Drying Air Temperature Research Articles

Thermo-kinetic behavior of closed-loop heat pump dryer with different drying chambers for holy basil leaves drying application: an experiment approach

ABSTRACT A closed-loop heat pump drier was designed and constructed with three different drying chambers (tray, fluidized bed, and integrated) to investigate the drying kinetics (drying rate and specific moisture evaporation rate) of holy basil leaves in this research work. The significance of drying temperature, air velocity, and mass of leaves on the performance of the dryer chambers was explored and compared through an experimental investigation. In addition, the present research focuses on analyzing the significance of drying air temperature (45, 50, and 55°C), air velocity (1.5, 2.0, and 2.5 m/s), and mass of holy basil leaves (5, 6, and 7 kg) on the performance of the dryer chambers. In tested combinations, the specific moisture evaporation rate and drying rate are higher in the integrated drying chamber. Notably, the effective moisture diffusivity coefficient exhibited a range of values from 2.68166 × 10−10 to 6.10243 × 10−10 m2/s. The design of the experiment approach is applied to optimize the number of experiments, and an analysis of variance was conducted to identify the most influential parameter. The results showed that temperature had a greater effect, accounting for 32% of the variation in the moisture evaporation rate.

Quality aspects of paddy grain and seed dried in HSTU mobile grain and seed dryer integrated with a dual heating system

Proper drying and excellence of dried grain and seed are the key concerns of millers, farmers and seed growers. The performance of a new Hajee Mohammad Danesh Science and Technology University (HSTU) mobile grain and seed dryer (HMD) integrated with dual heating system was assessed regarding the quality of dried seed and grain. The HMD was found to be capable of drying 720±10 kg paddy in a batch and drying period varied between 7 to 8 h at drying air temperatures of 65 oC. Paddy seeds of BRRI Dhan 49 and BRRI Dhan 89 were dried at 40 oC and the drying time required 9 to 10 h and 14 to 16 h in Aman and Boro season, respectively. Head rice yield and milling recovery varied from 59.50±0.16% to 61.61±0.54% and 74.95±0.09% to 75.70±0.59% for paddy dried in HMD. In addition, higher germination percentage (GP) of BRRI Dhan 49 varieties was found in Aman season that ranged from 86% to 88% which was dried in HMD in contrary to GP of paddy seeds dried under the sun. Moreover, higher GP was found from BRRI Dhan 89 varieties dried by HMD in Boro season. Also, the vigor index of HMD dried paddy seeds was more than the sun dried samples in both seasons. In conclusion, HMD integrated with a dual heating system is recommended for using at farm level as an alternative drying process for rapid and efficient handling of high-moisture grain and seed in Bangladesh and other subtropical nations in adverse climate.

Influence of Varying Drying Air Temperatures on Physico-chemical and Nutritional Characteristics of Bael (Aegle marmelos) Pulp

Drying is a critical process for preserving fruits, but the nutrients in fruits are highly sensitive to temperature. Finding an optimal drying temperature is crucial to maximizing the retention of nutritional and physico-chemical properties. This study investigated the effects of different drying air temperatures on properties of Bael fruit (Aegle marmelos) pulp. Fresh pulp (1000 g) was dried at 55°C, 65°C, and 75°C, and the resulting pulp was analyzed for physical, chemical, and nutritional changes compared to the fresh pulp. Statistical analysis was conducted through one-way ANOVA was done by Duncan's Multiple Range Test (DMRT) method. The results showed that drying at 65°C retained the most nutrition while preserving color and other physical properties. Color analysis indicated darkening and increased redness at higher temperatures. Chemical properties such as pH and ash content increased with drying, while titratable acidity was highest at 65°C. Nutritionally, protein content peaked at 65°C, while fat content increased steadily with drying air temperature. Fiber and ascorbic acid levels decreased as drying air temperatures rose. The Bael powder obtained by drying at 65oC could be very well used for making cookies and other value-added products.

