Control Volume

CONTROL VOLUME

Control volume is a fixed region in space chosen for the thermodynamic study of mass and energy balances for flowing systems. Therefore, it is a properly selected region in the space. In control volume both mass and energy can be exchanged with surrounding through its boundary. In other words the control volume is the open system. Generally, any arbitrary region in space can be selected as a control volume. There is no specific rule for selecting the control volume but a proper choice will make the analysis easier.

Control volume usually encloses a device which involves the mass flow such as a compressor, turbine or nozzle. The flow through these devices is best studied by selecting the region within the device as the control volume. The boundary of a control volume called control surface. The control volume may be fixed in size and shape. In addition to mass transfer, both work transfer and heat transfer are involved.