Optimization of a Biomass Micro-Gasification Process for the Production of Synthesis Gas From Palm Shell

This paper studied, through an experiment design, the significance of particle size, air speed and reactor arrangement for palm shell micro-gasification process in order to optimize the heating value of the syngas obtained. The range of variables was 8 to 13 mm for particle size, 0.8–1.4m/s for air velocity, and updraft or downdraft for the reactor type. It was found that the particle size and air velocity factors were the most significant in the optimization of the output variable, syngas heating value. A heating value of 2.69MJ / Nm3 was obtained using a fixed bed downdraft reactor, with a particle size of 13 mm and 1.4 m/s for air speed; verification of the optimum point of operation under these conditions verified that these operating conditions favor the production of a gas with a high energy value.

Diesel Emission Test Stand for Advanced SCR Control

The combination of increasingly challenging emissions regulations and impending Corporate Average Fuel Economy (CAFE) standards of 54.5 mpg by 2025 presents auto makers with a challenge over the next 10 years. The most promising technologies currently available for meeting high fuel economy and low emissions regulations are increased hybridization, turbo downsizing, and increased Diesel engine implementation. Combining these into a hybrid turbo Diesel is an ideal transition technology for the very near future as battery and other alternative fuels become viable for widespread automotive use. This paper presents a Diesel emission test stand to improve Selective Catalytic Reduction (SCR) systems for light duty Diesel vehicles, particularly hybrid power systems that experience many start-stop events. Advanced modeling and control systems for SCR systems will further reduce tailpipe emissions below existing Tier structures and will prepare manufacturers to meet increasingly stringent Tier 3 standards beginning in 2017. SCR reduces oxides of Nitrogen, NO, and NO2, from otherwise untreated Diesel emissions. Scientific study has proved that inhaling this harmful exhaust gas is directly responsible for some forms of lung cancer and a variety of other respiratory diseases. In addition to EPA Tier emissions levels and CAFÉ standards, the On-Board Diagnostics (OBD) regulations require every vehicle’s emission control systems to actively report their status during all engine-on vehicle operation. Testing and development with production NOx sensors and production SCR components is critical to improving NOx reduction and for OEMs to meeting strict Tier 3 light duty emission standards. The test stand was designed for straightforward access to the NOx sensors, injector, pump and all exhaust components. A Diesel Particulate Filter (DPF) followed by a Diesel Oxidizing Catalyst (DOC) precedes the Selective Catalytic Reducer (SCR) injector, mixing pipe and catalyst. An upstream NOx sensor reads engine-out NOx and the downstream NOx sensor reports the post catalyst NOx levels. Custom fabrication work was required to integrate the SCR mechanical components into a simple system with exhaust components easily accessible in a repeatable, controlled laboratory environment. A Diesel generator was used in combination with a custom designed resistive load bank to provide variable NOx emissions according to the EPA drive cycles. A production exhaust temperature sensor was calibrated and integrated into the software test manager. Production automotive NOx sensors and SCR injector, pump and heaters were mounted on a production light duty vehicle exhaust system. The normalized nature of NOx concentration in parts per million (ppm) allows the small Diesel generator to adequately represent larger Diesels for controls development purposes. Both signal level and power electronics were designed and tested to operate the SCR pump, injector, and three Diesel Exhaust Fluid (DEF) heating elements. An Arduino-based Controller Area Network (CAN) communications network read the NOx Diesel emissions messages from the upstream and downstream sensors. The pump, injector, solenoid, and line heaters all functioned properly during DEF fluid injection. CAN and standard serial communications were used for Arduino and Matlab/Simulink based control and data logging software. Initial testing demonstrated partial and full NOx reduction. Overspray saturated the catalyst and demonstrated the production NOx sensor’s cross-sensitivity to ammonia. The ammonia was indistinguishable from NOx during saturation and motivates incorporation of a separate ammonia sensor.

