Temperature response and drying characteristics of Palm Kernel Cake (PKC) in a Radial Packed Bed (RPB)

• Main Author: Phang, Hooi Kim
• Format: Thesis
• Language: English; English
• Published: 2013
• Subjects: TP248.13-248.65 Biotechnology
• Online Access: https://eprints.ums.edu.my/id/eprint/26675/1/24%20PAGES.pdf; https://eprints.ums.edu.my/id/eprint/26675/2/FULLTEXT.pdf; https://eprints.ums.edu.my/id/eprint/26675/

A batch type radial packed bed (RPB) was designed and fabricated for a palm kernel cake transport phenomena study. The RPB system consists of aeration control, heating control and data acquisition. A preliminary study of transport phenomena of non-fermented PKC for heat transfer and moisture mass transfer was conducted in the RPB. The heat and mass transfer (HMT) as a function of air temperature, initial moisture content and bed height was conducted at various particle mean sizes (0.80, 1.50, 2.68 mm) and various initial moisture content (25, 50, 75, 100% dry basis) with forced aeration. The steady state temperature of PKC was not affected by particle size, initial moisture content and bed height. The steady state value of moisture content was affected by particle size, initial moisture content and bed height. A longer duration was required for PKC to achieve the same final temperature increased with initial moisture content at fixed particle size, air flow rate and operating air temperature. Consequently, 1.50 mm PKC particle mean size and 50% dry basis initial moisture content were fixed in main HMT study.A factorial design of experiments was adopted to investigate the effect of air temperature (35, 45, 55 and 65 °C), aeration rate (65.33, 75.33, and 92.33 LPM), and bed height (8.50, 13.25, 18.00, 22.75 and 27.50 cm) on the HMT study. The bed shrinkage and changes in physical properties of PKC in HMT were assumed negligible. The HMT study of PKC in RPB air-water was modelled mathematically. For the transient heat transfer model, a first order process model was fitted to the inner temperature and outer temperature data with good agreement. The coefficients of determination (R2) were above 0.87. The moisture content data were compared and fitted to the different semi-empirical models such as Lewis, Henderson and Pabis, Logarithmic, Page and modified Page based on the ratio of the difference between the initial and final moisture content and the equilibrium moisture content. All the models fitted the drying data satisfactorily although they have slightly different value of R2. The Henderson and Pabis model which is simple and linearisable was chosen to model all the drying data. The temperature dependency of drying rate constant and effective diffusivity was described with the Arrhenius equation. The R2 for drying rate constant was as high as 0.9903 but the R2 for effective diffusivity was as high as 0.9732. Both semi empirical model, first order process model for heat transfer and Henderson and Pabis model for mass transfer adequately described the transport phenomena of PKC for the air temperature range of 35 to 65°C and air flow rate range of 65.33 to 92.33 LPM in air-water system of RPB.