Coordinated Fan and Coil Capacity Control for HVAC Setpoint Stability
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Solution Overview
Problem
HVAC systems face inefficiencies in regulating space temperature due to the lack of coordinated control between fan capacity and cooling/heating coil capacity, leading to suboptimal performance in maintaining setpoints, especially under varying load conditions.
Innovation Solution
The method involves varying the fan capacity and discharge air temperature of the cooling/heating coil within predetermined limits to maintain or modulate space temperature, using a control module that coordinates fan and coil control, allowing for multiple speed settings and variable speed operations to adjust airflow and temperature accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fan capacity and coil capacity are controlled independently, then the system structure is simple, but the space temperature regulation efficiency deteriorates
Solution Approach 1:
The patent combines fan capacity control and coil capacity control into a unified coordinated control system. The controller simultaneously manages both components based on space temperature feedback, enabling them to work together as an integrated system rather than independently, thereby improving overall temperature regulation efficiency.
Solution Approach 2:
The system implements feedback control by continuously monitoring space temperature and using this information to adjust both fan capacity and coil capacity. The controller receives temperature signals and dynamically modifies the operation of fan and coil to maintain the desired setpoint, creating a closed-loop control system.
2Measurement precision
If fan capacity is increased to maintain space temperature setpoint, then temperature control accuracy is improved, but energy consumption increases
Solution Approach 1:
The system dynamically changes fan capacity parameters based on actual temperature conditions. Instead of operating at constant high capacity, the fan capacity is adjusted according to the temperature deviation from setpoint, allowing accurate temperature control while minimizing energy consumption during steady-state conditions.
Solution Approach 2:
The fan capacity is made dynamic rather than static, allowing it to vary continuously based on temperature feedback. The system transitions between different operating states (high capacity during temperature deviation, low capacity during steady state), optimizing the balance between control accuracy and energy consumption.
3Adaptability or versatility
If coil discharge air temperature is varied to maintain space temperature, then system adaptability is improved, but control complexity increases
Solution Approach 1:
The coordinated control system serves multiple functions: it controls space temperature, adapts to varying load conditions, and manages both fan and coil operations. This multi-functional approach allows the system to handle diverse operating scenarios (different temperatures, loads, and conditions) through a single integrated control strategy.
Data Source
AI summary
A heating, ventilation, and air conditioning (HVAC) system includes a fan with a variable fan capacity; a coil with a variable discharge air temperature; and a controller configured to control the variable fan capacity of the fan and the variable discharge air temperature of the coil. The controller is configured to vary the variable capacity of the fan to maintain a space temperature at a space temperature setpoint while maintaining the variable discharge air temperature of the coil at a low discharge air temperature limit. The controller is configured to vary the variable discharge air temperature between a high discharge air temperature limit and the low discharge air temperature limit to maintain the space temperature at the space temperature setpoint while maintaining the variable capacity of the fan at a low fan capacity setting.