Multi-Compressor Chiller Staging Using Real-Time Efficiency Curves
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Solution Overview
Problem
Chiller systems with multiple compressors face inefficiencies due to varying cooling demands and compressor load and lift conditions, requiring dynamic management to optimize energy use.
Innovation Solution
Real-time modeling of compressor efficiency using parabolic models to determine composite efficiency curves, enabling the selection and staging of compressors to meet demand while minimizing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of compressors is increased to meet higher cooling demand, then cooling capacity is improved, but system efficiency deteriorates due to suboptimal load distribution
Solution Approach 1:
The system dynamically adjusts compressor staging decisions based on real-time efficiency curves that model compressor performance under varying load and lift conditions. The controller continuously evaluates which compressor configurations optimize efficiency for current demand levels, transitioning from static to dynamic control strategies.
Solution Approach 2:
The invention changes operational parameters by using efficiency curves that account for compressor load and lift conditions. Instead of fixed staging rules, the system adjusts compressor selection and operation based on modeled efficiency parameters that reflect current system state, enabling adaptive optimization of energy consumption.
2Adaptability or versatility
If compressor load and lift conditions vary to match cooling demand, then cooling flexibility is improved, but compressor efficiency deteriorates due to operation away from optimal points
Solution Approach 1:
The system implements feedback through efficiency curves that model compressor performance based on load and lift conditions. The controller uses this feedback to evaluate different compressor configurations and select those that maintain higher efficiency while meeting varying cooling demands, creating a closed-loop optimization system.
Solution Approach 2:
The system performs preliminary action by pre-modeling efficiency curves for compressors under various operating conditions. This allows the controller to predict which compressor configurations will be most efficient before making staging decisions, enabling proactive optimization rather than reactive adjustments.
3Loss of energy
If real-time efficiency modeling is implemented to optimize compressor selection, then energy efficiency is improved, but computational complexity increases
Solution Approach 1:
The system uses simplified parabolic models to approximate compressor efficiency curves, trading some modeling precision for computational simplicity and speed. These lightweight models can be rapidly evaluated in real-time by the controller without requiring complex calculations, making the approach practical for implementation.
Data Source
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AI summary
Multi-compressor chiller systems can be efficiently operated by determining real time efficiency curves for the compressors currently in operation, along with any compressors that may be added to address demand, and using these efficiency curves to determine changes to compressor operation to improve efficiency in meeting chiller demand. The efficiency curves can be parabolic curves. The data used to determine the efficiency curves can be obtained through operation at a variety of lift points and a variety of load points within those lift points. The efficiency curves can be solved to find intersections where there may be staging points for adding or subtracting compressors from operation to efficiently meet demand. This operation can be automated through a controller of a control system for the multi-compressor chiller system.