Meaning
Transient pressure wave generated in the cooling circuit by rapid pump acceleration or valve actuation creates mechanical stress on the cooling plate channels. This hydraulic impulse pressure can exceed the nominal operating pressure of the thermal management system by several times. It is a critical factor in evaluating the burst strength of cooling plates.
Joint Integrity
High-pressure spikes can deform the thin walls of aluminum channels and breach the brazed joints. These breaches cause coolant leaks that can short-circuit the high-voltage battery modules. Ensuring the channels can withstand these pulses is the main challenge in coolant plate design.
Fatigue Effect
Repetitive pressure pulses act as cyclic mechanical loads that degrade the strength of the cold plate over time. Each start-stop cycle of the coolant pump adds to the fatigue accumulator of the brazed joints. This fatigue effect can lead to pinhole leaks after thousands of thermal cycles.
Protection Method
Flow control valves with slow actuation times prevent the sudden stoppage of fluid that causes pressure waves. Accumulators or flexible hose sections can also absorb the shock of the moving fluid by expanding temporarily. Designers use these damping methods to limit the peak pressure spikes to safe levels during pump operation, ensuring that the cooling plates do not deform or leak even when the thermal management system operates at maximum flow rate.
