Inline heater overheating system and method
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Solution Overview
Problem
Inline dialysis fluid heaters can overheat if no or low flow conditions occur, posing a risk and requiring costly flow switches that may malfunction.
Innovation Solution
An inline heating system that determines the resistance of the heater element to detect no or low flow conditions by analyzing the rate of change in resistance, using an algorithm to deenergize the heater and trigger alarms if necessary, without relying on additional hardware like flow switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If an inline heater is used to heat dialysis fluid, then heating efficiency is improved, but the risk of overheating under no-flow or low-flow conditions increases
Solution Approach 1:
The system performs preliminary detection of flow conditions before heating occurs by monitoring electrical parameters (voltage, current, resistance) of the heater element. The control algorithm calculates heater resistance and compares it against expected values to detect no-flow or low-flow conditions before overheating can occur, preventing the harmful effect in advance
Solution Approach 2:
The system continuously monitors electrical parameters (voltage, current) and thermal parameters (inlet and outlet fluid temperatures) of the heater, calculates heater resistance in real-time, and uses this feedback to detect flow conditions. The control algorithm adjusts heating operation based on this feedback to prevent overheating while maintaining heating efficiency
2Difficulty of detecting and measuring
If flow switches are installed to detect no-flow conditions, then flow detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The system replaces mechanical flow switches with an electrical measurement-based detection method. By monitoring electrical parameters (voltage, current, resistance) and thermal parameters (fluid temperatures) of the existing heater element, the system infers flow conditions without requiring additional mechanical flow detection hardware, thereby reducing device complexity and cost
Solution Approach 2:
The heater element serves dual functions: it acts as both the heating device and the flow detection sensor. By measuring the electrical and thermal characteristics of the heater element during operation, the system can detect flow conditions using the existing component, eliminating the need for separate flow detection hardware
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
Effectively prevents overheating by detecting low or no flow conditions early, ensuring safe operation of the inline heater and reducing costs by eliminating the need for additional hardware.
Implementation Method 1
an inline heater including a heater element... a power source positioned to apply a voltage or current to power the inline heater
Implementation Method 2
determines a heater element resistance using the applied voltage or current and the measured at least one of the current or voltage... if the no flow or low flow condition is detected
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
An inline heating system (10) including an inline heater (20) including a heater element (26a, 26b); a control unit (50) configured to cause one of voltage or current to be applied to power the inline heater; and a current or voltage meter (66, 66a, 66b) positioned and arranged to measure the other of current or voltage at the heater element due to the applied voltage or current, wherein the control unit is further configured to determine a heater element resistance using the applied voltage or current and the measured current or voltage as part of a no flow or low flow condition detection algorithm implemented by the control unit, wherein the voltage or current applied to power the inline heater is stopped if the no flow or low flow condition is detected.