Method and device for detecting and evaluating bubbles in a liquid in a circuit, especially in a heat pump system
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Solution Overview
Problem
Existing methods for detecting leaks of flammable refrigerants in heat exchangers are complex, slow, and unreliable, especially when the refrigerant is partly liquid and partly gaseous, and they fail to trigger safety measures promptly.
Innovation Solution
A method using an ultrasonic sensor positioned downstream of a heat exchanger in a heat pump system, combined with an automatic air vent upstream and downstream, to detect gas bubbles of flammable refrigerant in a liquid medium, allowing for rapid and reliable detection and triggering safety measures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical or physical methods are used for detecting leaks in heat exchangers, then detection capability is provided, but the methods are very complex, slow, and/or unreliable
Solution Approach 1:
The patent extracts the detection function from complex chemical or physical methods and implements it using a simple ultrasonic sensor that detects bubbles directly in the liquid circuit. This extraction principle simplifies the detection system while maintaining or improving reliability by focusing on the fundamental indicator of leakage (bubbles) rather than using complex analytical methods.
Solution Approach 2:
The patent replaces complex chemical or physical detection methods with an ultrasonic detection system. The ultrasonic sensor uses acoustic waves to detect the presence of gas bubbles in the liquid, substituting mechanical/acoustic principles for complex chemical analysis or physical measurement systems.
2Reliability
If passive measures such as double-walled heat exchangers are used, then safety is increased, but device complexity increases and heat transfer efficiency decreases
Solution Approach 1:
The patent implements a self-service safety system where the detection and response mechanisms are integrated into the existing single-walled heat exchanger system. The ultrasonic sensor continuously monitors for bubbles, and the control system automatically responds to detected leaks, eliminating the need for complex passive double-walled structures while maintaining safety through active self-monitoring and self-response.
3Reliability
If automatic air vents are used to remove refrigerant, then partial safety improvement is achieved, but they cannot handle unlimited quantities and cannot trigger alarm or shutdown
Solution Approach 1:
The patent implements a feedback-based safety system where the ultrasonic sensor continuously monitors the liquid circuit for bubbles and provides real-time information to the control system. When bubbles are detected, the control system receives feedback and automatically triggers appropriate responses (alarm, shutdown, or activation of air vents), enabling the system to handle any quantity of refrigerant leakage rather than being limited by passive venting capacity.
4Loss of time
If ultrasonic sensor is positioned close to heat exchanger, then detection speed increases, but bubbles may dissolve before detection
Solution Approach 1:
The patent applies local quality by positioning the ultrasonic sensor in a specific location within the liquid circuit where bubbles are most likely to persist and be detectable. The sensor is placed in a region with favorable hydrodynamic conditions that prevent immediate bubble dissolution, optimizing both detection speed and reliability by exploiting local flow characteristics rather than using a generic sensor placement.
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
Enables fast and reliable detection of refrigerant leaks, minimizing safety risks by preventing false alarms and ensuring timely system shutdowns.
Implementation Method 1
the ultrasonic sensor emits, receives, and forwards suitable ultrasonic signals to an evaluation unit for detecting bubbles
Data Source
Figure 1
AI summary
The invention relates to a method for detecting the presence of gas bubbles in a liquid of a first closed circuit (1) by means of at least one ultrasonic sensor (9), wherein the ultrasonic sensor (9) is arranged downstream and above a heat exchanger (3) which can inject gas bubbles into the liquid in the event of leaks, wherein a first automatic vent (10) is located downstream and even further above the ultrasonic sensor (9), and wherein the ultrasonic sensor (9) emits, receives and forwards suitable ultrasonic signals to an evaluation unit (12) for the detection of bubbles.The invention also relates to a device for detecting gas bubbles in a liquid of a first circuit (1), wherein the first circuit (1) has a heat exchanger (3) for heat exchange with a second circuit (2) which is operated with a refrigerant, wherein further downstream but above the heat exchanger (3) in the first circuit (1) at least one ultrasonic sensor (9) and further downstream and even higher an automatic air vent (10) are arranged, and wherein the ultrasonic sensor (9) is connected to an evaluation unit (12) for detecting bubbles based on ultrasonic signals. This makes it possible to reliably detect in a heat pump system when refrigerant, in particular flammable refrigerant, enters a closed circuit in a building where this should not be present for safety reasons, and to initiate safety measures at an early stage.However, false alarms caused by air bubbles present in the system can be largely avoided.