Ari Darmawan Pasek

Municipal solid waste processing and separation employing wet torrefaction for alternative fuel production and aluminum reclamation

This study employs wet torrefaction process (also known as hydrothermal) at low temperature. This process simultaneously acts as waste processing and separation of mixed waste, for subsequent utilization as an alternative fuel. The process is also applied for the delamination and separation of non-recyclable laminated aluminum waste into separable aluminum and plastic. A 2.5-L reactor was used to examine the wet torrefaction process at temperatures below 200°C. It was observed that the processed mixed waste was converted into two different products: a mushy organic part and a bulky plastic part. Using mechanical separation, the two products can be separated into a granular organic product and a plastic bulk for further treatment. TGA analysis showed that no changes in the plastic composition and no intrusion from plastic fraction to the organic fraction. It can be proclaimed that both fractions have been completely separated by wet torrefaction. The separated plastic fraction product obtained from the wet torrefaction treatment also contained relatively high calorific value (approximately 44MJ/kg), therefore, justifying its use as an alternative fuel. The non-recyclable plastic fraction of laminated aluminum was observed to be delaminated and separated from its aluminum counterpart at a temperature of 170°C using an additional acetic acid concentration of 3%, leaving less than 25% of the plastic content in the aluminum part. Plastic products from both samples had high calorific values of more than 30MJ/kg, which is sufficient to be converted and used as a fuel.

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.

Experimental study on the heat transfer characteristics of a nuclear reactor containment wall cooled by gravitationally falling water

Gravitationally falling water cooling is one of mechanism utilized by a modern nuclear Pressurized Water Reactor (PWR) for its Passive Containment Cooling System (PCCS). Since the cooling is closely related to the safety, water film cooling characteristics of the PCCS should be studied. This paper deals with the experimental study of laminar water film cooling on the containment model wall. The influences of water mass flow rate and wall heat rate on the heat transfer characteristic were studied. This research was started with design and assembly of a containment model equipped with the water cooling system, and calibration of all measurement devices. The containment model is a scaled down model of AP 1000 reactor. Below the containment steam is generated using electrical heaters. The steam heated the containment wall, and then the temperatures of the wall in several positions were measure transiently using thermocouples and data acquisition. The containment was then cooled by falling water sprayed from t...

Heat transfer characteristics of building walls using phase change material

Minimizing energy consumption in air conditioning system can be done with reducing the cooling load in a room. Heat from solar radiation which passes through the wall increases the cooling load. Utilization of phase change material on walls is expected to decrease the heat rate by storing energy when the phase change process takes place. The stored energy is released when the ambient temperature is low. Temperature differences at noon and evening can be utilized as discharging and charging cycles. This study examines the characteristics of heat transfer in walls using phase change material (PCM) in the form of encapsulation and using the sleeve as well. Heat transfer of bricks containing encapsulated PCM, tested the storage and released the heat on the walls of the building models were evaluated in this study. Experiments of heat transfer on brick consist of time that is needed for heat transfer and thermal conductivity test as well. Experiments were conducted on a wall coated by PCM which was exposed on a day and night cycle to analyze the heat storage and heat release. PCM used in these experiments was coconut oil. The measured parameter is the temperature at some points in the brick, walls and ambient temperature as well. The results showed that the use of encapsulation on an empty brick can increase the time for thermal heat transfer. Thermal conductivity values of a brick containing encapsulated PCM was lower than hollow bricks, where each value was 1.3 W/m.K and 1.6 W/m.K. While the process of heat absorption takes place from 7:00 am to 06:00 pm, and the release of heat runs from 10:00 pm to 7:00 am. The use of this PCM layer can reduce the surface temperature of the walls of an average of 2°C and slows the heat into the room.

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.

Multi-production of solid fuel and liquid fertilizer from organic waste by employing wet torrefaction process

Preliminary survey showed that organic waste from the market is about 18.77%, or second largest in the total waste generation. Its management becomes a challenge, because it is not comprised only of organics but also mixed with small amount of plastics; therefore, conventional biological process will not achieve their maximum efficiency. Wet torrefaction is a thermal process in hot water medium, which will dissolve organic materials into water, effectively converting most solids into liquid product. Banana fruit stem and cabbage were chosen as the mixed organic waste representative, and treated in a 2.5 L reactor using saturated steam in the temperature range of 175 to 225 °C before being analyzed for their heating value in solid products as fuel precursors, and their nitrogen, phosphorus and potassium (NPK) contents in liquid products as liquid fertilizer precursors. It was found that for cabbage, the wet torrefaction process at 200 °C and 90 min resulted in 15.59 MJ/kg product heating value with NPK content of 3.43%. For banana fruit bunch stem, the wet torrefaction process at 225 °C and 30 min resulted in 17.64 MJ/kg product heating value with NPK content of 5.13%. It can be concluded that wet torrefaction process can simultaneously produce solid and liquid product as solid fuel and liquid fertilizer, respectively.Preliminary survey showed that organic waste from the market is about 18.77%, or second largest in the total waste generation. Its management becomes a challenge, because it is not comprised only of organics but also mixed with small amount of plastics; therefore, conventional biological process will not achieve their maximum efficiency. Wet torrefaction is a thermal process in hot water medium, which will dissolve organic materials into water, effectively converting most solids into liquid product. Banana fruit stem and cabbage were chosen as the mixed organic waste representative, and treated in a 2.5 L reactor using saturated steam in the temperature range of 175 to 225 °C before being analyzed for their heating value in solid products as fuel precursors, and their nitrogen, phosphorus and potassium (NPK) contents in liquid products as liquid fertilizer precursors. It was found that for cabbage, the wet torrefaction process at 200 °C and 90 min resulted in 15.59 MJ/kg product heating value with NPK con...

