Heat Exchanger Saturation Control Using Temperature Measurements
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Solution Overview
Problem
Current HVAC systems require complex and prone-to-fault flowmeters to determine the saturation level of heat exchangers, leading to inefficient pump capacity increases and economic concerns due to the third-power relationship between volume flow and heat transfer, necessitating a simplified method to monitor and control heat exchanger operation.
Innovation Solution
A method that measures at least three temperatures to determine the saturation level of the heat exchanger, allowing for control of the heat transfer medium flow on the primary side and potentially the secondary side, eliminating the need for a flowmeter by using temperature-based functions to limit volume flow when a predetermined saturation level is reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flowmeters are used to determine saturation level, then measurement precision is improved, but device complexity increases and reliability decreases due to prone-to-fault components
Solution Approach 1:
The patent extracts the flowmeter component from the system and replaces it with temperature sensors. By removing the flowmeter, the system becomes simpler and more reliable while still achieving saturation level determination through temperature-based calculations using the function Q = k·A·F·(ΔT)^n.
Solution Approach 2:
The patent replaces the mechanical flow measurement system with a thermal measurement system. Instead of mechanically measuring flow rate, the system uses temperature sensors to detect temperature differences and calculates heat transfer based on thermal principles, eliminating mechanical wear and faults.
2Productivity
If pump capacity is increased to maintain heat transfer at higher volume flows, then heat transfer efficiency is improved, but energy consumption increases due to the third-power relationship
Solution Approach 1:
The patent implements dynamic control of the heat exchanger operation by continuously monitoring temperature differences and adjusting the volume flow based on the calculated saturation level. This allows the system to operate dynamically at optimal points rather than requiring constant high pump capacity, reducing energy consumption while maintaining heat transfer efficiency.
Solution Approach 2:
The patent employs feedback control by using temperature measurements to determine the current saturation level and using this information to adjust the volume flow. The controller receives temperature signals and adjusts the heat transfer medium flow to maintain optimal operation, preventing unnecessary pump energy consumption.
3Quantity of substance
If volume flow is increased beyond saturation level, then heat transfer capacity is improved, but operational efficiency deteriorates due to diminishing returns
Solution Approach 1:
The patent applies partial action by determining the saturation level and limiting the volume flow to this point rather than continuously increasing it. By using the temperature-based saturation calculation to set an optimal flow limit, the system achieves sufficient heat transfer capacity without the excessive action of continuously increasing flow beyond saturation, thereby maintaining operational efficiency.
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 simplifies the monitoring and control of heat exchanger saturation, reducing the need for flowmeters, optimizing pump capacity, and maintaining heat transfer efficiency by using temperature measurements to manage volume flow, thereby enhancing the operational efficiency and economic viability of HVAC systems.
Implementation Method 1
at least three of the four temperatures TinW, ToutW, TinL and/or ToutL are measured and that the respective saturation level of the heat exchanger is determined from these measured temperatures
Implementation Method 2
a heat exchanger through which a heat transfer medium flows on a primary side... and which emits on a secondary side a heat flow to a secondary medium
Implementation Method 3
the heat flow emitted in the heat exchanger 15 to the air flow 16 is determined by the mass flow on the primary side of the heat transfer medium, the inlet temperature TinW thereof at the inlet of the heat exchanger 15 and the outlet temperature ToutW thereof at the outlet
Data Source
AI summary
A method for operating a heat exchanger, through which a heat transfer medium flows on a primary side, entering the heat exchanger with a first temperature and exiting the heat exchanger with a second temperature. The heat transfer medium emits on a secondary side a heat flow to a secondary medium flowing through the heat exchanger in the case of heating or, in the case of cooling, absorbs a heat flow from the secondary medium which enters the heat exchanger with a third temperature and exits the heat exchanger again with a fourth temperature. The heat exchanger is capable of transferring a maximum heat flow. At least three of the four temperatures are measured and the respective saturation level of the heat exchanger is determined from these measured temperatures and is used for controlling the operation of the heat exchanger.