Brake system for a compressor
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Solution Overview
Problem
Existing HVAC&R systems face challenges in quickly reducing the rotational speed of the impeller during transitions from active to inactive operating modes, leading to prolonged downtime and inefficiency, as conventional methods are either time-consuming or costly when additional components like brakes are implemented.
Innovation Solution
The implementation of a braking system that utilizes the backflow of working fluid to rapidly reduce the impeller's rotational speed by adjusting pre-rotation vanes and a variable geometry diffuser, allowing the system to quickly reach an idle state, thereby enabling quicker transitions between operating modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional methods are used to reduce impeller rotational speed, then system simplicity is maintained, but shutdown time is prolonged
Solution Approach 1:
The system uses the working fluid itself to provide the braking function. The working fluid flows through the impeller in reverse direction during shutdown, creating a braking torque that slows the impeller rotation. This eliminates the need for separate braking components while utilizing the existing working fluid circulation system.
Solution Approach 2:
Instead of using the working fluid to drive the impeller forward during compression, the system reverses the working fluid flow direction during shutdown to create a braking effect. The diffuser and pre-rotation vanes are adjusted to enable reverse flow, which generates opposing torque on the impeller to rapidly reduce rotational speed.
2Speed
If additional braking components are added, then impeller speed reduction is faster, but system cost and complexity increase
Solution Approach 1:
The diffuser and pre-rotation vanes, which normally serve to compress and direct the working fluid during active operation, are made adjustable to serve a dual function: enabling reverse flow during shutdown to provide braking. This multi-functionality eliminates the need for dedicated braking components while achieving rapid speed reduction.
Solution Approach 2:
The system dynamically adjusts the diffuser angle and pre-rotation vane position based on operating mode. During shutdown, these components are adjusted to optimize reverse flow conditions for braking, while during active operation they return to their compression-optimized positions. This dynamic adjustment enables rapid speed reduction without permanent structural modifications.
3Productivity
If impeller rotational speed is reduced quickly, then productivity is improved, but system control complexity increases
Solution Approach 1:
The controller monitors system operating mode and automatically adjusts the diffuser and pre-rotation vane positions accordingly. During shutdown mode, the controller actuates the adjustable diffuser and pre-rotation vane to enable reverse flow for braking. This automated feedback control achieves rapid speed reduction without requiring complex manual control mechanisms.
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 solution allows for faster system shutdown and restart, reducing downtime and maintaining efficiency by using the working fluid's backflow to quickly lower the impeller's speed, thus enabling quicker transitions between active and inactive modes without the need for additional costly components.
Implementation Method 1
utilizes the backflow of working fluid to rapidly reduce the impeller's rotational speed
Data Source
AI summary
A heating, ventilation, and/or air conditioning (HVAC) system includes a compressor having an impeller configured to rotate and drive a working fluid through a working fluid circuit of the HVAC system in an active operating mode. The HVAC system further includes a controller configured to, in response to receiving an input indicative of a transition to operate in an inactive operating mode, suspend the active operating mode by interrupting a supply of power to the compressor, adjust pre-rotation vanes of the compressor, a variable geometry diffuser of the compressor to a first position, or both to enable a backflow of the working fluid through the compressor for a first interval of time, and, after the first interval of time has elapsed, adjust the pre-rotation vanes, the variable geometry diffuser, or both to a second position to block the backflow of the working fluid through the compressor.