Plate Heat Exchanger Insulating Coating for Thermal Stress Relief
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Solution Overview
Problem
Aluminum plate heat exchangers in cryogenic processes, such as air separation plants, face high thermal stresses during startup and restart due to large temperature differences, leading to material fatigue and potential damage, as the system's temperature equalization causes steep temperature gradients.
Innovation Solution
A plate heat exchanger design featuring heat-exchange passages with heat-insulating coatings on certain sections of the partitions and heat-conducting elements, reducing thermal stresses by minimizing heat transfer during startup and allowing the system to withstand more operational cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the heat exchanger operates with high heating surface density for compact design, then the compactness and heat transfer efficiency are improved, but the thermal stress during startup and restart increases due to rapid temperature changes
Solution Approach 1:
The patent applies heat-insulating coatings selectively at specific locations where thermal stress is most critical: at the inlets of heat exchange passages and on heat-conducting elements. This localized insulation reduces temperature gradients in high-stress areas without compromising overall heat transfer efficiency or compactness of the heat exchanger design.
2Area of stationary object
If the heat exchanger is designed with high heating surface density, then the heat transfer area is maximized, but the material fatigue from repeated thermal cycling during startups and restarts increases
Solution Approach 1:
Heat-insulating coatings are applied locally at inlet regions and on heat-conducting elements where temperature gradients are most severe during thermal cycling. This protects critical areas from repeated thermal stress and material fatigue while maintaining the overall high heating surface area and compact design of the heat exchanger.
3Productivity
If the heat exchanger allows rapid heat transfer for efficient operation, then the heat transfer efficiency is improved, but the temperature gradients during startup cause harmful thermal stresses
Solution Approach 1:
Heat-insulating coatings are applied selectively at inlet regions and on heat-conducting elements where temperature gradients are most severe during startup and restart. This localized insulation mitigates harmful thermal stresses in critical areas while allowing rapid heat transfer to continue efficiently in the bulk of the heat exchanger.
Solution Approach 2:
The heat-insulating coating acts as an intermediary layer between the fluid and the heat exchanger walls at critical locations. This intermediary reduces the rate of heat transfer at the inlet and on heat-conducting elements during startup, preventing excessive temperature gradients and thermal stress while allowing efficient heat transfer to resume once the system reaches operating temperature.
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 heat-insulating coatings reduce temporal and local temperature gradients, thereby minimizing thermal stresses and extending the service life of the heat exchanger by allowing it to endure a higher number of startups and restarts without damage.
Implementation Method 1
several partitions and/or several heat-conducting elements each have a coating made of a heat-insulating material
Implementation Method 2
designed to indirectly transfer the heat from a first fluid to another, second fluid
Implementation Method 3
The fluids in the plate heat exchanger are guided in separate heat exchange passages
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a plate heat exchanger (10) having a plate heat exchanger block (11), which has a plurality of partitions (4, 5) arranged parallel to one another in the form of separating plates which form a plurality of heat exchange passages (1a, 1b) for fluids which are to be brought into indirect heat exchange relationship with one another. The heat exchange passages are closed off from the outside by lateral strips (8), and each heat exchange passage (1a, 1b) has an inlet (9) for inflow of a fluid and an outlet (19) for outflow of the fluid. According to the invention, one or more partitions (4, 5) and/or one or more heat-conducting elements (2, 3) in each case have a coating (41) made of a heat-insulating material. The invention further relates to a method for producing a polymer laminate and to a method for joining prefabricated polymer components to each other.