Discharge pressure calculation from torque in an HVAC system
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Solution Overview
Problem
Current methods for determining refrigerant charge level in vapor compression systems are manual, time-consuming, and prone to human error, as they rely on empirical measurements and charts, failing to accurately reflect optimal charge levels under varying operating conditions.
Innovation Solution
A system and method that utilize compressor torque or current information to estimate discharge pressure and calculate subcooling, allowing for precise determination of refrigerant charge through a control unit that maps torque or current data to pressure and temperature values, facilitating self-charging and charge monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual charging methods using pressure gauges and temperature measurements are used, then refrigerant charge level can be determined, but the process is time-consuming and prone to human error
Solution Approach 1:
The patent replaces manual mechanical measurement methods (pressure gauges, temperature probes, charts) with an automated electronic system that uses a torque sensor to directly measure compressor torque and a processor to calculate discharge pressure and subcooling. This substitution eliminates manual reading and interpretation steps, thereby reducing time and human error while maintaining or improving measurement precision.
Solution Approach 2:
The system enables self-charging capability by automatically calculating discharge pressure and subcooling from torque measurements, allowing the HVAC system to self-diagnose and self-adjust refrigerant charge levels without requiring manual intervention from technicians. This self-service approach reduces both time and potential for human error in charge determination.
2Measurement precision
If empirical charging methods using subcooling charts are used, then charge level can be assessed, but the method fails to accurately reflect optimal charge levels under varying operating conditions
Solution Approach 1:
The patent implements a dynamic charging system that continuously monitors torque and calculates discharge pressure and subcooling based on real-time operating conditions. Unlike static empirical charts, this dynamic system adapts to varying conditions (indoor/outdoor temperatures, airflow, humidity) by continuously updating calculations, thereby maintaining measurement precision across diverse operating scenarios.
Solution Approach 2:
The system incorporates feedback mechanisms where the processor continuously receives torque data, calculates discharge pressure and subcooling, and uses this information to determine optimal charge levels. This closed-loop feedback approach allows the system to adapt to changing operating conditions and maintain accurate charge determination, improving both precision and adaptability compared to open-loop empirical methods.
Data Source
AI summary
A method for determining system subcooling in a vapor compression system including a compressor, a condenser, an expansion device and an evaporator operatively connected in a serial relationship in a refrigerant flow circuit, the method including receiving information indicative of a compressor torque or compressor current; and determining a degree of system subcooling in response to the receiving of the information.