The effect of channel height on flow boiling heat transfer and chf in flat minichannels with local heating

Clarifying the heat-transfer characteristics with local heating is important for some applications such as microelectron-ics cooling. This paper presents experimental data on heat transfer and critical heat flux (CHF) for water subcooled (T-sub = 75 K) flow boiling in flat minichannels with height of 0.2-3 mm and width of 30 mm under intense local heating (power of up to 1 kW from a heater with an area of 1 cm(2)) in a wide range of mass flux (10-340 kg/m(2)s). The growth dynamics of vapor bubbles was studied using high-speed visualization. The obtained data on the critical heat flux are compared with the data known from the literature for micro-and minichannels. The results obtained show that the intensity of heat transfer and the critical heat flux substantially decrease with decreasing channel height. A simple power-law correlation is proposed for estimating the critical heat flux in channels with local heating.