Techno-economic analysis of a hybrid solar-electric dryer

Nwakuba, N. R.; Okafor, Victor Chijioke; Okorafor, O.O.

doi:10.1080/15567036.2020.1782537

Cited by 15 publications

(21 citation statements)

References 35 publications

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“…This, therefore, elevated the products' sensitive heat as well as improved the evaporative potential of the drying medium (air) which created less pressure of moisture for swift diffusion. A greater fraction of the sensitive and latent thermal energy supplied to the system was lost through turbulence in the drying chamber as a result of high airflow which shortened the residence period of the supplied heat, similar scientific studies (Azadbakht, Torshizi, Ziaratban, & Aghili, 2017;Beigi, 2016;Jindarat et al, 2011;Nwakuba et al, 2018;Nwakuba, Okafor, et al, 2020) in which the obtained η_ d -values ranged from 2.50 to 54.37%. It was, therefore, found that the garden egg sample with slab geometric shape conceded the highest value of η_ d , whereas the white carrot with spherical geometry had the least value (Figure 7b).…”

Section: Drying Efficiency (η _ D )supporting

confidence: 64%

“…(b) Schematic representation of the product geometric shapes: (i) sphere, (ii) cylinder, and (iii) slab sample geometric dimensions are shown in Figure 1b. The initial moisture content of the samples was determined as reported in Nwakuba, Chukwuezie, et al (2020) and Nwakuba, Okafor, et al (2020). Each drying rack contained a sample size of 400 g measured using an electronic weighing balance with a sensitivity of ±0.01 g (0.01-100 g, ACS-ZE11, Camry Instr.…”

Section: Preparation Of Sample and Experimental Proceduresmentioning

confidence: 99%

“…The specific energy consumption (Q sp ) per kilogram of moisture in the product sample was calculated thus (Ndukwu et al, 2020;Nwakuba, Okafor, et al, 2020):…”

Section: White Carrotmentioning

confidence: 99%

“…The perishable and seasonal nature of agro‐materials especially vegetable products poses a tremendous challenge to their storability and net economic value (Kian‐Ppou & Karatas, 2019; Nwakuba, Chukwuezie, et al, 2020; Nwakuba, Okafor, et al, 2020). In Nigeria, about 50% of vegetables produced per year rot as a result of their considerable amount of water ranging between 80 and 90% (Idah, Obajemihi, Adeboye, & Olaniyan, 2014; Joardder, Alsbua, Akram, & Karim, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Influence of product geometry and process variables on drying energy demand of vegetables: An experimental study

Nwakuba

Ndukwe

Paul

2021

J Food Process Engineering

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The changing aspects of energy and its high demand during convective drying of food products prompted this present study, which aims at investigating the impact of product geometric shapes and process parameters on the energy demand of vegetables during convective drying. It considered three distinctive shapes (sphere, S g ; cylinder, C g ; and slab, R g ) of vegetables (cucumber, garden egg, and white carrot) at constant sample volume, dried in a laboratory convective dryer. The Box-Behnken Design tool was used to design the experiment and explored the effects of material geometries at varying drying conditions (air temperature: 50, 60, and 70 C; air velocity: 1.0, 1.5, and 2.0 ms −1 ) on the total and specific drying energy demand, drying efficiency, percent product shrinkage, and drying time of the fresh vegetables. Results obtained revealed that the spherical-shaped samples exhibited high moisture diffusion and gross reduction in drying time (120 min), thus greater potential for energy and drying system improvement. The values of the effective moisture diffusion, D e (0.72 × 10 −10 ≤D e ≤ 2.13 × 10 −9 m 2 s −1 ) increased with drying temperature, and the maximum D e -value was obtained for the S g -carrot sample. The percent product shrinkage ranged between 78.66-94.73% for the C g -garden egg and S g -cucumber samples, respectively. The specific energy demand of the fresh cucumber, eggplant, and white carrot samples varied significantly (p >.005) with sample geometry. The maximum specific energy demand (16.38 ± 0.41 MJ/kgH 2 O, respectively) was obtained for the cylindrical shaped samples, whereas the minimum specific energy demand of 9.06 ± 0.24 MJ/kgH 2 O was yielded by the spherical shaped samples. The mean energy and drying efficiencies of the system ranged from 3.25 to 12.26% and 7.22 to 28.24%, respectively; whilst drying time ranged between 470 and 840 min.At the optimum process variables of 69.85 C, 1.22 ms −1 , 0.999 geometric shape, and −0.9977 crop sample, the specific energy demand, drying time, drying efficiency, and percent shrinkage were found to be 14.21 ± 0.84 MJkg −1 , 820 ± 9.00 min, 22.76 ± 0.74%, and 92.104 ± 1.00%, respectively. Prospects for future application and recommendations for further studies were suggested.

