Heat Exchanger Temperature Control Using Linear Difference Model
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Solution Overview
Problem
Conventional temperature control methods using logarithmic average temperature difference struggle to achieve high accuracy in controlling the temperature of a medium through heat exchange.
Innovation Solution
A temperature control apparatus and method that adjust the temperature of a heat medium based on the expression TH-in-R=E×(TH-in-SV), where TH-in is the temperature of the medium supplied to the heat exchanger, R is the target temperature of the medium discharged, E is the heat exchange rate, and SV is the temperature of the heat medium supplied, to improve temperature control accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If logarithmic average temperature difference is used in heat exchange control, then the control scheme is simple and widely applicable, but the temperature control accuracy is insufficient
Solution Approach 1:
The patent changes the fundamental parameter used for temperature control from logarithmic average temperature difference to a linear temperature difference model. By using the simple temperature difference (TH-in - SV) instead of the complex logarithmic average temperature difference, the patent achieves both high temperature control accuracy and computational simplicity. This parameter transformation allows the system to reach target temperature with ±0.1°C precision while avoiding complex calculations.
2Speed
If feedforward control scheme is used, then the speed of response is increased, but the temperature control accuracy is compromised
Solution Approach 1:
The patent transforms the control parameter from logarithmic average temperature difference to a linear temperature difference model, which works optimally with feedforward control. This parameter change enables the feedforward control scheme to achieve both fast response speed and high temperature control accuracy simultaneously, resolving the traditional trade-off between response speed and control precision.
Solution Approach 2:
The patent incorporates feedback mechanisms to continuously monitor the actual temperature and adjust the heat medium temperature accordingly. By combining feedforward control with feedback correction, the system maintains fast response while achieving high temperature control accuracy within ±0.1°C of the target.
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
Enhances temperature control accuracy by stabilizing the discharge temperature within ±0.1°C of the target temperature, reducing processing load and enabling easier integration with programmable logic controllers.
Implementation Method 1
controls, through heat exchange between a medium subject to temperature control and a heat medium in a heat exchanger
Data Source
AI summary
A temperature control apparatus controls, through heat exchange between a medium subject to temperature control and a heat medium in a heat exchanger, a temperature TH-out of the medium subject to temperature control discharged from the heat exchanger. The temperature control apparatus adjusts a temperature based on expression (1): TH-in−R=E×(TH-in−SV) [in expression (1), TH-in denotes a temperature of the medium subject to temperature control supplied to the heat exchanger, R denotes a target temperature of the medium subject to temperature control discharged from the heat exchanger, E denotes a heat exchange rate of the heat exchanger, and SV denotes a temperature of the heat medium supplied to the heat exchanger].