HVAC Valve Opening Control Using Flow and Temperature Difference
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Solution Overview
Problem
Existing HVAC systems face inefficiencies in energy exchange due to high fluid flow rates through thermal energy exchangers, which do not result in significant energy exchange improvements, and require predefined temperature thresholds that may not match new or replaced thermal energy exchangers.
Innovation Solution
A method and control device that measure the flow and temperature difference across thermal energy exchangers to determine a control criterion, adjusting the valve opening based on this criterion to optimize energy exchange, using a function that increases flow with increasing temperature difference, and calibrating parameters based on environmental characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high fluid flow rates are used through thermal energy exchangers, then the fluid transport speed increases, but the efficiency of thermal energy exchange decreases
Solution Approach 1:
The valve opening is dynamically adjusted based on real-time measurements of fluid flow rate and temperature difference. The control device continuously modifies the valve position to maintain optimal flow conditions, transitioning from static to dynamic control to maximize thermal energy exchange efficiency while accommodating varying operational demands.
Solution Approach 2:
The system changes the flow rate parameter dynamically by adjusting valve opening based on measured temperature differences and flow rates. This parameter adjustment ensures the fluid flows at optimal velocities for heat exchange, preventing both excessive speed that reduces efficiency and insufficient speed that limits energy transfer.
2Device complexity
If predefined temperature threshold values are used for valve control, then the control logic is simple, but the system cannot adapt to new or replaced thermal energy exchangers
Solution Approach 1:
The control device automatically determines optimal control parameters by measuring actual fluid flow rates and temperature differences. Instead of relying on pre-programmed thresholds, the system self-adjusts to the specific characteristics of each thermal energy exchanger, eliminating the need for manual reconfiguration when exchangers are replaced or upgraded.
Solution Approach 2:
The system implements continuous feedback loops that measure fluid flow rate and temperature difference, then use this information to adjust valve opening. This closed-loop control adapts to different thermal energy exchangers automatically, as the feedback from actual measurements guides the control decisions regardless of exchanger type or condition.
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 the efficiency of thermal energy exchangers by optimizing fluid flow and energy exchange, ensuring efficient operation even with changing environmental conditions and thermal exchanger types, without the need for predefined threshold adjustments.
Implementation Method 1
the flow rate of the fluid through the valve is determined by a flow sensor
Implementation Method 2
the supply temperature to and the return temperature from the thermal energy exchanger are determined by temperature sensors
Implementation Method 3
regulate the flow of a fluid through a thermal energy exchanger of the HVAC system and thereby adjust the amount of energy exchanged by the thermal energy exchanger
Data Source
Figure 1
Figure 2a~3
Figure 4~5
AI summary
For controlling the opening of a valve (10) in an HVAC system (100) to regulate the flow φ of a fluid through a thermal energy exchanger (2) of the HVAC system (100) and adjust the amount of energy E exchanged by the thermal energy exchanger (2), determined are the flow φ through a valve (10) and the temperature difference ΔT = T in - T out between the supply temperature T in of the fluid entering the thermal energy exchanger (2) and the return temperature T out of the fluid exiting the thermal energy exchanger (2). The opening of the valve (10) is controlled depending on the flow φ and the temperature difference ΔT. For example, the opening of the valve (10) is controlled depending on a control criterion c = ƒ(φ, ΔΤ), calculated from the flow φ and the temperature difference ΔT.