Simulation of high pressure freezing processes by enthalpy method

Generalized enthalpy model of a high-pressure shift freezing process

“…We compare the predicted plateau times of our model to the experimental data, and also to the plateau times predicted by other HPSF models (table 1). For the big sample, we compare them with the theoretical times calculated by ; for the small sample , we compare them with those predicted in Norton et al (2009). The times in table 1 are not given as such in Norton et al (2009), where instead a 'reduction in plateau time' (%) was given; this refers to how long the plateau time has been reduced when compared with atmospheric pressure freezing (APF) process.…”

“…However, we remark that calculated the plateau times taking into account the amount of ice instantaneously produced after expansion, and the time required to freeze the sample at atmospheric pressure, but did not obtain them as a result from a heat-transfer model. Norton et al (2009), for the small sample case, proposed a one-dimensional heat-transfer model for the food sample, but they did not model the heat transfer in the pressurizing medium. They assumed a boundary condition of the third class at the surface between the food and the pressurizing fluid, and had to choose the surface heat-transfer coefficient to best fit the experimental curve, i.e.…”

“…Kowalczyk & Delgado (2007) performed dimensional analysis of the governing equations describing high-pressure processes with forced and free convection, giving a general overview of thermo-fluid-dynamical mechanisms of these kinds of processes. Norton et al (2009) developed a one-dimensional finite-difference numerical model based on the enthalpy formulation to simulate high-pressure freezing of tylose, agar gel and potatoes. This model by Norton et al uses a version of the enthalpy equation derived for constant pressure systems, adapting it to their system by accounting for pressure effects on the latent heat.…”

“…If the pressure is constant, then equation (2.6) reduces to the enthalpy equation used in Voller et al (1990). In the enthalpy model of a HPSF process developed by Norton et al (2009), the pressure term on the right-hand side of (2.6) was neglected.…”

“…A few studies on HPIF have been carried out (Kowalczyk et al 2004;Urrutia Benet et al 2004), and there are numerous papers and reviews dealing with HPAF (Otero & Sanz 2003;Fernández et al 2006;Norton et al 2009) and HPSF . It is generally accepted that for the purposes described above, HPSF processes are the most advantageous (Fernández et al 2006).…”