Vortex Flow Sensor Gas Bubble Detection for Heat Pump Safety
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Solution Overview
Problem
Existing methods for detecting gas bubbles in heat pump systems, particularly those using flammable refrigerants like propane, are not sufficiently sensitive, leading to unreliable detection and potential safety hazards due to the risk of creating an ignitable mixture with room air.
Innovation Solution
The implementation of a Vortex flow sensor in the secondary circuit of a heat pump system, which monitors the frequency signal and evaluates parameters such as duty ratio, maximum frequency, and frequency jumps to detect gas bubbles, triggering a safe shutdown to prevent gas escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing detection methods are used, then device complexity is reduced, but measurement precision and reliability of gas bubble detection deteriorate
Solution Approach 1:
The vortex flow sensor is designed to perform multiple functions: it measures fluid flow rate using vortex frequency and simultaneously detects gas bubbles by monitoring duty cycle deviations. This multi-functionality eliminates the need for separate detection devices, maintaining low system complexity while achieving high detection precision through the sensor's ability to identify both normal flow patterns and gas bubble-contaminated flow patterns.
2Reliability
If existing detection methods are used, then device complexity is low, but reliability of safety detection deteriorates
Solution Approach 1:
The control unit continuously monitors the duty cycle of the vortex flow sensor signal and compares it against expected ranges. When gas bubbles are detected through duty cycle deviation, the system provides feedback by triggering an alarm or shutting down the pump. This feedback mechanism ensures high reliability by immediately responding to gas bubble presence, preventing unsafe operation while using the existing flow sensor infrastructure.
3Measurement precision
If vortex flow sensor with duty cycle monitoring is used, then measurement precision of gas bubble detection is improved, but device complexity increases
Solution Approach 1:
The vortex flow sensor's existing signal processing circuitry is utilized to generate and monitor the duty cycle parameter. The control unit, which already processes vortex frequency for flow measurement, is extended to also monitor duty cycle deviations for gas bubble detection. This self-service approach allows the existing electronics to perform dual functions without requiring completely new processing systems, thereby improving detection precision while limiting the increase in overall device complexity.
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 enhances the sensitivity and reliability of gas bubble detection, enabling timely shutdown of the heat pump to prevent hazardous gas escapes and ensure safety, even with flammable refrigerants.
Implementation Method 1
monitoring a frequency signal of a flow sensor, wherein the flow sensor is designed as a vortex flow sensor
Data Source
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AI summary
A method for detecting gas bubbles in a fluid flow of a secondary circuit of a heat pump system, comprising the following steps: monitoring a frequency signal of a flow sensor, wherein the flow sensor is designed as a vortex flow sensor and is arranged in the secondary circuit, and switching the heat pump to a safe state when gas bubbles are detected by means of the monitored frequency signal of the flow sensor, wherein the monitoring of the frequency signal comprises monitoring at least one, preferably several and particularly preferably all of the following signal parameters: a duty cycle, a maximum occurring frequency and a frequency step.