Question

Please show all work leading towards the solutions and have the solutions in the correct units.

4. To enhance heat transfer from a silicon chip of width W 4 mm on a side, a copper fin is brazed to the surface of the chip. The pin length and diameter are L = 20 mm and D 4 mm, respectively, and atmospheric air at V- 10 m/s and To 300 K is in cross flow over the pin. The surface of the chip, and hence the base of the pin, are maintained at a temperature of Tb - 400K. Assume there is no contact resistance. Assuming the chip to have a negligible effect on flow over the pin, what is the average convection coefficient for the surface of the pin? (2 pts) For this, you need to calculate Nu first. Nu can be expressed as Nu - CRemPr' where n - 1/3 for cylinders, and C and m are empirical values from Table 7.2. Find appropriate values for the thermal conductivity of copper k, and air properties needed using Table A.1. and Table A.4. and list them at the beginning of the solution. (2 pts) TABLE 7.2 Constants of Equatin 7.52 for Air the cireular cylinder in cross flow [, 12] Rep 0.989 0.911 0.683 0.193 0.027 0.330 0.385 0.466 0.618 0.805 04-4 4-40 40-4000 4000-40,000 40,000-400,000 ть

Answer 1