Air-Side Economizer Control Without Humidity Sensors
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Solution Overview
Problem
Existing HVAC systems face inefficiencies in regulating outdoor air intake due to inaccurate humidity sensing and the difficulty in determining optimal operating conditions, leading to inefficient economizer cycles.
Innovation Solution
A sensor-free control system utilizing a finite state machine and extremum seeking control to regulate outdoor air intake, transitioning between states based on heating, cooling, and damper control signals to minimize mechanical cooling load and optimize ventilation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional sensor-based economizer control is used, then outdoor air intake can be regulated, but humidity sensing inaccuracies lead to suboptimal control decisions
Solution Approach 1:
The patent removes humidity sensors from the economizer control system entirely. Instead of using sensor measurements, the system extracts control decisions from analyzing the operational states and control signals of existing HVAC components (cooling coils, heating coils, dampers, fans), eliminating the source of measurement inaccuracy while maintaining control functionality.
Solution Approach 2:
The system introduces a finite state machine as an intermediary that translates the states of HVAC components into economizer control decisions. This intermediary processes information from cooling coil states, heating coil states, damper positions, and fan operation to determine optimal outdoor air intake, replacing direct humidity measurement with indirect inference from component behavior.
2Measurement precision
If multiple sensors are used to determine optimal operating conditions, then control accuracy can be improved, but system complexity and cost increase
Solution Approach 1:
The patent extracts essential control information from the operational states of existing HVAC components rather than adding new sensors. By monitoring cooling coil on/off states, heating coil states, damper positions, and fan operation, the system obtains sufficient data for economizer control without introducing additional measurement devices, thereby reducing system complexity.
Solution Approach 2:
The HVAC system's existing components provide the information needed for economizer control through their own operational states. The cooling coils, heating coils, dampers, and fans essentially 'self-report' their status, which the finite state machine uses to infer optimal operating conditions without requiring separate sensing systems.
3Temperature
If mechanical cooling is used to maintain temperature, then indoor comfort is ensured, but energy consumption increases during suitable outdoor conditions
Solution Approach 1:
The system dynamically adjusts the economizer cycle operation based on real-time analysis of HVAC component states and outdoor conditions. The finite state machine continuously evaluates whether to operate in economizer mode (using outdoor air for free cooling) or mechanical cooling mode, optimizing the balance between indoor temperature control and energy consumption by adapting to changing conditions rather than using fixed control rules.
Data Source
AI summary
Systems and methods for regulating the amount of outdoor air that is introduced into a building are shown and described. These systems and methods utilize extremum seeking control logic to vary the flow of outdoor air into the building in response to cooling load determinations.