Secondary Coolant Pump Control for Critical Loop Pressure
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Solution Overview
Problem
Refrigeration systems face challenges in efficiently managing coolant flow to maintain optimal temperature in temperature-controlled storage devices, leading to inefficient energy consumption and wear on system components due to the inability to accurately adjust coolant pressure in secondary coolant loops.
Innovation Solution
A secondary coolant refrigeration system with variable speed pumps and a controller that measures loop pressures, identifies critical loops by determining the pressure furthest from a setpoint, and adjusts pump speed to compensate, using a sorting module and PID controller to ensure precise pressure regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If loop averaging algorithm is used to control pump speed, then energy management is improved, but temperature control precision deteriorates because it does not account for critical loops with pressure furthest from setpoint
Solution Approach 1:
The patent applies local quality by transitioning from a global averaging approach to a localized critical-loop-focused approach. Instead of treating all coolant loops uniformly with loop averaging, the system identifies the specific loop with pressure furthest from setpoint and directs control attention and corrective action specifically to that critical loop, making the control quality non-uniform and adapted to local needs.
Solution Approach 2:
The patent changes the control parameter from an averaged pressure value to the differential pressure of the critical loop (the loop with pressure furthest from setpoint). This parameter change enables the system to respond to the most critical condition in the system, improving temperature control precision while still maintaining energy management benefits through variable speed pump control.
2Adaptability or versatility
If variable speed pumps are used to adjust coolant pressure, then cooling requirement matching is improved, but system complexity increases due to need for pressure sensors and control algorithms
Solution Approach 1:
The patent implements feedback control by using pressure sensors to continuously monitor coolant loop pressure and comparing it to a setpoint. The control system uses this feedback information to dynamically adjust pump speed, creating a closed-loop control system that adapts to changing cooling requirements while providing structured complexity management.
Solution Approach 2:
The system applies self-service by using the pressure differential information itself to drive the control decision-making process. The critical loop identification and corrective speed calculation are performed automatically by the control system based on sensor inputs, reducing the need for external intervention or complex manual control strategies.
3Loss of energy
If pump speed is adjusted based on average pressure, then energy consumption is reduced, but wear on system components increases due to inadequate response to critical loops
Solution Approach 1:
The patent applies preliminary action by proactively identifying the critical loop before severe temperature deviations occur. By continuously monitoring pressure differentials and identifying the loop with pressure furthest from setpoint, the system takes preventive control action to address potential problems before they lead to excessive wear or system failures.
Solution Approach 2:
The feedback mechanism enables the system to respond to actual system conditions rather than operating on fixed schedules or average values. By continuously monitoring pressure differentials and adjusting pump speed based on real-time critical loop identification, the system optimizes energy consumption while preventing conditions that would lead to increased component wear.
Data Source
AI summary
A system and method is provided for controlling the operation of secondary coolant pump(s) in a refrigeration system having a secondary coolant system that circulates the coolant to applicable cooling loads, and a primary refrigeration system that chills the coolant in the secondary coolant system. The system and method for controlling the pumps measures the pressure of the plurality of secondary coolant fluid loops, sorts the measurements to identify a secondary coolant fluid loop with a pressure farthest from a setpoint, and adjusts pump speed to compensate for the critical loop (i.e., the secondary coolant fluid loop with a pressure furthest from the setpoint).