Sayem Zafar

An Investigation into a Small Wind Turbine Blade Design

A small wind turbine blade was designed to be aerodynamically efficient, economical and easy to be manufactured. Aerodynamic analysis was conducted using commercially available software. The aerodynamic analysis suggested laminar flow airfoils to be the most efficient airfoils for such use. Blade geometry was determined after calculating baseline geometric values to have low weight and drag while yielding maximum torque. The blade span was constrained such that the complete wind turbine can be roof-top mountable. The blade was designed without any taper or twist to comply with the low cost and ease of manufacturing requirements. For low cost and favorable strength to weight ratio, fiberglass-epoxy was used as the blade material. Computer simulated structural test results suggested that skin thickness of 1 mm of fiberglass-epoxy can sustain the loads on the blade. The wind turbine blade produces 3.1 N lift with 6.3 N.m torque at 4 m/s wind speed. Since it uses a relatively inexpensive material, fiberglass-epoxy, the cost of the blade is low. Fiberglass-epoxy is also easy to work with hence it contributes towards manufacturing ease. Overall, the research was successful in designing a wind turbine blade that is easy to be manufactured, economical and has high torque.

Design and Evaluation of a Rooftop Wind Turbine Rotor With Untwisted Blades

A small horizontal axis wind turbine rotor was designed and tested with aerodynamically efficient, economical and easy to manufacture blades. Basic blade aerodynamic analysis was conducted using commercially available software. The blade span was constrained such that the complete wind turbine can be rooftop mountable with the envisioned wind turbine height of around 8 m. The blade was designed without any taper or twist to comply with the low cost and ease of manufacturing requirements. The aerodynamic analysis suggested laminar flow airfoils to be the most efficient airfoils for such use. Using NACA 63-418 airfoil, a rectangular blade geometry was selected with chord length of 0.27[m] and span of 1.52[m]. Glass reinforced plastic was used as the blade material for low cost and favorable strength to weight ratio with a skin thickness of 1[mm]. Because of the resultant velocity changes with respect to the blade span, while the blade is rotating, an optimal installed angle of attack was to be determined. The installed angle of attack was required to produce the highest possible rotation under usual wind speeds while start at relatively low speed. Tests were conducted at multiple wind speeds with blades mounted on free rotating shaft. The turbine was tested for three different installed angles and rotational speeds were recorded. The result showed increase in rotational speed with the increase in blade angle away from the free-stream velocity direction while the start-up speeds were found to be within close range of each other. At the optimal angle was found to be 22° from the plane of rotation. The results seem very promising for a low cost small wind turbine with no twist and taper in the blade. The tests established that non-twisted wind turbine blades, when used for rooftop small wind turbines, can generate useable electrical power for domestic consumption. It also established that, for small wind turbines, non-twisted, non-tapered blades provide an economical yet productive alternative to the existing complex wind turbine blades.Copyright

Energy Production Through Wind Using Personal Use Wind Turbines: A UAE Case Study

A model study is conducted to investigate the possible wind energy harnessing potential of a recently designed personal use wind turbine, PWT, having efficient and economical blades. The study is conducted for the conditions usually found in United Arab Emirates, UAE. The PWT has a total length of 4.5 m while the disk diameter is 3 m. The PWT dimensions make it big enough to be used to power household appliances or to charge batteries yet small enough to be installed on rooftops or buildings. The wind turbine setup uses a tail vane to keep the wind turbine aligned with the airflow. The wind turbine blades are installed at an angle of 22°, with respect to the disk plane, as it gives the highest power. For electrical power generation, a permanent magnet generator is used which is rated for 250 RPM to 100 RPM. Gears are used to increase the generator RPM to six times than that of the wind turbine. The UAE wind data is used to find the total possible power from each wind turbine. Possible number of housing units, buildings and telecommunication towers are found, in UAE, where a PWT can be installed. An analysis is conducted for the energy and exergy potential of the wind turbine rotor. The clean energy potential of the PWT is also investigated when operated by their possible users. Calculations are made at variable wind speeds to represent the average wind speed during each month. It is concluded that a country like UAE can produce on average 500 MW using PWTs. The efficiencies come out to be low for summer months while high for winter months. It is also concluded that a system like PWT would help reduce the monthly billing cost by the end user.Copyright

