Modular Chiller Frequency Control for Stable Load Efficiency
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Solution Overview
Problem
Conventional air-conditioning systems with modular air-cooled water-cooled chillers experience inefficiencies due to frequent compressor start/stop cycles and large water temperature fluctuations, especially when transitioning to frequency conversion systems, leading to energy waste and suboptimal operation.
Innovation Solution
A smart control system that adjusts the compressor frequency based on load ratios and temperature differences to optimize energy efficiency, using a main controller to communicate with slave units and adjust their operating frequencies to maintain optimal energy efficiency within a defined range, reducing frequent start/stop cycles and stabilizing water temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If frequency conversion system is adopted, then energy efficiency can be improved, but frequent start/stop control causes energy waste and large water temperature fluctuation
Solution Approach 1:
The patent applies frequency conversion technology to enable dynamic adjustment of compressor operating frequency, transitioning from fixed-speed to variable-speed operation. The compressor frequency is dynamically adjusted based on water temperature difference, load ratio, and running time parameters, allowing the system to adapt to varying load conditions and eliminate frequent start/stop cycles, thereby improving energy efficiency while preventing energy waste.
Solution Approach 2:
The control system implements feedback mechanisms by continuously monitoring water temperature, load ratio, and compressor running time, then using this information to adjust compressor frequency. The main controller receives data from slave units and adjusts operating parameters based on actual system performance, creating a closed-loop control that optimizes energy efficiency while preventing excessive energy consumption.
2Adaptability or versatility
If frequency conversion system is adopted, then operational flexibility is improved, but compressor frequent start/stop causes large water temperature fluctuation
Solution Approach 1:
The system uses frequency conversion to enable dynamic compressor speed adjustment, replacing fixed-speed operation with variable-speed control. This allows the system to maintain stable water temperature by continuously adapting compressor output to match actual cooling/heating demands, eliminating the large temperature fluctuations caused by frequent start/stop cycles while preserving operational flexibility.
Solution Approach 2:
The control system incorporates running time as a key parameter, preventing compressors from starting too frequently by tracking how long they have been running. This preliminary action of monitoring running time before allowing restarts ensures that compressors operate continuously for adequate periods, stabilizing water temperature while maintaining the system's ability to respond to changing conditions.
3Device complexity
If conventional invariable-frequency compressor is used, then system simplicity is maintained, but frequent start/stop reduces reliability
Solution Approach 1:
The patent introduces frequency conversion technology to transform the simple but unreliable fixed-speed compressor system into a more complex yet reliable variable-speed system. By enabling continuous frequency adjustment based on actual load conditions, the system eliminates frequent start/stop cycles that reduce reliability, while the added complexity is justified by the significant improvement in operational reliability and energy efficiency.
Solution Approach 2:
The control system implements comprehensive feedback monitoring of water temperature, load ratio, and compressor running time to make intelligent decisions about compressor operation. This feedback mechanism prevents frequent start/stop events by continuously adjusting compressor frequency to match actual system needs, thereby improving reliability despite the increased control complexity.
4Use of energy by moving object
If frequency conversion system is adopted, then energy efficiency can be optimized, but control complexity increases
Solution Approach 1:
The patent applies frequency conversion with dynamic frequency adjustment based on multiple parameters (water temperature difference, load ratio, running time). While this increases control complexity compared to fixed-speed systems, the dynamic control enables significant energy efficiency improvements by matching compressor output to actual demand, making the added complexity necessary for optimal energy performance.
Solution Approach 2:
The control system uses feedback from multiple sensors to continuously monitor system conditions and adjust compressor frequency accordingly. This multi-parameter feedback control increases system complexity but enables precise energy optimization by responding to actual operating conditions, achieving energy efficiency gains that justify the enhanced control requirements.
Data Source
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AI summary
The present disclosure provides an air-conditioning system and a method for controlling the same. The air-conditioning system comprises a modular set including a plurality of frequency conversion modular units. The method comprises steps of: setting an optimized load ratio range for each of the plurality of frequency conversion modular units, within the optimized load ratio range, an operating energy efficiency of each of the plurality of frequency conversion modular units is greater than or equal to a predetermined energy efficiency value; inputting an energy adjustment amount; and setting different operations for the modular set according to the energy adjustment amount, including: a load operation; or a unload operation, wherein in the load operation, frequency adjustment amounts of the plurality of frequency conversion modular units are determined based on the energy adjustment amount and operating positions of the respective frequency conversion modular units participating in operating among the plurality of frequency conversion modular units within the optimized load ratio range, or in the unload operation, frequency adjustment amounts of the plurality of frequency conversion modular units are determined based on the energy adjustment amount and operating positions of respective frequency conversion modular units participating in operating among the plurality of frequency conversion modular units within the optimized load ratio range; and the load operation or the unload operation causes the modular set to operate within the optimized load ratio range.