Showing papers by "Dominicus Danardono Dwi Prija Tjahjana published in 2017"

Wind energy potential assessment to estimate performance of selected wind turbine in northern coastal region of Semarang-Indonesia

Abstract: The aims of this paper are to investigate the characteristic of the wind speed and wind energy potential in the northern coastal region of Semarang, Central Java, Indonesia. The wind data was gained from Meteorological Station of Semarang, with ten-min average time series wind data for one year period, at the height of 10 m. Weibull distribution has been used to determine the wind power density and wind energy density of the site. It was shown that the value of the two parameters, shape parameter k, and scale parameter c, were 3.37 and 5.61 m/s, respectively. The annual mean wind speed and wind speed carrying the maximum energy were 5.32 m/s and 6.45 m/s, respectively. Further, the annual energy density at the site was found at a value of 103.87 W/m2, and based on Pacific North-west Laboratory (PNL) wind power classification, at the height of 10 m, the value of annual energy density is classified into class 2. The commercial wind turbine is chosen to simulate the wind energy potential of the site. The POL...

Performance prediction of serpentine type compact magnetorheological brake prototype

Abstract: A magnetorheological brake (MRB) with serpentine flux type for ankle-foot orthosis (rehabilitation device) was assessed its performance regarding braking torque and dynamic range. This assessment was conducted based on a problem that the MRB did not generate sufficient braking torque for the orthosis device. The braking capability was appraised through analytical approached based on the prototype design. The magnetic circuit of the MRB design was firstly investigated its capability for generating magnetic flux at braking surface area using finite element method magnetic (FEMM) software. Governing equation was derived to determine the braking performance i.e. braking torque and dynamic range as a function of applied current. The main factors influencing the braking performance were magneto-induced shear stress, the clearance between rotor and stator, and braking surface area. Especially for shear stress, this factor was totally influenced by the magnetic flux generated within the braking area. These all fa...

Controller development of a passive control ankle foot orthosis

Abstract: This article focuses its efforts on the development of passive control foot orthosis featuring magnetorheological (MR) brake actuator. The MR brake was hypothesized as the ideal actuator due to it being able to generate actual braking torque according to the controller's desire. Here, the EMG sensor was utilized as the signal input of the foot movement. Meanwhile, the output of controller was driven to the MR brake in the form of direct current (DC). Fuzzy logic control was employed as the control strategy. The performance of the controller was evaluated experimentally. From the experiment, the controller was observed as able to perform as expectation theorized, measured through the output voltage and sensor inputs. However, the MR brake torque continues to receive little acknowledgement which could be due to insufficient output torque.

Experimental study on optimization of curvature blade impeller pump as turbine which functioned as power plant picohydro

Abstract: Pump as turbine or PAT is an application that promises to produce small-scale electric power supply. Compared to conventional turbines, pumps have low prices and available in the market with various sizes. Therefore, PAT is suitable for hydroelectric power generation for rural areas in Indonesian. The study emphasizes experiments aimed to find the best operating point of the pump as the turbine by modifying the curvature of the pump blade. A pump with a capacity of 563.22 liters / min and a total head of 20 meters was tested in the laboratory with a radius of curvature of the blade is modified Radius 11 (backward), 13 (backward), 15 (backward), Radial, 11 (forward), 13 (forward), 15 (forward) centimeter with head from 2, 3, 4 meters and connected to a generator. The results showed that the best is 31.39% efficiency at 4.2 liters / sec and the rotation of the turbine shaft 870 rpm at the head of 4 meters. Maximum power output is 90 watts which are enough to generate electricity for a small house. The exper...

Performance analysis of the electric vehicle air conditioner by replacing hydrocarbon refrigerant

Abstract: The thermal comfort in passenger cabins needs an automotive air-conditioning system. The electric vehicle air conditioner system is driven by an electric compressor which includes a compressor and an electric motor. Almost air-conditioning system uses CFC-12, CFC-22 and HFC-134a as refrigerant. However, CFC-12 and CFC-22 will damage the ozone layer. The extreme huge global warming potentials (GWP) values of CFC-12, CFC-22, and HFC-134a represent the serious greenhouse effect of Earth. This article shows new experimental measurements and analysis by using a mixture of HC-134 to replace HFC-134a. The result is a refrigerating effect, the coefficient of performance and energy factor increase along with cooling capacity, both for HFC-134a and HC-134. The refrigerating effect of HC-134 is almost twice higher than HFC-134a. The coefficient of performance value of HC-134 is also 36.42% greater than HFC-134a. Then, the energy factor value of HC-134 is 3.78% greater than HFC-134a.

