Jakarta, Indonesia

Darma Persada University

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Jakarta, Indonesia
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Gun Gun Ramdlan G.,University of Indonesia | Siswantara A.I.,University of Indonesia | Budiarso,University of Indonesia | Daryus A.,University of Indonesia | And 2 more authors.
International Journal of Technology | Year: 2016

As an initial analysis, numerical simulation has more advantages in saving time and costs regarding experiments. For example, variations in flow conditions and geometry can be adjusted easily to obtain results. Computational fluid dynamics (CFD) methods, such as the k-ε model, renormalization group (RNG) k-ε model and reynolds stress model (RSM), are widely used to conduct research on different objects and conditions. Choosing the appropriate model helps produce and develop constant values. Modeling studies as appropriate, i.e., in the turbulent flow simulation in the wind tunnel, is done to get a more accurate result. This study was conducted by comparing the results of the simulation k-ε model, RNG k-ε model and RSM, which is validated by the test results. The air had a density of 1,205 kg/m3, a viscosity of 4×10-5 m2/s and a normal speed of 6 m/s. By comparing the simulation results of the k-ε model, RNG k-ε model and RSM, which is validated by the test results, the third turbulence model provided good results to predict the distribution of speed and pressure of the fluid flow in the wind tunnel. As for predicting the turbulent kinetic energy, turbulent dissipation rate and turbulent effective viscosity, the k-ε model was effectively used with comparable results to the RSM models. © IJTech 2016.


Hendroko R.,Darma Persada University | Wahyudi A.,University of Muhammadiyah Malang | Wahono S.K.,Indonesian Institute of Sciences | Praptiningsih G.A.,University of Indonesia | And 2 more authors.
International Journal of Technology | Year: 2013

One of the cultivation failure reasons of Jatropha curcas Linn (JcL) in Indonesia was that it was only recommended for Crude Jatropha Oil (CJO) production which is processed into biodiesel. CJO is only 17-25% of dry seed weight, while the waste residue is called seed cake. Another waste product is dried capsule husk (DH-JcL) which is about 30-80% of the fresh fruit weight and sludge CJO (S-CJO) or about 2-5% of the CJO. S-CJO was unutilized which is bad for the ecology when it is disposed. The research objective was the utilization of the S-CJO waste for bio-refinery and improvement productivity of biogas made from DH-JcL.The study was conducted at the research garden of PT Bumimas Ekapersada, Bekasi, West Java in November-December 2012. A liter one-stage digester was compiled completely as a randomized design (CRD) with three replications in a water bath at a temperature of 32°C. The materials used were DH-JcL of JatroMas cultivars in the toxic category which were mixed with the sludge S-CJO as a co-substrate about with 10% water at a ratio of 1:8. Observation variables were biogas production volume (water displacement method), pH and temperature in the outlet slurry. The preliminary study concludes that S-CJO is appropriate as the co-substrate DH-JcL. It can increase the biogas productivity with feed in less than 10% of S-CJO allocation per day. ©IJTech 2013.


The aim of this paper is to discuss the performance of a hybrid photovoltaic and thermal (PVT) collector by focusing on the utilization of Joule heating as additional heat for improving thermal efficiency, when both thermal and electrical energies are generated (PVT-mode), by comparing with when only the thermal energy is generated (T-mode). During the maximum power point and the peak irradiation, the temperature differential in PV material was increased due to the rise in current flow. The Joule heating or internal heating also increased proportional to the square of electric current. The conducted heat also increases through the PV surface to the thermal absorber in the PVT collector. For that reason, the experiment was performed using higher irradiation with a bigger PVT collector at four different inlet water temperatures, i.e., 12, 15, 20, and 25 °C. The water flow rate was 6.7 × 10−5 m3/s (≈4 L/minute). The irradiation data was collected for an hour from 12:00 to 13:00 to keep a steady-state thermal performance and also to minimize the hysteresis effect. In the present PVT collector's system and configuration, the result showed that even a moderate wind speed below 1 m/s results in a non-negligible loss of the thermal efficiency. The thermal efficiency of PVT collector in PVT-mode is higher than T-mode at the lower range of first order thermal efficiency gradient, when the inlet water temperature is close to the ambient air temperature, or when the total irradiation is high. The behavior of the thermal efficiency of PVT-mode also seems to be appreciably influenced by other factors, such as the internal heating during the operation. During the higher irradiation periods, the Joule heating effect has the potential to improve the thermal efficiency of PVT-mode up to 13%. The internal heating in PV cell apparently affects both the effective absorption and heat loss coefficient. The practical relevance of Joule heating in a real-life PVT system is for low temperature applications, such as swimming pool heating, low temperature source heat pumps, and floor heating. © 2017 Elsevier Ltd


