HVAC Return Temperature Flow Control to Reduce Low Delta-T Energy Loss
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Solution Overview
Problem
HVAC systems face inefficiencies due to excessive heat and water flow, leading to unwanted energy usage and low delta T, which existing methods fail to adequately address.
Innovation Solution
A method for controlling fluid flow through HVAC systems by comparing the return temperature with a threshold temperature dependent on the current flow, independent of supply temperature measurements, to optimize energy usage and prevent excessive flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the flow of fluid through the coil is increased to meet heating or cooling demand, then the heating or cooling capacity is improved, but the return temperature becomes too low (or too high) causing excessive energy usage at the generation and distribution levels
Solution Approach 1:
The patent applies dynamics by making the flow limitation adaptive rather than fixed. The system continuously adjusts the maximum allowable flow based on the actual return temperature measured during operation. When return temperature deviates from the design value, the controller dynamically modifies the flow limit to bring the system back toward optimal operation, resolving the contradiction between meeting demand and minimizing energy loss.
Solution Approach 2:
The patent implements feedback control by measuring the actual return temperature and using this information to adjust the flow limitation. The controller compares the measured return temperature with the design return temperature and modifies the maximum flow accordingly. This closed-loop feedback mechanism ensures the system operates efficiently while meeting heating or cooling demands, preventing excessive energy usage.
2Loss of energy
If the flow of fluid is limited to reduce energy usage, then energy efficiency is improved, but the heating or cooling capacity may become insufficient
Solution Approach 1:
The system dynamically adjusts the flow limitation based on actual operating conditions. Rather than imposing a fixed flow limit that might restrict capacity, the controller continuously adapts the maximum flow to match the thermal demands observed during operation. This ensures sufficient heating or cooling capacity is maintained while minimizing energy usage.
Solution Approach 2:
The patent changes the parameter of flow limitation from a fixed value to a variable that depends on return temperature. By adjusting the maximum flow parameter based on actual return temperature measurements, the system optimizes the balance between energy efficiency and heating/cooling capacity, allowing higher flows when needed and lower flows when efficient operation is achieved.
3Ease of operation
If a fixed threshold return temperature is used to control flow, then control simplicity is maintained, but additional operational points are lost and energy optimization is limited
Solution Approach 1:
The patent transforms the static threshold temperature control into a dynamic system. Instead of using a fixed threshold, the maximum flow is continuously adjusted based on the actual return temperature measured during operation. This dynamic approach maintains ease of operation through automated control while significantly increasing adaptability by allowing the system to operate efficiently across a wide range of conditions and demand levels.
Solution Approach 2:
The system changes the control parameter from a fixed threshold temperature to a variable maximum flow that adapts to actual operating conditions. This parameter change enables the system to utilize additional operational points by adjusting flow limits based on real-time return temperature measurements, thereby optimizing energy efficiency across diverse operating scenarios while maintaining simple automated control.
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 stabilizes return temperatures, reduces energy consumption, and provides additional operational points by preventing flow from exceeding design limits, thus enhancing energy efficiency.
Implementation Method 1
exchange of thermal energy between a primary side of the thermal energy exchange system (7) and a secondary side of the thermal energy exchange system (7)
Data Source
AI summary
Various embodiments of the present disclosure optimize energy usage of an HVAC system. For example, some embodiments include a method comprising: generating a flow through a heat exchanger; determining a return temperature of fluid having passed through heat exchanger; determining a current flow of the fluid through the heat exchanger; and controlling the flow of the fluid based on a comparison of the determined return temperature with a threshold temperature, wherein the threshold temperature is dependent on the current flow.