Compressor Gas Bearing Multi-Mode Feed for Pressure Support Stability
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Solution Overview
Problem
Refrigerant circuits with gas bearings in HVACR systems face challenges in maintaining stable operation due to inadequate pressure support from compressed gas, leading to potential damage from solid contact between the driveshaft and the gas bearing.
Innovation Solution
The refrigerant circuit operates in multiple modes: a first mode using gaseous working fluid for gas bearing support, a second mode using liquid working fluid when gaseous pressure is insufficient, and a third mode utilizing an auxiliary gas supply for backup support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gaseous working fluid is supplied to gas bearings for driveshaft support, then the gas bearing can provide cushioning support, but the pressure may be insufficient leading to solid contact and potential damage
Solution Approach 1:
A liquid working fluid is introduced as an intermediary substance to mix with the gaseous working fluid in the gas bearing. This liquid portion increases the density and pressure of the fluid supporting the driveshaft, preventing solid contact while maintaining the cushioning effect. The liquid acts as a mediator that enhances the pressure-transmitting capability of the originally insufficient gas.
Solution Approach 2:
The system changes the physical parameters of the working fluid by introducing a liquid portion to the gas bearing. This alters the fluid's density, compressibility, and pressure characteristics, transforming it from a low-pressure gas into a higher-pressure liquid-gas mixture capable of reliably supporting the driveshaft without solid contact.
2Stress or pressure
If liquid working fluid is supplied to gas bearings, then pressure support is improved, but the compressor speed must be reduced below gas maximum speed limit
Solution Approach 1:
The system dynamically adjusts the composition of the working fluid supplied to the gas bearing based on operating conditions. During high-speed operation, a liquid portion is mixed with the gas to maintain adequate pressure support. The controller modulates the liquid-gas ratio in real-time, allowing the system to operate at higher speeds than would be possible with gas alone, while still maintaining sufficient bearing pressure.
3Reliability
If multiple operating modes are implemented for different working fluid states, then system reliability is enhanced, but device complexity increases
Solution Approach 1:
The gas bearing system is designed to universally accept both gaseous and liquid working fluids, as well as mixtures of both states. The same gas bearing structure performs multiple functions: supporting the driveshaft during startup with gas alone, providing high-speed support with gas-liquid mixtures, and offering high-pressure support at lower speeds with liquid-gas mixtures. This multi-functionality reduces the need for separate bearing systems for 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 multi-mode operation ensures stable support of the driveshaft, preventing damage and allowing the compressor to continue operating even when compressed gas pressure is inadequate, thereby enhancing the reliability and longevity of the refrigerant circuit.
Implementation Method 1
one or more gas bearings to support the driveshaft... supplying a gaseous portion of the working fluid to the one or more gas bearings of the compressor, and supporting, with the one or more gas bearings, the driveshaft of the compressor using the gaseous portion of the working fluid
Implementation Method 2
supplying a liquid portion of the working fluid in the refrigerant circuit to the one or more gas bearings of the compressor... supplying the liquid portion of the working fluid compressed by the pump to the one or more gas bearings of the compressor
Data Source
AI summary
A method is described for operating a refrigerant circuit that includes a compressor with a driveshaft and one or more gas bearings for supporting the driveshaft. The method includes operating the refrigerant circuit in a first mode which includes supplying gaseous working fluid compressed by the compressor to the one or more gas bearings of the compressor, and the one or more gas bearings using the compressed gaseous working fluid to support the driveshaft. The method includes operating the refrigerant circuit in a second mode which includes supplying liquid working fluid to the one or more gas bearings of the compressor, and the one or more gas bearings using the liquid working fluid to support the driveshaft. A refrigerant circuit includes a compressor, a condenser, an expander, an evaporator, and a controller configured to selectively operate the refrigerant circuit in a least a first mode and a second mode.