Mechanical Engineering Answers

A chemical laboratory uses an air refrigeration cycle system operating between pressures of 4 bar and 16 bar. The air temperature after heat rejection to surrounding is 37oC and air temperature at exit of refrigerated lab is 7oC. The isentropic efficiencies of turbine and compressor are 0.85 and 0.8 respectively. Determine compressor and turbine work per TR; C.O.P; and power per TR. Take

Assume a large primary system that consist of a vessel containing warm water in the system with a temperature of 350,001k. An infinitesimal amount of its heat of 1050j is transferred to a secondary system consisting of a room air at a temperature of 350k. Consequently the water temperature drops to 349,999k. What is the entropy generation: A) If the system is cooled in air. B) If the heat removed from the primary system is used to run a cannot engine process and that rejected by the engine is transferred to the secondary system.

A restaurant food storage air conditioning working on air refrigeration cycle of 10 tonnes capacity works between 4 bar and 16 bar. The air leaves the cold chamber at 0oC and discharges air at 25oC to the expansion cylinder after air cooler. The expansion and compression cylinders are double acting. The mechanical efficiency of compressor and expander are 85% and 80% respectively. The compressor speed is 250 r.p.m and has a stroke of 250mm Determine: 1. C.O.P 2. Power required 3. Bore of compression and expansion cylinder (Assume isentropic compression and expansion as polytropic with n = 1.25)

An aircraft air conditioner works between the pressure limits of 1 bar and 5 bar. The temperature of the air entering the compressor from the cabin and expansion cylinder are 10oc and 25oC respectively. The expansion and compression follow the pv1.3=constant. Find the following: 1. The theoretical C.O.P of the refrigeration cycle: 2. If the load on the system assuming the actual C.O.P is 50% of the theoretical C.O.P 3. The stroke length and the piston diameter of single acting compressor running at 300 r.p.m and the volumetric efficiency is 85%. (Take L/d = 1.5 : cp = 1.005 kJ/kgK ; cv = 0.71 kJ/kgK )

A house initially at a temperature 310k during a hot summer day must be cooled to a temperature 294k while the ambient temperature is 310k. Obtain an expression for the minimum workdone required and determine the minimum work also required to cool a room containing the total area of 200 meter square with equivalent mass of 50 kilogram meter square of the living room.

A house initially at a temperature 310k during a hot summer day must be cooled to a temperature 294k while the ambient

temperature is 310k. Obtain an expression for the minimum workdone required and determine the minimum work also

required to cool a room containing the total area of 200 meter square with equivalent mass of 50 kilogram meter square of the

living room.

A house initially at a temperature 310k during a hot summer day must be cooled to a temperature 294k while the ambient temperature is 310k. Obtain an expression for the minimum workdone required and determine the minimum work also required to cool a room containing the total area of 200 meter square with equivalent mass of 50 kilogram meter square of the living room.

(A) Explain the main properties of turbulent pipe flow and how they are different from or similar to laminar pipe flow


(B) Briefly explain the Newton's laws and conservation of momentum.


(C) Define the term angular momentum equation.

(A) Oil flows in a pipe 100 mm bore diameter with a Reynolds number of 500. The density is 800 kg/m3. calculate the velocity of a streamline at a radius of 40 mm. the viscosity = 0.08 Ns/m2.


(B) Identify and discuss the features of external flow?

Predict the number of loading cycles to failure for cortical bone loaded to 2500 us in compression. Explain how bone remodeling can affect fatigue life