You are on a team working on designing a heat-exchanger that involves oil flow in two pipes with diameters da and db. if the mass flowrate of oil is the same in the two pipes, calculate the ratio of velocities in the pipes (va/vb) as a function of da and db.

An air compression refrigeration system is to have an air pressure of 100 psia in the brine tank and an allowable air temperature increase of 60°f for standard vapor compression cycle temperatures of 77 f entering the expansion cylinder and 14 f entering the compression cylinder, calculate the coefficient of performance a. 2.5 b 3.3 c. 4.0 d. 5.0