Brazed Plate Heat Exchanger Grooves for Integrated Temperature Probes
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Solution Overview
Problem
Brazed plate heat exchangers pose challenges in local temperature and heat flow measurements due to their compactness and monolithic construction, limiting the ability to detect operational issues like fluid distribution problems or phase changes, and existing measurement solutions are intrusive, costly, and complex.
Innovation Solution
A method of manufacturing brazed plate heat exchangers with integrated temperature probes by forming grooves in the plates, using removable wedges to allow probe insertion without disrupting the brazing process, and filling the space around the probe with a low-melting-point material to minimize thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If brazed plate heat exchangers are manufactured with compact monolithic construction, then heat exchange efficiency and pressure loss are improved, but local temperature and heat flow measurements become difficult
Solution Approach 1:
The plate is divided into multiple layers: first and second flat products that are brazed together, with grooves formed in at least one of them. This segmentation allows integration of measurement probes while preserving the compact heat exchange structure.
Solution Approach 2:
Temperature probes are nested within grooves formed in the plate structure. The probes are inserted into grooves in the first or second flat product, allowing local temperature measurement without disrupting the overall compact monolithic construction of the heat exchanger.
2Measurement precision
If temperature probes are inserted into tubes brazed between plates, then local temperature measurement is enabled, but thermal resistance increases and measurement accuracy decreases
Solution Approach 1:
The intermediate tube structure is completely removed. Instead of inserting probes into tubes brazed between plates, the invention forms direct grooves in the flat products themselves, eliminating the thermal resistance introduced by intermediate tubes while enabling direct probe contact with the plate for accurate measurement.
3Measurement precision
If probes are inserted between exchanger passages to measure heat flow, then heat flow measurement is possible, but the exchanger can no longer be brazed as a single piece and assembly complexity increases
Solution Approach 1:
Grooves for probe insertion are formed in the flat products before the brazing process. The first and second flat products are stacked with probes positioned in their respective grooves, then brazed together as a single integrated operation. This preliminary preparation of grooves allows the exchanger to be brazed as one piece while incorporating measurement capabilities.
4Measurement precision
If existing temperature measurement methods are implemented in brazed plate exchangers, then temperature measurement is possible, but the methods are intrusive and modify fluid flows within exchange passages
Solution Approach 1:
Measurement grooves are formed locally in specific regions of the flat products where temperature measurement is needed, rather than implementing global measurement systems. This allows localized temperature monitoring without intrusive elements that would disrupt fluid flow in other passages, maintaining the non-intrusive characteristic of the brazed plate structure.
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 precise, non-intrusive local temperature and heat flow measurements within the exchanger, improving operational control and reducing thermal resistance, thus enhancing measurement accuracy and maintaining the exchanger's compactness and performance.
Implementation Method 1
filling the space around the probe with a low-melting-point material to minimize thermal resistance
Implementation Method 2
bonded together by brazing in a vacuum furnace at temperatures which can be between 550 and 900 °C
Implementation Method 3
a second material having a melting temperature of less than or equal to 500°C, preferably less than or equal to 200°C, more preferably less than or equal to 100°C
Data Source
Figure 1
Figure 2(a)~3(c)
Figure 4(a)~4(c)
AI summary
The invention relates to a method for manufacturing a heat exchanger (1) of the brazed plate and fin type comprising the following steps: a) stacking with spacing a set of plates (2) parallel to each other and in a longitudinal direction (z) so as to define between said plates (2) a plurality of passages (3) adapted for the flow along the longitudinal direction (z) of a first fluid to be connected for heat exchange with at least a second fluid, said plates (2) being delimited by a pair of longitudinal edges (4a) extending along the longitudinal direction (z) and a pair of lateral edges (4b) extending along a lateral direction (x) perpendicular to the longitudinal direction (z), b) forming at least one of the plates (2) stacked in step a) by superimposing, along a stacking direction (y) perpendicular to the longitudinal (z) and lateral (x) directions,at least one first flat product (21) and a second flat product (22) stacked one on top of the other, at least one of the first and second flat products (21, 22) comprising at least one groove (12) extending parallel to the plates (2) and opening outwards from the stack through at least one opening (5) in a lateral or longitudinal edge (4a, 4b), c) arrange at least one removable wedge (11) in the groove (12), d) braze the assembly of plates (2), including the first flat product (21) onto the second flat product (22), e) remove the removable wedge (11) from the groove (12) through the opening (5), f) insert at least one temperature probe (14) into the groove (12).