Page 120 - DJJ20063- Thermodynamics 1
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DJJ20063- Thermodynamics 1
3.2.4 Definition of an open system.
An open system, or a control volume, as it is often called, is a properly selected region in
space. It usually encloses a device, which involves mass flow such as a boiler, compressor,
turbine or nozzle. Flow through these devices is best studied by selecting the region
within the device as the control volume. Both mass and energy can cross the boundary
of a control volume, as shown in Fig 3.2.4-1.
Fluid Inlet SURROUNDINGS
SYSTEM
QOUT
BOUNDARY WOUT
Fluid Outlet
Fig 3.2.4-1 Open system in boiler
3.2.5 Solve problem related to the mass flow rate using continuity equation
Equation of Continuity
This is an equation which is often used in conjunction with the steady flow energy
equation. It is based on the fact that if a system is in a steady state, then the mass of
fluid passing any section during a specified time must be constant.
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