Optimizing Sensitivity of Room Temperature CO2 Sensors through Co-Doped ZnO Nanorods By Magnetron Sputtering System

Metal oxide semiconductors (MOS) based gas sensors have been identified as a promising solution for future applications due to their exceptional electrochemical, physical, and gas sensing properties. Due to their excellent optical and electrical features, ZnO nanostructures have become increasingly popular for gas detection applications, mainly because of their abundant availability. Despite its potential, the ZnO-based sensors have challenges such as poor selectivity and high power consumption at elevated operating temperatures. Transition metal doping, for example with cobalt depicted decent promising results in high response and selectivity of ZnO nanomaterials towards certain gasses. This study investigates the sensitivity enhancement of room temperature CO2 sensors utilizing the cobalt-doped ZnO (CZO) nanorod architecture. The CZO thin films were deposited on glass substrates using radio frequency (RF) magnetron sputtering at varying powers. Structural, morphological, and gas response properties of the CZO thin films were analyzed.Figure 1 illustrates the evolution of resistance over time for CZO sensors when exposed to CO2 gas concentrations ranging from 1 to 500 ppm at room temperature in dry air. In this investigation, the response to gas follows a consistent linear pattern within the 1−300 ppm range. However, as the concentration rises, a noticeable deviation towards nonlinearity becomes more pronounced. The sensor exhibits a heightened response across various concentration levels: 1 (8.9), 50 (12.5), 100 (14.79), 150 (15.7), 250 (18.82), and 500 (23.52) ppm. Discrepancies in the sensor response are attributed to the distinct surface morphology inherent to each sensor type. The introduction of co-doping enhances the occurrence of point defects and oxygen vacancies within the CZO sensors. The Scanning Electron Microscopy (SEM) images reveal that the CZO material exhibits a highly organized surface morphology, characterized by densely packed spherical structures, and the cross-sectional analysis of the material shows a uniform thickness of 136 nm, indicating its potential applications in the field of sensing and detection, shown in figure 2. This study underscores the effectiveness of CZO nanorod architecture in rapidly detecting CO2 at room temperature, presenting promising avenues for environmental monitoring and sensing applications Figure 1

Enhancing skimmed milk powder functionalities through multicriteria optimization of outlet drying air temperature and spraying air pressure

This study investigated the effects of spraying air pressure and outlet air temperature on the physicochemical and functional properties of skimmed milk powder. Experimental design methodology showed that higher outlet air temperatures improved dry matter content, gelation ability, and flowability, but strengthened colour, moisture sensitivity, and favoured protein denaturation. Spraying air pressure primarily influenced particle size, affecting powder rheological properties and colour. This study highlights the importance of controlling drying parameters to optimize powder properties. The use of a genetic evolutionary algorithm in the optimization process allowed the simultaneous improvement of several functionalities of skimmed milk powder. The findings of this study can contribute to the development of enhanced powders with tailored properties for specific industrial applications.

MATHEMATICAL MODELLING OF DRYING PROCESS

The aim of this study is to experimentally investigate the drying kinetics of common basil using a solar drying unit. The tests consist in studying the effect of constant and variable drying air temperature on the drying kinetics. In this empirical approach, we aim to determine and compare drying characteristic curves under conditions where the drying air temperature is constant or variable. Subsequently, correlations describing the drying rate will be developed, these will be used at a later stage to size and model the solar dryer. Few numerical models have been used in the literature to explain the drying kinetics of common basil, in fact, given the complexity of the transport mechanisms and the diversity of products, a single model cannot represent all situations. This justifies an experimental study in the laboratory to determine the drying kinetics of a particular product.

Integrated solar dryer and distillation system with PCM and injection, powered by PVT panels and solar concentrator

This research introduces a novel hybrid system integrating solar drying, solar distillation, and photovoltaic thermal panels, aimed at drying agricultural products, producing clean drinking water, and conserving energy. The system enhances the drying air temperature using thermal energy storage materials and a solar dish concentrator connected to a hot water storage tank, ensuring continuous operation even after sunset. The solar distiller, equipped with energy storage materials and an air injection system, is integrated with an external condenser to condense water vapor before expulsion, thereby increasing freshwater productivity. The results revealed that the developed system achieved an accumulative freshwater productivity of 87.1 L per day. The rates of water removal from dried potato slices ranged from 0.18 to 0.91 kg/h between 8:00 am and 10:00 pm. Additionally, the system achieved a gain output ratio of 1.38, indicating a significant improvement in energy efficiency. This innovative system offers practical solutions to address energy and freshwater scarcity, especially in remote regions of the Middle East and North Africa (MENA) region, which are characterized by high solar irradiance. The implementation of such hybrid systems could contribute to sustainable development by reducing reliance on conventional energy sources and mitigating environmental pollution.

