Theses and Dissertation

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Browsing Theses and Dissertation by Author "Loemba, Aldé"

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    Comprehensive Assessment Of A Solar-Assisted Heat Pump Dryer Integrated With Thermal Energy Storage Materials: Performance, Techno-Economic Viability, And Life Cycle Analysis
    (NM-AIST, 2024-08) Loemba, Aldé
    Appropriate drying methods are essential for preserving nutrients in agricultural products. In most developing countries, open sun drying is the traditional method for drying agricultural products. Nevertheless, there are several risks associated with this method for agricultural products, such as microbial contamination, deterioration of quality, and animal loss. Because drying parameters can be easily controlled and the quality of the dried products is preserved, heat pump drying has recently been found to be an effective drying technique for agricultural products. Heat pump dryers are currently used in conjunction with solar drying systems to improve drying and thermal performance. However, in developing countries, particularly Sub-Saharan Africa, these devices are still in their infancy. The few reported heat pump dryers in Africa are made from locally available materials to keep them affordable, but very little is known about their techno-economic analysis and life cycle assessment. In addition, more works need to be done to maximize this device’s efficiency, because using solar-assisted heat pump dryers in non-sunny weather, or particularly at night, is difficult because solar is intermittent. This study therefore focused on designing, manufacturing, and investigating the performance, techno-economic viability, and life cycle analysis of a solar-assisted heat pump dryer integrated with thermal energy storage materials for drying agricultural products. Experiments were carried out to dry tomatoes, moringa oleiferaleaves, and cavendish bananas. Along with proximate, mineral, and vitamin analyses, the study also included performance, techno-economic and life cycle analysis of the proposed dryer. Results showed that the proposed dryer is an effective method to preserve nutrients of the dried products. Furthermore, the developed dryer showed good efficiency and demonstrated a noticeable decrease in the moisture content of the agricultural products tested. The dryer’s low energy consumption was proven by the coefficient of performance ranging from 2.54 to 3.69. Concurrently, the drying rate varied from 0.16 to 0.24%.min-1 The average dryer efficiency ranges from 12.52 to 23.23%, and the highest dryer efficiency was 80.69%. The highest dryer efficiency that was attained is higher than the 72% that is typically documented in the literature. Furthermore, the results showed that the dried products contained significantly higher concentrations of proximate parameters andminerals than the fresh ones, as evidenced by a p-value less than 0.05. In addition, interesting economic indicators were found by the techno-economic analysis, with a 1.5-year payback period and a 65% return on investment. This demonstrates that the investment in the proposed dryer can be recovered in a relatively short period of time. Results of the life cycle assessment revealed that the drying process using the proposed dryer has less environmental effects. These findings are consistent with previous research. Thus, the proposed solar-assisted heat pump dryer integrated with thermal energy storage system is a successful method to dry agricultural products. The findings highlight the significance of using thermal energy storage materials to improve both the efficiency and performance of solar-assisted heat pump dryers in agricultural product drying. Therefore, the proposed dryer is recommended for drying agricultural products