## 3 Results
### Energy Consumption and Energy Efficiency  
Previous works studying dehumidified-air-assisted spray drying have been limited only to the process characterization, mainly focusing on powder recovery. As this technology is leading to increased interest from researchers and industry, it is crucial to address the economic aspects, which have been never presented in the literature before. The rate of energy consumption (\(Q\)) during spray drying ranged from 3.4 \(\pm\) 0.0 to 7.3 \(\pm\) 0.0 kW, while the specific energy consumption (\(E_{s}\)) varied from 22.9 \(\pm\) 2.6 to 41.8 \(\pm\) 0.9 MJ/kg H\({}_{2}\)O (Table 4). Few researchers have addressed the issue of the \(E_{s}\) of traditional spray drying; however, [PERSON] (2008) stated that spray drying consumes 5 MJ/kg H\({}_{2}\)O in industrial scale operations [37]. The author highlights that spray drying is not a cost-effective method  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Variant** & **SDMD50** & **DASDMD50** & **DASDMD75** & **SDMP50** & **DASDMP50** & **DASDMP75** \\ \hline Viscosity [mPa-s] & 37.0 \(\pm\) 1.2 \({}^{\text{c}}\) & 16.5 \(\pm\) 0.8 \({}^{\text{a}}\) & 51.7 \(\pm\) 2.6 \({}^{\text{d}}\) & 24.3 \(\pm\) 0.2 \({}^{\text{b}}\) \\ H [\%] & 16.2 \(\pm\) 0.5 \({}^{\text{c}}\) & 15.5 \(\pm\) 0.3 \({}^{\text{c}}  
of drying in comparison to other methods, but it enables drying thermolabile materials and obtaining products of high quality; it is also less energy-consuming than freeze drying. [PERSON] and [PERSON] (2005) reported that the \(E_{s}\) for industrial spray dryers usually varies from 3 to 20 MJ/kg H\({}_{2}\)O, while for pilot scale spray dryers of lower throughput it can increase up to five times; this is confirmed as well by this research [38]. The effect of dehumidified air application can be observed: both \(Q\) and \(E_{s}\) increased for spray drying in the case of DASD, which resulted from an extra energy expenditure related to air dehumidification. The \(E_{s}\) of spray drying can be improved if a higher feed rate is applied; thus, the same amount of supplied energy is used for the evaporation of higher amounts of water. However, as was presented by [PERSON] et al. (2019) and [PERSON] et al. (2020), during DASD, especially at an inlet drying temperature as low as 80 \({}^{\circ}\)C, the feed rate has to be relatively low to make the evaporation possible [17; 20].  
The energy efficiency (\(\eta\)) of spray drying ranged from \(5.7\pm 0.0\) to \(10.5\pm 1.2\%\) (Table 4). The effect of the drying method can be clearly observed; however, there was no statistically significant importance of the carrier type and content, which is in good agreement with the conclusions of [PERSON] et al. (2012) [39]. The authors spray dried fish oil and reported that there was no effect of carrier type on the \(\eta\), as the solvent content in liquid feed prior to drying was the same. Regarding spray dried buckwheat honey, the difference in amount of water added to the liquid feeds was negligible. In contradiction to the findings of [PERSON] et al. (2012) and [PERSON] (2015), the \(\eta\) increased with an increase in temperature [39; 40]. However, previous studies did not include the drying air dehumidification that affected the \(\eta\) in this research due to additional heat consumption by the air dehumidification system. Due to such low energy efficiency of dehumidified-air-assisted spray drying, its application on an industrial scale has to be carefully deliberated, taking into account the possible benefits (higher content of sugar-rich material) and disadvantages (low feed rate and energy efficiency).