Energy analysis of a fruit drying plant in Adeiso, Ghana

The purpose of the project has been to work out recommendations that reduce the energy-related costs and environmental impact of HPW Fresh & Dry Ltd., a fruit drying factory in Ghana. The factory produces electricity with diesel and biogas but also purchases electricity from the national electricity company. Heat for the drying process is produced from biogas, kerosene and solar panels. In the project the energy system was analyzed by measuring production and consumption of heat and electricity. The project results show that the factory can become self-sufficient on heat if the available energy is used more efficient. The production units for both electricity and heat have low efficiencies. Inadequate insulation and sealing contributes to the poor performance of the heat system. The electricity measurements show that several electrical loads are unbalanced and that the three phase cooling machines are not fully utilized. The factory is recommended to invest in a new kerosene boiler and a roaster boiler for combustion of coconut waste. Furthermore, the biogas should be combusted in a boiler instead of in the now used combined heat and power engine (CHP), for improved utilization of the gas. Unused capacity of the three phase cooling machines could replace the less efficient single-phase cooling machines. Moreover, the electrical loads should be balanced and the usage of motors connected to the biogas plant minimized. By insulating pipings and seal leakages, heat losses and the need of cooling will decrease. Finally, the factory is recommended to install automatic regulation of the boilers to avoid over-heating of the storage tank.Syftet med projektet har varit att ta fram rekommendationer för hur HPW Fresh & Dry Ltd., en frukttorkningsfabrik i Ghana, kan minska sina energirelaterade kostnader och sin miljöpåverkan. Fabriken producerar el med diesel och biogas samt köper el från nationella elbolaget. Värme till torkprocessen produceras med biogas, fotogen och solpaneler. I projektet analyserades energisystemet genom att mäta produktion och konsumtion av värme och el. Resultaten från projektet visar att fabriken kan bli självförsörjande på värme om den tillgängliga energin används mer effektivt. Produktionsenheterna för både el och värme generellt har låga verkningsgrader. Bristfällig isolering och tätning bidrar till den låga prestandan i värmesystemet. Elmätningarna visar bland annat att flera elektriska laster är obalanserade samt att det finns outnyttjad kylkapacitet i fabrikens trefasiga kylmaskiner. Fabriken rekommenderas att investera i en ny fotogenvärmepanna samt en värmepanna för förbränning av kokosnötavfall. Vidare bör biogasen förbrännas i en värmepanna istället för i den nu använda kraftvärmemotorn, för att bättre utnyttja gasen. Outnyttjad kylkapacitet på de trefasiga kylmaskinerna kan ersätta mindre effektiva enfasiga kylmaskinerna. Dessutom bör de elektriska lasterna balanseras och driften av elmotorer till biogasanläggningen minimeras. Genom att isolera rör och täta värmeläckage kan värmeförluster och kylbehov minskas. Slutligen rekommenderas fabriken att installera automatisk reglering av värmepannorna för att undvika övervärmning av ackumulatortanken

Energisparläge i automationsindustrin : Potential för att minska tomgångsförluster med industriella styrsystem

Former studies have shown that a considerable part of industries’ energy usage can stem from idle times in the production. This thesis, carried out at Siemens Industry sector, evaluates the potential for using the control system to automatically put machines into energy saving mode during idle times. The main part of the thesis consists of a case study performed on machine tools at a Scania production site in Södertälje. Through load measurements the potential for energy savings was determined. The results show that there is a great potential for energy savings during idle times at the site. 20 to 50 percent of the machines’ energy usage can be reduced if they are put into energy saving mode when they are not used. However, the implementation of pause management in an existing control system is often too expensive to be motivated alone. Instead this should be considered before overhauls or rebuilds of machines and production sites. Another way of reducing costs can be to use a standard for pause management like PROFIenergy. A general conclusion is that industries with discrete manufacturing and long pause times have a great potential for energy savings. The same holds for machines with position control, such as robots and machine tools. The thesis also highlights the need for proper energy measurements at a production site in order to evaluate the potential for and results of an energy efficiency measure

Measuring Acceleration in Vehicles using the AccBox System : Results and Discussion

The goal of the project was to measure accelerations in cars, buses and motorcycles. A cubic wooden box was built and three (two-axis) acceleration sensors were installed. A Matlab-program that filters the signal and calculates the acceleration components was developed. Measuring the angular acceleration was more complicated than expected. With the current setup and software the box only measures the linear accelerations in three dimensions. The accelerations of cars and buses tested never exceed 1 g under normal urban driving. The motorcycle tested reached 2 g accelerations in the x-y-plane and 4 g in the z-direction