Study droplet-wire impact and its effect in the design of gas scrubbers
MetadataVis full innførsel
In this thesis droplet- wire impact and droplet fragmentation in a free stream has been studied experimentally. Impacting droplets of uniform size, 4 different wire sizes and 3 different impact velocities has been tested to obtain better knowledge about droplet behavior in gas/liquid separators. Number of droplets, size and velocity has been measured at the impact and in the fragmentation. Water droplets under atmospheric pressure are considered in the measurements. A variation in the fragmentation has been observed, where the impact velocity is the governing factor causing variation.Previously work on the subject has been presented in a litterateur review in this thesis. This covers the methods used today designing gas/liquid separators and variables of interest. It was revealed that today s design is largely based on empirical methods and testing of different systems. Expressions and equations for pressure drop, mesh characteristics and Separation mechanisms is presented.Experimental data has been used to validate a correlation, giving the size ratios of dripping drop to wire diameter for miscellaneous wire diameter and impact velocities. It was confirmed that this ratio is largest for small wires. The experimental data has also been used to look for an optimal droplet /wire diameter to enhance the separation efficiency in gas/liquid separators. The system turned out to be a bit more complex. One specific ratio for any given impact velocity was not found. Instead it was found that for large impact velocity the velocity should be decreased stepwise using thin wires. Large wires at high impact velocity create numbers of small droplets which are not wanted. A proposed solution for a wire mesh structure based on wire diameters of increasing size from inlet to outlet is presented based on the obtained data. This can be tested and developed further in future work on the subject.The procedure of doing these kinds of measurements, with its weaknesses, pitfalls andpotential of improvement has also been discussed in the thesis. It was concluded that the method used must be improved with regard to eliminate the manual steps in the procedure. More measurements on every setup must be performed, but this is too time- consuming with the manual steps involved. A more automatic method of recording the data, transfer it for analysis and the analysis itself must be developed.