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THERMODYNAMICS CHAPTER 5 MASS AND ENERGY ANALYSIS OF CONTROL VOLUMES…
THERMODYNAMICS
CHAPTER 5
MASS AND ENERGY ANALYSIS
OF CONTROL VOLUMES
Conservation of mass
:
mass = a conserved property
, meaning cannot be destroyed or created during a process (~ E)
for a
closed system
:
Mass syst = constant
control volume
Relation b/w E and mass (m):
E = m.c^2
c: the speed of light in a vacuum
c = 2.9979 x 10^8 m/s
The mass change due to energy change is absolutely negligible :question:
Mass and Volume Flow rates
differential mass flow rate of a fluid across a small area element dAc (SL4)
Vavg: average velocity
definition fo V avg :!:
definition of dAc :!:
volume flow rate = volume of fluid flowing
through a cross section per unit time
(m3/s)
THEN
(kg/s)
The conservation of mass principle for a control volume
MEANING
(kg)
OR
(kg/s)
General conservation of mass
General conservation of mass in rate form
OR
How to get those integrals :question:
Mass Balance of
Steady-Flow Processes
:
mCV = constant
mCV: the total amount of mass contained within a control volume
what is the mass flow rate :question: :<3:
For steady,
incompressible flow (single stream)
Mass balance
Flow Work & Energy of a Flowing fluid
Total Energy of Flowing fluid
Energy Transport by Mass
Energy Analysis of Steady Flow systems
: Under steady-flow conditions, the mass and energy contents of a control volume remain constant
AND
Under steady-flow conditions, the fluid properties at an inlet or exit remain constant (do not change with time)
Mass balance
Energy balance for a steady-flow system
with dt = 0 (steady)
OR
h instead of u is included :red_flag:
Energy balance relations with Sign Conventions
Some Steady Flow Engineering devices
Nozzles and Diffusers
Turbines and Compressors
Throttling valves
Mixing Chambers
Heat Exchangers
Pipe and Duct Flow
Energy Analysis of
Unsteady Flow Processes
DEFINITION
Mass balance
