Development and performance evaluation of a tray dryer powered by generator exhaust gas waste heat
| dc.contributor.author | Ononogbo, Chibuike | |
| dc.date.accessioned | 2025-06-20T12:55:10Z | |
| dc.date.available | 2025-06-20T12:55:10Z | |
| dc.date.issued | 2022-01 | |
| dc.description | Award of Doctoral thesis in Energy and power Engineering. It contains pictures, graphs, mathematical formulas, diagrams and graphs | |
| dc.description.abstract | Development and performance evaluation of a tray dryer powered by generator exhaust gas waste heat are presented. The test rig comprises a tray dryer, a turbine, a heat exchanger, an air blower, weight and temperature sensors and an Arduino driven control panel. The waste heat recovery equipment uses an axial flow turbine and a heat exchanger to extract the energy of the exhaust gas of a diesel engine generator for the purpose of drying. The system was assembled and subjected to no-load tests, and testing independently with indigenous variety of fresh maize grains of 1,500g batch size, and yam slices of 2200g batch size. Samples of the white yam slices of different thicknesses (1.0, 1.5 and 2.0cm) were prepared for the study using blanching water of 800 C and 30 minutes soaking time. The maize grains and yam slices were dried from initial moisture contents of 35.6% and 69.5% (wet basis) to final moisture contents of 10% and 12% (wet basis), respectively. The studies focused on the impacts of the drying air temperature and velocity on the drying energy indices (specific energy consumption, specific power demand, and thermal energy), drying rate, thermal efficiency of the crop dryer, moisture diffusion coefficient, and activation energy of the studied samples. The tests were run at varying drying air temperatures (50, 55, and 60℃ for the maize grains, and 55, 65 and 75℃ for the yam slices); and air velocities of 1.0, 1.5, and 2.0m/s for both sample products. The results of the no-load tests revealed that the higher the speed of the inlet ambient air through the waste heat recovery equipment, the faster the rate of heating of the drying chamber. It was also noticed that the drying chamber, initially at 31℃, was heated to a maximum temperature of 116.1 ℃ after only a period of 39 mins. Furthermore, the results obtained for the drying of the crop samples showed that the drying parameters had noticeable influences on the moisture diffusion of both the maize and yam samples. The drying air temperature and velocity had a direct relationship with the diffusion coefficient and drying rate of the crop samples, but showed an inverse relationship with the drying time of the crops. The thermal efficiency increased as the drying air temperature increased; whereas its values decreased as the drying air velocity increased. The drying air temperature had an inverse effect on the values of the specific power consumption of the dryer at constant air velocity, whereas its values increased as the drying air velocity increased at constant air temperature. The results of the optimization of the drying process parameters using Surface Response Methodology showed that the optimum drying conditions were 600C and 1 m/s for the maize grains; and 75 0C, 1.0 m/s and 1.0 cm thickness for the yam slices. For testing with existing thin-layer drying models in the literature, the Aghbashlo model was observed to be the most suitable drying model for describing the thin-layer drying behavior of the maize grains and 1cm yam slices; whereas the Demir et al model was the most suitable for the 1.5cm and 2cm yam slices. With visual inspection of the dried samples after a period of six months storage, it was observed that the dried products did not experience any form of deterioration like any bacterial growth. Hence, it is concluded that the application of waste exhaust heat gases of diesel standby generators to the drying of food products, would be helpful in preserving a considerable amount of primary fuel, thus providing a viable means of cost saving and amelioration of environmental degradation. Prospects for commercial applications as well as recommendations for additional studies were stated. | |
| dc.identifier.citation | Ononogbo, C. ( 2022 ). Development and performance evaluation of a tray dryer powered by generator exhaust gas waste heat. ( Unpublished Doctoral Thesis ). Federal University of Technology, Owerri. | |
| dc.identifier.uri | https://repository.futo.edu.ng/handle/20.500.14562/2029 | |
| dc.language.iso | en | |
| dc.publisher | Federal University of Technology, Owerri | |
| dc.rights | Attribution-NonCommercial-NoDerivatives 4.0 International | en |
| dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/4.0/ | |
| dc.subject | Waste heat recovery | |
| dc.subject | thermal efficiency | |
| dc.subject | drying | |
| dc.subject | global warming | |
| dc.subject | cost saving | |
| dc.subject | activation energy | |
| dc.subject | energy consumption. | |
| dc.subject | Department of Mechanical Engineering | |
| dc.title | Development and performance evaluation of a tray dryer powered by generator exhaust gas waste heat | |
| dc.type | Doctoral Thesis |