Flow Heater Control for Stable Outlet Temperature
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Solution Overview
Problem
Existing continuous-flow heaters face challenges in achieving precise temperature control at the outlet of a flow tube due to thermal inertia, leading to long preheating times and significant temperature fluctuations, especially at the start of a brewing process.
Innovation Solution
The system employs characteristic curves to control the heating and pumping power based on input parameters, including initial and outlet temperature values, to set a predetermined setpoint temperature at the flow tube outlet, accounting for thermal inertias and ambient conditions, and includes a second temperature sensor to calibrate and adjust heating and pumping values for precise temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If thermal regulation is used to control fluid temperature at the outlet, then temperature control is attempted, but thermal inertia causes long waiting times and large temperature fluctuations
Solution Approach 1:
The system performs preliminary actions by determining multiple temperature values (first temperature value with pump and heating device switched off, second temperature value with pump switched on and heating device operated at first power level, third temperature value with pump switched off and heating device switched on) before the actual heating process to calculate calibration factors and characteristic curves. This advance preparation enables immediate precise temperature control without waiting for thermal equilibrium.
Solution Approach 2:
The control device uses measured temperature values from temperature sensors to continuously monitor the actual fluid temperature and compares it with the target temperature. Based on this feedback, the control device adjusts the heating device power level and pump power level dynamically to maintain precise temperature control, compensating for thermal inertia effects in real-time.
2Temperature
If thermal regulation is used to control fluid temperature, then temperature adjustment is attempted, but thermal inertia causes large temperature fluctuations
Solution Approach 1:
The control device uses measured temperature values from temperature sensors to continuously monitor the actual fluid temperature and compares it with the target temperature. Based on this feedback, the control device adjusts the heating device power level and pump power level dynamically to maintain precise temperature control, compensating for thermal inertia effects in real-time.
Solution Approach 2:
The system transitions from static thermal regulation to dynamic control by continuously adjusting heating device power and pump power based on real-time temperature measurements and pre-calculated characteristic curves. This dynamic approach allows the system to adapt to changing thermal conditions and maintain stable temperature despite thermal inertia.
3Temperature
If circulation through heating element is used to reduce temperature fluctuations, then temperature stability is improved, but system complexity increases and brewing process is delayed
Solution Approach 1:
The invention extracts the temperature control function from complex circulation systems with valves and implements it directly in the flow tube through integrated heating devices and pump control. By removing the need for separate circulation loops and valuation systems, the solution simplifies the device while maintaining temperature stability.
4Reliability
If immersion sleeves are used for temperature control, then limescale resistance is improved, but manufacturing cost increases
Solution Approach 1:
The flow tube is constructed from uniform stainless steel material throughout, eliminating the need for specialized immersion sleeves. This homogeneous construction provides limescale resistance while simplifying manufacturing and reducing costs compared to multi-material assembly approaches.
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 allows for precise and constant temperature control at the flow tube outlet with minimal waiting times, reducing energy consumption and enabling short-term temperature changes, while eliminating the need for lengthy thermal equilibration.
Implementation Method 1
a heating device (12a, 12b) for heating the fluid in the flow tube (14), the heating device (12a, 12b) having a heat output and a calorific value
Implementation Method 2
a pump device (30) for pumping the fluid into the at least one flow tube (14)
Data Source
Figure 1
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AI summary
The present invention relates to a flow heater for heating a fluid, having at least one heating device (12a, 12b); at least one flow tube (14) for guiding the fluid with an inlet (16) and an outlet (18), wherein the flow tube (14) is thermally coupled to the at least one heating device (12a, 12b) and an inlet area (20), a central area (22) and a lead-out area (24); at least one first temperature sensor (26) which is arranged in the inlet area (20) of the flow tube (14); a pumping device (30) for pumping the fluid into the at least one flow tube (14); and a control device (34) coupled to the heating device (12a, 12b), the pumping device (30) and the first temperature sensor (26); wherein the control device (34) is designed to determine the following values before the start of a heating process: a first temperature value (T1) in the inlet area (20) of the flow tube (14) by means of the first temperature sensor (26) with the pump device (30) and the heating device ( 12a, 12b); and a second temperature value (T2) in the inlet area (20) of the flow tube (14) by means of the first temperature sensor (26) when the pumping device (30) is operating at a first specifiable power level and when the heating device (12a, 12b) is operating at a first specifiable one power level; wherein in the control device (34) the dependency of at least one setpoint temperature (Tsoll) of the fluid at the outlet (18) of the flow tube (14) on at least the first temperature value (T1), the second temperature value (T2), at least the first specifiable power level of the pump device (30) and different calorific values correlated with power levels of the heating device (12a, 12b), wherein the control device (34) is designed to control the heating device (12a, 12b) in such a way that it is operated with a power level that is set according to the stored dependence at a set power level of the pump device (30) to the target temperature (Tsetpoint) of the fluid at the outlet of the flow tube (14). It also relates to a corresponding method for operating a continuous-flow heater.