Experimental Study on Utilization of Indonesian Non-Recycled Organic Waste as Renewable Solid Fuel Using Wet Torrefaction Process

Municipal solid waste (MSW) is a complex problem in major cities in Indonesia that has not been resolved. MSW is currently only collected and disposed to final landfill. On the other hand, national energy security is also an issue to be solved. Utilization of MSW, which is dominated by organic waste, as solid fuel can be a solution for both problems. This paper discusses an experimental study on utilization of organic waste as renewable solid fuel using a wet torrefaction process. Four types of samples were chosen to represent the four types of organic waste in MSW with the highest mass fraction found in a field survey: leaf litter, food waste, vegetable waste and fruit waste. Each sample was treated with wet torrefaction under four conditions: 150, 175, 200 and 225 ºC with holding time 30 minutes. The experimental results showed that the optimum wet torrefaction temperature for mixed organic waste is between 200 and 225 °C, which is predicted to produce a solid product with a heating value (db) of 23.22-24.44 MJ/kg, volatile matter content of 61.18-66.00%, fixed carbon content of 26.04-31.35%, ash content of 7.47-7.96%, and energy yield equal to 58%. A higher operating temperature will increase the calorific value, followed by a decrease in mass yield as a consequence of the process severity degree. However, food waste torrefaction showed different characterisics: the increase in calorific value was followed by an increase in mass yield. This is unique and different from the results of wet torrefaction on other organic wastes.  Keywords: Indonesian organic MSW, national energy security, wet torrefaction, renewable solid fuel

PENGEMBANGAN PERSAMAAN KORELASI PENDIDHAN KOLAM UNTUK REFRIGERAN HIDROKARBON

Hydrocarbons (HC) are considered as the alterative substitutes of CFC and HCFC refrigerants. Using it as new refrigerants needs a complete knowledge of its characteristics. One of them is the boiling heat transfer coefficient. Series of experiments were carried out to investigate this characteristics. Experiments had been carried out with R-12 (CFC) and R-22 (HCFC) and their substitutes, HC-12 and HC-22. Tested refrigerant was conditiond at a saturated state and an electric heater immersed in the refrigerant pool of liquid was used as the boiling surface. Boiling heat transfer coefficient is determined as the ratio between the heat flux and the excess temperature on the boiling surface. The experimental results were compared between R-12 and R-22 with their substitutes. The experimental results were compared with the correlation equations proposed by researchers. Based on the analysis results, modified correlation equations are proposed for the tested refrigerants

ANALISIS DINAMIKA STRUKTUR PADA SISTEM FLEKSIBEL DI ANTARIKSA

Berdasarkan data-data penelitian sebelumnya, dalam makalah ini akan dibahas model pendidihan dan mekanisme perpindahan panasnya pada permukaan berpori dalam cairan refrijeran. Ditunjang dengan suatu kajian analitik, diusulkan tiga model pendidihan yang terjadi pada tiga daerah fluks panas yang berbeda. Pada fluks panas rendah terjadi pendidihan pada dasar permukaan berpori dan pada fluks panas tinggi terjadi pendidihan pada permukaan. Sedangkan model pendidihan yang ketiga adalah pendidihan antara yang terjadi pada daerah transisi antara daerah fluks panas rendah dan tinggi. Pada makalah ini akan dibahas pula suatu metoda dan persamaan korelasi untuk memperkirakan koeï¬sien perpindahan panas pada setiap daerah pendidihan

Pool boiling on porous surfaces in cryogenic and refrigerant surfaces

Experimental results for nucleate boiling, critical heat flux (CHF) and film boiling on flat plasma sprayed porous surfaces in cryogenic and CFC refrigerant liquids at atmospheric pressure are reported. Such coatings are shown to have excellent heat transfer performances, increasing not only the heat transfer coefficient in the nucleate and film boiling regime but also increasing the CHF. The effect of coating thickness, coating material and surface orientation are investigated. The results for nucleate boiling regime show that in low heat flux region (q &#60; 1 W.cm-2) and for coating thicker than 0.25 mm, the effect of coating thickness on boiling performance is not significant. In contrast, in high heat flux region, there is clearly an optimum coating thickness, which gives the highest heat transfer coefficients for a given value of heat flux. The heat transfer coefficient of the porous surfaces are higher in the cryogenic liquids compared to those in the CFC liquids. As expected the application of coating with higher thermal conductivity gives higher heat transfer coefficient. In the nucleate boiling regime, the heat transfer coefficient is not influenced by surface orientation. The experimental results also show that the coating thickness, coating material, and surface orientations strongly affect the CHF but they do not influence the film boiling performance. Based on the experimental results, boiling mechanism, models of vapour formation inside the coating and correlation equations are proposed. Comparison of the plasma sprayed porous surfaces with arc sprayed surfaces and with other commercially available enhanced surfaces are also discussed.</p