Performance of the drag type of Horizontal Axis Water Turbine (HAWT) as effect of depth to width ratio of blade

Abstract: Application of wind turbine to the water turbine is an interesting topic because of different energy momentum. A Horizontal Axis Water Turbine (HWAT) was proposed to produce energy in building the pipeline. A preliminary study using simulation and experimentally study of depth to width ratio of the blade was examined in order to determine optimum performance of the turbine using several variations of depth to width ratio of the blade with a constant head of 2 m and angle of the blocking system of 30°. Effect of the existing of different depth to width ratio of the blade for debit was reported. The optimal performance of the turbine was obtained at depth to width ratio of 0.29 that shown by highest obtained voltage of 8.62 Volt, the power output of 3.447 Watt and coefficient power of 2.73×10−2.

Slow pyrolysis of selected agricultural wastes: analysis of thermal degradation behavior

Abstract: The use of fossil fuels produces carbon dioxide (CO 2 ). Carbon dioxide is one of the greenhouse gasses that contributes to global climate change. Due to this issue, there is increasing the requirement for the use of renewable materials and development of the additional sustainable process. Agricultural waste that has the property of fast growth, is an alternative renewable energy. In this work the slow pyrolysis of selected agricultural wastes mixture (cassava peel-rice straw, rice straw-rice husk, and cassava peel-rice husk) were studied to determine thermal degradation behavior of the biomass. The process was conducted in a fixed bed reactor at temperatures 325 °C, at 10 °C/min heating rate and at 10 min holding time. Results revealed that the moisture content of agricultural wastes were 4.40 % (cassava peel-rice husk), 5.48 % (rice straw-rice husk) and 8.12 % (cassava peel-rice straw). The devolatilization process of the biomass was taken place in the temperature range from 189 o C to 325 o C. The volatile matter of each sample was 61.5% for cassava peel-rice husk, 58.5 % for rice straw-rice husk and 52.5 % for cassava peel-rice straw.

Wind Turbine Vertical Axis H Rotor Type with 1 KW Capacity at Suwuk Beach, Kebumen

Abstract: Tulisan ini membahas tentang analisa potensi energi angin di pantai Suwuk Kebumen dan perancangan turbin angin tipe H-Rotor yang sesuai dengan karakteristik angin di pantai tersebut. Analisa potensi energi angin menggunakan metode distribusi Weibull berdasarkan data kecepatan angin di lokasi pengukuran selama 2 tahun. Analisa distribusi Weibull menunjukkan karakteristik kecepatan angin di lokasi pengukuran yang akan dijadikan dasar dalam perancangan turbin angin H-Rotor. Perancangan turbin angin H-Rotor terdiri dari komponen-komponen seperti sudu, strut, dudukan strut, poros, tiang, dan generator. Diperoleh rancangan turbin angin H-Rotor dengan diameter x tinggi sebesar 2,7 x 2,7 meter menggunakan airfoil tipe NACA 0018 dengan kapasitas daya keluaran sebesar 1 kW.

Computational study: The influence of omni-directional guide vane on the flow pattern characteristic around Savonius wind turbine

Abstract: Standart Savonius wind turbine have a low performance such as low coefficient of power and low coefficient of torque compared with another type of wind turbine. This phenomenon occurs because the wind stream can cause the negative pressure at the returning rotor. To solve this problem, standard Savonius combined with Omni Directional Guide Vane (ODGV) proposed. The aim of this research is to study the influence of ODGV on the flow pattern characteristic around of Savonius wind turbine. The numerical model is based on the Navier-Stokes equations with the standard k-e turbulent model. This equation solved by a finite volume discretization method. This case was analyzed by commercial computational fluid dynamics solver such as SolidWorks Flow Simulations. Simulations were performed at the different wind directions; there are 0°, 30°,60° at 4 m/s wind speed. The numerical method validated with the past experimental data. The result indicated that the ODGV able to augment air flow to advancing rotor and decrea...