Intermediate seals (internal channel partition seals, different from peripheral edge seals) are placed inside a single‑layer flow channel among fins and formed via vacuum brazing. They serve four core functions: flow channel partitioning, structural pressure‑bearing capacity, brazing‑process optimization, and fluid flow equalization.
I. Fluid Partitioning: Prevent Cross‑Channel Internal Leakage (Core Sealing Function)
- Where multiple independent fluid passages are required between a pair of separator plates (e.g., hot‑cold dual channels of battery chillers, multi‑loop liquid cold plates), intermediate seals physically separate left‑right or front‑rear flow passages to fully isolate different media and avoid cross‑mixing and internal leakage.
- After vacuum brazing, the top and bottom faces of intermediate seals fuse with clad separator plates to form continuous sealing welds, eliminating inter‑layer internal fluid bypass. They constitute the critical structure for multi‑circuit radiators against internal leakage.
II. Structural Reinforcement & Pressure‑Resistant Deformation Resistance (Mandatory for High‑Pressure Radiators)
- Fins are thin and have low pressure resistance. Acting as rigid support pillars, intermediate seals prop against two adjacent separator plates, greatly boosting the overall core pressure resistance for high‑pressure liquid‑cooling conditions of new‑energy vehicles and energy‑storage systems.
- They disperse local stress induced by high channel pressure to prevent separator plate bulging and weld tearing. One or two intermediate seals are mandatory for high‑pressure radiators to reduce leakage failure rates during post‑brazing pressure testing.
- During pre‑brazing stacking and fixturing, intermediate seals position and lock fins, preventing fin shifting and collapse during handling and high‑temperature furnace cycles, and improving stacking accuracy.
III. Vacuum Brazing Process Optimization: Reduce Cold Joints and Erosion Defects
- Seals feature a slight side taper (3‰), creating capillary gaps after stacking. Under vacuum heating, the cladding braze alloy on separator plates fully wets seal end faces, producing full welds free of cold joints and material shortage.
- By partitioning oversized flow channels, intermediate seals mitigate uneven heat and localized over‑burning erosion over large fin zones. They block massive braze‑material migration and prevent insufficient welding at fin roots.
- During high‑temperature brazing, they conduct heat evenly to homogenize the internal temperature field of the core, lowering welding defects caused by local temperature differences and improving first‑pass brazing yield.
IV. Fluid Guidance & Flow Equalization: Improve Heat‑Dissipation Performance
- In elongated flow channels, intermediate seals divide one large water gallery into multiple narrow passages, forcing even coolant distribution. This suppresses wall‑hugging biased flow and low‑velocity central zones, raising overall heat‑exchange efficiency.
- Working with diversion fins, intermediate seals redirect fluid flow, eliminate vortex dead zones at channel ends, minimize local hot spots, and equalize surface temperature across the radiator.
V. Key Differences: Peripheral Seals vs Intermediate Seals
- Peripheral seals: Installed along the four edges of each flow layer, mainly preventing outward fluid leakage (external‑leakage protection).
- Intermediate seals: Installed inside flow channels, focusing on multi‑medium separation against internal leakage, internal structural pressure bearing and flow equalization. They are core reinforcing‑sealing components for multi‑circuit and high‑pressure plate‑fin radiators.
VI. Summary of Engineering Application Scenarios
- Battery chiller (hot‑cold dual‑channel): Intermediate seals separate water passages from refrigerant passages to stop refrigerant ingress into the water circuit.
- High‑power energy‑storage liquid cold plates & IGBT cooling cores: Intermediate seals resist pressure and suppress bulging to meet water‑pressure / oil‑pressure withstand test requirements.
- Large aspect‑ratio air‑cooled radiators: Intermediate seals secure fins and equalize flow, lowering fin‑collapse failure rates during vacuum brazing.
