Abstract:
One of the important measurements in chemical industrial units is the
measuring of the fluids velocity in different stages of industrial process.
Determination of this parameter is important for controlling the heat and mass
transfer. Hence, the present study is designed for this purpose by employing
laser technique.
A specific system was constructed using laser light. It consists of two
He-Ne lasers ( power of 1 mW and 632.8 nm wavelength) and a detection
system. The fluid system involves a centrifugal pump to change the fluid
velocity. Two fluids were employed; water and gasoil.
The detection system consists from a special electronic circuit
essentially built to detect the laser beams with a time counter. The
experiments were carried out at different fluid velocities.
The velocity measurements determined by laser system were based on
the basic principles of the velocity which is the linear change of distance as
function of time.
In the first run of the experiment with water, the water flows in the
glass tube create air bubbles which change the laser intensity incident on the
detector. When the intensity in the first detector changed the electronic
circuit started up the counter and then the counter stopped by the intensity
changed in the second detector. The velocity obtained was affected by the
4
bubble size, but it gave similar results wh
en the experiment was repeated for
the same velocity with different distances. Two tubes with 1 cm and 1.6 cm
outside diameter were used in these experiments.
In the second run of the experiments with gasoil, the work was done
without pump so it made the flow control poor and caused scattered results.
The obtained results showed significantly accurate results and a high
sensitivity of the system for any small change in the fluid velocity.
