Brazed Plate Heat Exchanger Probe for Freeze-Tolerant Sensing
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Solution Overview
Problem
Brazed plate heat exchangers face deactivation issues due to water temperatures dipping below subfreezing levels, which can occur momentarily or for short durations, leading to premature shutdown of refrigerant compression systems.
Innovation Solution
Incorporating a temperature sensor probe within the heat exchanger to monitor water temperature at a target point that can withstand higher pressure, providing feedback signals to a controller to distinguish between acceptable and unacceptable operations based on predefined temperature limits, thereby delaying system deactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If water temperature monitoring is performed at inlet or outlet, then system simplicity is maintained, but temperature measurement accuracy is insufficient due to pressure limitations
Solution Approach 1:
The patent introduces an intermediary probe structure that penetrates the heat exchanger wall to access the intermediate water passage, serving as a mediator between the external temperature sensor and the high-pressure internal water flow. This allows accurate temperature measurement at the target point without compromising the sealed high-pressure structure.
Solution Approach 2:
The patent transitions from monitoring temperature at boundary points (inlet/outlet) to monitoring at an internal target point within the intermediate water passage. This spatial dimensionality change enables measurement of the coldest water temperature that actually contacts the evaporator, providing superior measurement accuracy for system control.
2Reliability
If system deactivation occurs at first subfreezing temperature reading, then safety is ensured, but productivity is reduced due to premature shutdown
Solution Approach 1:
The patent implements preliminary action by providing advance notice to the user when water temperature approaches the freezing point, allowing preventive measures to be taken before actual freezing occurs. This early warning system maintains safety while avoiding unnecessary shutdowns for temporary temperature fluctuations.
Solution Approach 2:
The patent employs feedback control by continuously monitoring temperature at the target point and providing real-time feedback to the user. This enables dynamic adjustment of system operation based on actual temperature conditions, distinguishing between temporary dips and sustained freezing conditions, thereby maintaining productivity while ensuring safety.
3Measurement precision
If temperature sensor is positioned at target point in intermediate passage, then temperature monitoring accuracy is improved, but device complexity increases due to probe penetration requirements
Solution Approach 1:
The probe structure serves multiple functions: it penetrates the heat exchanger wall to access the intermediate passage, provides structural support for the temperature sensor, seals the penetration point to maintain pressure containment, and positions the sensor at the optimal target point. This multi-functionality reduces the need for separate components and simplifies the overall manufacturing process.
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
The solution effectively delays the deactivation of refrigerant compression systems by accurately monitoring water temperatures and providing timely feedback, ensuring continued operation even when temperatures briefly drop below the freezing point or for short durations.
Implementation Method 1
a temperature sensor extending into at least one intermediate water passage
Implementation Method 2
places the refrigerant in heat transfer relationship with the current of water
Data Source
AI summary
To continue operating a compression refrigerant system even while the system's brazed plate heat exchanger contains, in localized areas, water at or below its atmospheric subfreezing water temperature, a penetrating temperature probe senses the water temperature at a strategic intermediate point between the heat exchanger's water inlet and outlet. The brazed plate heat exchanger comprises a series of corrugated plates stacked and brazed together to create an alternating arrangement of water and refrigerant passages in heat transfer relationship with each other. In some examples, the idea is to take advantage of the principle that water has a lower freezing temperature at relatively high pressure and that the relatively small micro-channel passages of intermediate water passages within the brazed plate heat exchanger can withstand appreciably higher pressure than other areas within the heat exchanger, such as the areas at the heat exchanger's water inlet and water outlet.