Evaluation of an Integrated Fuel Cell-PV Panel System as a Hybrid UAV Powerplant

A model study was conducted to investigate the integration of a hybrid, fuel cell-PV panel power system for a small unmanned aerial vehicle (UAV). A hybrid power system is proposed as a substitute to the existing batteries to enhance the endurance of such systems. A UAV with wing area equivalent solar panel and 900Ah proton exchange membrane fuel cell, with stored pressurised hydrogen, is modeled. Maximum take-off weight of 100 N was used to make the UAV man-portable. The flight performance was simulated using available and calculated data. Aerodynamic analysis was conducted and the wing and tail geometries were determined to house the PV panels. The corresponding required power was then established from the drag and weight values. Measurements were made for the maximum required power for endurance. The results showed favorable increase in a small UAV’s flight performance when an integrated hybrid fuel cell-PV panel system is used. An endurance increment of 2384 seconds was achieved using a hybrid, fuel cell-PV panel, power system when compared to fuel cell only power system. The research proved the effectiveness of using fuel cell-PV panel hybrid system as a small UAV power plant. It also highlighted the effectiveness of using renewable sources to increase the endurance of a small UAV.Copyright

Murshed Testing and Analysis of R134a Clathrates with Additives for Cooling Applications

An experimental investigation is conducted to test the thermal behavior and characteristics of R134a clathrates with additives, as phase change materials (PCMs), for cooling applications, and their charging capabilities are analyzed and evaluated. The formation of refrigerant clathrates is investigated due to their potential use in active and in passive cooling applications such as in electronic and residential cooling. The PCMs are made using R134a clathrate and distilled water with different refrigerant proportions and five different additives. The main objective of using additives is to study their potential in enhancing the clathrate formation over a small temperature range under direct contact heat transfer. The PCMs are formed in glass tubes and their freezing onset and transformation time was recorded. The refrigerant R134a percentages of 25%, 30%, 35%, and 40% are used to form clathrate. For the additives, ethanol, sodium chloride, magnesium nitrate hexahydrate, copper, and aluminum were used. The PCMs are formed using controllable constant temperature water. The times for initial onset until the times, where the clathrate structure does not change (end-set), are recorded at regular intervals. The low charging time shows that the PCMs require low energy input to change its phase, whereas more time shows PCM takes more energy to do so. A comparative study is conducted to compare the charging time for different PCMs using the suggested additives. R134a refrigerant clathrate without any additive is used as the base case for comparison. The results show that metal additives reduce the freezing time (charging time), and ethanol and sodium chloride increase it, while magnesium nitrate hexahydrate maintains it the same as that of the base case of PCM. It is also found that the freezing time depends not only on the thermal properties of the used additives but also on their ability to mix homogenously in the refrigerant clathrate mixture. Furthermore, some additives are considered to be very useful in enhancing the clathrate formation with a stabilized crystalline structure. Finally, the PCMs with high latent heats over narrow temperature ranges are desirable as they offer high energy density at uniform reasonable temperatures applicable for cooling applications.

Crystal Growth Analysis of R134a Clathrate with Additives for Cooling Applications

An experimental investigation is conducted on crystal growth formation of R134a with additives, as phase change materials (PCMs), for cooling applications. The experimental investigation focuses on the crystal growth time and the characteristics of the formed PCMs. The formation of refrigerant clathrates at different operating conditions is investigated due to their potential use in active and passive cooling applications in electronic and residential cooling. The PCMs are made using R134a clathrate and distilled water with different refrigerant proportions and five different additives. The additives are used to improve the clathrate formation time and the crystal growth propagation under direct contact heat transfer mode. PCMs are formed in glass tubes and their crystal growth of freezing onset and crystal growth formation time is recorded at different operating temperatures. Refrigerant R134a percentages of 25%, 30%, 35%, and 40% are used to form clathrate. For the additives, ethanol, sodium chloride, magnesium nitrate hexahydrate, copper, and aluminum are used. PCMs are formed using controllable constant temperature water bath. The low crystal growth formation time showed that the PCM requires low energy input to change its phase, whereas more time shows PCM takes more energy to transform. A comparative study is conducted to compare the crystal growth formation time for different PCMs. R134a refrigerant clathrate without any additive is used as the base PCM. The results showed that metal additives reduced the crystal growth formation time, ethanol and sodium chloride increased the crystal growth formation time. Magnesium nitrate hexahydrate maintains it the same as that of the base PCM. It is also found that the freezing time depended not only on the thermal properties of the used additives but also on their ability to mix homogeneously in the refrigerant clathrate. Furthermore, some additives are considered to be very useful in enhancing the crystal growth formation of the clathrate with a stabilized crystalline structure. PCM with high latent heats over narrow temperature ranges are desirable as they offer high energy density at uniform temperatures applicable for cooling applications.

