Refrigerating apparatus and corresponding control device
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Solution Overview
Problem
Existing refrigerating systems face challenges in maintaining stable and efficient operation when both chilled water and cooling water flow rates are variable, as conventional methods struggle with accurate load detection and efficient control, particularly under partial load conditions, leading to potential damage and reduced reliability.
Innovation Solution
A control method that calculates the opening degree of the expansion mechanism using compressor capacity, which is derived from the current rotation number, capacity control mechanism opening degree, and divergence rate from the surge region, allowing for direct detection of operation load and coordination of refrigerant flow to maintain efficient chiller operation without requiring additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the flow rate of chilled water and cooling water are made variable to improve energy efficiency, then system efficiency is improved, but stable and efficient operation becomes difficult to maintain
Solution Approach 1:
The control device continuously monitors compressor operation parameters (rotation number, capacity control mechanism opening degree, operation head) and uses this feedback to dynamically calculate and adjust the expansion mechanism opening degree, maintaining stable operation under variable flow conditions
Solution Approach 2:
The system dynamically adjusts the expansion mechanism opening degree in real-time based on changing compressor parameters and water flow rates, allowing the system to adapt to variable operating conditions while maintaining efficiency and stability
2Measurement precision
If additional sensors are installed to detect abnormal flow rates, then flow rate detection precision is improved, but device complexity and cost increase
Solution Approach 1:
The control device uses the compressor's own operation parameters (which are already being monitored for control purposes) to calculate and detect abnormal water flow rates, eliminating the need for separate detection sensors
Solution Approach 2:
The existing control device performs multiple functions: it controls the expansion mechanism for efficiency and simultaneously detects abnormal flow rates by analyzing compressor parameters, making the system multi-functional without adding components
Data Source
AI summary
A refrigerating apparatus includes a centrifugal compressor, a capacity control mechanism that controls a capacity of the compressor by changing an opening degree of the capacity control mechanism, an expansion mechanism that reduces a pressure of a refrigerant, and a controller. The controller calculates an opening degree of the expansion mechanism using compressor capacity as one of a plurality of indices of change in load. The compressor capacity is obtained from a current rotation number of the compressor, an opening degree of the capacity control mechanism, and a divergence rate of a current operation head from a surge region.