Pre-treatment of Malaysian agricultural wastes toward biofuel production

Various renewable energy technologies are under considerable interest due to the projected depletion of our primary sources of energy and global warming associated with their utilizations. One of the alternatives under focus is renewable fuels produced from agricultural wastes. Malaysia, being one of the largest producers of palm oil, generates abundant agricultural wastes such as fibers, shells, fronds, and trunks with the potential to be converted to biofuels. However, prior to conversion of these materials to useful products, pre-treatment of biomass is essential as it influences the energy utilization in the conversion process and feedstock quality. This chapter focuses on pre-treatment technology of palm-based agriculture waste prior to conversion to solid, liquid, and gas fuel. Pre-treatment methods can be classified into physical, thermal, biological, and chemicals or any combination of these methods. Selecting the most suitable pre-treatment method could be very challenging due to complexities of biomass properties. Physical treatment involves grinding and sieving of biomass into various particle sizes whereas thermal treatment consists of pyrolysis and torrefaction processes. Additionally biological and chemical treatment using enzymes and chemicals to derive lignin from biomass are also discussed

Mathematical Modelling of a Box Type Solar Cooker Incorporating Contact Resistance

922-931A solar cooker is a device that uses solar energy to heat food to cook it. Solar cooking is used to reduce conventional fuel usage and improve the quality of food. Solar cookers have to deal with high concentration heat flows through the contact between metal parts of the absorber plate and the food vessel. For heat transfer, thermal contact resistance plays an important role and it is a major concern to reduce the thermal resistance at the contact. In the present work, mathematical modeling of a lightweight, energy-efficient box-type solar cooker is done by incorporating contact resistance. An experimental setup is developed to find out the thermal contact resistance and thermal contact resistance is evaluated for surface roughness of 0.2 Ra and 0.8 Ra for the Aluminum material. Performance tests of the cooker are carried out to get the figure of merits F1 and F2. Also, the load test with the measured thermal contact resistance is carried out with surface roughness of 0.8 and 0.2 Ra. For surface roughness of 0.2 Ra, the % error is observed as 19.77%, 13.69%, 13.68% considering thermal resistance at joints, and −42.89%, 18.95%, and 16.37% without considering thermal resistance at joints. For surface roughness of 0.8 Ra, the deviation is observed as 23.09%, 17.52%, 13.5% considering thermal resistance at joints and −42.89%, 18.95% and16.37% without considering thermal resistance at joints. The figure of merit F1 is calculated as 0.12 as compared to 0.11 for the commercial cookers, which shows that the newly designed cooker has higher optical efficiency. The figure of merit F2 is calculated as 0.42 against 0.38 for the commercial cookers. The results thus emphasize that thermal contact resistance is important and should be considered during modeling

IMECE2004-59949 DESIGN OF NOZZLE-LESS RADIAL INFLOW GAS TURBINE FOR SMALL CAPACITY (20kW) GAS TURBINE ENGINE

ABSTRACT In recent years, looking to the advantages of radial inflow gas turbine much research is focused in this area. The various applications like auxiliary drives in aircraft engine and automobile application where very high speed, compact size and greater specific power are the prime requirements, radial inflow is there by choice. The present work for the design of nozzle-less radial inflow turbine begins with power requirement of 20 kW, the parameters like temperature; pressure and mass flow rate required for the design are obtained from the detailed gas turbine cycle analysis. Based on the available data from cycle analysis initially preliminary design of rotor was developed, from the available loss models the efficiency of the turbine was found. The preliminary design provides the leading dimensions of the rotor with inlet and exit conditions. The objective of most designs will be to maximize the efficiency and/ or to develop the compact size. After completion of the preliminary design of turbine, it was felt necessary to optimized the result for best efficiency accordingly an analytical study was undertaken to study the influence of different parameters like inlet absolute Mach number, relative exit Mach number, solidity, relative velocity ratio and hub to shroud radius ratio on efficiency. VISUAL BASIC program is developed to study the effect of different parameters on efficiency. From the detailed loss analysis the selection of these parameters can be made to achieve optimum performance. It is believed that present work will provide necessary guidelines for the optimal design of radial inflow gas turbine

