Thermal energy conservation is at the heart of energy efficiency in process industries. This allows researchers to go for advances in CFD methods to track the requirement of thermal energy for various thermal processing applications. CFD models need to be incorporated into optimization principles to achieve efficient industrial process designs. In this study, entropy generation due to natural convection in right-angled triangular enclosures (cases 1-4) has been studied numerically for energy efficient processing of various fluids (Pr=0.025, 7 and 1000). It is found that maximum value of entropy generation due to heat transfer (S θ,max) occurs near the vertex of the enclosures for cases 1 and 3, near corner between left wall and bottom wall for case 2 and near lower portion of the right wall for case 4. On the other hand, maximum value of entropy generation due to fluid flow (S ψ,max) is observed near middle portions of the side walls for all cases and the location of S ψ,max mainly depends on the presence of high velocity gradients. The entropy generation rates and heat transfer rates were also shown for various angles. Triangular cavities with specific angles are recommended for various processing fluids. © 2012 The Institution of Chemical Engineers.