A thick-walled, stainless steel (AISI 316) pipe of inside and outside diameters 25 mm and 40 mm is heated electrically to provide a uniform heat generation rate of 0.8 × 106 W/m3. The outer surface of the pipe is insulated, while water flows through the pipe at a rate of 0.1 kg/s. Evaluate the properties of the stainless steel (AISI 316) at 400 K. Assume the tube surface is smooth and use the Gnielinski correlation for the Nusselt number. (a) If the water inlet temperature is 20°C and the desired outlet temperature is 40°C, what is the required pipe length, in m?

Determine the time of the day and month of the year at which the peak sensible cooling load occurs for a top floor, north-eastern corner room of an office building in durban for the following conditions: floor area: 8 x 8 x 3 m east and north walls: 115 mm face brick (outside), 20 mm air space, 115 mm ordinary brick (inside) with 15 mm plaster roof construction: suspended plasterboard ceiling, 450 mm air space, 150 mm concrete, 75mm screed, waterproofing no heat transfer across other surfaces window area 3x 1,5 m high in north wall only. ordinary glass with venetian blinds. lights and occupants : from 07: 00 to 18: 00 average light density: 25 w/m2 number of occupants : 5 seated, light office work room temperature 24°c