Thermo 2 Flashcards
What happens to properties in the quality region
@ constant pressure:
Temp remains constant, all others increase
What happens to properties in the superheated region
@ constant pressure, everything increases including temp
What is the conservation of mass principle for a control volume
Net mass transfer = net change mass in control volume / time
What is the mass balance for something at steady state
density 1 x area 1 x velocity 1 = density 2 x area 2 x velocity 2
What is flow work
The work required to push mass into or out of the control volume
It is necessary for maintaining a continuous flow through a control volume
What is a nozzle
A device the increases velocity of fluid by reducing pressure
What is a diffuser
A device that increases pressure by reducing velocity
What are the features of a nozzle and a diffuser
- No work input into devices
- Generally negligible heat transfer
What equation is used with for nozzles and diffusers
(v2^2)/2 - (v1^2)/2 = h1 - h2
How can you calculate dH (h2-h1)?
h2 - h1 = Cp (T2 - T1)
What is a pump
A device that transfers energy to a liquid flowing through it, resulting in increased pressure
What is a compressor and a blower?
Devices that transfer energy to a gas flowing through them, resulting in pressure increasing
What is a turbine
A device where work is done by a fluid on rotating blades, resulting in pressure decreasing
What are the features or pumps, compressors, blowers and turbines?
- heat transfer from device to surroundings is small is inlet fluid is flow to ambient
- KE and PE changes are negligible
Q=0 KE=0 PE=0
What equation is used for turbines, pumps, compressors and blowers?
Ws = m(h2-h1) (work done)
