When a man returns to his well-sealed house on a summer day, he finds that the house is at 32°C. He turns on the air conditioner, which cools the entire house to 20°C in 15 min. If COP of the air conditioner system is 2.5, determine the power drawn by the air conditioners. Assume the entire mass within the house is equivalent to 800 kg of air for which c = 0.72 kJ/kg – °C

A double-notched specimen with dimensions of h = 10cm, w = 3cm, and a thickness of t = 2mm is subjected to a load of P = 32kN. The material has a Young’s modulus of 180 GPa and Poisson’s ratio of v = 0.42

1. a) Determine the energy release rate for a crack length of a = 4mm

2. b) Does this satisfy the conditions for plane strain? Is the assumption of LEFM valid?

   [4 Marks]

3. c) Determine the minimum dimensions and crack length to satisfy the conditions of both plane

strain and LEFM.

We are drilling a hole at a depth of 4,000 ft with an 8 ½ in bit and a mud weight of 15 ppg, where the formation is abnormally pressurised. Formation pressure is 2400 psi, therefore a casing should be run at 4,500 ft to seal off this formation. There are Grade C-75 and N-80 casings available, C-75 Grade is 20.00 lb/ft (ID=6.456”, OD=7”) and N-80 is 17.00 lb/ft (ID= 6.538”, OD=7”). Analyse if both, neither or one of the casing Grades can withstand the formation pressure and will not collapse at the reported conditions. Use the API formulas and tables

An ideal Otto cycle with Argon as the working fluid has a compression ratio of 6.8. The minimum and maximum temperatures in the cycle are 450 R and 2,260 R. Assuming constant specific heats, determine

(a) the amount of heat transferred to the argon during the heat-addition process

(b) the thermal efficiency

(c) the thermal efficiency of a Carnot cycle operating between the same temperature limits