Mechanical Engineering Answers

01)  An inventor claims to have developed a heat engine that receives 700Kj of heat from a source at 500K and produces 300Kj of net work while rejecting the waste heat to a sink at 290K. is this reasonable claim?

01)  Refrigerant – R134a enters an adiabatic compressor as saturated vapor at 120kPa at a rate of 0.3m³/min and exits at 1MPa pressure. If the isentropic efficiency of the compressor is 80 percent, determine

a)     The temperature of the refrigerant at the exit of the compressor

b)     The power input, in kW. Also show the process on a T- s diagram with respect to the satuaration lines.

01)  Steam enters an adiabatic turbine at 8MPa and 500⁰C with a mass flow rate 3kg/s and leaves at 30kPa. The isentropic efficiency of the turbine is 0.90. neglecting the kinetic energy of the steam, determine

a)     The temperature at the turbine exit

b)     The power output of the turbine

Air is a cylindrical is compressed reversible and isothermallay from 95 kPa , 25°C to 290 kPa. The initial volume is 0.162m³. Determine the work input, heat transfer and the entropy Change of the air being compressed

. A gas turbine plant receives air at 1 bar and 290°K and compresses it to 5 bar. If the temperature of air after compression is 1000°K; find the thermal efficiency of the turbine.

Alow car spots car has aday coefficient of 0.29 and frantalace of 1.85m and travelling at 160km/hrs. How much polar is required to Over come are adynamic resistance if g=1.23kg/m?

A piston – cylinder device contains 1.2kg of nitrogen gas at 120kPa and 27⁰C. the gas is now compressed slowly in a polytropic process during which PV^1.3 = constant. The process ends when the volume is reduced by one – half. Determine the entropy change of nitrogen during this process.

A 1.0 mm diameter wire is maintained at a temperature of 360◦C and exposed to a convection environment at 40◦C with h=120 W/m2·◦C. Calculate the thermal conductivity that will just cause an insulation thickness of 0.25 mm to produce a “critical radius.” How much of this insulation must be added to reduce the heat transfer by 26.8 percent from that which would be experienced by the bare wire?

In a quick return motion mechanism of a Crank and slotted lever type the ratio of maximum velocities is 2.if the length of stroke is 25cm find(1) the length of the slotted lever,

(2)the ratio of time of cutting and written stroke and (3) the maximum cutting velocity per second if the Crank rotates is 30 r.p.n

In a quick return motion mechanism of a Crank and slotted Lever type the ratio of maximum velocities is 2