3. in a very hot and dry workplace outside air can be drawn in through water spray, and the air is cooled by the heat removed to evaporate the water (evaporative cooling). the data taken before and after installation of such an evaporative cooling system are given below: before installation after installation td (0c) 32.8 29.4 tg (0c) 46.1 35.0 twb (0c) 24.2 24.4 calculate the wet bulb globe temperature before and after installation of the system. also explain why dry bulb temperature (td) and globe temperature (tg) decrease while wet bulb temperature (twb) remains almost unchanged.

If the thermal strain developed in polyimide film during deposition is given as 0.0044. assume room temperature is kept at 17.3 c, and thermal coefficient of expansion for the film and the substrate are 54 x 10^-6c^-1 and 3.3 x 10^-6c^-1respectively. calculate the deposition temperature.

An electrical motor raises a 50kg load at a construct velencity .calculate the power of the motor, if it takes 40sec to raise the load through a height of 24m(take g =9.8n/g)

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?