Conventional heat transfer fluids like water, ethylene glycol and engine oil have poor heat transfer performance. Solid materials have higher thermal conductivities relative to heat transfer fluids, so the stable suspension of solid particles in conventional heat transfer fluids can be a kind of new and innovative coolants with improved heat transfer performance. In the present investigation Si water nanofluids and glycerol-water solution in different concentrations were used as cooling liquid in the jacket side of a reactor that was equipped with a conventional jacket without baffle. Heat transfer rates were measured for nanofluid and base liquid. The nanofluid concentration was between 0.005% - 0.8% volume fraction. For very dilute nanofluids ( less than 0.1% volume fraction ) no heat transfer enhancement was observed. For greater concentrations heat transfer rates augmented to some extent. Nusselt number increased with increasing the nanofluid concentration as well as Reynolds number. At 0.8% volume fraction of nanofluid the heat transfer coefficient increased between 4.5-10% compared to pure water by changing Reynolds number. By using the least square method to all the experimental data two correlations for water and nanofluid were obtained.