A midnight dumper discharges a truck load of industrial waste in a gravel pit. Three days after the truck is spotted, a sample of the remaining pool of pure waste is collected and is sent to laboratory for forensic analyses. Test results indicate that sample has a BOD5 of 80 mg/L O2 with a rate constant of 0.1/day. Three nearby factories generate organic wastes: a winery (ultimate BOD = 275 mg/L O2), a vinegar manufacturer (ultimate BOD = 80 mg/L O2) and a pharmaceutical company (ultimate BOD = 200 mg/L O2).

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

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?

For the closed feedwater heater below, feedwater enters state 3 at a pressure of 2000 psia and temperature of 420 °f at a rate of ix10 ibhr. the feedwat extracted steam enters state 1 at a pressure of 1000 psia and enthalpy of 1500 btu/lbm. the extracted er leaves at an enthalpy of 528.7 btu/lbm steam leaves as a saturated liquid. (16) a) determine the mass flow rate of the extraction steam used to heat the feedwater (10) b) determine the terminal temperature difference of the closed feedwater heater