Awall with an area of 25m² is made up of four layers. on the inside is plaster 15mm thick, then there is brick 100mm thick, then insulation 60mm thick and finally brick 100mm thick. the thermal conductivity of plaster is 0.1 w/mk the thermal conductivity of brick is 0.6w/mk the thermal conductivity of the insulations is 0.08w/mk the one side of the wall is in contact with air at 22°c and the other with air at -5°c. the surface heat transfer coefficient for both surfaces is 0.006 w/m²k. calculate the heat loss and the overall heat transfer coefficient.

Acommercial grade cubical freezer, 4 m on a side, has a composite wall consisting of an exterior sheet of 5.0-mm thick plain carbon steel (kst= 60.5 w/m k), an intermediate layer of 100-mm thick polyurethane insulation (kins 0.02 w/m k), and an inner sheet of 5.0- mm thick aluminium alloy (kal polyurethane insulation and both metallic sheets are each characterized by a thermal contact resistance of r 2.5 x 104 m2 k/w. (a) what is the steady-state cooling load that must be maintained by the refrigerator under conditions for which the outer and inner surface temperatures are 25°c and -5°c, respectively? (b) for power saving purpose, which wall material should be increased/reduced in. thickness in order to reduce 50% of the cooling load found in part (a)? redesign the thickness of the proposed material. 177 w/m-k). adhesive interfaces between the q=575.93 w