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All Journal Journal of Engineering and Technological Sciences Mesin
I Made Astina
Energy Conversion Research Division Faculty of Mechanical and Aerospace Engineering Institut Teknologi Bandung Jalan Ganesha no 10 Bandung 40132, West Java, Indonesia
Engineering Mechanical Engineering

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Comparative Study on Solar Collector’s Configuration for an Ejector-Refrigeration Cycle Senjaya, Raffles; Astina, I Made
Journal of Engineering and Technological Sciences Vol 40, No 1 (2008)
Publisher : ITB Journal Publisher, LPPM ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (434.828 KB) | DOI: 10.5614/itbj.eng.sci.2008.40.1.4

Abstract

Solar collector’s configuration plays important role  on solar-powered refrigeration systems  to work as heat source for generator . Three types of solar collector consisting  of flat plate, evacuated tube, and compound parabolic solar collectors  are  compared  to  investigate  their  performances.  The  performances consist of the behavior of heat which can be absorbed by the collectors, heat loss from  the  collectors  and outlet temperature of working fluid at several slopes of the  solar  collectors.  The  new  accurate  analysis  method  of  heat  transfer  is conducted  to  predict  the  performance  of  the  solar  collectors.  The  analysis  is based  on  several  assumptions,  i.e.  sky  condition  at  Bandung  is  clear  and  not raining from 08.00 until 17.00 and thermal resistance at cover and absorber plate is  negligible. The numerical calculation results confirm that performance of  the evacuated  tubes  solar  collector  at  the  same  operating  conditions  is higher  than the  others.  For  the  case  of  an  evacuated-tubes  solar  collector  system  with aperture area of 3.5 m2, the maximum heat which can be absorbed is 3992  W for the highest solar intensity  of  970 W/m2 at 12.00  with  horizontal position of  the solar  collector.  At  this  condition,  the  highest  outlet  temperature  of  water  is 347.15 K with mass flow rate 0.02 kg/s and inlet temperature 298 K.
THERMODYNAMIC PROPERTY MODEL OF WIDE-FLUID PHASE n-BUTANE Sarin, Chan; Astina, I Made; Darmanto, Prihadi Setyo; Sato, Haruki
Mesin Vol 22, No 2 (2007)
Publisher : Mesin

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Abstract

New thermodynamic property model for n-Butane expressed in form of the Helmholtz free energy equation is presented. The formulation consists of eight terms of the so-called ideal-gas part and eighteen terms of the residual part. This is a relatively short equation in comparison to the existing equations, which are widely accepted, including the newly published in year 2006. In its development, available accurate experimental data of fluid properties and theoretical approach from the intermolecular potential were simultaneously considered to insure accuracy and to improve reliability of the equation of state over wide range of pressures and temperatures, especially at low temperatures in which the refrigeration field is concerned. From the coverage of experimental data used in model’s development, the validity range is then from triple-point (134.895 K) to temperature of 589 K and pressure up to 69 MPa. The uncertainties with respect to different properties are estimated to be 0.02% in ideal-gas isobaric specific heat, 0.2% in density, 1% in heat capacities, 0.2% in vapor-pressure except at very low temperatures, 0.05% in saturated-liquid density, 0.02% and 0.8% in speed of sound in the vapour and liquid phases, respectively.
ANALYSIS OF USING ALTERNATIVE REFRIGERANTS FOR ENERGY SAVING IN DESIGN FRAMEWORK OF AIR-CONDITIONING SYSTEM Astina, I Made; Darmanto, Prihadi Setyo; Warsito, Warsito; Adryanto, Edwin
Mesin Vol 20, No 2 (2005)
Publisher : Mesin

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Abstract

Environmental issues enforce us to find environmental friendly alternative refrigerants. Increasing energy consumption as consequence of widespread usage of air-conditioning systems needs effort to find efficient systems. Use ability of alternative refrigerants and effect of modified vapor-compression cycles were investigated in this research. In figuring effects of their application on a real air-conditioning system, analysis of redesign of air-conditioning system was concerned to make clear the problem. The results confirm that a right selection of refrigerants to air-conditioning system can improve its performance. Energy saving and economical costs can be reduced significantly. Several groups of hydrocarbons (HC) and hydrofluorocarbons (HFC) have good thermodynamic performance and better than R-22 that will be phased out. By introducing these alternative refrigerants, carbon-dioxide (CO2) emissions can be reduced due to energy saving caused by increasing of the coefficient of performance (COP).
ANALISIS TERMODINAMIKA SIKLUS HIBRID UNTUK PEMBANGKIT LISTRIK TENAGA PANAS BUMI Astina, I Made; Kurniawan, Kadek Edy; Pastalozi, Merly
Mesin Vol 23, No 2 (2008)
Publisher : Mesin

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Abstract

Modification of the conventional cycle in a geothermaL power plant is an alternative way that can be conducted in efficient conversion of thermal energy to be electric energy. Combination of Brayton cycle with fossil fuel energy sources and Rankine cycle utilizing geothermal energy is interest of this study. Kamojang Geothermal power plant is chosen as an object of casestudy. A software was developed to accurately evaluate the thermodynamic cycle with any modification. The software is supported by thermodynamic properties database directly derived from equations of state. Hybrid cycle analysis was conducted by comparing the conventional geothermal system operating with independent Rankine cycle such as the current Kamojang geothermal power plant in accordance with rational data ernd assumptions.Simulation results show that 157.88% of power increment, 58.17% of efficiency increment for using organic working fluid R-134a. Replacing R-134a with organic working R-600 afford 162.89% of power increnrent and 63.76% of efficiency increment. Ratio of the net power increment respect to the heating input of fuel is 0.52. This high enhancement is achieved for gas turbine inlet temperature of 1100 celcius degree, pressure ratio of 20, gas temperatltre front steam heater at 350 celcius degree, steam temperature from the heater at 250 celcius degree, and organic turbine inlet pressure and temperature at 35 bars and 340 celcius degree, respectively.
SIMULASI BEBAN PENDINGINAN BATUAN DALAM REKAYASA TEROWONGAN Astina, I Made; Darmanto, Prihadi Setyo
Mesin Vol 10, No 1&2 (1994)
Publisher : Mesin

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Abstract

Rekayasa terowongan sering dihadapkan pada berbagai kendala. Salah satu kendala yang dikaji tulisan ini adalah adanya batuan panas pada suatu bagian tertentu dari terowongan yang akan digali. Kondisi ini tidak munguntungkan dari sisi teknik pengerjaannya mengingat kesulitan para pekerja. Salah satu solusi agar pekerjaan penggalian terowongan dapat dilakukan adalah dengan mendinginkan bagian batuan yang panas tersebut.Di dalam makalah ini akan dibahas teknik pendinginan yang akan digunakan dan estimasi beban di dalam terowongan agar proses penggalian dapat berjalan dengan lancar dan ekonomis. perhitungan beban pendinginan dengan cara numerik juga akan dibahas dalam makalah ini. Fenomenadan dan karakteristik fisik seperti sifat konduktifitas tanah dan batuan, kehomogenan sifat batuan panas dan sumber panas dari batuan panas perlu di pelajari lebih lanjut sehingga penyederhanaan berbagai parameter dalam perhitungan dan estimasi beban diharapkan tidak menyimpang jauh dari beban pendinginan sebenarnya yang terjadi di lapangan.
Co-Authors Adryanto, Edwin Darmanto, Prihadi Setyo Kurniawan, Kadek Edy Pastalozi, Merly Raffles Senjaya Sarin, Chan Sato, Haruki Warsito Warsito