Rapid restart chiller system
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Solution Overview
Problem
Chiller systems face delays in restarting after power interruptions, which can lead to overshooting target temperatures and system failures, due to the need for controller rebooting and constrained loading rates during startup.
Innovation Solution
Implementing a rapid restart mode for chiller systems that determines the restart mode based on power interruption duration and operational state, allowing for aggressive loading to quickly restore capacity while minimizing the risk of overshooting, using an uninterruptable power source to maintain controller power and avoid rebooting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the chiller uses constrained loading rates during startup to avoid overshooting target temperatures, then system safety is improved, but the restart speed deteriorates
Solution Approach 1:
The system dynamically adjusts the loading rate based on real-time conditions. During normal operation, the chiller can rapidly increase capacity when needed, while during staged operation or when approaching target temperature, the loading rate is constrained. This dynamic adjustment allows the system to achieve both fast response capability and safety, resolving the contradiction between restart speed and system safety.
Solution Approach 2:
The controller changes operational parameters (loading rates) based on the operating state. When the chiller is the primary unit or when there is a significant temperature margin, higher loading rates are permitted for faster restart. When the chiller is in staged operation or temperature is接近 target, lower loading rates are applied. This parameter adaptation resolves the contradiction by allowing fast restart when safe and slow restart when necessary.
2Reliability
If the controller goes through rebooting process when power is restored, then controller reliability is improved, but the response time deteriorates
Solution Approach 1:
The controller performs preliminary actions by maintaining its operational state in memory during power interruptions. When power is restored, it can resume operation immediately without full rebooting, as the critical data and control parameters were preserved. This preliminary preservation of state resolves the contradiction between controller reliability and response time.
Solution Approach 2:
The system extracts only the essential data that needs to be preserved during power interruptions (operational state, setpoints, critical parameters) and stores it in non-volatile memory. This selective extraction allows the controller to skip the full reboot process and directly resume control, achieving both reliability through data preservation and fast response through avoided rebooting.
3Productivity
If the chiller aggressively loads during restart to quickly restore capacity, then productivity is improved, but the risk of temperature overshooting increases
Solution Approach 1:
The system applies different loading strategies to different operational contexts. When the chiller is operating in a mode with large temperature margins or as a primary unit, aggressive loading is permitted. When operating in staged mode or with narrow temperature margins, constrained loading is applied. This local differentiation resolves the contradiction between productivity and temperature control safety.
Solution Approach 2:
The controller continuously monitors temperature, load conditions, and operational state, using this feedback to dynamically adjust the loading rate during restart. If temperature approaches the target or conditions change, the loading rate is automatically reduced to prevent overshooting. This feedback control allows aggressive loading when safe while preventing temperature overshooting, resolving the contradiction between productivity and safety.
Data Source
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AI summary
Chiller systems can include a controller that is configured to determine whether to restart the chiller in a rapid restart mode or a soft loading restart mode, and methods can include determining the mode for restarting the chiller. The soft loading restart mode controls the chiller to provide a comparatively gradual loading, to avoid overshooting a target temperature. The rapid restart mode more aggressively loads the chiller to return more rapidly to a particular load level. The determination of the restarting mode can be based on characteristics of the interruption of power to the chiller system. In chiller systems, the controller can receive power from an uninterruptable power source to maintain continuity of power. The logic used by the controller can be based on whether or not the controller shares continuity of power with other components of the chiller system.