Carrier optimisation in a pilot-scale high pressure sterilisation plant – An iterative CFD approach employing an integrated temperature distributor (ITD)

Abstract

High pressure thermal (HPT) processing is a candidate for commercial scale food sterilisation. During HPT processing, heat is generated volumetrically within the vessel as a result of rapid pressurisation, typically to pressures of 600 MPa or more. As for traditional retort processes, the temperature profile in the vessel should ideally be uniform at all stages of the process in order to minimise the occurrence of under- and over-processing of individual food containers. Insulating polymeric carriers are employed in (pilot-scale) HPT processing with the aim of maximising heat retention and improving temperature uniformity. However, polymeric carriers can occupy a large portion of the vessel volume, thus compromising load capacity. Load capacity issues are a limiting concern for scale-up of HPT processing to commercial scale. As tool for optimising polymeric carrier design, we have developed an iterative software routine that progressively alters the carrier wall thickness in a previously developed computational fluid dynamics (CFD) model, and coupled this with an integrated temperature distributor (ITD) routine, which allows us to describe, in a single parameter, overall process performance in terms of heat retention and uniformity. The use of the combined carrier wall thickness/ITD routines was demonstrated for optimising the design of a polymeric carrier in a 35 L pilot-scale high pressure sterilisation plant, the ITD concept to have applications in HPT processing beyond carrier design, including as a parameter to describe process safety.