Facade fires in tall buildings are currently occurring more than once a month globally that are responsible for many casualties and billions of dollars in losses. In particular, the tragic Grenfell Tower fire in London caused more than 70 fatalities raised the profile of facade fire hazard. This work used well-controlled irradiation up to 60 kW/m 2 to re-assess the fire hazard of typical flame-retardant aluminum composite panels (ACPs). We found that the vertically oriented ACPs with the "noncombustible" (A2-grade) and "limited-combustible" (B-grade) cores could still be ignited above 35 kW/m 2 and 25 kW/m 2 , after the front aluminum layer peeled off. The peak heat release rate of these ACPs could be higher than common materials like timber and PVC. Moreover, compared to the B-core panel, the A2-core panel showed a greater fire hazard in terms of a shorter ignition delay time, a higher possibility of the core peel-off, and a longer flaming duration. It is because the ACP is a complex system, and its fire hazard is not simply controlled by the core material. The structure failure of ACP in fire, including peel-off, bending, softening and cracking, could further increase the fire hazard. This research improves our understanding of the systematic fire behaviors of facade panels and helps rethink the fire risk and test methods of the building facade.
Thermal and hydraulic performances of various geometric shapes of a microchannel heat sink were evaluated numerically using Navier–Stokes equations. A heat sink comprised of a [Formula: see text][Formula: see text]cm2 silicon wafer was investigated with water as the cooling fluid. The performances of seven microchannel shapes were compared at the same microchannel hydraulic diameter and the same average height of the bottom silicon substrate. The thermal resistance, friction coefficient, and Nusselt number were calculated for a Reynolds number range of 50 to 500. The results show that an inverse trapezoidal shape gives the lowest thermal resistance for a Reynolds number up to 300. The values of [Formula: see text]Re are almost similar for all the shapes because of the constant hydraulic diameter.
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