Thermodynamics

Question 1

Draw the T-s diagram for the following?

What cycle is this

Answer 1

Brayton Stationary

Question 2

Draw the T-s diagram for the following?

What cycle is this?

Answer 2

Brayton Stationary

Question 3

Draw the T-s diagram for the following?

What cycle is this?

Answer 3

Rankine

Question 4

Draw the T-s diagram for the following?

What cycle is this?

Answer 4

Brayton Aerospace

Question 5

What are the symbols for the following table?

Answer 5

Question 6

What is the difference between T’ and T?

Answer 6

T’ is the isentropic temperature.

T is the real temperature.

Question 7

How do we check if a nozzle is choked? And what do we do if it is/isn’t?

Answer 7

Question 8

At the end of the nozzle, what 3 formulas are needed?

Answer 8

kg/m2 * m/s * m = kg/s

Question 9

What are the two formulas to find the Mach number?

Answer 9

Question 10

How do we calculate overall efficiency?

Answer 10

η = ηth x ηP

Question 11

Draw the T-s diagram for the following?

What cycle is this?

Answer 11

Brayton Stationary

Question 12

What is the formula for back work ratio?

Answer 12

BWR = Wc/Wt

Think back work = work done out the back to increase W(T)/W(Out)

Question 13

How do we find mass flow rate if we’re given volumetric flow rate?

Answer 13

Question 14

What is the equation for cycle efficiency?

Answer 14

η = Wnet / Qin

Question 15

What is the trick for pumps?

Where do we find the data?

What do we have to remember?

Answer 15

Constant specific volume (m3/kg) as the water is as dense as possible? Density <=> 1 / specific volume

Question 16

What is the COP for a refrigerator?

Answer 16

Question 17

What is the COP for a heat pump?

Answer 17

Question 18

Draw the T-s and P-v diagrams for a diesel engine?

Answer 18

Question 19

What does 1 bar = to in kPa?

Answer 19

1 bar = 100 kPa

Question 20

How do you calculate the mass fraction?

Answer 20

Question 21

Degrees Celsius to Kelvin?

Answer 21

x + 273 = x K

Question 22

Across a pump there is…?

Answer 22

Isentropic Compression

Question 23

Across a turbine there is…?

Answer 23

Isentropic Expansion

Question 24

How do we find the efficiency of a regenerator ηR?

Answer 24

Question 25

Label the following jet engine diagram?

Answer 25

Question 26

Draw the T-s diagram for a jet engine?

Answer 26

Draw it with real temperatures, hence the price chart movement

Question 27

Draw the internal structure of a jet engine?

Answer 27

Question 28

What is the formula for the efficiency of a compressor?

Answer 28

If in doubt, same as intake efficiency, as pre burner.

Question 29

What must you remember with aerospace gas turbines?

Answer 29

That γ changes. 1.4 -> Burn -> 1.33

Question 30

What do we need to do around the turbine and nozzle?

Answer 30

Stick to the formula sheet like glue.

Only use Isentropic T’5 to find P5. After that its real T only.

Question 31

What formula can we use when we have the compressor ratio?

Note: not the compressor PRESSURE ratio

Answer 31

Question 32

What can we do if constant pressure or constant volume to find q?

Answer 32

Const P, q = Cp(T2-T1)

Const V, q = Cv(T2-T1)

Both in the box on page 26

Question 33

How can we find the specific volume v if,

Start?

Isentropic?

Constant P?

Constant V?

Answer 33

Start:
v = 1/ρ. And ρ = P/RT. So v = RT/P

Isentropic:
Use any compression ratios etc. So v2 = v1/rv

Constant P:
T3/T2 <=> v3/v2

Constant V:
v4 <=> v1

Question 34

Draw the T-s and P-v diagrams for an Otto cycle?

Answer 34

Question 35

Through a condenser. How do we find h?

Answer 35

We use the temperature to find it, not pressure.

Think condensers care about lowering temperatures. So use that instead of pressure.

So hf ~= hf(T)