Pulsating flow optimization of triangular spiral microchannel heat sink: Entropy, exergy and thermo-economic analysis

In this paper, an isosceles triangular spiral microchannel heat sink is studied. Transient numerical simulations systematically investigate the effects of five sinusoidal velocity pulse frequencies and amplitudes on thermal-hydraulic characteristics, with a multi-dimensional evaluation system. Pulsed flow periodically disrupts flow and thermal boundary layers, enhancing near-wall heat transfer. Instantaneous inlet velocity, total pressure drop, average chip temperature, and average coolant temperature all exhibit sinusoidal variations with phase differences. Total entropy generation ranges from 0.02044 to 0.02095 W/K, highest at high amplitude and lowest at low amplitude (relative difference 2.49%). Heat transfer entropy generation accounts for 99.97% of system irreversibility, while friction contribution is negligible. Exergy efficiency remains between 92.13% and 92.32%, indicating excellent energy utilization quality. The thermal economic factor (TEF) ranges from 42,271 to 45,590; medium-amplitude conditions differ by less than 0.23%, achieving performance–economy balance. Annual operating cost is 8.99–9.70 yuan, with a maximum relative difference of 7.92% across conditions. Medium pulse parameters achieve optimal synergy for high-heat-flux dissipation. The findings provide references for designing energy-efficient pulsed-flow thermal management systems for high-heat-flux chips.