A man comes home on a summer day and finds that his house is at 35oC. He turns on the air conditioner. In 30 minutes the entire house is at 22oC. If the COP of the air conditioner is 2.8, calculate the powerthat must be supplied to it. Assume the house is sealed and contains 900 kg of air. Assume the air is an ideal gas with Cv* = 0.72 kJ/kgK.
A car engine consumes gasoline at a rate of 22 L/h and delivers 55 kW of power. Determine the efficiency of the engine assuming the gasoline has a heating value of 44,000 kJ/kg and a density of 0.8 g/cm3.
A power plant using an ideal Rankine power generation cycle operates at an evaporator pressure of 10 MPa with an outlet temperature of 900°C in the evaporator. The condenser operates at a pressure of 100 kPa and produces saturated liquid water. Determine the following:
a) The work produced by the turbine.
b) The heat given off by the condenser.
c) The work required by the pump.
d) The heat used by the boiler.
e) The overall efficiency of the cycle.
An automobile air conditioner uses a vapor-compression refrigeration cycle with the environmentally friendly refrigerant HFC-134a as the working fluid. Saturated liquid enters the expansion valve at 30°C and saturated vapor at -10°C enters the compressor. Determine the coefficient of performance for the refrigeration cycle.
In normal operation, a paper mill generates excess steam at 20 bar and 400°C. It is planned to use this steam as the feed to a turbine to generate electricity for the mill. There are 5,000 kg/hr of steam available, and it is planned that the exit pressure of the steam will be 2 bar.
Assuming the turbine is well insulated, what is the maximum power that can be generated by the turbine?
A real turbine operating under similar conditions to part (a) has an efficiency of 80%. Determine the amount of work performed by this turbine and the outlet temperature.