The effects of using various types of nanofluids and rotation on heat transfer and fluid flow characteristics in a helically coiled tube heat exchanger (HCTHE) are numerically investigated. Mainly, the effects of nanoparticles type (Al2O3, SiO2, CuO, ZnO), its concentration (1-4%), and particle diameter (25-80 nm), base fluid type (water, ethylene glycol, engine oil), towards the heat transfer and fluid flow characteristics are comprehensively analyzed. The three-dimensional steady, laminar flow and conjugate heat transfer governing equations of a balanced HCTHE are solved using the finite volume method. The results reveal that nanofluids can enhance the thermal properties and performance of the HCTHE but it is accompanied with a slight increase in pressure drop. It is found that the Nusselt number is highest using CuO-water nanofluid in this study. In addition, rotation can be used to enhance the heat transfer rates. (C) 2013 Elsevier B.V. All rights reserved.