Modeling of electrohydrodynamic drying process using response surface methodology

Abstract

Energy consumption index is one of the most important criteria for judging about new, and emerging drying technologies. One of such novel and promising alternative of drying process is called electrohydrodynamic (EHD) drying. In this work, a solar energy was used to maintain required energy of EHD drying process. Moreover, response surface methodology (RSM) was used to build a predictive model in order to investigate the combined effects of independent variables such as applied voltage, field strength, number of discharge electrode (needle), and air velocity on moisture ratio, energy efficiency, and energy consumption as responses of EHD drying process. Three-levels and four-factor Box–Behnken design was employed to evaluate the effects of independent variables on system responses. A stepwise approach was followed to build up a model that can map the entire response surface. The interior relationships between parameters were well defined by RSM.

Electrohydrodynamic drying of apple slices: Energy and quality aspects

“…This is in agreement with previous analysis of energy efficiency in EHD drying (Kudra and Martynenko, 2014). The efficiency increased with increasing of voltage applied, which is in agreement with Dalvand et al (2014).…”

“…The conclusion about negative effect of forced convection on EHD performance is in good agreement with results, obtained by other researchers (Dalvand et al, 2014;Balcer and Lai, 2004). Airflow significantly decreased energy efficiency of EHD drying because of at least two reasons: (i) concurrent effect of airflow on ionic wind, resulting in partial or full suppressing the electrohydrodynamic effect; (ii) increased energy consumption by air blower.…”

“…It should be noted that without convection it takes 25 h to reach the same moisture content (Fig 3a). Increase of electric field strength resulted in increased drying rate, which was expected for EHD drying (Dalvand et al, 2014). The most significant effect of EHD on drying rate was observed at the highest voltage and lowest air velocity in the range from 0 to 1 m/s.…”

“…It was found that the drying rate increased with the increase of electric field strength through either increased voltage or decreased gap (Dalvand et al, 2014). For example, wheat drying with multiple-needle electrode showed enhancement of drying rate by 1.7, 2.0 and 2.1 at 5, 7.5 and 10 kV/cm, respectively (Cao et al, 2004).…”

“…Usually, energy efficiency is estimated through specific energy consumption, which refers to energy used for evaporation of kg of water (kJ/kg) (Kudra, 2004). Most of researchers claim lower energy consumption of EHD as compared to ambient or hot air drying (Lai and Lai, 2002;Lai and Wong, 2003;Balcer and Lai, 2004;Wong and Lai, 2004;Lai and Sharma, 2005;Cao et al, 2004;Goodenough et al, 2007;Ahmedou et al, 2009;Esehaghbeygi and Basiry, 2011;Karami et al, 2012;Singh et al, 2012;Bai et al, 2012Bai et al, , 2013Dinani et al, 2014;Dalvand et al, 2014). It was found that the most energy efficient was a single-needle electrode with positive DC voltage in the range Nomenclature X(t) instantaneous moisture content, g/g db X 0 initial moisture content, g/g db m(t)…”