Low back pressure flow limiter
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Solution Overview
Problem
Chiller systems experience surge conditions due to pressure differential across the compressor, leading to unsteady flow and delayed recovery, as high-pressure fluid can flow backward, causing inefficiencies and instability.
Innovation Solution
A back-flow limiting device with a turbine wheel is placed downstream of the compressor, which dynamically restricts back-flow by rotating and imparting work on the fluid, even with near zero-pressure differential, using a single-stage axial turbine-bladed wheel with adjustable blade quantity and angle to control back-pressure effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-activated back pressure check valve is used to prevent high pressure fluid from flowing backward, then back-flow prevention is achieved, but the device complexity increases and back-pressure is high
Solution Approach 1:
The patent extracts the essential function of back-flow prevention from the complex spring-activated check valve mechanism and implements it through a simpler turbine wheel device. The turbine wheel, when rotating, creates a one-way flow path that prevents back-flow without requiring springs, valves, or complex mechanical components, thus achieving back-flow prevention with reduced device complexity.
Solution Approach 2:
The patent replaces the mechanical spring-activated valve system with a turbine-based fluid dynamic system. Instead of using mechanical springs and moving valve parts to prevent back-flow, the system uses the turbine wheel's rotation to create fluid dynamic conditions that inherently prevent reverse flow, substituting a mechanical system with a fluid dynamic one.
2Reliability
If a spring-activated back pressure check valve is used to prevent high pressure fluid from flowing backward, then back-flow prevention is achieved, but the back-pressure increases causing inefficiencies
Solution Approach 1:
The patent extracts the essential back-flow prevention function from the high back-pressure valve mechanism and implements it through a turbine wheel that allows near-zero pressure differential operation. The turbine's rotation creates a one-way flow path without requiring high back-pressure, thus achieving back-flow prevention with minimal pressure loss.
Solution Approach 2:
The patent changes the operating parameter from high back-pressure (required by spring-activated valves) to near-zero pressure differential (achieved by the turbine wheel). By altering the fundamental pressure parameter required for back-flow prevention, the system achieves the same reliability function with significantly reduced pressure stress and improved efficiency.
3Manufacturing precision
If a turbine wheel with multiple stages is used to control back-flow, then back-pressure control precision is improved, but the device complexity increases
Solution Approach 1:
The patent applies partial action by using a single-stage turbine wheel instead of multiple stages. The single stage provides sufficient back-pressure control precision for the application, and adding more stages would provide diminishing returns while increasing complexity. This principle of using just enough complexity to achieve the required precision is embodied in the single-stage design.
Solution Approach 2:
The patent optimizes the turbine wheel parameters (blade quantity, blade angle, wheel diameter) to achieve effective back-pressure control with a single stage. By carefully selecting and adjusting these parameters, the system achieves the necessary control precision without requiring multiple stages, thus maintaining simplicity while achieving the desired manufacturing precision.
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 device effectively prevents back-flow during surge conditions, allowing the compressor system to recover by maintaining turbine wheel rotation and reducing pressure on the primary compressor, thereby enhancing system stability and efficiency.
Implementation Method 1
A back-flow limiting device with a turbine wheel is placed downstream of the compressor, which dynamically restricts back-flow by rotating and imparting work on the fluid
Data Source
AI summary
One exemplary embodiment of this disclosure relates to a compressor system. The system includes a compressor and a back-flow limiting device. The back-flow limiting device has a turbine wheel and is arranged downstream of the compressor.