A review of direct contact condensation of steam on water droplets

Direct contact heat transfer is a natural phenomenon that occurs in nature. When steam contacts physically with water droplets, it results in direct contact condensation with high heat transfer rates. Due to its better heat transfer performance as well as its simplicity and less costly in construction and maintenance of equipment, this direct contact condensation is widely used in geothermal power plants, water desalination, chemical and nuclear industries. This paper reviews condensation process of pure and mixture of steam with non-condensable gas regarding to the condensation of steam on water droplets. The presence of non-condensable gases such as air, CO2, H2S, and other gases decrease equipment heat transfer efficiency. The observed parameters, modeling and heat transfer mechanisms are summarized in this paper based on the experimental and theoretical studies conducted by several researchers.Direct contact heat transfer is a natural phenomenon that occurs in nature. When steam contacts physically with water droplets, it results in direct contact condensation with high heat transfer rates. Due to its better heat transfer performance as well as its simplicity and less costly in construction and maintenance of equipment, this direct contact condensation is widely used in geothermal power plants, water desalination, chemical and nuclear industries. This paper reviews condensation process of pure and mixture of steam with non-condensable gas regarding to the condensation of steam on water droplets. The presence of non-condensable gases such as air, CO2, H2S, and other gases decrease equipment heat transfer efficiency. The observed parameters, modeling and heat transfer mechanisms are summarized in this paper based on the experimental and theoretical studies conducted by several researchers.

Numerical and experimental study on rocket stove combustion process for heating stirling engine

As an archipelago country, electrification in Indonesia is still limited in the main islands and has not reached the remote and outer islands due to the limited infrastructure of the country. To provide the electricity in the region, the small generator set is needed. However, the usage of the diesel fueled engine in the generator set is predicted to be more difficult in the future due to the fossil fuel price and rareness. The Stirling Engine offers the solution for such problem since it is able to utilize various type of fuel as energy sources. In this research, the further study was conducted on the performance of the 200-Watt Stirling engine’s furnace to provide the heat source. The type of furnace used in the stirling engine system is called Rocket Stove. The fuel used in this research was bamboo as one of the biomasses with enormous potential in the country. The numerical simulation was conducted to estimate the mass flow rate of the fuel. The experiment was conducted to obtain the rocket stove temperature distribution. Evaluation was then conducted to analyze the performance of the heat exchanger absorbing the heat of the flue gas. The results obtained from this research were the fuel rate required to produce sufficient heat to meet the heat requirement of Stirling Engine was 3.28 kg/h in bamboo and 1.43 kg/h in LPG. The average temperature distribution before the Heat Exchanger reached 788 ℃ with the standard deviation of 61 °C on the bamboo and the average temperature distribution before the Heat Exchanger reached 725 °C with the standard deviation of 3 °C on LPG. The effectiveness of heat exchanger used is 68%.As an archipelago country, electrification in Indonesia is still limited in the main islands and has not reached the remote and outer islands due to the limited infrastructure of the country. To provide the electricity in the region, the small generator set is needed. However, the usage of the diesel fueled engine in the generator set is predicted to be more difficult in the future due to the fossil fuel price and rareness. The Stirling Engine offers the solution for such problem since it is able to utilize various type of fuel as energy sources. In this research, the further study was conducted on the performance of the 200-Watt Stirling engine’s furnace to provide the heat source. The type of furnace used in the stirling engine system is called Rocket Stove. The fuel used in this research was bamboo as one of the biomasses with enormous potential in the country. The numerical simulation was conducted to estimate the mass flow rate of the fuel. The experiment was conducted to obtain the rocket stove temp...

Development of torre-briquetting process to convert mixed MSW into high energy density solid fuel

A combination of wet torrefaction and binderless briquetting processes, namely torre-briquetting process, has been developed in Indonesia to treat the mixed municipal solid waste into a solid fuel. A mixture of organic and plastic waste was treated in a 2.5 L reactor using saturated steam in the temperature range of 175 to 225°C. Afterwards, the products were briquetted in varied pressure of 500 to 1000 bar. It was observed that the wet torrefaction process at the temperature of 225°C, residence time of 30 min and sample-to-water ratio of 1:2.5 was able to produce the solid product with heating value of up to 5923 kcal/kg, equivalent to that of bituminous coal. In the briquetting aspect, the briquetted product showed adequate drop test durability of 90% at 1000 bar briquetting pressure. The density of the briquette however, has not reached the standard of 1000 kg/m3, presumably due to the presence of large sized plastic in the briquette. The results suggest that by employing wet torrefaction, the organic fibers in the mixed waste are trapped into the plastic matrix, producing granules which are suitable for briquetting. Therefore, the torre-briquetting process can be a revolutionary solution to treat the MSW without any separation required to produce high caloric solid fuel.A combination of wet torrefaction and binderless briquetting processes, namely torre-briquetting process, has been developed in Indonesia to treat the mixed municipal solid waste into a solid fuel. A mixture of organic and plastic waste was treated in a 2.5 L reactor using saturated steam in the temperature range of 175 to 225°C. Afterwards, the products were briquetted in varied pressure of 500 to 1000 bar. It was observed that the wet torrefaction process at the temperature of 225°C, residence time of 30 min and sample-to-water ratio of 1:2.5 was able to produce the solid product with heating value of up to 5923 kcal/kg, equivalent to that of bituminous coal. In the briquetting aspect, the briquetted product showed adequate drop test durability of 90% at 1000 bar briquetting pressure. The density of the briquette however, has not reached the standard of 1000 kg/m3, presumably due to the presence of large sized plastic in the briquette. The results suggest that by employing wet torrefaction, the organic ...