Compressor Flooded Start Management Using Adaptive Bump Start Feedback
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Solution Overview
Problem
Conventional vapor compression systems face issues with 'flooded starts' of compressors, where liquid refrigerant accumulates in the compressor sump during extended shutdowns, potentially causing damage and noise, as existing methods often rely on predetermined numbers of bump starts without ensuring complete evaporation.
Innovation Solution
A method that initiates a series of bump starts, monitoring suction pressure and temperature differentials to determine if liquid refrigerant remains in the sump, continuing the sequence until all liquid is evaporated, ensuring a safe and reliable start by adapting to the specific conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a predetermined number of bump starts are performed, then the compressor can clear some liquid refrigerant, but liquid refrigerant may remain in the sump causing potential damage and noise
Solution Approach 1:
The system implements feedback control by monitoring suction pressure changes during and after bump starts. The controller compares the suction pressure after each bump start to determine whether liquid refrigerant remains in the sump, continuing bump starts only until the pressure change indicates complete evaporation. This feedback mechanism ensures reliable liquid removal without requiring predetermined fixed sequences.
Solution Approach 2:
The system dynamically adjusts the bump start control parameters based on real-time suction pressure measurements. Instead of using a fixed predetermined sequence, the controller modifies the number and duration of bump starts according to the actual evaporation progress, as indicated by pressure parameter changes, thereby optimizing both reliability and control simplicity.
2Reliability
If multiple bump starts are performed to ensure complete evaporation, then liquid refrigerant is cleared from the sump, but the process time increases
Solution Approach 1:
The feedback mechanism monitors suction pressure changes to detect when liquid evaporation is complete. By measuring the pressure differential between before and after bump starts, the system determines the exact moment when all liquid has evaporated, immediately terminating further bump starts. This prevents unnecessary time delays while ensuring complete liquid removal for reliable operation.
3Ease of operation
If bump starts are performed without monitoring pressure differentials, then the control process is simpler, but it is impossible to determine when liquid refrigerant has been completely evaporated
Solution Approach 1:
The system uses suction pressure monitoring as a feedback signal to accurately detect liquid evaporation status. By measuring pressure changes during and after bump starts, the controller can precisely determine when all liquid has evaporated, converting a complex measurement task into a simple pressure comparison operation that maintains both accuracy and ease of operation.
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 adaptive approach ensures that only the necessary number of bump starts are performed to clear the compressor sump of liquid refrigerant, reducing the risk of damage, noise, and extending compressor life by ensuring a vapor-only start, thus enhancing reliability and efficiency.
Implementation Method 1
The compressor is initiated for a bump start sequence to evaporate any liquid refrigerant that may have migrated into the compressor
Data Source
AI summary
A method is provided for managing a flooded start of a compressor in a vapor compression system. Following an initial bump start, a determination is made as to whether working fluid in a liquid state remains in the sump of the compressor. If working fluid in a liquid state remains in the compressor sump, an additional bump start of the compressor is completed, followed by another determination as to whether working fluid in a liquid state still remains in the compressor sump. If working fluid in a liquid state remains in the compressor sump, another bump start of the compressor is initiated and the sequence repeated until no working fluid in the liquid state remains in the compressor sump. A normal start of the compressor may be initiated after determining no working fluid in the liquid state remains in the compressor sump.