Vol. 22 No. 2 (2007)

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…

The limited application of ozone depleting substance (ODS) such as CFC and HCFC refrigerants has encourage researchers to find a new alternative refrigerant. Hydrocarbon refrigerant such as R-290 (propane) has been widely used because it is environmentally friendly, save energy, and drop-in substitute. However, hydrocarbon refrigerants are flammable and categorized as A3 class refrigerant, so that the application of the refrigerants are limited by safety standard. In this research, an effort to lower the flammability of R-290 has been carried out. Series of flammability test have been done to…

Electro Discharge Machining Wire Cut (EDM Wire Cut) is one of non-conventional machining process which is used by many manufacturer industries. Technology development demands this process can produce high quality product with good productivity. To fulfill this demand, optimization of machining processes that involves several variables can be done. When doing the optimization of machining condition, an algorithm using mathematical model is needed to calculate the optimum values of process variables. There are many optimization techniques and methods which can be chosen, one of them is Genetic…

Start process, particularly cold start condition is considered important to be focused in terms of emission reduction due to high unburned hydrocarbon (HC) concentration in the exhaust gas. Several methods have been proposed and implemented for reducing exhaust gas emission during starting condition. In this paper will be discussed the addition of hydrogen into intake air in order to reduce the level of HC emission during cold start condition. Using this method, the combustion process during starting will be improved to produce better combustion. This paper describes an experiment conducted…

Trimethylolethane (TME) trihydrate particle suspended in water is a proper substance for latent heat transportation in cooling systems, since it has high heat transfer and thermal capacity. Additives, oleyl bishydroxyethyl methyl ammonium chloride as surfactant and sodium salicylate as counter-ion, were added into TME slurry to reduce its friction factor. Aditives influence on particle size distribution and rheological characteristic of TME are investigated in this study. It is found that the additives do not influence particle size at crystallization point, but they clearly inhibit further…

The oil price has been increasing since the last few years. Since then the utilization of hydro power plant has also been increasing. The hydro power plant is very well known as environtmental friendly power plant and therefore its utilization is demanded all around the world. Indonesia has planned to build up until 488 MW micro and mini hydro power plant until the year 2020. Half of this is micro-hydro power plant and the other half is mini-hydro power plant. The turbines for micro-hydro power plant have been produced locally, but the other half which are mini-hydro power plant are still…