Screw Compressor Oil Preheating and Cooling Without a Crank Heater
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Solution Overview
Problem
Screw compressors face inefficiencies due to the need for a crank heater to warm up lubricant oil and refrigerant before startup, which consumes significant power and requires additional management to maintain lubrication at predetermined temperatures, leading to potential damage during startup.
Innovation Solution
An energy system that includes a screw compressor, condenser, expansion device, evaporator, and a lubricant oil heat-exchanging unit to heat the lubricant oil before startup and cool it during operation, utilizing a heating medium for efficient temperature control without additional heaters, thereby reducing power consumption and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crank heater is installed to warm up the screw compressor before startup, then the lubricant oil and refrigerant can be heated to prevent damage during startup, but the power consumption increases significantly and system efficiency is lowered
Solution Approach 1:
The system uses itself to heat the lubricant oil - the heating medium that would otherwise be wasted is redirected through the lubricant oil heat-exchanging unit to heat the oil before startup, making the system self-servicing without external heaters
Solution Approach 2:
The patent converts the harmful effect of high-temperature heating medium (which would be wasted) into a beneficial heating source for the lubricant oil, transforming potential energy waste into useful preheating function
2Reliability
If additional devices are installed to maintain lubricant oil at predetermined temperatures, then the screw compressor can be properly managed for lubrication, but the device complexity and cost increase
Solution Approach 1:
The heating medium flow path serves multiple functions - it can be redirected to the evaporator for normal cooling operation or to the lubricant oil heat-exchanging unit for preheating, making the same system infrastructure serve multiple purposes without adding dedicated heating devices
Solution Approach 2:
The patent merges the heating function into the existing cooling system by integrating the lubricant oil heat-exchanging unit with the heating medium flow path, combining preheating and cooling functions into a unified system rather than adding separate heating equipment
3Loss of energy
If the heating medium is used to heat the lubricant oil before startup, then the power consumption is reduced and energy efficiency is improved, but the system requires additional flow path configuration
Solution Approach 1:
The system performs preliminary heating of the lubricant oil before the screw compressor startup using the heating medium, preparing the oil in advance to prevent damage during startup and eliminate the need for high-power heaters during 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
The system efficiently heats the lubricant oil before startup and cools it during operation, reducing power consumption and eliminating the need for additional heaters, thus improving energy efficiency and preventing damage from low pressures during startup.
Implementation Method 1
a lubricant oil heat-exchanging unit configured to perform a heat-exchanging operation of the heating medium on an evaporator heat source flow path and lubricant oil including a refrigerant inside the screw compressor, to heat the lubricant oil by the heating medium before the screw compressor starts up
Implementation Method 2
to cool the lubricant oil by the heating medium discharged from the evaporator after the evaporator is heated by the heating medium, after the screw compressor starts up
Data Source
AI summary
A heating medium supplied to an evaporator is used to heat lubricant oil in a screw compressor before the screw compressor starts up, and no additional heater for heating the lubricant oil in the screw compressor is required. When the screw compressor operates, the heating medium discharged from the evaporator after the evaporator is heated by the heating medium, is used to cool the lubricant oil. The lubricant oil heated by a lubricant oil heat exchanger is directly injected into a motor and a screw rotor so that introduction of a liquid refrigerant into a compressive chamber is reduced when the screw compressor starts up later. The lubricant oil introduced into the motor is discharged toward a lubricant oil storage portion before the screw compressor starts up so that the liquid refrigerant is prevented in advance from being introduced into the screw rotor when the screw compressor starts up.