A window air conditioner that consumes 1 kW of electricity when running and has a coefficient of performance of 4 is placed in the middle of a room, and is plugged in. The rate of cooling or heating this air conditioner will provide to the air in the room when running is,(a) 4 kJ/s, cooling, (b) 1 kJ/s, cooling, (c) 0.25 kJ/s, heating,(d) 1 kJ/s, heating, (e) 4 kJ/s, heating

# Category: Statistics

## A freezer is maintained at 20°F

A freezer is maintained at 20°F by removing heat from it at a rate of 75 Btu/min. The power input to the freezer is 0.70 hp, and the surrounding air is at 75°F. Determine,(a) The reversible power,, (b) The irreversibility, and, (c) The second-law efficiency of this freezer.

## A windmill with rotor diameter of 30 m takes 40%

A windmill with rotor diameter of 30 m takes 40% of the kinetic energy out as shaft work on a day with 20oC and wind speed of 30 km/h. What power is produced?

## A windmill takes a fraction of the wind kinetic

A windmill takes a fraction of the wind kinetic energy out as power on a shaft. In what manner does the temperature and wind velocity influence the power? Hint: write the power as mass flow rate times specific work.

## A wind turbine is rotating at 15 rpm

A wind turbine is rotating at 15 rpm under steady winds flowing through the turbine at a rate of 42,000 kg/s. The tip velocity of the turbine blade is measured to be 250 km/h. If 180 kW power is produced by the turbine, determine, (a) The average velocity of the air and, (b) The conversion efficiency of the turbine. Take the density of air to be 1.31 kg/m3.

## A 90 wt% Ag-10 wt% Cu alloy is heated to

A 90 wt% Ag-10 wt% Cu alloy is heated to a temperature within the b + liquid phase region. If the composition of the liquid phase is 85 wt% Ag, determine:,(a) The temperature of the alloy,(b) The composition of the b phase,(c) The mass fractions of both phases

## A water-heater is covered up with insulation

A water-heater is covered up with insulation boards over a total surface area of 3 m2. The inside board surface is at 75°C and the outside surface is at 20°C and the board material has a conductivity of 0.08 W/m K. How thick a board should it be to limit the heat transfer loss to 200 W?

## A 50 wt% Pb-50 wt% Mg alloy is slowly cooled

A 50 wt% Pb-50 wt% Mg alloy is slowly cooled from 700(C (1290(F) to 400(C (750(F).,(a) At what temperature does the first solid phase form?,(b) What is the composition of this solid phase?,(c) At what temperature does the liquid solidify?,(d) What is the composition of this last remaining liquid phase?

## A four-stroke turbocharged V-16

A four-stroke turbocharged V-16 diesel engine built by GE Transportation Systems to power fast trains produces 3500 hp at 1200 rpm. Determine the amount of power produced per cylinder per, (a) Mechanical cycle and, (b) Thermodynamic cycle.