An electronic instrument is cooled by air blown through the case. air is supplied at 20? c and is exhausted at 70? c. pressure remains essentially atmospheric (101.3 kpa) find: a. the change in internal energy (per kg) of air as it flows through b. the change in specific volume (%) c. the amount of heat the air picks up, per kgair

Awall of 0.5m thickness is to be constructed from a material which has average thermal conductivity of 1.4 w/mk. the wall is to be insulated with a material having an average thermal conductivity of 0.35 w/mk so that heat loss per square meter shall not exceed 1450 w. assume inner wall surface temperature of 1200°c and outer surface temperature of the insulation to be 15°c. calculate the thickness of insulation required.