Aryadi Suwono

Characterization of Alkanes and Paraffin Waxes for Application as Phase Change Energy Storage Medium

Abstract Latent thermal energy storage is one of the favorable kinds of thermal energy storage methods considered for renewable energy source utilization, as in solar photothermal systems. Heat is ...

Measurement of property relationships of nano-structure micelles and coacervates of asphaltene in a pure solvent

We have made some progress in studies towards formation and measurement of the behavior of asphaltene micelles nano-structures that might be formed to serve as elements of nano-materials and also on synthetic strategies for creating such structures. An investigation of the micellization and coacervation measurements of asphaltenes in polar solvents at various concentrations and temperatures are made. The critical micellization concentration (CMC) and the micelle coacervation point (MCP) of nano-structure asphaltene micelles are measured using viscometry. At concentration above the CMC, asphaltene in the solution will self-associate, saturation phase will be formed and then at a higher concentration asphaltene nano-structure micelles in the solution will coacervate represented by a second sharp point of inflection corresponding to the asphaltene MCP and finally, at a higher concentration the aggregation of asphaltenes coacervates will occur. As a result of these measurements, for the first time it has become possible to produce phase diagrams for the whole range of asphaltene micellization and micelle coacervation.

Prediction of solubility of biomolecules in supercritical solvents

The supercritical .uid extraction (SFE) is considered an appropriate alternative for separation of biomolecules from food and pharmaceutical products. A major di2culty in utilizing the SFE for biomolecules has been the di2culty in measurement and prediction of their solubilities in supercritical solvents at various pressures and temperatures for process optimization. Lack of data for intermolecular energy parameters and=or critical properties, acentric factors, and molar refractions limits us to the use of the simple equations of state for prediction of their solubilities in supercritical solvents. In this report, six di8erent cubic equations of state are used to predict the solubility of cholesterol and � -carotene, as two representative biomolecules, in supercritical .uids. They are the van der Waals, Redlich–Kwong, Mohsen-Nia–Moddaress–Mansoori (MMM), Peng–Robinson (PR) and Patel–Teja and modi=ed PR equations. It is shown that the two-parameter MMM equation is more accurate than =ve of the other equations and comparable to the modi=ed PR equation in predicting the solubility of cholesterol and � -carotene in supercritical .uids. ? 2001 Elsevier Science Ltd. All rights reserved.

Prediction of molar volumes, vapor pressures and supercritical solubilities of alkanes by equations of state

Abstract A generalized cubic equation of state which can represent all the cubic equations is introduced and thermodynamic property relations for it are presented. Five cubic equations of states with respective mixing rules are used to predict molar volumes and vapor pressures of pure alkanes (from methane till n-tritriacontane) and solubilities of solid wax components (high molecular weight alkanes) in supercritical solvents. They are the RK (Redlich-Kwong), MMM (Mohsennia-Modarress-Mansoori), RM (Riazi-Mansoori), PR (Peng-Robinson), and SRK (Soave-Redlich-Kwon) equations of state. The experimental data necessary to compare the equations of state are taken from the literature. It is demonstrated that the SRK equation of state is more accurate for predicting vapor pressures of alkanes. The RM equation of state is shown to be more accurate for predicting molar volumes of saturated and sub-cooled liquid alkanes as well as molar volumes of alkanes in their supercritical condition. For the solubility of wax c...

Upgrading the Indonesian's Low Rank Coal by Superheated Steam Drying with Tar Coating Process and its Application for Preparation of CWM

An upgrading process of Indonesia low rank coal, which consists of atmospheric superheated steam drying and tar coating process was proposed to improve the coal quality. An experiment using Sumatera Bunko coal, which is a lignite class coal, has been carried out. The effects of upgrading parameters such as coal size, steam temperature, drying time and tar-coating process were investigated. The coal upgrading process on pulverized coal for CWM preparation was also done. CWMs with various coal concentrations were prepared using the upgraded coal as well as the just steam-dried coal as raw material. Polystyrene sulfonate (PSS) was used as dispersing additive in the CWM. The obtained CWMs were characterized and compared. The comparison with some CWM prepared by other methods is also discussed.