Combining Ultra-Turrax and ultrasonic homogenization to achieve higher vitamin E encapsulation efficiency in spray drying

Vitamin E, a soluble antioxidant widely used in the food and pharmaceutical industries, is rich in tocopherols and phytosterols. Since vitamin E molecules are highly sensitive to oxidation, encapsulation is a viable and effective technique for preservation of the properties of Vitamin E and improving its stability during storage, maintaining the nutritional value. In this work, the aim was to encapsulate concentrated vitamin E using a combination of Ultra-Turrax and ultrasonication to achieve higher encapsulation efficiency in spray drying. In the first stage, the vitamin E oil was encapsulated employing only Ultra-Turrax homogenization, with subsequent optimization of spray drying. The coating materials used were maltodextrin and whey protein isolate. Optimization of the spray drying step evaluated the effects of the drying air temperature (T) and the feed flow rate (Q), to obtain better yields and a high-quality product. In the second stage, the use of ultrasonication in an additional homogenization step was evaluated, aiming to further improve the encapsulation process. The results showed that the best drying conditions (first stage) were T = 180 °C and Q = 0.6 L/h, which provided the highest yield (67.73%) and high encapsulation efficiency (73.73%). The microspheres produced had similar properties, with mean diameters ranging from 0.64 to 12.99 μm. In the second stage of the investigation, the application of ultrasonication immediately after the Ultra-Turrax homogenization enabled the encapsulation efficiency to be increased to 94.05%, with a yield of 57.54%, using an ultrasonication time of only 7 min. This showed that addition of the ultrasonic homogenization step to the process greatly improved the encapsulation efficiency and could be used to produce vitamin E-enriched powder microcapsules by spray drying, with application in the food industry.

On the industrial solar drying of tomatoes in Biskra : A preliminary study

The objective of this study is to carry out a pre-feasibility study of solar industrial drying as a preliminary step before investing in large-scale solar drying projects in Algeria. Our primary goal is to promote the use of industrial solar dryers and to incite public authorities and industrials to invest in this promising niche. This work aims to strengthen the contribution of renewable energies and particularly solar energy in the sustainable development of the agri-food sector. Indeed, using solar energy will reduce the energy consumption and decrease greenhouse gas emissions of drying process. The prefeasibility analysis is achieved using the RETScreen Suite. Our study aims to investigate energy consumption of an industrial solar dryer of tomatoes, located in the city of Biskra. Various parameters as solar collector type and drying air temperature were tested and discussed. The obtained results showed a reduction in energy consumption up to 35%. Likewise, the reduction of GHG emissions recorded very favorable rates. This study's findings provide a preliminary vision for investors in the agri-food sector to build their project so they may maximize their profit while supporting the environment by lowering carbon emissions.

CONVECTIVE DRYING OF CHOKEBERRY CV. “VIKING” AND MODELING OF DRYING KINETICS

In this study, the effects of drying air temperatures (50, 60, 70, and 80°C) and velocities (0.5, 0.8, and 1.2 m/s) on chokeberry quality during convective drying were evaluated. The drying time decreased significantly with increasing drying air temperatures and velocities, from 2265 minutes at 50°C to 195 minutes at 80°C, and from 360 minutes at 0.5 m/s to 240 minutes at 1.2 m/s at 70°C. Higher drying air temperatures and velocities also enhanced the fruit color quality. The best antioxidant activity, anthocyanin, and phenolic content were achieved at 70°C with dryin air velocities between 0.5 m/s and 1.2 m/s. The Midilli et al. model provided the best fit for the drying kinetics, with high accuracy (R²≥0.9978, χ²≤0.0003, RMSE≤0.0161).

Optimization of thermal photovoltaic hybrid solar dryer for drying peanuts

The drying of agricultural products is traditionally carried out using solar radiation. However, this process is time-consuming and also unreliable in locations having cold and humid environments. This study experimentally investigates an innovative air collection system integrated with a dryer. The study focuses on the drying analysis of peanuts utilizing three operational modes of a solar dryer: forced convection, natural convection, and traditional open-sun drying. Key parameters including solar radiation intensity, moisture extraction, and outgoing air temperature from the collector were studied. Solar radiation served as the primary energy source, driving the solar dryer's operation within a drying air temperature range of 33 °C–58 °C, applied to 8 kg of peanuts. Initially, the peanuts exhibited a moisture content of 72 %. The developed solar dryer subsequently reduced the moisture content of the peanut by 18 %. The study evaluated three key aspects: electrical efficiency, thermal efficiency, and overall thermal efficiency of the proposed hybrid collector and solar dryer system, conducted from 9 a.m. to 4 p.m. Results indicate that the forced convection mode of solar drying outperformed the other modes, demonstrating superior effectiveness. These findings hold significant implications for the advancement of solar dryer technology, offering valuable insights for the wider solar drying community.

