The optimum vortex tube experimental designing by the support of a multi-attribute decision-making technique.

The Ranque-Hilsch vortex tube is a simple components device with many features, easy manufacturing, no maintenance needs, low cost, and does not produce any harmful waste for the environment, also rather it is one of the applications of environmentally friendly renewable energies. The main problem is how to select the optimum case among 64 results with three important and required parameters: The cold air mass fraction, the cold air temperature drop, and the coefficient of performance. The technique of Multi-Attribute Decision-Making was applied in addition to the Weighted Fraction Method to rank the results according to the effect of the weight of each of the three parameters, but this is not enough so it has been a new proposed coefficient named "Coefficient Decision Scale-Space" was used to enlarge the space between results, in addition to another proposed coefficient named "Coefficient Of Anomalous" which is used to evaluate the performance of the four methods. The results of the methods showed that the optimize case is at Length / inside diameter ratio = 13, cold mass fraction = 0.8, and inlet pressure = 6.0 bar, cold air outlet temperature drop = 18.9°C, and coefficient of performance = 0.0992. By applying the Coefficient Of Decision Scale-Space: the Weighted Fraction Method recorded 11.025 %, while the Multi-Attribute Decision-Making sub methods recorded 2.214 % up to 3.581 %, and by applying the coefficient of anomalous: the Weighted Fraction Method recorded zero in the anomalous results, while in the other methods the anomalous results reached up to 44%. which means the proposed method gives better clear results. [ABSTRACT FROM AUTHOR]