Experimental Investigation of Hydraulic-Pneumatic Regenerative Braking System

Design and development of energy efficient vehicles is of paramount importance to the automobile industry. Energy efficiency can be enhanced through recovery of the kinetic energy lost in the form of waste heat during braking. The kinetic energy could be converted into a reusable energy source and aid in acceleration, hence the braking system would contribute to improving the overall efficiency of a vehicle. Hydraulic-Pneumatic Regenerative Braking (HPRB) systems are a hybrid drive system that works in tandem with a vehicle’s engine and drivetrain to improve efficiency and fuel-economy. A HPRB system functions by recovering the energy typically lost to heat during vehicle braking, and storing this energy as a reusable source that can propel a vehicle from a stop. The major advantages of a HPRB system are that a vehicle would not require its engine to run during braking to stop, nor would the engine be required to accelerate the vehicle initially from a stop. The benefit realized by this system is an increase in fuel-efficiency, reduced vehicle emissions, and overall financial savings. An HPRB system aids in slowing a vehicle by creating a drag on the driveline as it recovers and stores energy during braking. Therefore, HPRB system operation reduces wear by minimizing the amount of work performed by the brake pads and rotors. An experimental investigation of Hydraulic-Pneumatic Regenerative Braking (HPRB) system was conducted to measure the system’s overall efficiency and available power output. The HPRB in this study is a 1/10th lab-scale model of a light-duty four wheel vehicle. The design/size was based on a 3500 lbs light-duty four wheel vehicle with an estimated passenger weight of 500 lbs. It was assumed that the vehicle can accelerate from 0–15 mph in 2 seconds. The aim of this work is to examine the effect of heat losses due to irreversibility on energy recovery. The experimental facility consisted of a hydraulic pump, two hydraulic-pneumatic accumulators, solenoid and relief valves, and data acquisition system. The HPRB system did not include any driveline components necessary to attach this system onto a vehicle’s chassis rather an electric motor was used to drive the pump and simulate the power input to the system from a spinning drive shaft. Pressure transducers, Hall effects sensor, and thermocouples were installed at suction and discharge sections of the hydraulic and pneumatic components to measure hydrodynamic and thermos-physical properties. The measured data were used to determine the system’s energy recovery and power delivery efficiency. Results showed that the HPRB system is capable of recovering 47% of the energy input to the system during charging, and 64% efficient in power output during discharging with an input and output of 0.33 and 0.21 horsepower respectively. Inefficiencies during operation were attributed to heat generation from the gear pump but especially due to the piston accumulator, where heat loss attributed to a 12% reduction in energy potential alone.

Thermal Performance of a Borehole Heat Exchanger Located in Guayaquil-Ecuador Using Novel Heat Transfer Fluids

An analysis of thermal performance of a vertical Borehole Heat Exchanger (BHE) from a close loop Ground Source Heat Pump (GSHP) located in Guayaquil-Ecuador is presented. The project aims to assess the influence of using novels heat transfer fluids such as nanofluids, slurries with microencapsulated phase change materials and a mixture of both. The BHEs sensitive evaluation is performed by a mathematical model in a finite element analysis by using computational tools; where, the piping array is studied in one dimension scenario meanwhile its surroundings grout and ground volumes are presented as a three dimensional scheme. Therefore, an optimized model design can be achieved which would allow to study the feasibility of GSHP in buildings and industries in Guayaquil-Ecuador.

Analysis and Comparison of Biochar From Pilot Scale Downdraft Gasifier

Gasification is incomplete combustion of solid fuel that results in the production of vapor, often referred to as syngas or producer gas, char, and tar. When this process is applied to biomass, the resulting char, referred to as biochar, is produced and has been shown to enhance soil fertility and crop growth. As part of a broader effort, this work examines how the gasification process impacts the biochar generated through downdraft gasification. In contrast to previous publications, which only focused on the syngas compositions, this research paper expands the analysis to the composition of the biochar produced in the gasification systems. In a large-scale gasifier, corn grains at about a 15% moisture level are inserted into a pilot scale downdraft gasifier from the top. In this system, both air and fuel move in the same direction. The air entering the setup is controlled using a damper. Corn grains entering the gasifier pass through a drying zone where the moisture content in it is removed. The dry corn then passes through a combustion and pyrolysis zone, followed by a reduction zone. The high temperature present at the bottom in the reduction zone cracks any tar present in the syngas produced. This syngas exits from the bottom of the gasifier. The char produced has a residence time from half an hour to several hours. About 20% of the fuel that’s inserted in the gasifier is converted to biochar. An ultimate and proximate chemical composition analysis, BET porosity analysis, and an SEM image analysis were carried out on the biochar produced from this system. From the SEM analysis, a surface area of 2.38 m2/g was obtained. From the ultimate and proximate analysis, it was observed that the biochar had higher carbon content and a lack of volatile components compared to other reported biochars and levels similar to activated carbon. From the BET porosity analysis, both small scale and large-scale pores were observed but quantified comparison with other biochar is still on going. Porosity is known to be an important factor in biochar effectiveness as a soil amendment.