Essential oil distillation residue as environmentally friendly feedstock in gasification: effect of dry air flow rate and temperature on gasification performance

Essential oil distillation residue as environmentally friendly feedstock in gasification: effect of dry air flow rate and temperature on gasification performance

Operational parameters optimization of convection air-drying with ultrasound pretreatment of Cyperus rotundus L. tubers by RSM

Drying is an important step in the postharvest processing of agricultural products, as it allows the product to be preserved by reducing water activity to safe values, which stops microorganism growth and enzymatic reactions. In this context, the objective of this study was to assess how various drying temperatures, combined with ultrasonic pretreatment, affect drying rates and essential oil production. Assays were conducted according to a Central Composite Rotational Design, considering two factors with the following intervals: duration of the ultrasonic bath from 0 to 40 min, drying air temperature from 40 to 70 °C. The optimization was carried out using Response Surface Methodology (RSM). The essential oil was extracted by hydrodistillation and its constituents were identified by gas chromatography coupled to mass spectrometry. Histochemical analyses of fresh tubers were performed. The Midilli model was the one that best described the drying kinetics of Cyperus rotundus in all treatments. The drying time of C. rotundus tubers was dependent only on temperature (decreasing linear effect), it was possible to describe the variation in drying time as a function of temperature. It was not possible to adjust a model for ultrasonic bath time or drying temperature that would optimize both essential oil yield and the drying time of C. rotundus tubers. However, in this study, shorter drying times were observed compared to previous studies on C. rotundus tubers drying in the shade at room temperature. A total of 29 chemical constituents have been identified in the essential oil extracted from C. rotundus tubers, of which the majority are: 3,4-dimethyl-3-cyclohexen-1-carboxaldehyde (19.23%); caryophyllene oxide (17.63%); and α-cyperone (9.54%). Histochemical analyses of C. rotundus tubers showed the presence of starch, phenolic compounds, and lipids.

Experimental and numerical investigation of the incorporation of an air temperature controller for indirect solar dryers

Solar drying systems often face the challenge of overheating due to uncontrolled solar collectors, which can degrade the quality of dried products by destroying enzymes, vitamins, and their chemical composition. To address this issue, we developed and validated a new control system for stabilizing drying air temperature using both experimental and CFD numerical methods. This system not only effectively maintains the desired air temperature but also extends the lifespan of solar collectors by adjusting their exposure during periods of excessive solar radiation. The experimental results demonstrated that without the control system, the air temperature peaked at 72 °C, leading to potential product degradation. In contrast, the control system has succeeded in stabilizing the air temperature at an optimum level. Additionally, the validated CFD model confirmed the effectiveness of this control technique in various climatic conditions, including cold semi-arid, typically Mediterranean, hot semi-arid, and sub-desert conditions. The findings underline the importance and necessity of temperature control in solar drying systems, as well as the effectiveness of the CFD method in predicting system performance. Furthermore, this work significantly enhances the efficiency and applicability of solar drying technology, offering a practical solution for improving product quality and system durability.

Effect of Blanching Temperature and Convective Hot Air-drying Temperature of Orange Peel Slices on Its Quality Evaluation