A comparative assessment of two experimental methods for aerodynamic performance evaluation of a car

518-522This paper presents experimental investigation of aerodynamics of a car named ADRENe, representative of small segment of current popular car spectrum, through wind tunnel tests. Out of two different strategies adopted for experimentation, one relies on measurement of pressures in effective domain upstream and downstream of car, and other relies on pressure distribution along centerline, over car profile. A good agreement between performance values obtained by these two methods independently, suggest their reliability and suitability for further experimentation purposes

Study of Flow Patterns in Radial and Back Swept Turbine Rotor under Design and Off-Design Conditions

Paper details the numerical investigation of flow patterns in a conventional radial turbine compared with a back swept design for same application. The blade geometry of a designed turbine from a 25kW micro gas turbine was used as a baseline. A back swept blade was subsequently designed for the rotor, which departed from the conventional radial inlet blade angle to incorporate up to 25° inlet blade angle. A comparative numerical analysis between the two geometries is presented. While operating at lower than optimum velocity ratios (U/C), the 25° back swept blade offers significant increases in efficiency. In turbocharger since the turbine typically experiences lower than optimum velocity ratios, this improvement in the efficiency at off-design condition could significantly improve turbocharger performance. The numerical predictions show off-design performance gains of the order of 4.61% can be achieved, while maintaining design point efficiency

FEDSM2005-77122 FLOW IN ATOMIZERS: INFLUENCE OF DIFFERENT PARAMETERS ON THE PERFORMANCE CHARACTERISTICS OF PLAIN ORIFICE ATOMIZER AND PRESSURE SWIRL ATOMIZER OF A FUEL INJECTION SYSTEM OF GAS TURBINE COMBUSTOR

ABSTRACT The atomization process is essentially one in which bulk liquid is converted into small drops. Basically, it can be considered as a disruption of the consolidating influence of surface tension by the action of internal and external forces. In the absence of such disruptive forces, surface tension tends to pull the liquid into the form of a sphere, since this has the minimum surface energy. Liquid viscosity exerts a stabilizing influence by opposing any change in system geometry. On the other end, aerodynamic forces acting on the liquid surface may promote the disruption process by applying an external distortion force to the bulk liquid. Breakup occurs when the magnitude of the disruptive force just exceeds the consolidating surface tension force. In twin fluid atomizers of the air-blast type and air assist type, atomization and spray dispersion tend to be dominated by air momentum forces, with hydrodynamic processes playing only a secondary role. With pressure swirl nozzles, the internal flow characteristics are of primary importance, because they govern the thickness and uniformity of the annular liquid film formed in the final discharge orifice as well as the relative magnitude of the axial and tangential components of velocity of this film. It is therefore of great practical interest to examine the interrelationships that exist between internal flow characteristics, nozzle design variables, and important spray features such as cone angle and mean drop size. The various equations that have been derived for nozzle discharge coefficient are discussed because this coefficient not only affects the flow rate of any given nozzle but also can be used to calculate its velocity coefficients and spray cone angle. Consideration is also given to the complex flow situations that arise on the surface of a rotating cup or disk. These flow characteristics are of basic importance to the successful operation of atomizers, because they exercise a controlling influence on the nature of the atomization process, the quality of atomization, and distribution of drop sizes in the spray. For plain orifice atomizers, the key geometrical variables are the orifice length and diameter. Final orifice diameter is of prime importance for pressure swirl atomizers. The absence of any theoretical treatment of the atomization process has led to the evolution of empirical equations to express the relationship between the mean drop size in a spray and the variable liquid properties. This paper includes the study of different parameters that affect the flow in plain orifice and pressure swirl atomizers. The paper also includes the performance characteristics of plain orifice and pressure swirl atomizers