Compressor with flooded start control
Solution Overview
Problem
Compressors in refrigeration systems face operational issues when flooded with liquid refrigerant, leading to rapid depletion of lubricant, which can cause premature wear and reduce reliability, and traditional crankcase heaters increase energy costs and are less effective for fast liquid migration rates.
Innovation Solution
A system and method for flooded start control that uses cycling on/off cycles to gradually pump out liquid refrigerant, allowing time for lubricant return and reducing the need for crankcase heaters, by employing a control module that monitors sensor data to determine optimal cycling parameters based on system conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the compressor operates continuously to pump out liquid refrigerant quickly, then the liquid removal speed is improved, but the lubricant is rapidly depleted causing premature wear and reduced reliability
Solution Approach 1:
The patent implements periodic on/off cycling of the compressor during flooded start conditions. The control module monitors liquid refrigerant levels and cycles the compressor between on and off states, allowing liquid to be gradually pumped out during on-periods while preventing rapid lubricant depletion during off-periods. This periodic action resolves the contradiction by balancing liquid removal speed with lubricant conservation, thereby maintaining compressor reliability.
2Reliability
If crankcase heaters are used to prevent liquid migration, then the liquid migration prevention is improved, but energy consumption increases
Solution Approach 1:
The patent employs the compressor's own operation to prevent liquid migration through controlled cycling. During off-periods of the cycling operation, liquid refrigerant migration to the crankcase is naturally prevented without requiring external heating. The compressor's intermittent operation creates conditions that self-regulate liquid migration, eliminating the need for energy-consuming crankcase heaters while maintaining reliable liquid migration prevention.
3Temperature
If crankcase heaters are used to heat the crankcase, then the heating effectiveness is improved, but the device complexity increases
Solution Approach 1:
The patent removes the crankcase heater component from the system entirely. Instead of adding heating capability to prevent liquid migration, the invention extracts this unnecessary component and relies solely on controlled compressor cycling to achieve the same protective function. This simplifies the system by eliminating the heater, its controls, and associated complexity while maintaining the essential function of preventing liquid-related damage.
4Quantity of substance
If the compressor cycles on/off to gradually pump out liquid, then the lubricant conservation is improved, but the time required for liquid removal increases
Solution Approach 1:
The patent implements a feedback control system that monitors liquid refrigerant levels in the crankcase and adjusts the compressor cycling parameters accordingly. The control module uses sensor feedback to determine when liquid levels are sufficiently reduced, allowing the compressor to transition from cycling operation to continuous operation. This feedback mechanism optimizes the balance between lubricant conservation during cycling and efficient liquid removal over time.
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 enhances compressor operation by maintaining lubrication, reducing energy consumption, and eliminating or minimizing the need for crankcase heaters, thereby improving compressor reliability and efficiency while lowering energy costs.
Implementation Method 1
the compressor may begin operation in a flooded state. In such case, the compressor may quickly pump out all of the liquid refrigerant
Implementation Method 2
crankcase heaters have been used to heat the crankcase of the compressor to prevent or reduce liquid migration to the compressor
Implementation Method 3
crankcase heaters can be effective for slow rates of liquid migration
Implementation Method 4
the compressor lubricant is generally soluble with the liquid refrigerant. As such, when the compressor is flooded with liquid refrigerant, the lubricant normally present in the lubricant sump can dissolve in the liquid refrigerant, resulting in a liquid mixture of refrigerant and lubricant
Data Source
AI summary
A system and method for flooded start control of a compressor for a refrigeration system are provided. A sensor generates sensed data corresponding to a condition of the refrigeration system. A control module is configured to operate the compressor in a flooded-start control mode including operating the compressor according to a cycle with a first time period during which the compressor is on and a second time period during which the compressor is off. The control module operates the compressor in an initial time period, without using the flooded-start control mode, with liquid refrigerant present in the compressor and monitors the sensed data from the sensor. The control module operates the compressor in the flooded start control mode after determining the first time period, the second time period, or a number of cycles, based on the sensed data monitored during the initial time period.