Drying characteristics of orange peel was investigated by blanching and convective hot air drying of orange peel slices (of 3mm thickness) at the temperature 40ºC, 50ºC and 60ºC. Drying models i.e. Lewis, Henderson and Pabis and Page were fitted to the experimental data on moisture ratio with respect to time. The page model fitted well r^2≥0.976 and MSE≤0.0012 among all the models tested for the experimental data. Effective diffusivity (Deff) at time (t) for orange peel were 0.086×10-8m2/s, 1.834×10-8m2/s and 2.017×10-8m2/s which was blanched at 72ºC:10 min, 82ºC:8min and 92ºC:5 min and dried at 40ºC; 0.0903688×10-8m2/s, 1.077×10-8m2/s and 1.898×10-8m2/s which was blanched at 72ºC:10 min, 82ºC:8min and 92ºC:5 min and dried at 50ºC; 1.168×10-8m2/s, 1.422×10-8m2/s and 1.579×10-8m2/s which was blanched at 72ºC:10 min, 82ºC:8min and 92ºC:5 min and dried at 60ºC. The activation energy (Ea) for moisture diffusion was found to be 2.244×104 kJ/mole, 2.523×104 kJ/mole and 1.262×104 kJ/mole. The quality parameter i.e. T.S.S was in 20 to 60(°B), acidity was in the range of 0.32 to 18.09 %, reducing sugar was in the range of 19.05 to 6.21 % non-reducing sugar was in the range of 2.56 to 10.13%, total sugar was in the range of 9.08 to 25.8%, pH was in the range of 5.4 to 3.6%, ascorbic acid was in the range of 18.2 to 34.76%, yellowness index was in the range of 77.76 to 154.40 and protein was in the range of 8.60 to 11.24% on orange peel powder prepared from blanching at 72ºC: 10 min, 82ºC: 8min and 92ºC: 5 min dried at 40⁰C, 50⁰C and 60⁰C respectively were determined and discussed.

Assessing the exergy sustainability of a paddy drying system driven by a biomass gasifier.

Paddy parboiling in rice industries is an energy-intensive process that requires huge attention for energy conservation, fuel economy, and sustainability. Thus, several research initiatives have been undertaken to adopt a suitable energy conversion system in such industries to improve thermal efficiency and reduce environmental impact. In this study, exergy performance and exergy-based sustainability indicators have been investigated on a reversible bed paddy dryer coupled with a rice husk-fuelled downdraft gasifier. The experiment was conducted at the optimum operating conditions such as an equivalence ratio of 0.2 in the gasifier and a drying air temperature of 80℃ in the dryer. The exergy efficiency of the reversible bed dryer and the gasifier were 65.53% and 70.92% respectively. The lowest exergy efficiency of 35.29% was seen in the combustion chamber since a huge exergy destruction of 2.75kW occurred. Therefore, the combustion chamber has a high potential improvement of about 1.66kW. Due to less exergy destruction, the gas cooler and air duct showed high exergy efficiency of 62.36% and 76.2% respectively and the lowest values in exergy-based sustainability indicators. The assessment of environmental and sustainability factors on each component showed that the combustion chamber has a high waste exergy ratio of 0.688, environment effect factor of 1.95, exergy destruction coefficient of 0.69, and exergy sustainability index of 0.51.

Modeling a hybrid solar- gas dehydrating plant for agro-industrial products

The article presents the development of a mathematical model for a dehydrating plant with a processing capacity of 100 to 200 kg of fresh product with both solar and gas thermal sources. The comprehensive plant model is based on mass and energy balances that consider the impact of real environmental conditions into the process. The model reproduces an experimental pineapple dehydration process with a maximum relative error of 7 %. According to our simulation results, reducing infiltration rate into the drying tunnel from 20 % to 0 % leads to a 7 °C increase in air drying temperature. This represents a reduction in drying time of 24 min. A 30 min reduction in drying time was observed when the drying airflow was decreased by 50 %. While increasing the airflow by 70 % results in 10 min longer drying time. When the minimum drying air temperature was increased from 40 °C to 70 °C, the drying time was reduced by 90 min. This reduces the use of electrical energy but increases the use of gas. Therefore, we estimated a energy total cost of $12.20 per 100 kg batch. Given the limited number of hybrid plant models in the literature, the integral dynamic modeling strategy offers an interesting option due to its flexibility, as it can be extended to the analysis of different plants and products. Furthermore, it enables the potential establishment of design, operation, and control strategies that could result in the process intensification.

Drying kinetics, thermodynamic properties and physicochemical characteristics of Rue leaves

