Refrigerant Filling Control for Accurate CO2 Charge Measurement
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Solution Overview
Problem
Conventional air conditioning service devices face challenges in accurately determining the exact amount of refrigerant R744 or CO2 to be refilled due to changes in state, particularly the liquid to gaseous phase ratio, leading to inaccuracies in the compensation quantity and ultimately the filling quantity, especially in systems using carbon dioxide as a refrigerant.
Innovation Solution
The method involves conditioning the refrigerant to an initial supercritical value in an intermediate container before filling, with intermittent interruptions in the inflow process to prevent liquid accumulation in the filling line, ensuring the refrigerant remains in a supercritical or gaseous state, and using a control unit to manage the inflow along the upper boundary line of the two-phase region, allowing precise determination of the filling quantity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional filling methods are used with continuous inflow of refrigerant, then the filling process is simple and fast, but the accuracy of determining the actual compensation amount deteriorates due to liquid refrigerant accumulation in the filling line system
Solution Approach 1:
The filling process uses periodic action by interrupting the continuous inflow of refrigerant at defined intervals. The control unit stops the inflow temporarily to allow liquid refrigerant to settle in the intermediate container, then resumes inflow. This periodic interruption pattern continues until the desired filling quantity is achieved, preventing liquid accumulation in the filling line system and enabling accurate compensation amount determination.
Solution Approach 2:
An intermediate container is introduced as a mediator between the storage container and the air conditioning system. This intermediate container serves as a buffer that temporarily holds refrigerant and allows liquid to settle during interruption phases. The weighing cell measures the mass change of this intermediate container, providing accurate data for determining the compensation amount while isolating the measurement from the filling line system where liquid accumulation would otherwise occur.
2Productivity
If the refrigerant is allowed to flow continuously from the storage container into the air conditioning system, then the filling speed is high, but the liquid to gaseous phase ratio becomes difficult to control leading to inaccurate filling quantity
Solution Approach 1:
The filling process alternates between inflow phases and interruption phases. During inflow phases, refrigerant flows quickly from the storage container through the intermediate container into the air conditioning system, maintaining high productivity. During interruption phases, the flow stops briefly to allow phase separation and liquid settling in the intermediate container. This periodic pattern enables both fast filling and precise control of the liquid to gaseous phase ratio.
Solution Approach 2:
Before the refrigerant enters the filling line system, it is pre-conditioned in the intermediate container during interruption phases. The liquid refrigerant has time to settle and separate from the gaseous phase in the intermediate container before the next inflow phase begins. This preliminary action ensures that when inflow resumes, the refrigerant is in the desired phase state, preventing unpredictable phase changes in the filling line system.
3Ease of operation
If liquid refrigerant is allowed to accumulate in the filling hose, then the filling process is simpler, but the actual compensation amount cannot be determined with sufficient accuracy
Solution Approach 1:
The intermediate container acts as a mediator that captures and holds liquid refrigerant during interruption phases, preventing it from accumulating in the filling hose. The weighing cell measures the mass of the intermediate container, which includes any liquid refrigerant present. This allows accurate determination of the compensation amount (the mass of refrigerant remaining in the filling line system) without liquid actually accumulating in the hose, maintaining both simplicity and accuracy.
Solution Approach 2:
The weighing cell provides continuous feedback on the mass of the intermediate container during the filling process. By monitoring the mass change and comparing it to the expected mass based on the defined filling quantity, the control unit can determine when the actual compensation amount has been reached. This feedback mechanism enables accurate compensation amount determination while maintaining a simple filling process structure.
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 enables precise measurement of the refrigerant filled into the air conditioning system, reducing the uncertainty in the compensation amount and ensuring the filling quantity meets manufacturer specifications, even in varying conditions.
Implementation Method 1
an intermediate container (17) in which the refrigerant is allowed to flow in and in which the amount of refrigerant is determined using a weighing cell (21)
Implementation Method 2
which can be filled with refrigerant from a storage container (18) using a compressor (22)
Implementation Method 3
The intermediate container is provided with a heating unit (23)
Implementation Method 4
at least when an aggregate state of the refrigerant is reached in the two-phase region
Data Source
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AI summary
The invention relates to a method and a device for filling an air conditioning system with a defined filling quantity of refrigerant (e.g. R744 carbon dioxide) from a storage tank via a filling line system. Before filling, the refrigerant is conditioned to an initial value (100) in an intermediate container and, starting from this initial value (100), the refrigerant is allowed to flow into the evacuated air conditioning system via the filling line system. At least when a state of aggregation of the refrigerant in the two-phase region is reached, further inflow is interrupted at intervals to achieve a change in the state of aggregation that runs essentially in stages along the upper boundary line (O) of the two-phase region.