Method and system for estimating loss of refrigerant charge in a refrigerant vapor compression system
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Solution Overview
Problem
Refrigerant vapor compression systems (RVCS) face challenges in accurately estimating refrigerant charge loss, leading to inefficient service intervals and potential system failures due to imprecise refilling practices, which can result in costly compressor damage and increased maintenance needs.
Innovation Solution
A method and system utilizing a level sensor to monitor refrigerant in the receiver and a heat rejecting heat exchanger, combined with a level model that estimates refrigerant presence based on operating parameters like temperature, to accurately determine refrigerant loss and improve service intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a receiver is used to store refrigerant to accommodate variations in charge, then the system can handle operating condition variations, but it becomes virtually impossible to estimate the charge under normal running conditions
Solution Approach 1:
The patent extracts the measurement function from the dynamic operating system by implementing a pump-down procedure. This procedure temporarily stops refrigerant circulation and accumulates refrigerant in the receiver, creating a static measurement state where charge can be accurately assessed without the interference of normal operational variations.
Solution Approach 2:
The patent performs preliminary actions by conducting the pump-down procedure at scheduled intervals before normal operation resumes. This preliminary charge assessment allows the system to establish baseline charge levels and detect losses before they become critical, enabling proactive maintenance scheduling.
2Reliability
If fixed service intervals are defined to compensate for refrigerant loss, then system reliability is maintained, but service efficiency decreases due to unnecessary or premature service calls
Solution Approach 1:
The patent implements a feedback mechanism where charge assessment data from pump-down procedures is continuously monitored and analyzed. This feedback loop enables the system to dynamically adjust service scheduling based on actual charge loss rates, triggering service alerts only when loss thresholds are exceeded, thereby optimizing service intervals according to real system conditions.
Solution Approach 2:
The patent transitions from static fixed service intervals to dynamic condition-based service scheduling. The service intervals are adjusted dynamically based on measured charge loss rates, allowing the system to extend intervals when loss is minimal and shorten them when loss accelerates, optimizing both reliability and service efficiency.
3Ease of operation
If service personnel refill with a roughly estimated amount of refrigerant, then the refilling process is simple and quick, but the precision of refilling is poor which may cause compressor damage
Solution Approach 1:
The patent performs preliminary charge assessment through pump-down procedures before the refilling operation. This preliminary measurement provides service personnel with accurate baseline data on existing charge levels and loss rates, enabling them to calculate precise refilling quantities needed to restore optimal charge without overfilling or underfilling the system.
Data Source
AI summary
A level sensor is configured to provide a receiver level indicating an amount of the refrigerant present in the receiver and a level model provides a heat rejecting heat exchanger estimate indicating an amount of the refrigerant present in the heat rejecting heat exchanger based on a temperature of the refrigerant. From the sensor and the model, a loss of refrigerant from the refrigerant vapor compression system is estimated.