Fig. 5. Effect of reciprocating conditions on heat transfer coefficients in reciprocation agitation thermal processing: (a) overall heat transfer coefficient (U); (b) fluid-to-particle heat transfer coefficient (hfp).
Article from Food and Bioproducts Processing 94:169-179
AnikaSingh, Anubhav PratapSingh, Hosahalli S.Ramaswamy
Abstract
The conventional methodology was refined for calculating the heat transfer coefficients (U and hfp) under rapid heating conditions. The conventional methodology of hfpevaluation became unreliable and/or non-reproducible under rapid heating conditions such as those encountered during reciprocation thermal processing. This was due to fluctuations in gathered transient temperatures during rapid reciprocating motion and due to very short equilibration times (EQT) (heat-up time to 1 °C below operating temperature).
In this method, U and hfp were calculated employing temperature profiles predicted by using an average retort temperature (after the come-up period) and heat penetration parameters, instead of real data points from experimental temperature profile as used in conventional methodology. The method was validated for various reciprocation frequencies (0–3 Hz) and amplitudes (0–20 cm). Results revealed that the refined methodology was robust and produced reliable and consistent values of U and hfp, under both slow and rapid heating conditions. Also, the heat transfer coefficient values, using the developed method, consistently matched the results and trends observed with conventional methods. A parameter sensitivity analysis was also conducted and the effects of perturbations of different parameters employed in the refined methodology were reported.