Question

Problem 5.2 a) You are responsible for roasting a pig at a picnic. The pig is roughly cylindrical and about 20 cm in diameter, 35 cm long It is roasted over a propane flame whose properties are similar to those of air at 250 C. Assume that the pig is cooked when it reaches 125 oC· The initial pig temperature is 10 c. If the pig is to be served at 6:00 PM, at what time should you commence cooking, a) Assume that the heat transfer coefficient is large. b) Assume that the heat transfer coefficient is h= 20 W/m-K c) Most cook books suggest that rolled roast be cooked 30 minutes per lb in an oven at 300 F. Discuss the applicability of such a general cooking rule.

The properties of air @250 C are: rho=0.6746kg/m^3, c=1033 J/kg K, k=0.04104 W/m K and alpha=5.89e-5 m^2/s

Answer 1

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