The choice of the shape and number of cooling channels is critical when seeking for the best design of a liquid rocket engine thrust chamber. Trade-off has to be considered among the different constraints that must be satisfied in terms of thrust chamber mass and resistance to mechanical and thermal loads, while keeping acceptable the power spent to make the coolant flow in the channels. In this study attention is focused on the phenomenon of thermal stratification that occurs in liquid rocket engine cooling channels due to their asymmetric heating. Its role is studied with a suitable engineering approach that allows to emphasize when rectangular cross section channels become inefficient due to stratification. A parametric analysis is carried out on a reference configuration showing the margins required to satisfy specific wall temperature constraints. (C) 2019 Elsevier Ltd. All rights reserved.