Tambunan A.H.,Bogor Agricultural University | Manalu L.P.,Bogor Agricultural University | Abdullah K.,Darma Persada University
Drying Technology | Year: 2010

Exergy analysis is considered as an effective tool and has been widely used for assessing energy status of a thermal process from thermodynamic point of view. In this article, the exergy analysis is applied to the assessment of sensible thermal storage for a solar drying system. The objective of this study is to evaluate the role of the heat transfer process to the simultaneous exergy charging and discharging of the storage system in relation to the solar drying system. The results show that exergy loss ratio, which was regarded as the fraction of transferred exergy to the drying chamber, varied with the charging time and reached a minimum value at a certain charging time. The minimum exergy loss ratio and the time to reach the value are strongly dependent on the number of transfer units (NTU). The ratio of exergy loss at NTU¬sim;0 was 86%, greater than the value of practical interest. Accordingly, the application of sensible heat storage for a solar drying system will exert only a small effect to the temperature of the drying air entering the drying chamber. © 2010 Taylor & Francis Group, LLC.


Marlinda,Tokyo University of Agriculture and Technology | Uyun A.S.,Darma Persada University | Miyazaki T.,Tokyo University of Agriculture and Technology | Ueda Y.,Tokyo University of Agriculture and Technology | Akisawa A.,Tokyo University of Agriculture and Technology
Energies | Year: 2010

A numerical investigation of the double-effect adsorption refrigeration cycle is examined in this manuscript. The proposed cycle is based on the cascading adsorption cycle, where condensation heat that is produced in the top cycle is utilized as the driving heat source for the bottom cycle. The results show that the double-effect cycle produces a higher coefficient of performance (COP) as compared to that of the conventional single-stage cycle for driving temperatures between 100 °C and 150 °C in which the average cycle chilled water temperature is fixed at 9 °C. Moreover, the COP of the double-effect cycle is more than twice that of the single-stage cycle when the temperature reaches 130 °C. It is also observed that the adsorbent mass ratio of the high temperature cycle (HTC) to the low temperature cycle (LTC) affects the performance of the double-effect adsorption refrigeration cycle. © 2010 by the authors.


Abdullah K.,Darma Persada University
IMETI 2011 - 4th International Multi-Conference on Engineering and Technological Innovation, Proceedings | Year: 2011

One of the effort to solve poverty problem, starting 2007, the government of Indonesia has launched a national Energy Self Sufficient Village (ESSV) program aiming, create the spirit of self help for villagers so that they are capable to fulfil their own basic energy needs for cooking, lighting, and to improve their wellbeing by cleverly utilizing locally available renewable energy sources to generate economic activities. By 2010 there were already more than 630 ESSVs have been established throughout the country. Each ESSV establishment has required between IDR 400 million (US$ 47, 000) to IDR 1, 2 billion (US$141, 000) for each ESSV depending of types of renewable energy sources available in the village. The program however, needs continuous long term monitoring and evaluation using university program to ensure it sustainability. The paper describes how Darma Persada University could help mitigating the current problems faced in implementing the ESSV program.


