Supercritical Fluid Generator Cooling via Secondary Buffering
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Solution Overview
Problem
Supercritical carbon dioxide (sCO2) turbo generator efficiency is hindered by windage and heat generation, with pumping power being a parasitic loss, and perfect seals are undesirable due to heat removal considerations.
Innovation Solution
A supercritical fluid system with a secondary working fluid, such as hydrogen or helium, is introduced to cool and buffer the generator rotor, reducing windage and pumping power while maintaining efficient power conversion by mixing with the primary working fluid and separating it within the compressor to direct cooling to the turbine and generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If pumping out the generator cavity to manage windage, then windage is reduced, but pumping power loss increases
Solution Approach 1:
A secondary working fluid is introduced as an intermediary substance in the generator cavity to manage windage effects. This secondary fluid acts as a mediator between the primary sCO2 working fluid and the generator rotor, reducing windage losses while avoiding the need for high-power pumping operations. The secondary fluid creates a buffering effect that diminishes the harmful windage forces without requiring extensive pumping to maintain extreme vacuum conditions.
2Loss of energy
If using seals to reduce pumping requirements, then pumping power loss is reduced, but heat removal capability deteriorates
Solution Approach 1:
The cooling function is extracted from the primary sCO2 working fluid by introducing a separate secondary working fluid specifically dedicated to heat removal. This secondary fluid flows through the generator cavity and absorbs heat from the rotor, then is cooled and recirculated. By separating the sealing and cooling functions into different fluid systems, the patent achieves both reduced pumping requirements and effective heat removal without relying on perfect seals.
3Temperature
If allowing leakage past seals for heat removal, then heat removal is improved, but pumping requirements increase
Solution Approach 1:
The secondary working fluid serves as an intermediary that handles both the heat removal and the pressure buffering functions. By introducing this intermediate substance, the system can maintain a pressure gradient that limits excessive leakage of primary working fluid past seals while still achieving effective cooling. The secondary fluid absorbs the heat transfer function and creates a pressure buffer zone that reduces the driving force for unwanted leakage, thereby balancing cooling effectiveness with pumping power requirements.
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 reduces windage and pumping power losses, maintains low generator rotor temperatures for efficient power conversion, and improves overall system efficiency by utilizing a secondary working fluid for cooling and buffering within the supercritical fluid system.
Implementation Method 1
Heat generated within the generator rotor needs to be removed for the generator efficiency to remain high. Leakage past seals into a generator cavity is typically used to cool the generator before being pumped back to the sCO2 cycle pressures.
Implementation Method 2
the secondary working fluid flow path passes along the rotor to provide cooling thereto
Implementation Method 3
The primary working fluid and the secondary working fluid are compressed and mixed within the compressor to form a mixture of the two fluids
Implementation Method 4
the separator is a cyclone separator or a gravity separator
Implementation Method 5
the separator is a cyclone separator or a gravity separator
Data Source
AI summary
Supercritical fluid systems and aircraft power systems are described. The systems include a compressor, a turbine, and a generator. A primary working fluid flow path has a primary working fluid that passes through the compressor, a separator, the turbine, and back to the compressor. A secondary working fluid flow path having a secondary working fluid that passes through the generator, the compressor, the separator, and back to the generator. The primary working fluid and the secondary working fluid are compressed and mixed within the compressor to form a mixture of the two fluids and the separator separates the mixture of the two fluids to direct the primary working fluid back to the turbine and the secondary working fluid to the generator.