The math section of the aspire test focuses on a student's ability to:

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

Athin walled concentric tube exchanger is used to cool engine oil from 160°c to 60°c with water that is available at 25°c acting as a coolant. the oil and water flow rates are each at 2 kg/s, and the diameter of the inner tube is 0.5 m and the corresponding value of the overall heat transfer coefficient is 250 w/m2. oc. how long must the heat exchanger be to accomplish the desired cooling? cpwater=4.187 kj/kg-candcpengine el=2.035 kj/kg·°c, oil . 120]

What is the heat treatment of metals? what is the benefit of it? why and how it's useful? answer in details, do not write by hand.