Experimental and Numerical Simulations of a Solar Air Heater for Maximal Value Addition to Agricultural Products

Zuhair Qamar (), Anjum Munir (), Timothy Langrish, Abdul Ghafoor and Muhammad Tahir
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Zuhair Qamar: Department of Farm Machinery & Power, University of Agriculture Faisalabad, Punjab 38000, Pakistan
Anjum Munir: Department of Energy Systems Engineering, University of Agriculture Faisalabad, Punjab 38000, Pakistan
Timothy Langrish: School of Chemical and Biomolecular Engineering, The University of Sydney, Camperdown, NSW 2006, Australia
Abdul Ghafoor: Department of Farm Machinery & Power, University of Agriculture Faisalabad, Punjab 38000, Pakistan
Muhammad Tahir: Department of Agronomy, University of Agriculture Faisalabad, Punjab 38000, Pakistan

Agriculture, 2023, vol. 13, issue 2, 1-17

Abstract: Agriculture is the backbone of Pakistan’s economy. Currently, the agricultural sector is facing many challenges, especially post-harvest losses, which result in lower yield and profitability. These losses may be reduced by developing indigenous post-harvest processing technologies, such as drying out of agricultural products to enhancement of their sustainability and reduce transportation costs. The country has the advantage of an abundant amount of solar insulation, which can be effectively utilized to operate post-harvest machinery, particularly solar heaters and dryers. Currently, conventional solar heaters face challenges due to lower efficiencies. Therefore, in this study, a solar air heater (SAH), having a size 1220 × 610 × 65 mm, was designed and developed to be connected to a milk powder spray drying system for converting raw milk to powder. Computational fluid dynamics (CFD) were used to anticipate air flow and temperature distribution across the SAH to evaluate optimal performance parameters. An air mass flow rate of 0.01 kgs −1 was required, with the CFD predicting an outlet temperature of 82 °C compared with the experimental observation of 73 °C. The pressure drop across the SAH was recorded to be 0.0000434 bar at this flow rate, which is negligible, with the SAH operating near ambient pressure. The overall heat loss coefficient for convection was 2.27 W. m −2 ·K −1 . The energy losses from the SAH were 37% and the useful energy was 63% of the total energy provided to the SAH. The breakeven point of SAH at a minimum of 4 h of daily usage was 3700 h or 2.5 years. The solar air heater used as a preheater for a spray dryer can save 30 PKR·kWh −1 of energy.

Keywords: solar air heater (SAH); computational fluid dynamics; performance optimization; milk powder; agricultural drying; post-harvest losses (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2023
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