A 100 m x 25 m detention pond is proposed for a 7.5-ha site. The detention pond is 2.0 m deep under control (pre-storm) conditions and the water-quality depth is 2.0 cm. Storage in the detention pond is to be discharged offsite via a triangular weir whose vertex is at the control elevation, and the flow rate over the weir, Q [m3/s], is given by: 5/2 Q H  0.08 where H is the height of the water surface above the vertex of the weir [m]. The average annual rainfall at the site is 120 cm, and the average runoff coefficient is 0.75. Determine the evacuation time and the average detention time in the pond.

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

Steel is coated with a thin layer of ceramic to protect against corrosion. what do you expect to happen to the coating when the temperature of the steel is increased significantly? explain.

During a steady flow process, the change of energy with respect to time is zero. a)- true b)- false