Control system for HVAC comprising an air-handling unit and a terminal unit and method of operating said control system
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Solution Overview
Problem
HVAC systems face challenges in optimizing energy consumption due to complex modeling and repetitive measurement techniques, which are time-consuming and difficult to implement effectively.
Innovation Solution
A control system that calculates the slope of total power consumption as a function of temperature or humidity to adjust the supply air temperature from the air-handling unit, balancing energy usage between the AHU and terminal units, using a hill climbing technique to minimize energy consumption without requiring complete calculation of cost functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex modeling or repetitive measuring techniques are used to optimize energy consumption, then energy optimization accuracy is improved, but implementation complexity and time consumption increase
Solution Approach 1:
The patent extracts only the essential information needed for optimization - the slope of energy consumption - rather than using complete cost function models. This is achieved by calculating the derivative of energy consumption with respect to supply air temperature, which simplifies the optimization problem to finding where this slope equals zero, eliminating the need for complex repetitive modeling while maintaining optimization accuracy
Solution Approach 2:
The patent changes the optimization approach from using complete cost function models to using the derivative (slope) of energy consumption with respect to temperature. By focusing on the rate of change rather than the complete function, the system achieves optimization through simpler parameter calculation - specifically finding the temperature where dE/dT = 0, which represents the minimum energy consumption point
2Measurement precision
If complete cost function modeling is used to calculate optimal operating points, then optimization accuracy is improved, but calculation time and computational resources increase
Solution Approach 1:
The patent extracts only the essential information needed for optimization - the slope of energy consumption - rather than using complete cost function models. This is achieved by calculating the derivative of energy consumption with respect to supply air temperature, which simplifies the optimization problem to finding where this slope equals zero, eliminating the need for complex repetitive modeling while maintaining optimization accuracy
Solution Approach 2:
The patent uses partial action by calculating only the derivative (slope) of the energy consumption function rather than the complete cost function itself. This partial approach - finding where dE/dT = 0 - is sufficient to locate the optimal operating point without requiring full model evaluation, significantly reducing computational time while achieving the same optimization goal
3Measurement precision
If physical measurement of energy consumption at different operating points is performed, then optimization data accuracy is improved, but measurement time and system disruption increase
Solution Approach 1:
The patent implements continuous feedback by using real-time measurements of supply air temperature and energy consumption to calculate the slope dE/dT. This feedback mechanism allows the system to dynamically adjust the supply air temperature to maintain operation at the optimal point where the slope equals zero, providing accurate optimization data through continuous monitoring rather than discrete repetitive measurements
Data Source
Figure 1
Figure 2~3
AI summary
Rather than complex modeling or time consuming repetitive measuring for optimizing an HVAC system, a slope or change in energy use as a function of a change in a variable (e.g., temperature or humidity) is used to adjust the variable. In an HVAC system, the temperature or humidity of supplied air from the AHU (12) is set based on the derived slope. The energy usage to heat and/or cool supplied air at the terminal units (22) is balanced with the energy usage to heat and/or cool the air to be supplied by the AHU (12). The slope of the total energy usage may be indicated by a sum of flow rates.