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 usage and performance.
Innovation Solution
A method and system that includes a valve control mechanism using a controller with a processor and memory to adjust a setpoint based on temperature differences across a coil, incorporating features like pulse generation, change-limiting, and reevaluation to optimize fluid flow and energy 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 system dynamically adjusts the valve setpoint based on real-time temperature differential measurements rather than using fixed static control parameters. The controller continuously monitors ΔT across the coil and modifies the valve position setpoint accordingly, enabling the system to adapt to changing conditions and avoid inefficient operating zones.
Solution Approach 2:
The system implements feedback control by measuring the temperature differential across the coil and using this information to adjust the valve setpoint. The controller receives temperature inputs, calculates ΔT, and modifies the valve position based on whether ΔT is above or below a threshold, creating a closed-loop control system that prevents energy waste.
2Use of energy by moving object
If the valve setpoint is adjusted frequently to optimize energy efficiency, then energy consumption is reduced, but system stability may be compromised
Solution Approach 1:
The control system uses partial action by adjusting the valve setpoint only when the temperature differential crosses a predefined threshold, rather than continuously modulating the valve position. This threshold-based approach prevents excessive control actions while still achieving energy savings by avoiding inefficient operating zones.
Solution Approach 2:
The system implements periodic evaluation of the temperature differential to determine when setpoint adjustments are necessary. By monitoring ΔT at regular intervals and triggering adjustments only when threshold conditions are met, the system achieves energy efficiency without causing instability from continuous or erratic control actions.
3Device complexity
If simple on-off control is used, then the control system remains simple, but energy efficiency is reduced due to operation in inefficient zones
Solution Approach 1:
The system changes the control parameter from simple on-off valve positioning to dynamic setpoint adjustment based on temperature differential. The controller modifies the valve position setpoint as a continuous parameter rather than using discrete on-off states, enabling the system to operate efficiently across varying conditions while maintaining relatively simple control logic.
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
The solution effectively maintains a desired temperature change across coils, reducing energy consumption and improving system performance by preventing operation within inefficient zones and adjusting setpoints dynamically to maintain optimal energy use.
Implementation Method 1
a coil that facilitates heating or cooling
Data Source
AI summary
A method for controlling flow in a heating, ventilation, and air conditioning (HVAC) system includes adjusting a setpoint associated with a valve based on a temperature change across a heating or cooling coil to reduce energy waste. The method includes 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, determining that the difference between the first temperature measurement and the second temperature measurement is below a threshold, and adjusting a setpoint associated with the valve. Additional control features may be provided to improve system behavior such as a pulse generation feature, a change-limiting feature, and a reevaluation feature.