In boiling water at 1 atm pressure outside a stainless-steel tube with a surface temperature of 410F, the heat-transfer coefficient h in the absence of radiation is 32 Btu/h*ft^2*F. If the emissivity of the stainless steel is 0.8, will radiation significantly augment the rate of boiling (e.g., by more than 5 percent)? Assume that the vapor film is transparent to radiation and the boiling liquid is opaque.

Six insulated containers hold 72 g of water at 24°C. A small copper cylinder is placed in each cup; the masses and initial temperatures of the cylinders vary as given below. Rank the containers from largest to smallest according to the maximum temperature of the water in each container after the cylinder is added. You may assume that the cylinder is completely submerged in the water. (Use only ">" or "=" symbols. Do not include any parentheses around the letters or symbols.) %3D A. m = 193 g; T = 34°C B. m = 386 g; T = 48°C C. m = 579 g; T = 47°C D. m = 386 g; T = 21ºC E. m = F. m = 193 g; T = 54°C %3D = 579 g; T = 33°C %3D

P2

A father and son conducted the following simple experiment on a hot dog which measured 12.5 cm in length and 2.2 cm in diameter. They inserted one food thermometer into the midpoint of the hot dog and another one was placed just under the skin of the hot dog. The temperatures of the thermometers were monitored until both thermometers read 20°C, which is the ambient temperature. The hot dog was then placed in 94°C boiling water and after exactly 2 min they recorded the center temperature and the skin temperature of the hot dog to be 59°C and 88°C, respectively. Assuming the following properties for the hot dog: r = 980 kg/m3 and cp = 3900 J/kg·K and using transient temperature charts, determine (a) the thermal diffusivity of the hot dog, (b) the thermal conductivity of the hot dog, and (c) the convection heat transfer coefficient.