Optics Modules in Parallel Overall System Impedance(Resistance, DP(inH20) curve vs Q(CFM). If you have 48 of these module located at the faceplate of a system then a) what is the overall system resistance/DP curve due to the faceplate, b) and what is the operation point using 4 of the fans in parallel from problem 3)

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?

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

What is the heat treatment of metals? what is the benefit of it? why and how it's useful? answer in details, do not write by hand.