Conceptual design of an innovative gas–gas ceramic compact heat exchanger suitable for high temperature applications.

The development of an innovative and highly efficient heat exchanger (HE) solution for gas–gas heat recovery is one of the major objectives of the HYDROSOL-beyond project which aims at enhancing the process efficiency for producing hydrogen from water dissociation with concentrated sunlight. Because of the very high temperature level of the process (up to 1400 °C), an innovative ceramic HE design was proposed with an integrated lattice structure, as secondary surface, to maximize the heat transfer. To assist the design of the HE, a multiscale approach was adopted: a 1D model based on global correlations was developed and a 3D computational fluid dynamics model of the secondary surfaces were generated. The former was applied to assess the performance of the entire HE; while, the latter was exploited to study in detail the thermo-fluid dynamics behavior of a HE core element and to provide the global correlations to be integrated into the 1D model. In this work, the effect of several parameters and operating conditions, namely, number of channels, number of lattice layers located into each channel, solid material exploited for the HE structure, parting plates thickness, heat transfer fluid velocity, radiation heat transfer and solid material emissivity, on the HE effectiveness are reported and accurately described. Furthermore, based upon the results obtained, guidelines on the HE design to maximize its performance are also provided. [ABSTRACT FROM AUTHOR]