Sampson UZOMA, Nnaemeka NWAKUBA, Kelechi ANYAOHA

Response Surface Optimization of Convective Air Drying Process in a Hybrid PV/T Solar Dryer

The increasing demand for improved techno-economic and efficient drying systems has impelled research on optimization study of solar drying process. This paper discusses the optimization of red pepper slices during drying process in a hybrid photovoltaic-thermal (PV/T) solar dryer using response surface approach. The study was conducted in humid tropical Nigerian environment characterized by intermittent solar irradiance, prompted by humid wind effect from regional water bodies. The effects of varying drying air temperatures (50, 60 and 70oC), air velocities (1.0, 1.5 and 2.0 m/s), and sample thicknesses (10, 15, and 20 mm) on the total energy consumption, drying efficiency, %shrinkage, and drying time of pepper samples were investigated using a 33-factorial treatment design. The results obtained were built-in and the responses plotted in 3-D surface plots and evaluated statistically to obtain variable relationships. The total and specific energy consumption ranged between 1.31 – 38.9 kWh and 6.92 – 62.76 kW/kg, respectively. The mean system drying efficiency varied between 6.73 - 35.14%, whereas the percentage shrinkage ranged between 56.91 - 73.90%. The drying time varied from 125.5 ± 7 - 205.5 ± 10 mins. At the optimum drying conditions of 70oC air temperature, 1.88 m/s air velocity and 14.31 mm sample thickness and desirability of 0.903, the total energy consumption, drying efficiency, shrinkage, and drying time were obtained as 4.03kWh, 20.46%, 67.05% and 183.8 mins, respectively. The predicted models had R2-values ranging between 0.9228 - 0.9989, which were verified and validated for accuracy using diagnostic plots and percentage error deviations. The results of this study indicate how indispensable some variables and process conditions are to the performance of hybrid PV/T solar dryer.

Keywords:

