How do you calculate the rate of heat transfer between two bodies with a small area of physical contact.

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

Figure out the odd statement about ceramics in the following (a) good insulators of heat and electricity (b) usually less desire than metals (c) ductile in nature (d) contains both metallic and nonmetallic elements

Aspeed reducer has 20 full-depth teeth and consists of a 20-tooth steel spur pinion driving a 50-tooth cast-iron gear. the horsepower transmitted is 12 at a pinion speed of 1200 rev/min for a diametral pitch of 8 teeth/in and a face width of 1.5 in, find the contact stress