Effect of Twisted-Tape Turbulators and Nanofluid on Heat Transfer in a Double Pipe Heat Exchanger

Table 1

Physical properties of the nanoparticles.

Types of nanoparticles	Nanosized particles	Special surface	Purity percent	Appearance		The apparent density
TiO2	30 nm	>60 m^2/g	+99.9	White powder		0.7 g/m^3
Certificate of analysis (content of elements)
TiO2	Fe	Cr	Co	pb	As	Hg
99.9%	0.005%	0.005%	0.01%	66 ppm	120 ppm	78 ppm