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Bali, Indonesia

Rasta I.M.,Bali State Polytechnic | Wardana I.N.G.,Brawijaya University | Hamidi N.,Brawijaya University | Sasongko M.N.,Brawijaya University
ARPN Journal of Engineering and Applied Sciences

This paper presents an experimental investigation on effects of corn oil to ice nucleation phenomenon of a corn oil - water solution immersed in a tank containing super-cooled liquid mixture of water and propylene glycol. Temperature of water and propylene glycol mixture was to be maintained as low as -20 °C. The corn oil-water solution is a new PCM candidate to be investigated for medium temperature refrigeration applications. Thermal energy storage characteristics of the PCM candidate were established and tested at various concentrations using a T-history method. Ice nucleation below freezing point in water/ice at temperatures ranging from -6 °C to -4 °C was induced by mixing corn oil with water to form an oil-water solution. As most of the solution consisted of water, this PCM became a strong candidate for under 0 °C applications. The PCM should be capable to maintain product temperatures of a medium temperature refrigeration system between -1 °C and +5 °C. © 2006-2016 Asian Research Publishing Network (ARPN). Source

Indonesia has abundant renewable energy resources. In 2005 this country, however, only consumed 0.38% renewable energy of the total energy consumption. Most of the energy sources of the country are from fossil fuels which result in high CO2 emissions. Solar energy systems would be as an option to reduce the CO2 emissions of this country. This paper studied the application of solar energy to provide cooling for medium temperature food refrigeration based on Indonesian weather conditions. The paper additionally analyzed the environmental impact relating to CO2 emissions, and investigated the economical aspect. CFD-Fluent software was applied on modeling the modification of the absorption chiller generator to enable it to operate with heat from solar radiation, while F-Chart and Microsoft Excel spreadsheet were used to analyze the solar system and the economical viability of the technology. The results showed that the optimum modification of the absorption chiller was to use a jacket for heat addition. CFD modeling with Fluent using Diphyl THT as the heat transfer fluid (HTF) indicated that the system would function optimally at fluid temperature input of 180°C, whereas the optimum average temperature of the chiller generator would be 170°C. The proposed technology was found economically less viable for food refrigeration compared to the vapor compression cycle using R-404A but it could provide a significant impact on the environment by a reduction of 37% CO2 emissions. © (2014) Trans Tech Publications, Switzerland. Source

Putra I.K.G.D.,Udayana University | Prihatini P.M.,Bali State Polytechnic

Communication between doctor and patient play an important role in determining the diagnosis of the illness suffered by the patient. Consultation time constraints led to insufficient information obtained to produce a diagnosis. This limitation is overcome by developing an expert system using fuzzy logic to represent the vagueness of symptoms experienced by patients and the certainty factor represents a relationship between the symptoms and disease. Fuzzy logic method begins with the acquisition of knowledge to produce the facts and rules, implication process, composition and defuzzification. The result of defuzzification used in the calculation of sequential and combined certainty factor which represent the belief percentage of diseases diagnosis that suffered by the patient. The results of the expert diagnosis with expert system for the given cases indicates the system, has the similarity diagnosis with the expert at 93.99%. Source

Suarta I.M.,Bali State Polytechnic | Wardana I.N.G.,Brawijaya University | Hamidi N.,Brawijaya University | Wijayanti W.,Brawijaya University
Journal of Combustion

The role of hydrogen bond molecule clustering in laminar burning velocities was observed. The water in hydrous ethanol can change the interaction between water-ethanol molecules. A certain amount of water can become oxygenated which increases the burning velocity. The hydrogen bond interaction pattern of ethanol and water molecules was modeled. Based on the molecular model, azeotropic behavior emerges from ethanol-water hydrogen bond, which is at a 95.1%v composition. The interaction with water molecule causes the ethanol molecule to be clustered with centered oxygenated compound. So, it supplies extra oxygen and provides intermolecular empty spaces that are easily infiltrated by the air. In the azeotropic composition, the molecular bond chain is the shortest, so hypothetically the burning velocity is anticipated to increase. The laminar burning velocity of ethanol fuel was tested in a cylindrical explosion bomb in lean, stoichiometric, and rich mixtures. The experimental result showed that the maximum burning velocity occurred at hydrous ethanol of 95.5%v composition. This discrepancy is the result of the addition of energy from 7.7% free ethanol molecules that are not clustered. At the rich mixture, the burning velocity of this composition is higher than that of anhydrous ethanol. © 2016 I Made Suarta et al. Source

Santika W.G.,Bali State Polytechnic | Sudirman,Bali State Polytechnic | Nyoman Suamir I.,Bali State Polytechnic
ARPN Journal of Engineering and Applied Sciences

The present study offers technical and economical analyses of grid-connected hybrid power systems for a large scale production industry located in Bali. The peak load of observed system can reach 970.630 kW consuming on average 16 MWh of electricity a day. Software HOMER was utilized as the optimization tool. The proposed hybrid renewable energy systems consist of wind turbines, a PV system, a converter, and batteries. The system is connected to the grid. Optimization results show that the best configuration is the Grid/Wind hybrid system with the predicted net present cost of -884,896 USD. The negative sign indicates that revenues (mostly from selling power to the grid) exceed costs. The levelized cost of electricity of the system is predicted to be -0.013 USD/kWh. The present study also conducts sensitivity analysis of some scenarios i.e. 50% and 100% increases in grid electricity prices, 50% reduction of PV and WECS prices, and 10 USD and 50 USD carbon taxes per ton CO2 emission. Implications of the findings are discussed. © 2006-2016 Asian Research Publishing Network (ARPN). Source

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