Method of managing compressor start for transport refrigeration system
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Solution Overview
Problem
New environmentally friendly refrigerants used in transport refrigeration systems exhibit high solubility in oil at low ambient temperatures, leading to viscosity degradation and component failure due to low evaporation flooded start conditions.
Innovation Solution
A method is introduced to manage compressor start operations by controlling a valve upstream of the compressor to lower the saturated suction temperature of the refrigerant below ambient temperature, thereby reducing solubility and improving oil viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If new environmentally friendly refrigerants are used in transport refrigeration systems, then environmental compliance is improved, but oil viscosity degradation occurs due to high solubility at low ambient temperatures
Solution Approach 1:
The patent changes the temperature parameter of the refrigerant by controlling the suction modulation valve to maintain saturated suction temperature between -10°F and 30°F. This parameter change reduces refrigerant solubility in the oil, preventing viscosity degradation and component failure while maintaining environmental compliance with newer refrigerants
Solution Approach 2:
The system uses feedback control by monitoring ambient temperature and saturated suction temperature to dynamically adjust the suction modulation valve position. This feedback mechanism ensures the temperature differential is maintained to prevent harmful solubility effects while allowing use of environmentally friendly refrigerants
2Reliability
If the suction modulation valve is controlled to lower saturated suction temperature below ambient temperature, then oil viscosity is improved, but the system complexity increases
Solution Approach 1:
The control system automatically adjusts the suction modulation valve based on temperature sensor feedback without requiring external intervention. The system self-regulates to maintain the critical temperature differential, improving reliability while managing complexity through automation rather than manual control
Solution Approach 2:
The suction modulation valve serves multiple functions: it normally modulates refrigerant flow for cooling control, and simultaneously acts as a temperature control device during compressor start-up to prevent solubility issues. This multi-functionality reduces the need for additional components, managing system complexity
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 method effectively increases the viscosity of the refrigerant-oil mixture, enhancing compressor reliability and lubrication, even under low ambient conditions, by creating a favorable temperature difference between the sump and saturated refrigerant temperatures.
Implementation Method 1
adjusts the pressure of the refrigerant to lower the saturated suction temperature of the refrigerant to be below the ambient temperature
Implementation Method 2
the solubility of the refrigerant in the newer oil is shown to be very high and degrades the viscosity of the oil... effectively increases the viscosity of the refrigerant-oil mixture
Data Source
AI summary
A method of managing a compressor start operation, the method includes controlling a valve disposed upstream of a compressor to lower a saturated suction temperature of a refrigerant to be below an ambient temperature while starting the compressor.