Problem 1:
Two kilogram of air initially at 5 bar and 350 K and four kilogram of carbon monoxide initially at 2 bar and 450 K are confined on opposite sides of a rigid, well-insulated container by a partition. The partition is free to move inside the container and allows energy transfer from one gas to the other, without any energy storage in the partition, until equilibrium is attained. Consider constant specific heats for both gases.
(a) Calculate the final temperature (K) at equilibrium.
(b) Determine the final pressure (bar) at equilibrium.
(c) What is the volume (m3) occupied by air and carbon monoxide at equilibrium?
Problem 2:
A reciprocating compressor initially contains air in a piston-cylinder device at 0.95 bar and 67?C occupying 0.1 m3 (State 1). Air is compressed in a polytropic process with PV1.3 = constant until the final volume is 0.02 m3 (State 2). Consider variable specific heats for air.
(a) Calculate the heat transfer (kJ) during the compression process.
(b) Show the process on P-V diagram. Label states and show property values.
Problem 3:
A hair dryer can be considered as a duct with a few layers of electric resistors placed in it and a fan forcing air through the resistors so that the air is heated. Consider air entering a 1200 W hair dryer at 1 bar and 22?C (State 1) and leaving at 47?C (State 2). The cross- sectional area of the hair dryer at the exit is 60 cm2.
(a) Calculate volumetric flow rate (m3/s) of air at the inlet of the hair dryer.
(b) What is the velocity (m/s) of air at the exit of the hair dryer?
Problem 4:
Liquid water at 25?C flows through a constant diameter pipe from a reservoir at an altitude of 2000 m (State 1) to another reservoir at an altitude of 1000 m (State 2). Consider that the pipe is perfectly insulated and that the atmospheric pressure at both reservoirs is the same.
Calculate the temperature (?C) of liquid water at the exit of the pipe.
Problem 5:
Two streams of R-134a flow into a non-insulated diffuser. Stream 1 enters at a pressure of 2 bar and 20?C (State 1) with a velocity of 200 m/s through an area of 0.1 m2 while stream 2 enters as saturated vapor at 2 bar (State 2) with a velocity of 100 m/s through an area of 0.05 m2. R-134a exits the diffuser at 2.8 bar and 40?C (State 3) with a velocity of 20 m/s.
(a) Calculate mass flow rate (kg/s) of the refrigerant at the exit of the diffuser.
(b) Find area (m2) at the exit of the diffuser.
(c) What is the rate of heat transfer (kW) for the diffuser? Is the heat transfer into or out of the diffuser?
Problem 6:
An adiabatic steam turbine is directly coupled to an adiabatic air compressor and a generator i.e. the compressor and the generator are powered by the steam turbine. Steam at the rate of 25 kg/s enters the turbine at 12 MPa and 520?C (State 1) and exits the turbine with a quality of 92% at 10 kPa (State 2). Air enters the compressor at 98 kPa and 295 K (State 3) and exits at 1000 kPa and 620 K (State 4) at the rate of 10 kg/s.
Calculate the net power (MW) delivered to the generator by the turbine.