Thermal characteristics of non-edible oils as phase change materials candidate to application of air conditioning chilled water system

The addition of phase change material in the secondary refrigerant has been able to reduce the energy consumption of air conditioning systems in chilled water system. This material has a high thermal density because its energy is stored as latent heat. Based on material melting and freezing point, there are several non-edible oils that can be studied as a phase change material candidate for the application of chilled water systems. Forests and plantations in Indonesia have great potential to produce non-edible oil derived from the seeds of the plant, such as; Calophyllum inophyllum, Jatropha curcas L, and Hevea braziliensis. Based on the melting temperature, these oils can further studied to be used as material mixing in the secondary refrigerant. Thermal characteristics are obtained from the testing of T-history, Differential Scanning Calorimetric (DSC) and thermal conductivity materials. Test results showed an increase in the value of the latent heat when mixed with water with the addition of surfactant. Thermal characteristics of each material of the test results are shown completely in discussion section of this article.

Application of calcium chloride as an additive for secondary refrigerant in the air conditioning system type chiller to minimized energy consumption

One way to resolve the energy problem is to increase the efficiency of energy use. Air conditioning system is one of the equipment that needs to be considered, because it is the biggest energy user in commercial building sector. Research currently developing is the use of phase change materials (PCM) as thermal energy storage (TES) in the air conditioning system to reduce energy consumption. Salt hydrates have been great potential to be developed because they have been high latent heat and thermal conductivity. This study has used a salt hydrate from calcium chloride to be tested in air conditioning systems type chiller. Thermal characteristics were examined using temperature history (T-history) test and differential scanning calorimetry (DSC). The test results showed that the thermal characteristics of the salt hydrate has been a high latent heat and in accordance with the evaporator temperature. The use of salt hydrates in air conditioning system type chiller can reduce energy consumption by 51.5%.

APPLICATION OF HYDROCARBON BASED REFRIGERANTS FOR AIR CONDITIONING IN INDONESIA

Electrical energy consumption in air conditioning systems reaches 60% to 70% of the total electric energy consumption in buildings. Therefore, saving electrical energy consumption in air conditioning systems would have a significant impact on the national electrical energy consumption. Currently, the air conditioning sectors were having a dilemma on finding the alternative substitutes for CFC and HCFC refrigerants which are proven to cause destruction of the ozone layer and contribute to the effects of global warming. This paper will discuss the problems faced by an Article 5 country similar to Indonesia in phasing-out HCFC especially in air conditioning and refrigeration sectors. This paper will also discuss the possibility to use hydrocarbon-based refrigerants, which have zero ozone depletion potential (ODP) and low global warming potential (GWP), in air conditioning sectors. Some results of field applications of this refrigerant will be reported, and in general it can be concluded that the air conditio...

Phase change materials development from salt hydrate for application as secondary refrigerant in air-conditioning systems

Salt hydrate for application as secondary refrigerant in the air-conditioning system are selected based on the slurry forming according to the evaporator temperature 5°C–12°C. Research development of salt hydrate for application is done in three stages, namely; the study of the properties, flow, and heat transfer characteristics, also applications in air-conditioning systems. The study of the properties of the phase change materials is in the form of latent heat, freezing and melting temperature, thermal stability properties, viscosity, and rate of corrosion. The study of flow and heat transfer characteristics determine the effect of salt hydrates on the pressure drop and heat transfer in a heat exchanger. Studies on the application of the air-conditioning system is made to use a type of cooling room air-handling units and fan coil unit. The results of the researches for each of two stages are described in the discussion of the current article. The characteristics of salt hydrates from Na2HPO4 and CaCl2 are fitted to be applied as secondary refrigerant. This material has high latent heat value and matched phase change temperature, as well as a very low corrosion rate. This material also demonstrates excellent heat transfer performance, in which an increase as much as 18.62% for salt hydrate from calcium chloride and 13.9% for salt hydrate from disodium hydrogen phosphate. For its flow characteristics, there was a less significant increase on pressure drop for Na2HPO4.