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Journal : Reaktor

Prediction Of Solubility Of Solid N-Paraffins In Supercritical Fluids Using Modified Redlich-Kwong Equation Of State Ratnawati Ratnawati
Reaktor Volume 08 No.1 Juni 2004
Publisher : Dept. of Chemical Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (4222.272 KB) | DOI: 10.14710/reaktor.8.1.1-6

Abstract

Three equation of state are used to predict solubilities of solid n-pafaffins in supercritical fluids. The equations are the Redlich-Kwong, the Soave-Redlich-Kwong, and equation proposed by Hartono et.al. (2003; 2004). Both the last two equations were formed by modificating the Redlich-Kwong equqtion of state. With the binary interactions parameter, kif , equals zero, the equations proposed by Hartono et.al. is better than both the Redlich-Kwong and the Soave-Redlich-Kwong equations of state are. Upon optimization with kif as the adjustable parameter, the equation of state proposed by Hartono et.al. is closer to the experimental data than the other equqtions are. For 142 data points of 12 systems the equation proposed by Hartono et. Al. gives the average deviation of 36.6%, while the Redlich-Kwong and the Soave-Redlich-Kwong give 66.7% and 65.8%, respectively.Keywords : equation of state, solubility, supercritical
Nutritional Characteristics and Potential Applications of Flour Prepared from Indonesian Wild White Yam (Dioscorea esculenta L.) Diah Susetyo Retnowati; Ratnawati Ratnawati; Andri Cahyo Kumoro
Reaktor Volume 19 No. 2 June 2019
Publisher : Dept. of Chemical Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (228.632 KB) | DOI: 10.14710/reaktor.19.2.43-48

Abstract

Gembili or wild white yam (Dioscorea esculenta L.) is one of underutilized tubers that can be found during dry season in Indonesia and other Southeast Asian countries. Although it has been consumed as staple food by people for centuries during famine, no further studies have been conducted to explore its potentials in food applications. This work aims to study the preparation, characterization and potential analysis of Gembili flour for use as raw material in novel foods development. Creamy white flour was obtained from white yam tuber from milling and sieving of dried tuber chips. The flour has water content about 12.08%, which is acceptable for storage. No lipid was detected. In addition, the protein, ash, and fiber content of the flour were respectively 3.00%, 1.27%, and 9.04%. The carbohydrate and amylose contents of the flour were 86.69% and 29.92% indicating its suitability for energy source. As expected, the cyanide content is very low of about 1.688 ppm suggesting that it is safe for consumption. Refer to those properties, Gembili flour can be a promising raw material for the preparation of bakery, cookies, noodle and confectioneries.Keywords: proximate composition, flour, white yam, food, preparation
Design of Propellant Composite Thermodynamic Properties Using Rocket Propulsion Analysis (RPA) Software Anita Pinalia; Bayu Prianto; Henny Setyaningsih; Prawita Dhewi; Ratnawati Ratnawati
Reaktor Volume 22 No. 1 April 2022
Publisher : Dept. of Chemical Engineering, Diponegoro University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (478.592 KB) | DOI: 10.14710/reaktor.22.1.1-6

Abstract

Rocket Propulsion Analysis (RPA) is software for predicting the performance of a rocket engine. It is usually used in conceptual and preliminary design. Heat capacity and specific impulse are two properties related to the performance of a propellant. This work aimed to design AP/HTPB-based solid propellant composite with various compositions and predict the heat capacity and specific impulse using the RPA software. The materials used were ammonium perchlorate (AP) as the oxidizer, Hydroxy-Terminated Polybutadiene (HTPB) as the fuel binder, Al powder as the metal fuel, and other additives. Four propellants with different formulations were prepared and tested for heat capacity and specific impulse. The experimental heat capacity was obtained using a differential scanning calorimeter (DSC), while the specific impulse was obtained using a bomb calorimeter. The same propellant formulations were used as the input to the RPS to predict the heat capacity and specific impulse. The results show that the experimental heat capacity of the propellant ranges from 1.576 to 4.08 J g–1 K–1, and the simulation result ranges from 1.78 to 3.48 J g–1 K–1. The overall average deviation is 16.3%. The predicted specific impulse at vacuum and sea level ranges from 231.3 to 234.0 s and from 219.8 to 220.9 s, respectively. Meanwhile, the experimental specific impulse at vacuum and sea level varies from 236.2 to 240.3 s and from 228.5 to 232.9 s, respectively. The overall average deviation is 3.7%. Therefore, the RPA is reliable for predicting specific impulse of propellant, but it is not accurate enough for predicting the heat capacity of propellant composite.