2) poorly treated municipal wastewater is discharged to a stream. the river flow rate upstream of the discharge point is qu/s = 8.7 m3/s. the discharge occurs at a flow of qd = 0.9 m3/s and has a bod concentration of 50.0 mg/l. assuming that the upstream bod concentration is negligible. (a) what is the bod concentration just downstream of the discharge point? (b) if the stream has a cross-sectional area of 10 m2, what would the bod concentration be 50 km downstream? (bod is removed with a first¬-order decay rate constant equal to 0.20/day.)

Apiston-cylinder with a volume of 0.25 m3 holds 1 kg of air (r 0.287 k/kgk) at a temperature of 100 c. heat transfer to the cylinder causes an isothermal expansion of the piston until the volume triples. how much heat is added to the piston-cylinder?

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?

Give heat transfer applications for the following, (i) gas turbines (propulsion) ) gas turbines (power generation). (iii) steam turbines. (iv) combined heat and power (chp). (v) automotive engines