Photocell, vegetables energy, efficiency, product quality,

PDF

___

Abano, E.E., Ma, H., Qu, W. (2014). Optimization of drying conditions for quality dried tomato slices using response surface methodology. Journal of Food Process and Preservation, 38, 996 - 1009.
Afolabi, T.J., Akintunde, T.Y. and Oyelade, O.J. (2014). Influence of drying conditions on the effective moisture diffusivity and energy requirements of ginger slices. Journal of Food Research, 3(5): 103 – 112.
Ahmad, W.M., Zakaria, S.B., Aleng, N.A., Halim, N.A. and Ali, Z. (2015). Box-Cox transformation and bootstrapping approach to one simple t-test. World Applied Sciences Journal, 33(5): 704 – 908.
Anaeke, N.A.G., Mbah, G.O and Edeani, N.J. (2018). Response surface methodology for optimization of ot air drying of water yam slices. International Journal of Scientific and Research Publications, 8(8):248 – 259.
Azadbakht, M., Torshizi, V.M., Ziaratban, A. and Aghili, H., 2017. Energy and exergy analysis during eggplant drying in a fluidized bed dryer: Agricultural Engineering International, CIGR E-Journal. 19(3), 177-82.
Beigi, M. (2016). Energy efficiency and moisture diffusivity of apple slices during convective drying. Food Science and Technology, 36 (1), 145 - 150. Boughali, S., Benmoussa, H., Bouchekima, B., Mennouche, D., Bouguettaia, H. and Bechki, D. (2009). Crop drying by indirect active hybrid solar– electrical dryer in the eastern Algerian Septentrional Sahara: Solar Energy, 83(2009), 2223–2232.
Corzo, O., Bracho, N., Vasquez, A. and Pereira, A. (2008). Optimization of a thin layer drying process for coroba slices. Journal of Food Engineering, 85: 372 – 380.
Darvishi, H., Asi, R.A., Asghari, A., Najafi, G., and Gazori, H.A. (2013). Mathematical modeling, moisture diffusion, energy consumption and efficiency of thin-layer drying of potato slices: Journal of Food Process Technology, 4 (3), 215 - 229. Dianda, B., Ousmane, M., Kam, S., Ky, T. and Bathiebo, D.J. (2015). Experimental study of the kinetics and shrinkage of tomato slices in convective drying: African Journal of Food Science, 9(5), 262-271.
Duffie, J.A., Beckman, W.A. (2006). Solar Engineering of Thermal Process. Wiley, New York.
Erbay, Z. and Icier, F. (2009). Optimization of hot air drying of olive leaves using response surface methodology. J. Food Eng. 91:533 - 541.
Freedman, D., Pisani, R. and Purves, R. (2007). Statistics 4th, W.W Norton & CO, New York, Pp. 20 -23.
Hafezi, N, Sheikhdavoodi, M.J. and Sajadiye, S.M. (2015). The effect of drying kinetic on shrinkage and colour of potato slices in the vacuum-infrared drying method. International Journal of Agricultural and Food Research, 4(1):24 – 31.
Han, Q.H., Yin, L.J., Li, S.J., Yang, B.N., Ma, J.W. (2010). Optimization of process parameters for microwave vacuum drying of apple slices using response surface method. Drying Technology. 28(4):523-532.
Kumar, D., Prasad, S. and Murthy, G.S. (2011). Optimization of microwave-assisted hot air drying conditions of okra using response surface methodology. Journal of Food Science and Technology, 4:1-13.
Lopez-Vidana, E.C., Mendez-Lagunas, L.L. and Rodriguez-Ramirez, J. (2013). Efficiency of a hybrid solar-gas dryer. Solar Energy, 93 (2013), 23 – 31.
Minaei, S., A. Motevali, D. and Khoshtagaza, M.H. (2011). Evaluation of energy consumption in different drying methods. Energy Conversion and Management, 52 (2): 1192-1199.
Minaei, S., Chenarbon, H.A., Motevali, A. and Arabhosseini, A. (2014). Energy consumption, thermal utilization efficiency and hypericin content in drying leaves of St. John’s Wort (Hypericum Perforatum): Journal of Energy in Southern Africa, 25(3), 27 – 35.
Mortezapour, H., Ghobadian, B., Khostaghaza, M.H. and Minaei, S. (2012). Performance analysis of a two-way hybrid photovoltaic/thermal solar collector. Journal of Agricultural Science Technology, 14: 767 – 780.
Ndukwu, M.C., Simo-Tagne, M., Abam, F.I., Onwuka, O.S., Prince, S., Bennamoun, L. (2020a). Exergetic sustainability and economic analysis of hybrid solar-biomass dryer. Heliyon, 6(e03401):1-13. https://doi.org/10.1016/j.heliyon.2020.e03401.
Ndukwu, M.C., Onyenwigwe, D., Abam, F.I., Eke, A.B., Dirioha, C. (2020). Development of a low-cost wind-powered active solar dryer integrated with glycerol as thermal storage. Renewable Energy, 154(2020): 553 – 568.https://doi.org/10.1016/j.renene.2020.03.016.
Nwakuba, N.R., Asoegwu, S.N. and Nwaigwe, K.N. (2016a). Energy requirements for drying of sliced agricultural products: a review. Agricultural Engineering International. CIGR E-Journal, 18(2), 144-155. Nwakuba, N.R., Asoegwu, S.N. and Nwaigwe, K.N. (2016b). Energy consumption of agricultural dryers: an overview. Agricultural Engineering International: CIGR Journal, 18(4):119-132.
Nwakuba, N.R., Chukwuezie, O.C., Asonye, G.U., Asoegwu, S.N. (2018). Energy analysis and optimization of thin layer drying conditions of okra. Arid Zone J. Eng. Tech. Env. 14 (2018): 135 - 154.
Nwakuba, N.R. (2019). Optimization of energy consumption of a solar-electric dryer during hot air drying of tomato slices. Journal of Agricultural Engineering, 50(4): 150 - 158. Doi https://doi.org/10.4081/jae.2018.876
Poonia, S., Singh, A.K. and Jain, D. (2018). Design development and performance evaluation of photovoltaic/thermal (PV/T) solar dryer for drying of ber (Zizyphus mauritiana) fruit. Cogent Engineering, 5:1-18. https://doi.org/10.1080/23311916.2018.1507084.
Tiwari, G.N. (2012). Solar Energy Fundamentals, Design, Modeling and Application. Narosa Publishing House PVT Ltd., New Delhi, pp. 203 – 250.
Reyes, A., Mahn, A., Huenulaf, P. and Gonzalez, T. (2014). Tomato dehydration in a hybrid solar dryer. Chemical Engineering Processing Technology, 5(2014), 1-8.
Sanusi, M.M. and Ayinde, I.A. (2013). Profitability of pepper production in derived savannah zone of Ogun State, Nigeria. International Journal of Agriculture and Food Security 4 (1): 401-410.
Sumic, Z., Vakula, A., Tepic, A., Cakarevic J., Vitas, J. and Pavlic, B. (2016). Modeling and optimization of red currants vacuum drying process by response surface methodology (RSM). Food Chemistry, 203:465-475.
Uzoma, S., Nwakuba, N.R. and Anyaoha, K.E. (2019). Performance of Hybrid Photovoltaic/Thermal Crop Dryer in Hot Humid Nigerian Region. Journal of Agricultural Engineering, 2(XLIV): 56 – 75.