Consider filling a gas cylinder with ethane from a high-pressure supply line. Before filling, the cylinder is empty (vacuum). The valve is then opened, exposing the tank to a 3-MPa line at 500K until the pressure of the cylinder reaches 3MPa. The valve is then closed. The volume of the cylinder is 50L. For ethane, use the truncated virial equation of state, in pressure: Z=PVm/(RT)=1+B’P with B’=-2.8 x 10^-8 m^3 /J

a. What is the temperature immediately after the valve is closed?
b. If the cylinder then sits in storage at 293K for a long time, what is the entropy change of the universe (from the original unfilled, state)?

Explain the difference laminar and turbulent flow. explain it with the shear stress and the velocity profiles.

Fluids at rest possess no flow energy. a)- true b)- false

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