In this experimental work, heat transfer and thermal performance factor of double-pipe exchanger pipes with rotated inclined elliptical (RIE) inserts are examined. The rotation angle the turbulators (?), slant (?), perforation diameters (dp) were in range 0????90?, 15????25?, 0.5mm?dp?1.5mm, respectively. perforations can substantially intensify flow unsteadiness disturb boundary layer to impro...

introduction the chemical characteristic of groundwater as a major source of water supply for human life is an important factor in determining the usage of it for agriculture, industry and drinking. useful techniques and different methods of studying the chemical composition of groundwater such as correlation coefficient, descriptive statistics, factor analysis and cluster analysis provide an u...