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Section: Drying Efficiency (η _ D )supporting

confidence: 64%

Section: Preparation Of Sample and Experimental Proceduresmentioning

confidence: 99%

“…The specific energy consumption (Q sp ) per kilogram of moisture in the product sample was calculated thus (Ndukwu et al, 2020;Nwakuba, Okafor, et al, 2020):…”

Section: White Carrotmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of product geometry and process variables on drying energy demand of vegetables: An experimental study

Nwakuba

Ndukwe

Paul

2021

J Food Process Engineering

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“…The major problem with most of these dryers is their susceptibility to weather differences. Hybrid solar dryers work on solar energy from any of the standard sources such as fossil fuels, biomass, or electricity (Hossain et al, 2018;Nwakuba, Okafor, & Okorafor, 2020).…”

mentioning

confidence: 99%

Assessment of kinetics, effective moisture diffusivity, specific energy consumption, and percentage of thyme oil extracted in a hybrid solar‐electric dryer

Karami

Tahvilian

2020

J Food Process Engineering

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This research deals with the analysis process of thyme in a hybrid (solar‐electric) dryer. The drying process was administered using three air velocities of 1, 1.5, and 2 m/s and four temperatures of 40, 50, 60, 70°C. The drying rate developed with the increase in temperature and air velocity, therefore decreased the drying time. Ten mathematical models were applied to predict the drying kinetics of thyme. Consequently, the best model to describe the drying kinetics of thyme was Midilli model. The values activation energy and effective moisture diffusivity were ranged between 10.9 to 16.33 kJ/mol and 2.172 × 10–10 to 1.23 × 10–10 m2/s, respectively. The oil yield was significantly affected by drying situations. The essential oil of the leaves was determined by hydrodistillation. So, the highest essential oil amount equal to 2.4 CC (vol/wt) was obtained at temperature of 40°C and air velocity of 1.5 m/s.Practical ApplicationsDrying is the most significant process to maintain agricultural crops. The purpose of drying crops is the decrease of the moisture content to a level that provides secure storage over an extended term, and significant influence on the quality of dried crops. In this research, drying kinetics of Thyme at different air velocity and air temperatures in hybrid dryer were studied. Moreover, simplistic models for the simulation of the drying process were offered. Consequently, the aim of this work was to Introducing a new hybrid dryer for herbal plants, to decrease volatile loss or degradation of essential oil extracted from Thyme. It is application in medicinal plants post‐harvest technology.

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Economic analysis and drying kinetics of a geothermal‐assisted solar dryer for tomato paste drying

et al. 2021

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BACKGROUND:The economic value of many fruit and vegetables is often linked to the ability to preserve such natural products. In the case of tomatoes, the manufacture of 1 kg of powder or concentrate requires the evaporation of about 16 kg water kg −1 dry matter. In the present work, the effectiveness and economic analysis of solar drying systems for drying of tomato paste with and without geothermal water heat exchanger (GWHE) were studied. RESULTS:The GWHE integration significantly increased the recorded drying temperature up to 53.41 °C, with an improvement of 11.5 °C compared to the conventional dryer. Moreover, the drying temperature inside the drying chamber exceeded ambient temperature after sunset and at night by 30.8 °C. GWHE ensured a continuous drying process, while drying time was 22 consecutive hours, compared to the basic dryer with 18 h in 3 days. Effective moisture diffusivity was found to be 1.617 × 10 −9 and 1.202 × 10 −9 m 2 s −1 for hybrid and basic drying systems, respectively, using the slope. Three methods were used to perform economic analysis. The cumulative present worth of savings, at 23 382.6 USD, is much higher than the capital cost of the hybrid dryer, at 467 USD. The payback period is quite acceptable, at 2.21 years as compared to dryer lifetime of 15 years. Therefore, the hybrid dryer will dry tomato paste without additional charges for 12.79 years and is recommended for a large-scale tomato paste dryer.CONCLUSION: The hybrid system with GWHE ensures a continuous drying process during night-time, in addition to reduced drying time. The economic study revealed a high feasibility for the hybrid dryer, with a short payback period.

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Techno-economic analysis of a hybrid solar-electric dryer

Cited by 15 publications

References 35 publications

Influence of product geometry and process variables on drying energy demand of vegetables: An experimental study

Influence of product geometry and process variables on drying energy demand of vegetables: An experimental study

Assessment of kinetics, effective moisture diffusivity, specific energy consumption, and percentage of thyme oil extracted in a hybrid solar‐electric dryer

Economic analysis and drying kinetics of a geothermal‐assisted solar dryer for tomato paste drying

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