A cold storage room has walls made of 220 mm of brick on the outside, 90mm of plastic foam, and finally 16mm of wood on the inside. The outside and inside air temperatures are 25ºC and -3ºC. If the inside and outside heat transfer coefficients are 30 and 11 W/m2 ºC respectively, and thermal conductivities of brick, foam and wood are 0.99,0.022 and 0.17 W/mºC respectively. Determine i) The rate of heat removal by refrigeration if the total wall area is 85 m2 ii) The temperature of the inside surface of the brick

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

Two technicians are discussing the intake air temperature (iat) sensor. technician a says that the computer uses the iat sensor as a backup to the engine coolant temperature (ect) sensor. technician b says that the powertrain control module (pcm) will subtract the calculated amount of fuel if the air measures hot. who is correct

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