Non-invasive temperature diagnostic method
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Solution Overview
Problem
Existing methods for diagnosing refrigerant charge and airflow in HVAC systems are invasive, leading to refrigerant venting, introduction of non-condensables, and contamination, which contribute to global warming and inefficiency.
Innovation Solution
A non-invasive temperature diagnostic method that uses temperature measurements to diagnose refrigerant charge and airflow faults, including undercharge and overcharge, without connecting refrigerant pressure sensors, thereby reducing refrigerant venting and improving diagnostic accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If refrigerant pressure gauges are connected to Schrader valves for diagnosing refrigerant charge and airflow, then diagnostic information can be obtained, but refrigerant is vented to the atmosphere causing global warming
Solution Approach 1:
The patent extracts the essential diagnostic information (temperature measurements) from the invasive pressure gauge connection method. By measuring temperatures at accessible locations (return air, supply air, outdoor air, refrigerant lines) and calculating derived parameters (temperature split, liquid over ambient temperature), the system obtains diagnostic accuracy equivalent to pressure gauge methods without requiring invasive connections that cause refrigerant venting
Solution Approach 2:
The patent replaces the mechanical intrusion of pressure gauges with a thermal field-based diagnostic approach. Instead of mechanically connecting to the refrigerant system to measure pressure, the system uses temperature sensors to measure thermal conditions and calculates the same diagnostic information (refrigerant charge status, airflow conditions) through thermodynamic relationships, eliminating the need for physical connection to Schrader valves
2Measurement precision
If refrigerant pressure gauges are connected to Schrader valves, then refrigerant charge diagnosis is possible, but non-condensables (air and water vapor) are introduced into the system
Solution Approach 1:
The patent extracts diagnostic information through non-invasive temperature measurements rather than invasive pressure gauge connections. By measuring temperatures in the refrigerant lines and calculating derived parameters, the system obtains refrigerant charge diagnosis information without opening the system to atmospheric air that would introduce non-condensables
Solution Approach 2:
The patent uses temperature measurements as an intermediary to obtain diagnostic information without direct contact with the refrigerant system. Temperature sensors placed on the exterior of refrigerant lines act as intermediaries, allowing the diagnostic system to 'read' system conditions through thermal conduction without breaking the system seal that would allow air and moisture contamination
3Measurement precision
If refrigerant pressure gauges are connected to Schrader valves, then system pressure measurements are obtained, but the refrigerant system becomes contaminated with incompatible materials
Solution Approach 1:
The patent replaces the mechanical pressure measurement system with a thermal-based diagnostic system. By measuring temperatures and using thermodynamic calculations to determine system state (including conditions equivalent to pressure information), the system obtains the same diagnostic capabilities without mechanical intrusion that would allow contamination
Solution Approach 2:
The patent changes the measurement parameter from pressure (requiring invasive connection) to temperature (measurable non-invasively). By measuring temperature instead of pressure and calculating derived parameters (temperature split, liquid over ambient temperature), the system achieves equivalent diagnostic information about refrigerant charge and system conditions without the contamination risks of pressure gauge connection
4Measurement precision
If temperature measurements are taken at multiple locations, then diagnostic accuracy improves, but measurement time and equipment complexity increase
Solution Approach 1:
The patent performs preliminary calculations of derived parameters (temperature split, liquid over ambient temperature) directly from the measured temperatures. By pre-calculating these diagnostic indicators and comparing them against diagnostic criteria, the system quickly determines system status without requiring lengthy analysis procedures, reducing measurement time while maintaining high diagnostic accuracy
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 method reduces refrigerant emissions by 30 to 50%, improves diagnostic accuracy, and reduces the time and equipment needed for HVAC system testing, while maintaining or improving cooling capacity and efficiency.
Implementation Method 1
A non-invasive temperature diagnostic method that uses temperature measurements to diagnose refrigerant charge and airflow faults
Data Source
AI summary
A Non-invasive Temperature Diagnostic (NTD) method for evaluating proper operation, undercharge, or other faults of a Heating, Ventilating, Air Conditioning (HVAC) system based on measurements of temperature or HVAC system airflow. Measurements may comprise return-air wetbulb temperature (RWT), return-air drybulb temperature (RDT), supply-air drybulb temperature (SDT), actual temperature split (ATS) equals RDT minus SDT, required temperature split (RTS) based on RDT and RWT, delta temperature split (DTS) equals ATS minus RTS, outdoor-air temperature (OAT), suction temperature (ST), liquid temperature (LT), or liquid over ambient (LOA) based on LT minus OAT. The method can diagnose at least one HVAC system fault selected from a group consisting of: refrigerant restriction, low airflow, low-cooling capacity, condenser/evaporator heat exchanger fault, refrigerant undercharge/overcharge, non-condensables, failed capacitor, HVAC blower fan relay fault, and condenser contactor fault. The ATS and airflow measured before and after correcting HVAC system faults are used to calculate an energy-efficiency improvement.