Integration of Solar Thermal System for Improved Energy Consumption in Low Temperature Industrial Processes, Case: Harar Brewery.
Creators: name: G/Hawariat, Ashenafi
Publisher: name: National Academic Digital Repository of Ethiopia
Year: 2016

description: The objectives of this paper are to analyze thermal energy production of heat pipe evacuated tubes solar collector and investigate the integration of solar thermal system with conventional system in low-temperature industrial processes in Harar Brewery Factory. In this study, Matlab program and RET Screen software were implemented to identify technical and financial feasibility of the system. Six low temperature processes, such as feed water pre-heating, kegging, CIP, Mashing at 780C, bottle cleaning and mashing at 520C were selected in the industry for integration of solar thermal system. The total annual conventional thermal energy consumption of the selected processes is 11,176.18MWthr. This covers 54.15% of the annual total thermal energy consumption in the industry from the chemical energy of fuel (20638.23MWthr). The solar thermal system of a single heat pipe evacuated tubes solar collector was analyzed. The maximum outlet water temperature is 800C for mass flow rate of 47.52 kg/hr through the manifold. However, the maximum outlet water temperature is 520C in mashing process for the mass flow rate of 75.60kg/hr. and, the maximum outlet water temperature for bottle cleaning at 650C. It should have a mass flow rate of 66.6kg/hr. The maximum instantaneous efficiency is during sun shine and sun set hours. And, the minimum instantaneous efficiency is 84.96% on March 31 at 11:00 in the morning for the mass flow rate of 47.52kg/hr. However, the minimum instantaneous efficiency is 83.02% when the mass flow rate is 66.6kg/hr. And, the minimum instantaneous efficiency of the system is 62.19% when the mass flow rate of water is 75.60kg/hr. The maximum solar thermal energy harvested form a single collector at a mass flow rate of 47.52kg/hr is 3.19KWt on March 31 at 11:00 in the morning. However, the highest daily solar thermal energy produced on March 12 is 22.01KWthr and the lowest daily solar thermal energy produced on July 19 is 3.66KWthr. The appropriate location of solar collectors is identified to harness the maximum possible solar energy. The optimal number of collectors needed for partial supply of thermal energy to the industry are 368 (30 for mashing at 520C, 62 for mashing at 780C, 59 for bottle cleaning, 22 for feed water pre heating, 168 for CIP and 27 for kegging ). The Annual solar thermal energy production was analyzed for all processes. Those are 127.03MWhr, 333.47Mwhr and 1613.98MWhr for mashing at 520C, bottle cleaning and other thermal processes at 78-800C respectively. The total annual solar thermal energy harvested for all selected processes is 2074.48MWhr. vi Due to the integration of solar thermal system in low temperature industrial processes, the consumption of conventional thermal energy for the selected processes are reduced to 9101.70MWhr/year. Which means 18.56% of thermal energy consumption for selected processes in the industry could be saved. However, the total annual thermal energy consumption of the industry is reduced to 18147.76MWthr. This means 12.07% (10.05% from selected processes, 2.01% from overall heat loss and 0.01% from pre heating of fuel) of the fuel consumption in the industry is saved. In other way, 205,840.65 liter of furnace oil is saved every year. The total initial investment cost of the project is $440,864 (50% is project equity and the remaining is project debt). This project saves $165,813 of the annual cost of the industry for thermal energy application and reduces 729.54 tons of carbon dioxide (CO2) emission per year. The project equity is returned back with 1.6 years.