) having a motor (32) and a refrigeration circuit (12) including an evaporator (72) and a condenser (70) fluidly coupled to the compressor. The system may further include a first sensor (80) producing a signal indicative of one of current and power drawn by the motor, a second sensor (110) producing a signal indicative of a saturated condensing temperature, and a third sensor (84) producing a signal indicative of a liquid-line temperature. Processing circuitry (88) may processes the current or power signal to determine a derived condenser temperature and may compare the derived condenser temperature to the saturated condensing temperature received from the second sensor to determine a subcooling associated with a refrigerant charge level of the refrigeration circuit.