Chapter 5, Problem 5.69P

During a plant visit, it was noticed that a 12-m-long section of a 10-cm-diameter steam pipe is completely exposed to the ambient air. The temperature measurements indicate that the average temperature of the outer surface of the steam pipe is 75°C when the ambient temperature is 5°C. There are also light winds in the area at 10 km/h. The emissivity of the outer surface of the pipe is 0.8, and the average temperature of the surfaces surrounding the pipe, including the sky, is estimated to be 0°C. Determine the amount of heat lost from the steam during a 10-h-long work day. Steam is supplied by a gas-fired steam generator that has an efficiency of 80 percent, and the plant pays $1.05/therm of natural gas. If the pipe is insulated and 90 percent of the heat loss is saved, determine the amount of money this facility will save a year as a result of insulating the steam pipes. Assume the plant operates every day of the year for 10 h. State your assumptions.

An old fashioned ice cream kit consists of two concentric cylinders of radii Ra and Rb. The inner cylinder is filled with milk and ice cream ingredients while the space between the two cylinders is filled with an ice-brine mixture. Ice cream begins to form on the inner surface of the inner cylinder. To expedite the process, would you recommend rotating the inner cylinder? Justify your recommendation. icecream/ ice-brine Ra Rb

Find temperatures STRICTLY USING RITZ APPROXIMATION METHOD