Generally, medicinal plants are harvested with high amount of water, so it is essential to subject the product to drying as soon as possible to prevent degradation before application. Most compounds from medicinal plants are sensitive to drying processes, so it is important to adjust the drying conditions. The objective of this study was to describe the drying of Rue (Ruta chalepensis L.) leaves, select the models that best fit each drying condition, determine the activation energy and thermodynamic properties of the leaves, and evaluate their quality after drying. Leaves were harvested with moisture content of 3.55 ± 0.05 kg water kg−1dry matter and subjected to drying at temperatures of 40, 50, 60 and 70 °C. Valcam model showed the best fit to represent the drying kinetics of Rue leaves at temperatures of 40 and 70 °C, and Midilli model proved to be better for the temperatures of 50 and 60 °C. Effective diffusion coefficient increased linearly with the increase in drying air temperature, and the activation energy was 60.58 kJ mol−1. Enthalpy, entropy and Gibbs free energy values ranged from 57.973 to 57.723 kJ mol−1, from − 0.28538 to − 0.28614 kJ mol−1 K−1 and from 147.34 to 155.91 kJ mol−1, respectively, for the temperature range of 40–70 °C. Drying air temperature promoted darkening or tendency to loss of green color; increase in drying air temperature leads to greater discoloration, as well as a higher concentration of total phenolic compounds (about 221.10 mg GAE mL−1 g–1 dm), with a peak at temperature of 60 °C.

Effect of foaming agents and dilution ratio on physicochemical and bioactive compounds profile of dried palmyra pulp

The study was carried out to observe the effect of glycerol monostearate (1.0 %, 2.0 %, and 3.0 %), soy protein isolate (0.5 %, 1.0 %, and 1.5 %) and dilution ratio (1:1, 1:1.5) on foam characteristics at whipping time of 4 min. All the samples were incorporated with 0.5 % methyl cellulose (MC) as foam stabiliser and 5 % maltodextrin (MD) as drying aid. The effect of different drying air temperatures (60 °C and 70 °C) at foam thickness of 4 mm on phytochemical, biochemical and functional quality attributes was studied. The efficacy of artificial neural network (ANN) on foam-mat drying kinetics was tested. Foam expansion of the palmyra pulp increased to 108 % when added with 2 % GMS and diluted to 1:1.5. The increase was even more up to 138 % when the same diluted pulp was added with 1.5 % SPI. On the contrary, the foam retention and the foam stability were reduced at a higher dilution ratio. GMS (2 %) or SPI (1 %), each diluted at a 1:1 ratio, exhibited better foaming and colour characteristics. Drying was faster in pulp foamed with SPI (1 %) than in pulp incorporated with GMS (2 %). Non-foamed pulp showed lower drying rates and produced a compact sheet-like mat with a relatively harder and sticky texture. Effective moisture diffusivity values ranged from 1.820 × 10−8 to 2.721 × 10−8 (m2/min) and increased with an increase in the drying temperature. The tansig transfer function of ANN modelling could best predict the moisture ratio with drying time for all the foamed and non-foamed samples. Quality analysis showed that the palmyra pulp foamed with 0.5 % MC, 5 %, MD, and 1 % SPI, diluted at a 1:1 ratio, whipped for 4 min, and dried at 70 °C with foam thickness of 4 mm could produce the powder with best quality attributes. The developed powder was found to possess 79.341 ± 0.998 mg GAE/100 g of total phenolic content, 72.669 ± 0.964 % of antioxidant activity, 60.526 ± 0.975 mg/100 g of ascorbic acid content, 35.287 ± 0.973 % of reducing sugar, 15661 ± 192 µg/100 g of β-carotene with water absorption and hygroscopicity of 2.374 ± 0.827 g/g and 38.487 ± 1.020 % respectively.

Effect of Hot Air Drying Temperature on Drying Kinetics, Physico-Chemical Properties, and Energy Consumption of Culture Asparagus (Asparagus officinalis L.)

Influences of drying air temperatures on drying time, specific energy consumption as well as product quality of culture asparagus were investigated in hot-air drying. The drying properties of asparagus samples were performed in a laboratory scale convection dryer at three different temperatures. The drying times of asparagus samples were found as 1200, 630 and 510 min for 50, 60 and 70 °C, respectively. In regard to the data obtained, Midilli et al. model is superior to other models to describe drying behavior of asparagus samples. The effective moisture diffusivity values of asparagus samples were calculated between 6.32 ∙ 10−9−1.62 ∙ 10−8 m2/s and the activation energy was estimated as 43.59 kJ/mol. The highest rehydration content and the least total color change were found in asparagus slices dried at 50 °C. Energy consumption values for asparagus samples dried at 50, 60 and 70 °C temperatures were obtained as 10.14, 5.32 and 4.31 kWh, respectively. In terms of energy consumption values, the best efficiency among all drying temperatures was obtained at 70 °C. It has been determined that the specific energy consumption decreased with increasing temperature.