A composite wall separates combustion gases at 2600°C from a liquid coolant at 100°C, with gas- and liquid-side convection coefficients of 50 and 1000
(a) Sketch the equivalent thermal circuit corresponding to steady-state conditions. In variable form, label appropriate resistances, temperatures, and heat fluxes.
(b) Under steady-state conditions for which the chip heat dissipation is qc" = 30,000 W/m2, what is the chip temperature?
(c) The maximum allowable heat flux, qc",m, is deter- mined by the constraint that the chip temperature must not exceed 85°C. Determine qc",m for the fore- going conditions. If air is used in lieu of the dielec- tric liquid, the convection coefficient is reduced by approximately an order of magnitude. What is the value of qc",m for ho = 100 W/m2 · K? With air cool- ing, can significant improvements be realized by using an aluminum oxide circuit board and/or by using a conductive paste at the chip/board inter- face for which Rt", c = 10-5 m2 · K/W?