Compressor Motor Cooling Circuit With Sub-Cooled Start-Up Flow
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Solution Overview
Problem
Refrigerant systems face challenges in providing adequate motor cooling, especially during start-up when there is a lack of motor cooling fluid, and existing systems do not effectively sub-cool the motor cooling fluid for enhanced cooling efficiency.
Innovation Solution
The refrigerant system incorporates a sub-cooling circuit with a sub-cooling heat exchanger and a sub-cooling line that conveys sub-cooling fluid between the main refrigerant loop and the motor cooling line upstream of the compressor, along with a motor cooling line that includes a pump to pressurize the motor cooling fluid, ensuring adequate cooling of the motor and associated components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refrigerant is conveyed from the main refrigerant loop to the motor for motor cooling, then the motor cooling function is provided, but there is a lack of motor cooling fluid during start-up
Solution Approach 1:
The sub-cooling circuit pre-cools the refrigerant in the motor cooling line upstream of the motor before the motor starts operating. This preliminary cooling action ensures that adequate cooling fluid is available immediately at start-up, eliminating the delay that would otherwise occur while waiting for cooling fluid to become available.
2Temperature
If a sub-cooling circuit is added to sub-cool the motor cooling fluid, then the cooling efficiency is enhanced, but the device complexity increases
Solution Approach 1:
The sub-cooling circuit is integrated with the existing motor cooling line and main refrigerant loop, merging multiple cooling functions into a unified system. The sub-cooling heat exchanger is positioned to utilize the existing refrigerant flow, combining sub-cooling and motor cooling operations rather than requiring completely separate systems.
Solution Approach 2:
The motor cooling line serves dual purposes: it provides cooling to the motor during operation and serves as a sub-cooling pathway upstream of the motor. The same refrigerant line and heat exchanger components perform multiple functions, reducing the need for additional dedicated components.
3Reliability
If a pump is added to pressurize the motor cooling fluid, then the fluid supply reliability is improved, but the device complexity and energy consumption increase
Solution Approach 1:
The pump is integrated into the motor cooling line and utilizes the motor's operation to drive refrigerant circulation. The system leverages the motor's own运行 to provide the pressurization needed for cooling fluid circulation, reducing or eliminating the need for separate external pumping systems.
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 configuration ensures effective motor cooling and sub-cooling, enhancing the overall cooling efficiency and providing a reliable supply of motor cooling fluid at start-up, even when initial fluid availability is limited.
Implementation Method 1
a sub-cooling heat exchanger in communication with the motor cooling line at a point upstream of the motor
Implementation Method 2
a pump to pressurize the motor cooling fluid
Data Source
AI summary
The disclosed refrigerant system includes a compressor having a motor that is cooled by motor cooling fluid provided to the motor from the main refrigerant loop by a motor cooling circuit. The system also includes a sub-cooling circuit to cool the motor cooling fluid.