Thermodynamics

What is the Clausius statement of the second law?

It's impossible to construct a heat engine which operates in reverse without a network input from the surroundings

what is the Kelvin-Plank statement of the second law?

It is impossible for any heat engine to receive heat from a single thermal reservoir and to produce an equivalent quantity of work

What is the first law of thermodynamics?

Q12-W12= E2-E1

What is a system?

a fixed quantity of material

What is the difference between control volume and system?

For control volume material crosses the boundary

what is rp for a typical open-cycle gas turbine?

10 to 30

what is the efficiency for a typical open-cycle gas turbine?

20-40%

1-2 compression stroke in a real otto cycle

compression of air and petrol vapour mixture

2-3 in a real otto cycle

spark ignites mixture, increasing pressure

3-4 power stroke in a real otto cycle

expansion of combustion products

4-1 in a real otto cycle

exhaust stroke, induction stroke

why might engine power be less than expected?

air breathed by the engine is at a lower density than the ambient air

1-2 compression in a real open cycle gas turbine engine

compression of air in compressor

2-3 in a real open cycle gas turbine engine

combustion of fuel in chambers, small pressure drop

3-4 expansion in a real open cycle gas turbine engine

expansion of combustion products in turbine

stage 1-2 of the joule cycle (compressor)

isentropic compression

stage 2-3 of the joule cycle (combustor)

isobaric heat addition

stage 3-4 of the joule cycle (turbine)

isentropic expansion

stage 4-1 of the joule cycle

isobaric heat rejection

why is stage 2-3 modelled as isobaric in a diesel cycle?

Combustion is slow compared to the movement of the piston

what happens to joule cycle efficiency when pressure ratio increases?

increases

When is specific net work in the joule cycle a maximum?

at medium pressure ratio

what is the difference between a jet engine and joule cycle?

in a jet engine the turbine provides only enough work to drive the compressor