O-1

A 4,530-sq ft heating surface counterflow economizer is used in conjunction with a 150,000-lb per hr boiler. The inlet and outlet water temperatures are 210 and 310 F. The inlet and outlet gas temperatures are 640 and 375 F. Find the over-all heat transfer coefficient in Btu per hr per sq ft per F.

O-2

A surface feed-water heater is to be designed to heat 500,000 lb of water per hr from 200 to 390 F; the heater is to be straight condensing with no desuperheat or subcooling zones. Saturated steam at 400 F is to be used as the heating medium; drains leave as saturated liquid at 400 F. The tubes are 7/8 in. outside diameter with 1/16-in. walls. The heater is to have two water passes and it has been estimated that the over-all coefficient of heat transfer is 700 Btu/(hr)( F)(sq ft) of outside tube surface. Specify the number and length of the tubes.

O-3

A company is heating a gas by passing it through a pipe with steam condensing on the outside. It is proposed to triple the capacity of the heater by changing its length while maintaining the same terminal conditions as regards temperature. What percentage change in length is necessary?

O-4

A properly designed steam-heated tubular preheater is heating 45,000 lb per hr of air from 70 to 170 F when using steam at 5 psig. It is proposed to double the rate of air flow through the heater and yet heat the air from 70 to...