Heat transfer in conductive monolith structures

Honeycomb structures made of highly thermal conductive materials (e.g. certain metals) have been proposed as attractive catalyst supports with enhanced heat transfer properties. Recently prototypes of such materials have become available, enabling experimental investigations on their heat transfer properties, including packaging into tubes. This work is focused on the heat transfer performance of conductive monolith structures packaged into heat exchanger tubes. Several parameters such as monolith material structure and properties and packaging tolerances are investigated. Heat transfer coefficients on the order of 1000 W/m(2) K and higher were measured. The results are analyzed applying a detailed model based on a fundamental understanding of the relevant phenomena. It is demonstrated that it is necessary to consider the variations of the thermal expansion of the monolith and the tube over the length of the monoliths. By including thermal expansion, the model is in excellent agreement with the experimental results without the need of any fitting parameter. The results are used to develop some design guidelines. In addition some implications of the heat transfer performance for the relevant applications in multitubular reactors as well as some new potential application areas are discussed. (c) 2005 Elsevier Ltd. All rights reserved.