A Sensitivity Analysis for Effective Use of CO2 for Heat Mining in Geothermal Reservoirs

Carbon dioxide (CO2) emitted from various sources, mainly fossil fuel power plants, is considered responsible of the global warming effect. Many processes and techniques are still under research for CO2 capture and sequestration. On the other hand, it is proposed that the geothermal heat be mined from geothermal reservoirs using captured CO2. In this sense, some theoretical studies show feasibility of using supercritical carbon dioxide (sCO2) as a heat mining media in such geothermal reservoirs. In this work, it is carried out a set of numerical simulations to determine the most effective distance between injection and production wells for extracting geothermal energy utilizing sCO2 (Water is used for comparison). In the study, the permeability is considered in the range of 0.5 mD to 3.5 mD, with the aim of determining also the critical point in which sCO2 works better than water (H2O) as a working fluid. The remaining properties such as volume, density and other thermal properties remain fixed. Afterwards, it is constructed a numerical model which is implemented in TOUGH2 and PETRASIM 5 software to simulate the cases established. In the model, it is considered a simplified control volume, i.e. only one well for injection and one for production, assuming a constant flow rate at the inlet and at the outlet, meaning that sequestration is not taken into account. A length of 300 meter is defined for reservoir thickness, considering also a pressure and temperature of 100 bar and 200 °C, respectively. The energy mined is estimated for a period of twenty-five years. As typically, the sensitivity analysis is performed by varying only one property and keeping the remaining properties constant, isolating in this way the effect of such variable. Results show that for small permeabilities H2O works better than sCO2, but it is possible to assure that for permeabilities greater than 1 mD, sCO2 presents more advantages as extracting heat media instead of water. Both, H2O and sCO2 show a linear behavior. A deep analysis is necessary to carry out, because results shows that sCO2 works better in an intermediate zone (greater than 200 meter length, but smaller than 800 meter length). An unusual behavior is presented when the distances between the wells are varied; water shows a linear behavior increasing monotonically, while sCO2 shows a nonlinear behavior for some distances sCO2 works better. As expected, the more the distance, the greater the amount of the energy mined due to the volume related with each one of the distances.

An Ignition Delay Study of Category A and C Aviation Fuel

Ignition delay of category A and C alternative aviation fuels have been investigated using a rapid compression machine (RCM). Newly introduced alternative jet fuels are not yet comprehensively understood in their combustion characteristics. Two of the category C fuels that will be primarily investigated in this study are Amyris Farnesane and Gevo Jet Fuel Blend. Amyris direct sugar to hydrocarbon (DSHC) fuel (POSF 10370) come from direct fermentation of bio feedstock sugar. Amyris DSHC is mainly composed of 2,6,10-trymethly dodecane, or farnesane. Gevo jet blend stock fuel is alcohol to jet (ATJ) fuel (POSF 10262) produced from bio derived butanol. Gevo jet blend stock is composed with iso-dodecane and iso-cetane, and has significantly low derived cetane number of 15. The experimental results are compared to combustion characteristics of conventional jet A fuels, including JP-8. Ignition delay, the important factor of auto ignition characteristic, is evaluated from pressure trace measured from the RCM at University of Illinois, Urbana-Champaign. The measurements are made at compressed pressure 20bar, intermediate and low compressed temperature, and equivalence ratio of unity and below. Direct test chamber charge method is used due to its reliable reproducibility of results. Compared to category A fuels, different combustion characteristics has been observed from category C fuels due to their irregular chemical composition.

Three Dimensional Single-Walled Carbon Nanotube Foams for Ultrahigh Energy Density Lithium Air Battery Cathodes

This paper highlights our progress in developing pristine single-walled carbon nanotubes (SWCNTs) into functional materials for lightweight, conductive cathodes in lithium air (Li-air) batteries. We outline a process to produce foams of single-walled carbon nanotubes using liquid processing routes that are free of additives or surfactants, using polar solvents and electrophoretic deposition. To accomplish this, SWCNTs are deposited onto sacrificial metal foam templates, and the metal foam is removed to yield a freestanding, all-SWCNT foam material. We couple this material into a cathode for a Li-air battery and demonstrate excellent performance that includes first discharge capacity over 8200 mAh/g, and specific energy density of ∼ 21.2 kWh/kg (carbon) and ∼ 3.3 kWh/kg (full cell). We further compare this to the performance of foams prepared with SWCNTs that are dispersed with surfactant, and our results indicate that surfactant residues completely inhibit the nucleation of stable lithium peroxide materials — a result measured across multiple devices. Comparing to multi-walled carbon nanotubes produced using the same technique indicates a discharge capacity of only ∼ 1500 mAh/g, which is over 5X lower than SWCNTs in the same processing technique and material architecture. Overall, this work highlights SWCNT materials in the absence of impurities introduced during experimental processing as a lightweight and high performance electrode material for lithium-air batteries.

