A method, a controller and a system for estimating loss of refrigerant charge in an RVCS 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 and a heat rejecting heat exchanger estimation model based on operating parameters like temperature to accurately determine the refrigerant loss, enabling precise timing of service intervals and correct refilling amounts by calculating the sum of receiver and heat exchanger levels.
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 invention divides the refrigerant charge measurement problem into two separate measurements: one for the receiver (using a level sensor) and one for the heat rejecting heat exchanger (using temperature-based estimation). This segmentation allows accurate charge estimation even when the receiver buffer is present, as each component's refrigerant amount can be independently measured or estimated.
2Reliability
If fixed service intervals are defined to compensate for refrigerant loss, then system failures can be avoided, but the service timing is inefficient and imprecise
Solution Approach 1:
The invention implements continuous monitoring of refrigerant charge levels through level sensors and temperature-based estimation models. This feedback mechanism provides real-time information about actual refrigerant loss, enabling dynamic adjustment of service intervals based on actual system conditions rather than fixed schedules, thereby optimizing both reliability and time efficiency.
3Ease of operation
If refilling is performed with a roughly estimated amount of refrigerant, then the procedure is simple, but it focuses on avoiding over-filling while causing costly compressor breakdown and imprecise service
Solution Approach 1:
The invention performs preliminary measurement of the existing refrigerant charge using level sensors and estimation models before refilling. This preliminary action provides accurate baseline data, enabling precise calculation of the exact amount of refrigerant needed to reach the target charge level, thereby eliminating both over-filling and under-filling issues while maintaining operational simplicity.
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
This approach allows for real-time, precise estimation of refrigerant loss, improving service intervals, reducing the risk of system failures, and enabling more accurate refilling, thus enhancing the reliability and efficiency of RVCS operations.
Implementation Method 1
providing a level sensor configured to provide a receiver level indicating an amount of the refrigerant present in the receiver
Implementation Method 2
The high pressure side comprises a heat rejecting heat exchanger, e.g. in the form of a gas cooler or a condenser which during use becomes warm
Implementation Method 3
The low pressure side comprises an evaporator which during use becomes cold
Implementation Method 4
a suction side of a compressor... a discharge side of the compressor
Data Source
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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 RVCS system is estimated.