The wastewater treatment plant for pine city discharges 1 × 105 m3 /day of treated waste to the pine river.
immediately upstream of the treatment plant, the pine river has an ultimate cbod of 2 mg/l and a flow of 9 × 105 m3 /day.
at a distance of 20 km downstream of the treatment plant, the pine river has an ultimate cbod of 10 mg/l.
the state’s department of environmental quality (deq) has set an ultimate cbod discharge limit for the treatment plant of 2,000 kg/day. the river has a velocity of 20 km/day. the cbod decay coefficient is 0.1/day.

is the plant in violation of the deq discharge limit?

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?

An air compression refrigeration system is to have an air pressure of 100 psia in the brine tank and an allowable air temperature increase of 60°f for standard vapor compression cycle temperatures of 77 f entering the expansion cylinder and 14 f entering the compression cylinder, calculate the coefficient of performance a. 2.5 b 3.3 c. 4.0 d. 5.0

How much power could a wind turbine produce if it had the following specifications? cp = 0.45 -d=1.2kg/m3 d=50m v 5m/s