Title: Comparison of environmental pollution and social cost analyses in different drying technologies

Authors: Ali Motevali; Hassan Jafari; Esmaeili Zakipour Molkabadi; Songming Zhu; Reza Tabatabaee Koloor; Ahmad Taghizadeh-Alisaraei

Addresses: Department of Mechanics of Biosystem Engineering, Sari Agricultural Sciences and Natural Resources University, Sari, Iran ' Department of Mechanics of Biosystem Engineering, Sari Agricultural Sciences and Natural Resources University, Sari, Iran ' Department of Mechanics of Biosystem Engineering, Sari Agricultural Sciences and Natural Resources University, Sari, Iran ' College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou, 310058, China ' Department of Mechanics of Biosystem Engineering, Sari Agricultural Sciences and Natural Resources University, Sari, Iran ' Department of Biosystems Engineering, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran

Abstract: Four different widely used dryers (i.e., recirculation, fluidised-bed, hybrid hot-air/infrared, and hybrid microwave/hot-air dryers) were used to analyse the gas emissions from different drying processes of Aloe vera. According to the results, the highest and lowest actual specific energy consumption were 306.977 and 3.182 kWh/kgwater reported for fluidised-bed and hybrid microwave/hot-air dryers, respectively. Given the energy consumption of different dryers, the highest CO2, SO2 and NOx emission levels were 314.651, 4.689 and 0.827 kg/kgwater for the steam power plant, 337.06, 1.195 and 1.778 kg/kgwater for the gas turbine plant, and 190.940, 0.714 and 1.161 kg/kgwater for the combined-cycle power plant. The lowest energy consumption was reported for drying with the microwave/hot-air dryer at 60°C, airflow velocity of 0.3 m/s and power level of 300 W. The highest and lowest social costs for the microwave/hot-air dryer under the said conditions were 0.12 and 0.08 USD for evaporating 1 kg water, which belonged to gas turbine and combined-cycle plants, respectively. According to the results, the lowest emission level was observed in the combined-cycle power plant when burning natural gas.

Keywords: environmental pollution; greenhouse gases; Aloe vera; power plants; social costs; drying technology.

DOI: 10.1504/IJGW.2020.10031891

International Journal of Global Warming, 2020 Vol.22 No.1, pp.1 - 29

Received: 07 Aug 2019
Accepted: 25 Jan 2020

Published online: 09 Oct 2020 *

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