Systems and methods for flow control in an HVAC system
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Solution Overview
Problem
Existing building management systems (BMS) and HVAC systems often operate inefficiently, leading to energy waste due to inefficient control of fluid flow through heating or cooling coils, which results in suboptimal energy consumption and performance.
Innovation Solution
A method and system that adjust the setpoint of a valve controlling fluid flow through an HVAC coil based on temperature differences between the inlet and outlet, utilizing a controller with a processor and memory to execute a control application that calculates temperature differences and adjusts the setpoint to maintain a desired temperature change, incorporating features like pulse generation, change-limiting, and reevaluation to optimize efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional flow control methods are used in HVAC systems, then the system can operate continuously, but energy is wasted due to inefficient operation in suboptimal zones
Solution Approach 1:
The control application continuously monitors the temperature differential across the coil and uses this feedback to dynamically adjust the valve setpoint. When the temperature differential falls below a threshold indicating inefficient operation, the system modifies the setpoint to move the system out of the inefficient zone, thereby reducing energy waste while maintaining effective temperature control.
Solution Approach 2:
The system transitions from static flow control to dynamic control by continuously adjusting the valve setpoint based on real-time temperature differential measurements. This dynamic adjustment allows the system to adapt to changing conditions and avoid fixed inefficiencies associated with traditional continuous operation at constant settings.
2Loss of energy
If the valve setpoint is adjusted frequently to optimize efficiency, then energy savings improve, but system stability may be compromised
Solution Approach 1:
The control application implements change-limiting logic that prevents excessive or overly frequent adjustments to the valve setpoint. By limiting the magnitude and frequency of setpoint changes, the system achieves energy savings through targeted adjustments while avoiding instability that could result from overly aggressive control actions.
Solution Approach 2:
The system uses periodic evaluation of the temperature differential with threshold-based triggering to determine when setpoint adjustments are necessary. This periodic monitoring approach with defined thresholds ensures adjustments occur at appropriate intervals rather than continuously, maintaining system stability while achieving energy optimization.
3Productivity
If the system operates without reevaluation logic, then the control algorithm is simpler, but the system cannot adapt to changing conditions and operates inefficiently
Solution Approach 1:
The control application incorporates reevaluation logic that proactively assesses whether the current valve setpoint remains optimal under changing system conditions. By performing preliminary evaluations before making adjustments and using threshold-based triggering, the system adapts to changing conditions efficiently without requiring overly complex continuous optimization algorithms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances energy savings and improves the performance of the HVAC system by preventing operation within inefficient zones, conserving power, and ensuring adequate heating or cooling, thereby reducing energy consumption and maintaining desired temperature conditions.
Implementation Method 1
receiving a first temperature measurement associated with an inlet of the coil, receiving a second temperature measurement associated with an outlet of the coil, calculating a difference between the first temperature measurement and the second temperature measurement
Data Source
AI summary
A system for controlling flow of a fluid through a heat exchanger in a heating, ventilation, or air conditioning (HVAC) system includes a flow control device operable to adjust the flow of the fluid through the heat exchanger, temperature sensors positioned to obtain a temperature differential of the fluid across the heat exchanger, and a controller configured to compare the temperature differential to a threshold. Responsive to the temperature differential being less than the threshold, the controller is configured to calculate an adjusted setpoint for the flow control device as a function of both the temperature differential and the threshold and operate the flow control device to adjust the flow of the fluid through the heat exchanger in accordance with the adjusted setpoint.