Question

One hundred btu is added to 1 lbm of air at a constant volume
whose initial conditions are 85F and 35psia. If c_{v}= 0.19
Btu/lbmR, determine final pressure, the final temperature and the
change in entropy for the process. (MW=29)

Answer #1

A piston cylinder contains 2 lbm of air and operates at a
constant pressure of 400 psia. The initial volume is 1 ft.3 and the
initial temperature is 100°F. The final volume is 4 ft.3 and the
final temperature is 1780°F. Determine the work and its direction
(in or out) and the heat transfer and its direction, in
Btu/lbm.

1) The cp and the cv of air are, respectively, 0.24
and 0.17 Btu/Ibm.oR respectively. If 1000 Btu is added as heat to
20 Ibm of air in a nonflow, constant-pressure process, what is the
final temperature? How much work is done by the gas if the initial
temperature is 100 oF.

A rigid tank contains 20lbm of air at 80ºF and 35
psig. Heat is added until the pressure doubles to 70 psig.
Rair = 0.3704 psia-ft3/lbm-R
Draw the P-v and T-v diagrams for the problem.
What is the volume of the tank ft3?
What is final temperature of the air in ºF?
How much heat is transferred in the process in Btu?

1. A tank of air contains 100 ft^3. The pressure and temperature
are 1000 F and 100 psia. The air
is cooled to 100 F.
a. Find the mass of the air
b. Find the initial energy of the tank (Btu)
c. Find the final energy of the tank (Btu)
d. Compute the heat (Btu)
2. Water is contained inside a constant pressure piston cylinder
device. The initial temperature
and quality of the water are x=0 and T=300 F. The...

Air at 1 atm and 20 0C occupies an initial volume of 1000 cm3 in
a cylinder. The air is confined by a piston which has a constant
restraining force so that the gas pressure always remains constant.
Heat is added to the air until its temperature reaches 260 0C.
Calculate (a) the heat added (b) the work done by the gas, (c) the
change in internal energy of the gas.

A closed, rigid steel tank contains 1 lbm of water, initially at
260 F and a quality of 60%. The tank is fitted with a paddle wheel
and the water is stirred until the temperature is 350 F. The tank
is well insulated on the outside and the steel is in thermal
equilibrium with the water. The mass of the steel tank itself (not
including water) is 60 lbm and the specific heat of the tank is
0.115 Btu/lbm·R. Changes...

Air is contained in a rigid, well-insulated container
of volume 3 m3. The air undergoes a process from
an initial state with a pressure of 200 kPa and temperature of 300
K. During the process, the air
receives 720 kJ of work from a paddle wheel. Model the air as an
ideal gas with constant specific
heats. Evaluate the specific heats at 300 K. Neglect changes in
kinetic energy and potential energy.
Determine the mass of the air in kg,...

In a Dual cycle the heat transfer during the constant volume
process is double that during the constant pressure process. The
compression ratio is 14 and the air initial conditions are 1 bar
and 27oC. If the maximum pressure in the cycle is 60 bar,
calculate:
Maximum temperature
Heat added at constant volume and constant pressure per kg of
air
Cycle thermal efficiency
Net work per kg of air
Exergy destroyed associated with the cycle. Assume the source
temperature to...

A closed, rigid steel tank contains 1 lbm of water, initially at
260F and a quality of 60%. The tank is fitted with a paddle wheel
and the water is stirred until the temperature is 350F. The tank
is well insulated on the outside and the steel is in thermal
equilibrium with the water. The mass of the steel tank itself (not
including water) is 60 lbm and the specific heat of the tank is
0.115 Btu/lbm·R. Changes in kinetic...

In an isobaric process if the the initial volume of air
is 2.3 litres at a temperature of 15°C and a pressure of 55kPa. If
the final temperature is 190° C
a) The final volume
b) The mass of air
c) The work done
d) The heat transferred

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