In this work

the laminar convective heat transfer performance and the pressure drop of water-based nanofluids containing Al

2

O

3

TiO

2

and SiO

2

nanoparticles flowing through a straight circular tube were experimentally investigated. The experimental results showed that addition of small amounts of nano-sized Al

2

O

3

and TiO

2

particles to de-ionized water increased heat transfer coefficients considerably

while the SiO

2

nanofluids showed the opposite behavior attracting the authors' interests. An average of 16% and 8.2% increase in heat transfer coefficient were observed with the average of 28% and 15% penalty in pressure drop for Al

2

O

3

and TiO

2

nanofluids.