Concept selection, design methods and validation for fuel cell thermal insulation applications operating in high temperatures
Editor: Boks, Casper; Sigurjonsson, Johannes; Steinert, Martin; Vis, Carlijn; Wulvik, Andreas
Author: Salminen, Pauli V. J.; Haeri, Shahab N.; Ahlgren, Esa A.; Kuosmanen, Petri O.
Institution: Aalto University, Finland
Section: Methodology: General Applications
Solid Oxide Fuel Cell (SOFC) systems operate at high temperatures (600–900 °C) and thus thermal insulation is essential part of the system. Concept selection for the thermal insulation is pivotal to the system design as it has a significant effect on system dimensions, instrumentation, support of components and compensation of thermal expansion. A proper thermal insulation concept should be selected at the very beginning of the project as it has strong interactions with other subsystems of the SOFC unit. In this study a fuel cell engineering team defines a set of essential requirements for thermal insulation of SOFC fuel cell systems. Pairwise comparison methods are used to set weighting values for the defined requirements and then thermal insulation concepts are evaluated by quantitative and subjective analyses in order to identify the highest ranking concept. The second part of this study presents design principles for systems which operate at high temperature, such as methods for compensating the thermal expansion of structural components, free thermal expansion and thermal center. Together with these principles numerical calculations can be used to verify and evaluate structural design before it is constructed. These principles are then demonstrated by presenting the experimental test apparatus which is designed according to these rules. This apparatus is used to conduct a set of experiments in order to evaluate differing thermal insulation concepts. The test results are presented in the third part. Together with conceptual study the experimental results prove that the proposed concept is an improvement to the prior methods of thermal insulation. Moreover, this concept is now approved by our industrial partners and it is in service in their products.