Method for Determining the Efficiency of Generation of a Genset Coupled to a Biomass Gasification Process

This research is based on obtaining a mathematical model to determine the efficiency of generating a generator coupled to a biomass gasification process. To do this, it is initially simulated internal combustion engine at the Aspen hysys® licensed software, in order to obtain the shaft work and a representative model of the generation efficiency of the motor; according to the characteristics of the power cycle and product gas from the gasification of agricultural biomass prevailing in the Department of Córdoba – Colombia: Cotton waste (Gossypium hirsutum), Rice husk (Oryza sativa), Sesame stalk (Sesamum indicum), Corn cob (Zea mays) and Coconut fiber (Cocos nucifera). Subsequently, the generator efficiency is evaluated by the electric power generation simulation phase in the Simulink Toolbox of the MATLAB® software. The deterministic mathematical models resulting from the simulations above are adjusted by statistical techniques to experimental data and a regression model that assesses the overall system efficiency is obtained. Such efficiencies range from 16 to 20%. Therefore it is concluded that the use of representative crops biomass product’s calorific values in the Department of Córdoba -Colombia, are profitable for electric power generation. On the other hand, it is important to note that experimental data’s reliable and monitored way acquisition was performed through the SCADA developing; it allowed real time process variables’ intervention presentation.

The Droplet Burning Characteristics of Algae-Derived Renewable Diesel, Conventional #2 Diesel, and Their Mixtures

Bio-derived fuels have received significant attention for their potential to reduce the consumption of petroleum-based liquid fuels, either through blending or direct use. Bio-feedstocks that employ algae, in particular heterotrophic microalgae, which convert sustainable plant sugars into renewable oils are especially attractive because the sugar that feeds this process can come from many sources — from sugarcane to corn, and even waste biomass, also known as cellulosic sugars. The microalgae grow in the dark and transforms sugar into nearly any oil type for almost any purpose anywhere, all while drastically compressing production time, from months and years to a matter of days. Much of the work in this area has focused on fuel production technologies. Little research has been reported on the combustion performance of algae-derived fuels, with most of the effort being directed to more system-level studies associated with combustion in engines. In this paper, we report the results of experiments that address some more fundamental multiphase combustion characteristics of algae-derived fuels relevant for spray combustion, namely a configuration involving a single isolated burning droplet. Experimental conditions are created that promote near spherical symmetry such that the gas flow arises primarily through the evaporation process (i.e., stationary droplets are ignited by spark discharge in stagnant air in the standard atmosphere and the droplet burning history is recorded in a free-fall facility that minimizes the influence of buoyant convection). The combustion symmetry that results, in which the droplet and flame are concentric spheres, facilitates the understanding of the combustion process while providing useful validation data for basic models of droplet burning that assume one-dimensional gas transport. Experiments were performed using algae-derived renewable diesel, and its performance was compared to #2 diesel fuel and a mixture of algal renewable diesel/#2 diesel (0.5 v/v). Additionally, the results of detailed chemical analysis are reported where it is shown that the composition of the algae-based diesel that was employed in the experiments was comprised of a complex mixture of aromatics and normal alkanes. The highly sooting propensity of these components resulted in droplet flames being luminous and producing soot during the burning history. A comparison of the flame brightness suggests that the sooting propensities are in the order of #2 diesel > renewable diesel #2 diesel blend > algae renewable diesel, which is consistent with observations of the sooting dynamics from back-lit droplet images. In spite of this difference in sooting propensities, algal renewable diesel droplets were found to have burning rates that are very close to #2 diesel and the mixture. Furthermore, the relative position of the flame to the droplet was almost indistinguishable for the fuels examined. These results suggest that algae renewable diesel could potentially be considered a drop-in replacement for conventional diesel fuel, or at the least serve as a useful additive to reduce the consumption of petroleum-based #2 diesel fuel.