HVAC Thermal Power Transfer Control Using Flow-Based Estimation
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Solution Overview
Problem
Existing HVAC systems face challenges in accurately controlling thermal power transfer in dynamic environmental conditions due to the need for multiple sensors to measure environmental variables, which is not sufficient for precise control during transient events and processes.
Innovation Solution
A method that uses a flow sensor to measure fluid flow through a thermal energy exchanger and determines an estimated thermal power transfer based on a defined flow rate to delta-T mapping, allowing the controller to generate control signals to regulate the flow and pressure, thereby controlling the thermal power transfer without requiring temperature sensors for supply and return temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple temperature sensors are used to measure supply and return temperatures for accurate power transfer calculation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the temperature sensors from the measurement system. Instead of measuring both supply temperature (T_s) and return temperature (T_r) separately with temperature sensors, the invention uses only a flow sensor to measure fluid flow rate (q) and derives power transfer information solely from flow measurements through a control unit that calculates Q = q * ΔT, where ΔT is obtained from the flow measurement and pre-stored characteristics of the thermal energy exchanger.
Solution Approach 2:
The patent creates a virtual model or copy of the thermal energy exchanger's performance characteristics by pre-storing the relationship between flow rate and temperature differential (ΔT) in the control unit. This stored characteristic curve allows the system to determine ΔT from flow rate measurements without physical temperature sensors, effectively using a digital copy of the exchanger's thermal behavior to replace physical temperature measurement devices.
2Ease of manufacture
If basic power transfer calculation Q≈φ·ΔT is used in stable scenarios, then calculation simplicity is improved, but measurement precision deteriorates in transient conditions
Solution Approach 1:
The patent implements a dynamic measurement and control approach where the system continuously adapts to changing operating conditions. The control unit receives real-time flow rate measurements (q) and dynamically determines the temperature differential (ΔT) based on pre-stored flow rate to ΔT mapping that captures the thermal exchanger's behavior across all operating conditions. This allows accurate power transfer calculation Q = q * ΔT during both stable and transient conditions, eliminating the need for separate stable/transient calculation methods.
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 enables precise control of thermal power transfer in HVAC systems under dynamic conditions with a reduced need for sensors, improving efficiency and accuracy by minimizing the difference between setpoint and estimated thermal power transfer.
Implementation Method 1
a flow sensor measures the flow of fluid through the thermal energy exchanger
Implementation Method 2
the energy exchange or the power transfer, correspondingly, is adjusted by regulating the amount of energy delivered by the thermal energy exchanger to heat or cool a room
Implementation Method 3
a thermal energy exchanger of a Heating, Ventilating and Air Conditioning HVAC system
Data Source
AI summary
A method of controlling a thermal power transfer of a thermal energy exchanger (80) of an HVAC system (1), the method comprising: receiving, by a controller (10), a setpoint thermal power transfer (Power SP); measuring, by a flow sensor (52), a measured flow of fluid (ϕact) through the thermal energy exchanger (80); determining, by the controller (10), an estimated thermal power transfer (Power EST), using the measured flow of fluid (ϕact) and a defined flow rate to delta-T mapping; comparing, by the controller (10), the setpoint thermal power transfer (Power SP) and the estimated thermal power transfer (Power EST); and regulating, by the controller (10), the flow (ϕact) of the fluid (W) through the thermal energy exchanger (80) based on the comparing.