Energy Harvesting Using Small Renewable Energy Sources: UAV Application

A renewable energy harvesting system is designed and tested for micro power generation. Such systems have applications ranging from mobile use to off-grid remote applications. This study analyzed the use of micro power generation for small unmanned aerial vehicle (UAV) flight operations. The renewable energy harvesting system consisted of a small wind turbine, flexible type PV panels and a small fuel cell. Fuel cell is considered the stable source while PV and wind turbine produced varying power output. The load of around 250 W is simulated by a small motor. The micro wind turbine with the total length of 4.5 m and the disk diameter of 1.8 m is tested. The micro wind turbine dimensions make it big enough to be used to charge batteries yet small enough to be installed on rooftops or easily transportable. The wind turbine blades are installed at an angle of 22°, with respect to the disk plane, as it gives the highest rotation. The voltage and current output for the corresponding RPM and wind speeds are recorded for the wind turbine. Two 2 m and a single 1 m long WaveSol Light PV panels are tested. The PV tests are conducted to get the current and voltage output with respect to the solar flux. The variation in solar flux represented the time of day and seasons. A 250 W PEM fuel cell is tested to run the desired load. Fuel cell’s hydrogen pressure drop is recorded against the output electrical power and the run time is recorded. System performance is evaluated under different operating and environmental conditions. Data is collected for a wide range of conditions to analyze the usability of renewable energy harvesting system. This energy harvesting method significantly improves the usability and output of the renewable energy sources. It also shows that small renewable energy systems have existing applications.Copyright

Thermodynamic Evaluation of a Small Wind Turbine

A small personal use wind turbine (PWT) is studied and tested for power, exergy and energy evaluation under different operating conditions. The wind turbine incorporates non-twisted blades of 1.5 m span and 0.27 m chord, using NACA 63418 airfoil. Using the earlier test results at pitch angles of 22°, 34° and 38° between the wind speeds of 4 m/s to 7 m/s, torque produced by each blade is determined. It is desired to calculate the torque as it is difficult to measure it for a small wind turbine. Using the governing equations and available computational fluid dynamics software, the total torque on each blade is determined. The resultant torque yielded the mechanical power output of the PWT. Using the available power, energy and exergy in the air flow, corresponding efficiencies are determined. To determine the changes in energy and exergy with respect to the wind speed, wind-chill factor expression is utilized. Results are collected for a wide range of wind speeds and pitch angles. Power, energy, exergy and their corresponding efficiency is evaluated to determine the optimal use pitch angle and ambient conditions. The pitch angles of 22° and 38o yielded high efficiencies although 22° produced the higher rotational speed as compared to 38°. The result suggests better performance for continuous wind speed conditions at low pitch angles — with respect to the rotating plane. For non-continuous wind conditions, higher pitch angles appeared beneficial.Copyright

Test and analysis of thin film photovoltaic (TFPV) for UAV application

A study was conducted to investigate the performance of thin film flexible PV panels. The experimental study was conducted to simulate the performance of the panels for the conditions found during the unmanned aerial vehicle (UAV) flight in the city of Sharjah. Two 2 m and a single 1 m WaveSol Light PV panels were tested for the study. The 2 m panels are for each wing while the 1 m panel is for the horizontal stabilizer. WaveSol Light PV panels were considered for this research because of their relative light weight, high current and compatible voltage output. These PV panels also have a convenient width which can easily be mounted on the UAV wings and stabilizer. The panels were tested to measure the voltage and current over the test period of 19 minutes. A detailed parametric study was conducted to evaluate the flight duration and the performance of the UAV for regular operations. The study predicted the operational range and flight performance based on the motor power requirement, PV panel system type and fuel cell capacity. The best case scenario achieved the endurance increase of 4.5 hours while the worst case achieved an endurance of 0.4 hours.

Efficiency Assessment of Crude Oil Distillation Systems

The assessment of energy and exergy efficiencies is conducted on a crude oil distillation system for three different cases. Each case defines efficiency in a unique way with different inputs and outputs. First case treats the heat transfer rate as useful output and the heat gained from the heaters as input. For the second case, we consider the heat provided by the heaters as input and the heat transfer rate in the distillation system as output. The third case treats the heat provided by the heaters as input and heat transfer rate along with the heat of exhaust gases as useful output. The system efficiencies are studied parametrically by changing the amount of heat transfer rate and the ambient temperatures. The results show that case 1 has the baseline energy and exergy efficiencies at 53 % and 25.3 % respectively. Case 2 has the efficiencies at 40 % for energy and 23.3 % for exergy efficiency. Case 3 efficiencies are at 72 % for energy while exergy efficiency is at 65 %. Case 1 has the highest efficiencies, followed by case 3 then the least efficient is case 2. Utilizing the unused energy, as a useful input to some other system, improves the overall efficiency of the plant and saves operating cost while making the system more environmentally friendly.