Question

Your new engine design consists of a piston cylinder arrangement. The engine operates with mostly air and a small amount of fuel. The system undergoes a cycle. The initial Pressure and temperature are p1= 1bar and T1= 27°C. The system undergoes a power cycle consisting of the following process:

Process 1-2 constant volume to a pressure, P2 of 4 bars

Process 2-3 expansion of pv=constant

Process 3-1 constant-pressure compression

Draw the system and pv diagrams

If P2 is 4 bars, find T2. List assumptions

Using “cold” cp or cv data, find the heat added in kJ/kg during the constant volume process.

Use the ideal gas air table to find Δu for the constant volume process

Find the specific work for the expansion process

What process name is associated with the expansion process?

What is the total change in specific internal energy for the cycle?

Calculate the net specific work for the cycle

Calculate the thermal efficiency for the cycle

Answer #1

In a cylinder/piston arrangement, air is compressed in a
reversible polytropic process to a final state of 800 kPa, 500 K.
Initially air is at 110 kPa and 25oC. During the
compression process heat transfer takes place with the ambient
maintained at 25oC. Assume air as an ideal gas (R =0.287
kJ/kg) and has constant specific heats of Cp = 1.004
kJ/kgK and Cv = 0.717 kJ/kgK. If the mass of air in the
cylinder is 0.1286 kg, determine
a)...

A cylinder if fitted with a floating piston oriented
horizontally (the air is the system and by having a floating piston
it maintains constant pressure). It contains 24.5 L of air at 25.0C
and 1 bar pressure. The system is then heated to 250.0C. Air can be
considered a diatomic gas and therefore would have a Cv = 5R/2,
where R is the ideal gas constant. Also for gases Cp = Cv +R. How
much work was done (in J)...

1) An ideal gas is contained in a
piston-cylinder device and undergoes a power cycle as follows:
1-2 isentropic compression from an initial
temperatureT1= 20 degree celsius with a compression ratio
r = 5
2-3 constant pressure heat addition 3-1 constant volume heat
rejection
The gas has constant specific heats with cv = 0.7
kJ/kg·K and R= 0.3 kJ/kg·K.
(a) Sketch the
P-v and T-s diagrams for the cycle.
(b) Determine the heat
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A 0.2 m3 piston-cylinder initially contains 400 K air. A heavy
frictionless piston maintains a pressure of 500 kPa abs. Then, a
weakness in the cylinder wall blows out and creates a hole. Air
escapes through the hole until the piston drops far enough to cover
the hole. At that point, the volume is half the initial volume.
During this process, 75 kJ of heat is transferred to the 100 kPa,
300 K surroundings. Using Cp = 1.005 kJ/kg-K and...

A closed piston-cylinder system contains a 120
moles of neon, a monatomic ideal gas, at pressure
PA = 2.5 atm
and volume VA = 0.80
m3. It undergoes the following cyclic
process:
A -> B: I
There is isothermal expansion to volume double of the original.
B -> C:
Constant-volume process back to its original pressure .
C -> A:
Constant-pressure process back to its initial state
a) Draw a Pressure volume diagram for the cycle. You
don't need to...

Three kilograms of air within a piston-cylinder assembly
executes a Carnot power cycle. The isothermal expansion occurs at
700K from 1.25 bar to 0.85 bar; the air can be treated as an ideal
gas. If the cycle thermal efficiency is 65%,
- determine the temperature of the isothermal compression
- calculate the net work developed for the cycle in kJ
- draw the cycle on both Pv and Ts diagrams, labelling the types of
processes and including arrows to show...

A Diesel cycle engine is analyzed using the air standard
method. Given the conditions at state 1, compression ratio
(r), and cutoff ratio (rc) determine the efficiency and other
values listed below.
Note: The gas constant for air is R=0.287 kJ/kg-K.
--Given Values--
T1 (K) = 322
P1 (kPa) = 120
r = 11.5
rc = 1.6
Specific internal energy (kJ/kg) at state 1: 229.86
Relative specific volume at state 1= 520.52
Relative specific volume at state 2= 45.26
Temperature...

A Diesel cycle engine is analyzed using the air standard
method. Given the conditions at state 1, compression ratio
(r), and cutoff ratio (rc) determine the efficiency and other
values listed below.
Note: The gas constant for air is R=0.287 kJ/kg-K.
--Given Values--
T1 (K) = 322
P1 (kPa) = 120
r = 11.5
rc = 1.6
Specific internal energy (kJ/kg) at state 1: 229.86
Relative specific volume at state 1= 520.52
Relative specific volume at state 2= 45.26
Temperature...

a) Calculate delta S(system) for the reversible heating of 1 mol
of ethane from 298K to 1500 K at constant pressure. Use Cp = 5.351
+ 177.669x10-3 T – 687.01x10-7 T ^2 + 8.514x10-9 T ^3 (J/mol K).
Consider the reversible Carnot cycle discussed in class with 1 mol
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A piston cylinder device containing 0.5 kg of water has initial
volume of 0.5L. The device starts and goes through a Carnot cycle
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will reach is 1.5 times the minimum temperature of water and during
heat rejection process, water goes from saturated vapor to
saturated liquid phase Find: 1. QH & QL for this cycle 2. TH
& TL for this cycle . 3. Maximum and minimum pressures that...

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