Mathematical Modelling of Date Palm Drying using Far-infrared Radiation and Heat Pump Dryer

Kamonrak Kangkham*, Sakchai Dondee, Prasopsuk Rittidech and Wasan Pinate


The literature traversed disclosed information that the thin-layer drying characteristic of date palm under intergraded far-infrared radiation (FIR) and heat pump dryer has not been investigated. Widespread throughout the world, the date palm fruit is currently gaining popularity for its health-protective properties and nutritional qualities.
The mathematical modelling of the date palm drying was evaluated. The ‘deglet nour’ variety was used in this experimentation. The variables of drying were far-infrared intensity, air temperature, and initial moisture content of the deglet nour, the values of drying variables were 650, 750 and 850 W/m2, 0.3 m/s, 40oC and 74% d.b., respectively. Newton, Henderson and Pabis, Logarithmic, Two-term, and Wang & Singh were fitted to predict the moisture ratio (MR) of the deglet nour. Four statistical tools, correlation coefficient (R2), efficiency model (EF), root mean square error (RMSE) and chi-square were used to analyze the fittings. The results from the experiments found that the moisture content of the deglet nour was decreased exponentially with drying time. The drying rate is increased with the increase of far-infrared intensity. Among the models proposed, the Two-term model precisely represented the deglet nour drying under combined far-infrared radiation and heat pump drying with a correlation coefficient (R2) and efficiency model (EF) of determination higher than 0.9968 and 1.0000, respectively. The root mean square error (RMSE), and chi-square was lower than 0.0082 and 0.00009, respectively. The deglet nour is very interesting and acceptable for the food industry in Thailand