Local thermal measurements of a confined array of impinging liquid jets for power electronics cooling

The local surface temperature, heat flux, heat transfer coefficient, and Nusselt number were measured for an inline array of circular normal jets of single phase liquid water impinging on a copper block. An experimental 2-D surface map was obtained by translating the jet array relative to the sensors. The effects of variation in jet height, nozzle length, and Reynolds number were investigated. The local maximum heat transfer coefficients were observed within the stagnation region for all configurations with secondary peaks occurring halfway between the jets. The maximum local heat transfer coefficient of 15,600W=m
²
K and local Nusselt number of 80.5 were observed for H/D
_n
= 1, L
_n
/D
_n
= 2, and ReD
_n
= 14,000; while the maximum surface average heat transfer coefficient of 13,700W=m
²
K and average Nusselt number of 71.0 were observed for H/D
_n
= 3, L
_n
/D
_n
= 0, and ReD
_n
= 14,000.