A composite model for the average heat flux using both pure fluids and nanofluids is established incorporating microlayer evaporation, transient conduction due to bubble departure, and microconvection due to bubble growth and movement. Our model also takes into account bubble influence area interference. The average heat flux and the critical heat flux (CHF) when the surface dryout fraction exceeds a certain value are predicted. Nanofluid properties were calculated and the contact angles obtained from experiments were utilized in the present model. The analytical heat flux and CHF values using both regular fluids and nanofluids were compared with the experimental results and existing theories and were found to be in close agreement. It was found that CHF enhancement value increases to 3.54 as the contact angle decreases from 80 degrees to 20 degrees, which is in agreement with recent experimental results. (C) 2014 Elsevier Ltd. All rights reserved.