Forced air at 25c and 10m/s is used to cool chips on a circuit board. consider a chip, 4mm x 4mm, located 120mm from the leading edge of the board. an empirical correlation has been established for the local nusselt number: 3185.0xxprre04.0nu= estimate the surface temperature of the chip if it is dissipating 30mw. (thermophysical properties of air at 25c are needed to solve this problem. state your reference source for this information.)

What precautions should you take to prevent injuries when dealing with heavy loads?

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?

The drive force for diffusion is 7 fick's first law can be used to solve the non-steady state diffusion. a)-true b)-false