Modelling of Future Energy Demand for Tanzania

This paper present modelling of long-term energy demand forecast in the main economic sectors of Tanzania. The forecast of energy demand for all economic sectors is analyzed by using the Model for Analysis of Energy Demand (MAED) for a study period from 2010-2040. In the study three scenarios namely business as usual (BAU), low economic consumption (LEC) and high economic consumption scenario (HEC)  were formulated to simulate possible future long-term energy demand based on socio-economic and technological development with the base year of 2010. Results from all scenario suggests an increased energy demand in consuming sectors with biomass being a dominant energy form in service and household sectors in a study period. Predicted energy demand is projected to increase at a growth rate of 4.1% and reach 74 MTOE in 2040 under BAU scenario. The growth rates for LEC and HEC are projected at 3.5% and 5.1% reaching 62 MTOE and 91 MTOE in 2040 respectively. Electricity demand increases at a rate of 8.5% to reach 4236 kTOE in 2040 under BAU scenario while electricity demand under LEC and HEC increases to 3693 kTOE and 5534 kTOE in 2040 respectively. Sectrorial predicted demand results under both scenarios determines high demand of biomass for service and household sectors with decreasing demand of biomass in industry sector. Transport sectors predicted energy demand pattern suggests an increased demand in passenger transport than freight transport in both scenarios. Final energy demand per capita in both scenario show an increased trend with lower growth in LEC scenario while there is a decrease in energy intensity throughout study period. Key Words: MAED, energy demand, energy demand forecasting, energy demand modellin

A comparative study and application of continuously variable transmission to a single main rotor heavy lift helicopter

Rotorcraft transmission design is limited by empirical weight trends that are proportional to the power/torque raised to the two-thirds coupled with the relative inexperience industry has with the employment of variable speed transmission to heavy lift helicopters of the order of 100,000 lbs gross weight and 30,000 installed horsepower. The advanced rotorcraft transmission program objectives are to reduce transmission weight by at least 25%, reduce sound pressure levels by at least 10 dB, have a 5000 hr mean time between removal, and also incorporate the use of split torque technology in rotorcraft drivetrains of the future. The major obstacle that challenges rotorcraft drivetrain design is the selection, design, and optimization of a variable speed transmission in the goal of achieving a 50% reduction in rotor speed and its ability to handle high torque with light weight gears, as opposed to using a two-speed transmission which has inherent structural problems and is highly unreliable due to the embodiment of the traction type transmission, complex clutch and brake system. This thesis selects a nontraction pericyclic continuously variable transmission (P-CVT) as the best approach for a single main rotor heavy lift helicopter to target the above mentioned obstacle for drivetrain design and provides advancement in the state of the art of drivetrain design over existing planetary and split torque transmissions currently used in helicopters. The goal of the optimization process was to decrease weight, decrease noise, increase efficiency, and increase safety and reliability. The objective function utilized the minimization of the weight and the constraint is the tooth bending stress of the facegears. The most important parameters of the optimization process are weight, maintainability, and reliability which are cross-functionally related to each other, and these parameters are related to the torques and operating speeds. The analysis of the split torque type P-CVT achieved a weight reduction of 42.5% and 40.7% over planetary and split torque transmissions respectively. In addition, a 19.5 dB sound pressure level reduction was achieved using active gear struts, and also the use of fabricated steel truss like housing provided a higher maintainability and reliability, low cost, and low weight over cast magnesium housing currently employed in helicopters. The static finite element analysis of the split torque type P-CVT, both 2-D and 3-D, yielded stresses below the allowable bending stress of the material. The goal of the finite element analysis is to see if the designed product has met its functional requirements. The safety assessment of the split torque type P-CVT yielded a 99% probability of mission success based on a Monte Carlo simulation using stochastic- petri net analysis and a failure hazard analysis. This was followed by an FTA/RBD analysis which yielded an overall system failure rate of 140.35 failures per million hours, and a preliminary certification and time line of certification was performed. The use of spherical facegears and pericyclic kinematics has advanced the state of the art in drivetrain design primarily in the reduction of weight and noise coupled with high safety, reliability, and efficiency.Ph.D.Committee Chair: Dr. Daniel Schrage; Committee Member: Dr. Mark Costello; Committee Member: Dr. Olivier Bauchau; Committee Member: Dr. Robert Loewy; Committee Member: Mr. Charles Crawfor

Design, construction and performance evaluation of aBox type solar cooker with a glazing wiper mechanism

This research work describes the performance evaluation of a double-glazed box-type solar oven with three reflectors and with a vapor wiper mechanism fabricated using locally available materials. The box cooker has external box dimensions of 600 mm × 600 mm × 250 mm and pyramidal internal box dimensions of 460 mm × 460 mm top face and 300 mm × 300 mm bottom face with depth of 150 mm. The thermal performance was tested as per the ASAE International Test procedure and Bureau of Indian Standards (BIS) for testing the thermal performance of a box-type solar cooker. The obtained test results after employing required calculations were figures of merit F1 = 0.123 Km2/W, F2 = 0.540, the standard cooking power P50 = 36 W and the cumulative efficiency to be 22%, whereas with the application of the wiper mechanism, it was found that F1 = 0.123, F2 = 0.827, the standard cooking power (P50) = 51 W, and the cumulative efficiency to be 31.4%. The standard boiling time of 1.43 kg of water was calculated to be 53.54 and 88.84 minutes for the cooker with and without the application of wiper mechanism respectively. The thermal distribution of the cooker was modeled using interior box geometry as a boundary condition with ANSYS 15.0. The temperature distribution inside the box was simulated and the maximum wall temperature was found to be 139 ℃. This was lower than the experimental results by 22 ℃. The method of modeling and simulation of the cooker with and without a wiper mechanism is similar except for the variation of the transmittance of the glass due to shading of vapor which can be deducted from the cumulative efficiency for the latter case. The results show that using the vapor wiper mechanism increases the cumulative efficiency by 9.4% and reduces the boiling time by 35.3 minutes. Finally, the techno-economic analysis shows that the cooker with a vapor wiper mechanism has a good reliability for outdoor cooking of food and is economically feasible

The Economics of Renewable Energy Sources into Electricity Generation in Tanzania

The study analyzes the economics of renewable energy sources into electricity generation in Tanzania. Business as usual (BAU) scenario and renewable energy (RE) scenario which enforce a mandatory penetration of renewable energy sources shares into electricity generations were analyzed. The results show total investment cost for the BAU scenario is much lower as compared to RE scenario while operating and maintenance variable costs are higher in BAU scenario. Primary energy supply in BAU scenario is higher tied with less investment costs as compared to RE scenario. Furthermore, the share of renewable energy sources in BAU scenario is insignificant as compared to RE scenario due to mandatory penetration policy imposed. Analysis concludes that there are much higher investments costs in RE scenario accompanied with less operating and variable costs and lower primary energy supply. Sensitivity analysis carried out suggests that regardless of changes in investments cost of coal and CCGT power plants, the penetration of renewable energy technologies was still insignificant. Notwithstanding the weaknesses of renewable energy technologies in terms of the associated higher investments costs, an interesting result is that it is possible to meet future electricity demand based on domestic resources including renewables