PERBANDINGAN PERSAMAAN KOEFISIEN PERPINDAHAN KALOR KESELURUHAN UNTUK PERANCANGAN PENUKAR KALOR

This paper concerns with comparison of various heat transfer equations which can be used in the design of a shell and tube heat exchanger for combustion gas and air. A computer programme which also includes the thermodynamics properties of the gas and air was made for that purpose. Characteristics of the heat exchangers are then compared with the existing industrial heatexchanger. It was found that the overall heat transfer coefï¬cient equation proposed by Babcock &amp; Wilcock gives the best results

Geometry Analysis and Effect of Turbulence Model on the Radial Rotor Turbo-Expander Design for Small Organic Rankine Cycle System

Organic Rankine Cycle (ORC) is one of the most promising technology for small electric power generations. The geometry analysis and the effect of turbulence model on the radial turbo-expanders design for small ORC power generation systems were discussed in this paper. The rotor blades and performance were calculated using several working fluids such as R134a, R143a, R245fa, n-Pentane, and R123. Subsequently, a numerical study was carried out in the fluid flow area with R134a and R123 as the working fluids. Analyses were performed using Computational Fluid Dynamics (CFD) ANSYS Multiphysics on two real gas models, with the k-epsilon and SST (shear stress transport) turbulence models. The result shows the distribution of Mach number, pressure, velocity and temperature along the rotor blade of the radial turbo-expanders and estimation of performance at various operating conditions. The operating conditions are as follow: 250,000 grid mesh flow area, real gas model SST at steady state condition, 0.4 kg/s of mass flow rate, 15,000 rpm rotor speed, 5 bar inlet pressure, and 373K inlet temperature. By using those conditions, CFD analysis shows that the turbo-expander able to produce 6.7 kW and 5.5 kW of power when using R134a and R123, respectively

PENGARUH ETANA PADA REFRIGERAN HIDROKARBON

Hydrocarbon refrigerant is one kind of refrigerants, which is developed to substitute CFC and HCFC. The substances contained in hydrocarbon refrigerant are etane, propane, normal butane, and iso butane. Ethane is being suspected on reducing the performance of refrigerator. This paper deals with theoretical study of ethane influence in hydrocarbon refrigerant. First of all it is necessary to create software for evaluating thermodynamics properties. This software has many choices for prescribed thermodynamics properties. According to the analysis, it is known that the more ethane content in HCR-12, the more deviation of saturated pressure-temperature curves between HCR-12 and R-12. While in HCR-22 when the pressure is less that 4 bar, it is known that the more ethane content, the more deviation of saturated pressure-temperature curve between HCR-22 and R-22. However, if the pressure is above 4 bars, it is known that the more ethane, the saturated pressure-temperature curve is close to the one of HCR-22 with 4% ethane content. On performance test of standard refrigeration system using the refrigerant, it is known that the more ethane content in HCR-12 and HCR-22, COP of the system decreases gradually. The average temperature in evaporator and condensor also declines

Feasibility of Recovering Energy from Municipal Solid Waste to Generate Electricity

Population growth and economic development in Indonesia have increased the production of municipal solid waste (MSW) in many big cities, causing sanitary problems. The (MSW) disposal problem can be solved by applying an appropriate technology that can reduce the volume of the waste effectively and efficiently. Waste-to-Energy (WTE), or Energy-from-Waste (EFW), is one of the most effective and efficient technologies for reducing the waste volume. Energy recovered from the waste can be used for thermal or electricity generation. This paper deals with a feasibility study of utilizing MSW for generating electricity. A survey and investigation of waste characteristics, including waste composition, chemical and physical composition, and heating value, were carried out for typical Bandung MSW. An average heating value of 1500 kcal/kg can be expected from pre-treated MSW to be used as a fuel for direct combustion in a WTE plant. A typical design for a small-scale WTE plant is shown in this paper and also an energy analysis is provided. Approximately 800 kW of electric power can be generated from 50 tonnes of MSW per day

Feasibility of Recovering Energy from Municipal Solid Waste to Generate Electricity

Population growth and economic development in Indonesia have increased the production of municipal solid waste (MSW) in many big cities, causing sanitary problems. The (MSW) disposal problem can be solved by applying an appropriate technology that can reduce the volume of the waste effectively and efficiently. Waste-to-Energy (WTE), or Energy-from-Waste (EFW), is one of the most effective and efficient technologies for reducing the waste volume. Energy recovered from the waste can be used for thermal or electricity generation. This paper deals with a feasibility study of utilizing MSW for generating electricity. A survey and investigation of waste characteristics, including waste composition, chemical and physical composition, and heating value, were carried out for typical Bandung MSW. An average heating value of 1500 kcal/kg can be expected from pre-treated MSW to be used as a fuel for direct combustion in a WTE plant. A typical design for a small-scale WTE plant is shown in this paper and also an energy analysis is provided. Approximately 800 kW of electric power can be generated from 50 tonnes of MSW per day