HVAC system and control method thereof
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Solution Overview
Problem
HVAC systems in large spaces, such as subway stations, face challenges in maintaining comfortable temperatures due to the lack of suitable control methods for air handling units, leading to system oscillation and high energy consumption, as the fan and valve are coupled, preventing independent control.
Innovation Solution
Implementing a decoupling control method for the fan and valve in the HVAC system, where the fan and valve are independently controlled to adjust their parameters separately, allowing for optimized operation and reduced energy consumption by monitoring return air temperature and adjusting fan speed and valve opening degree accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the fan and valve are controlled in a coupled manner, then the control structure is simple, but system oscillation occurs and temperature control precision deteriorates
Solution Approach 1:
The patent segments the coupled control of fan and valve into two independent control loops. The fan speed is controlled based on return air temperature deviations, while the valve opening is adjusted based on supply air temperature requirements. This segmentation eliminates the oscillation caused by coupled control and improves system stability.
2Ease of operation
If the fan operates at fixed speed, then the control method is simple, but the system cannot adapt to load changes and energy consumption increases
Solution Approach 1:
The patent implements dynamic fan speed control by introducing a frequency converter that adjusts fan rotation speed based on return air temperature deviations. This allows the system to adapt to varying load conditions in large spaces while maintaining simple control logic through automated temperature-based regulation.
3Power
If the fan speed is increased to meet cooling load, then the cooling capacity is sufficient, but energy consumption increases
Solution Approach 1:
The patent changes the operating parameters of the fan by adjusting its rotation speed according to actual cooling load requirements. When return air temperature deviations are small, the fan operates at lower speed; when deviations are large, speed increases. This parameter adjustment maintains sufficient cooling capacity while optimizing energy consumption.
Data Source
AI summary
The present application discloses a control method for an HVAC system in a relatively large spatial place and the HVAC system. The HVAC system comprises an air handling unit, and the air handling unit is provided with a valve through which a fluid medium passes and a fan; and the method comprises: monitoring a return air temperature of air circulated back to the air handling unit; providing a return air temperature setpoint of the HVAC system; and performing decoupling adjustment on one of the fan and the valve, and then adjusting the other of the fan and the valve so that the return air temperature is close to the return air temperature setpoint. According to the present application, the HVAC system can operate in a steady and energy-saving way.