Darsono M.,Darma Persada University | Wijaya E.,Darma Persada University
Telkomnika | Year: 2013

Design of circular polarization microstrip antenna array was developed to support micro-satellite technology. Circular polarization antenna array used for data transmission applications operating in the S band frequencies from the satellite to the ground station. In this study of the patch array using proximity coupling techniques in this study to obtain high gain and wide of bandwidth. The structure of the antenna array design consists of four identical square patch elements and to use the concept of corporate transmission line fed power divider network uses three transformers quarter-lambda T-junction. Bandwidth impedance matching for resonance between two patches is 3/4 λ antenna system for center frequency of 2.25 GHz. The antenna is designed using the method of moments through simulation with microwave office software applications. The results of simulations and measurements obtained antenna parameters, such as: bandwidth of return loss <-10 dB above 100 MHz resonant frequency shifted to 1.75%, VSWR (1 to 2), the bandwidth of axial ratio <3 dB is 1.6% (narrowband) and the maximum directivity (gain) is 9.128 dB. Overall study results showed good performance antenna array with circular polarization properties, high gain and operates in the S band frequency micro satellite system.


Kamaruddin A.,Darma Persada University | Uyun A.S.,Darma Persada University | Chan Y.,Darma Persada University
International Energy Journal | Year: 2014

A continuous flow hybrid ICDC (Integrated Solar-collector-Drying Chamber) solar dryer has been designed and constructed. The proposed dryer then was tested using rough rice with different loading quantity under outdoor conditions. The unique feature of this solar dryer is that it can dry the products simultaneously in three locations within the dryer, namely, within the pneumatic conveyor, within the collector-drying chamber, and above a feed hopper. Experimental results have shown that electric power requirement to transport between 0.5 - 0.7 tons/hr., of rough rice from the feed hopper to the drying chamber was between 500 - 600 W and equivalent to 0.87 W/kg/hr-0.89 W/kg/hr.


Chan Y.,Darma Persada University | Dyah T.M.N.,Darma Persada University | Kamaruddin A.,Darma Persada University
Energy Procedia | Year: 2015

The coventional flat bed dryer has the demerit of having nonhomogeneous drying results. Therefore, to obtain nonhomogeneous drying result recirculating type solar dryer with pneumatic conveyor as the recirculating equipment will be. As the grains transported within the penumatic conveyor rapid heat and mass transfer occur resulting in even drying process and make the final results of the drying process homogene. The complete solar dryer was comprised of a feed hopper, centrifugal blower, pneumatic conveyor and a transparent structure acting as drying chamber containing a hopper with vortex at the top. Pneumatic conveyor was used to make recirculation of the grain and to perform continuous drying process. Spherical model was used to predict the drying time.Test with 104 kg of rough rice indicated that the drying time required to reduce the moisture content of rough rice from 28.4% w.b to the final moisture of 14.3% w.b was 5 h. During the test the drying temperature was kept constant at 50.1 oC and RH of 21.73%. The required power for the pneumatic conveyor was 581 W with total energy input of 210.7 MJ including LPG and solar radiation. The resulting drying efficiency was 22.4% with specific energy of 15.2 MJ·kg-1 water evaporated. © 2015 The Authors.


Chan Y.,Darma Persada University | Dyah N.,Darma Persada University | Abdullah K.,Darma Persada University
Energy Procedia | Year: 2015

A novel recirculation type ICDC solar dryer has been designed, constructed and tested. The solar dryer was comprised of a feed hopper, centrifugal blower, pneumatic conveyor and a transparent structure acting as drying chamber containing a hopper with vortex at the top. Test with 104 kg of rough rice indicated that the drying time required to reduce the moisture content of rough rice from 28.4% wet basis (wb) to the final moisture of 14.3%wb was 5 hrs. During the test the drying temperature was kept constant at 50.1 °C and relative humidity (RH) of 21.73%. The required power for the pneumatic conveyor was 581 W with total energy input of 210.7 MJ including LPG and solar radiation. The resulting drying efficiency was 22.4% with specific energy of 15.2 MJ/kg of water evaporated. Another test using 200 kg with initial moisture content (m.c.) of 27.6%wb.of rough rice have shown that the required drying time to achieve the final moisture of 14.3% was 8 hrs. During the test the drying temperature was kept at 46.9 °C, and RH of 21.7%. The drying efficiency was 31.7% with specific energy of 10.7 MJ/kg water evaporated. © 2015 The Authors. Published by Elsevier Ltd.

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