Compressor Flooded Start Control Using Periodic On/Off Cycling
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Solution Overview
Problem
Compressors in refrigeration systems face operational issues when flooded with liquid refrigerant, leading to lubricant depletion and potential damage due to lack of lubrication during startup, which traditional crankcase heaters are ineffective in addressing, especially for fast liquid migration rates.
Innovation Solution
A system and method for flooded start control that uses temperature sensors and control modules to implement short on/off cycles, allowing gradual pumping of liquid refrigerant and lubricant, enabling the compressor to heat up and preventing premature lubricant depletion, thereby reducing the need for crankcase heaters and minimizing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the compressor operates continuously in a flooded state, then liquid refrigerant is quickly pumped out, but the compressor operates without lubrication causing damage to moving parts
Solution Approach 1:
The patent implements periodic on/off cycling during flooded start conditions. The controller monitors liquid refrigerant levels and activates the compressor in short on-cycles followed by off-cycles, allowing liquid to be gradually removed while preventing complete lubricant depletion. This periodic operation resolves the contradiction by balancing liquid removal speed with lubrication maintenance.
2Reliability
If crankcase heaters are used to prevent liquid migration, then liquid refrigerant accumulation is reduced, but energy costs increase due to electrical consumption
Solution Approach 1:
The patent enables the compressor to self-manage flooded conditions through controller-monitored on/off cycling. Instead of continuously heating the crankcase with external electrical power, the system uses the compressor's own operational cycles to gradually remove liquid refrigerant and prevent flooding, eliminating the need for continuous crankcase heater operation and reducing energy consumption.
3Reliability
If crankcase heaters are used to heat the compressor, then liquid migration is reduced for slow rates, but they are ineffective for fast liquid migration rates
Solution Approach 1:
The patent implements dynamic on/off cycling that adapts to different liquid migration rates. The controller monitors system conditions and adjusts the cycling frequency and duration based on the rate of liquid accumulation. For fast migration rates, more frequent cycling is applied; for slow rates, less frequent cycling suffices, providing adaptability across different operating conditions.
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 effectively manages liquid refrigerant and lubricant in compressors, enhancing operational efficiency, reducing energy costs, and extending compressor lifespan by preventing premature wear and malfunction.
Implementation Method 1
A temperature sensor that generates temperature data corresponding to at least one of a compressor temperature and an ambient temperature
Implementation Method 2
determines an amount of liquid present in the compressor based on the temperature data and the off-time period
Implementation Method 3
allowing gradual pumping of liquid refrigerant and lubricant, enabling the compressor to heat up
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
A system and method for flooded start control of a compressor for a refrigeration system is provided. A temperature sensor generates temperature data corresponding to at least one of a compressor temperature and an ambient temperature. A control module receives the temperature data, determines an off-time period since the compressor was last on, determines an amount of liquid present in the compressor based on the temperature data and the off-time period, compares the amount of liquid with a predetermined threshold, and, when the amount of liquid is greater than the predetermined threshold, operates the compressor according to at least one cycle including a first time period during which the compressor is on and a second time period during which the compressor is off.