On board chiller capacity calculation
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Solution Overview
Problem
Conventional methods for managing chiller systems with variable flow are inefficient and costly due to reliance on external flow measurements, leading to improper staging and reduced efficiency.
Innovation Solution
Measuring compressor speed and refrigerant pressure within the chiller system to calculate load and make operational adjustments, eliminating the need for external flow sensors and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external flow measurement devices are used in variable flow systems, then system capacity can be calculated, but system complexity and cost increase
Solution Approach 1:
The patent extracts the capacity calculation function from external flow measurement devices and relocates it to the chiller's internal controller. The controller now calculates capacity using only internal sensors (compressor speed, refrigerant pressures, and temperatures) that are already part of the chiller system, eliminating the need for external flow meters and their associated complexity.
Solution Approach 2:
The chiller system performs its own capacity calculation using its existing internal sensors and controller. The controller utilizes measurements of compressor speed, refrigerant pressures at the evaporator and condenser, and refrigerant temperatures to compute system capacity without requiring external measurement devices, making the system self-sufficient.
2Measurement precision
If external flow measurement devices are installed, then capacity calculation is possible, but reliability decreases due to added components
Solution Approach 1:
The patent removes the unreliable external flow measurement components from the system and extracts the capacity calculation function to the chiller's internal controller. This eliminates the single point of failure that external devices represent while maintaining the ability to calculate capacity accurately using redundant internal sensor data.
Solution Approach 2:
The patent prepares for potential measurement failures by using multiple internal sensors (compressor speed, multiple pressure sensors, temperature sensors) to calculate capacity. This redundancy provides a backup measurement approach that cushions against the failure of any single sensor, thereby maintaining reliability without external devices.
3Quantity of substance
If conventional capacity calculation methods are used with variable flow, then flow measurement is obtained, but control accuracy deteriorates due to improper staging
Solution Approach 1:
The patent changes the parameters used for capacity calculation from flow rate (measured by external devices) to a combination of compressor speed, refrigerant pressures, and temperatures. These parameters directly reflect the chiller's actual operating state and cooling capacity, providing more accurate control decisions for staging multiple chillers.
Solution Approach 2:
The controller continuously monitors compressor speed, refrigerant pressures, and temperatures to calculate actual capacity in real-time. This feedback mechanism allows the control system to accurately determine when to stage chillers on or off based on actual capacity needs rather than relying on potentially inaccurate external flow measurements.
Data Source
AI summary
A method of controlling operation of an air conditioning system (10) includes measuring a compressor speed of one or more chillers (12) of an air conditioning system and measuring a refrigerant pressure of the one or more chillers of the air conditioning system. A chiller load is calculated using the compressor speed and the refrigerant pressure. An air conditioning system includes one or more chillers. Each chiller includes a compressor (22), a condenser (30) operably connected to the compressor, and an evaporator (28) operably connected to the compressor and the condenser. A controller (34) is operably connected to the one or more chillers and is configured to calculate a chiller load utilizing a measurement of compressor speed and a measurement of refrigerant pressure of the chiller.