-60-
อั
ตราส
วนความชื้
นของพริ
กชี้
ฟ
าที่
คำนวณได
จากสมการเอมไพริ
คเคิ
ลสามารถทำนายผลการทดลอง
ได
ดี
กว
าจากสมการการอบแห
งทางคณิ
ตศาสตร
แบบทฤษฎี
คำสำคั
ญ :
พริ
กชี้
ฟ
า; สั
มประสิ
ทธิ์
การแพร
; ความชื้
นสมดุ
ล; สมบั
ติ
ทางกายภาพ
Abstract
The main objectives of this paper are to determine some thermo-physical properties of long
red pepper and develop mathematical model for predicting the drying kinetics of long red pepper.
To determine the thermal-property of long red pepper, initial moisture content of long red pepper is
varied between 876 – 1036 % dry basis. The apparent density, specific heat capacity, percentage of
void and equilibrium moisture content of long red pepper are determined. The results show that an
apparent density, specific heat capacity and percentage of void have highly relation to initial moisture
content of polynomial equation form. To determine equilibrium moisture content of long red
pepper using static method, the result shows that the Chung & Pfost (1967) equilibrium moisture content
isotherm model was the best fitting with the experimental data. It was founded that equilibrium
moisture content increased with the temperature for relative humidity range form 10 – 70 percent.
Considering the drying kinetics, long red pepper was thin-layer by inlet air temperature of 45 – 65
o
C
and constant air velocity of 1.0 m/s. The experimental result of moisture ratio indicates that
the drying rate is effected by inlet drying air temperature and the moisture ratio exponentially
decreases with increases of drying time. The Page model was found to be a better model and the
effective diffusivity varied form 1.73 x 10
-9
- 3.50 x 10
-9
m
2
/s. For determining moisture ratio
using Fick’s law, it shows that the simulated data of empirical equation is more suitable for predicting
evolution of moisture ratio compared to that obtained of the analytical solution of drying theory.
Keywords :
Long red pepper; Effective diffusivity; Equilibrium moisture content; Physical property.
