text: In the last ten years, many experiments have been conducted numerically and analytically to validate the importance of nanofluids.
  From the table 1 it is clear that nanofluid-based collector have a higher efficiency than a conventional collector. So, it is clear that we can improve conventional collector simply by adding trace amounts of nano-particles.
  It has also been observed through numerical simulation that mean outlet temperature increase by increasing volume fraction of nanoparticles, length of tube and decreases by decreasing velocity.