Potential of algae for the biofuel production

Transcription

1 Potential of algae for the biofuel production, Department of Mechanical Engineering (MECH). Microalgae have been recognized as a major source of biomass for the production of biofuels (Figure 1). They are specifically included in the future objectives for the production of new generation biofuels in Europe. This high interest is due to their impressive growing rate and Figure 1: There is a high interest for microalgae, due to their yearly yield that are obtained in lab test. However to make the production economically viable, upscaling high growth rate and yearly yield (source: NOAA). is needed. This expansion has a negative e ect on the biomass production yied, therefore current research is mainly focussing on finding the most e cient production set-up, algae strain and entire production cycle. The ultimate goal of this Master thesis is to provide an alternative production solution for biofuel from algae. At the moment the focus lays on biodiesel production from algae oil or the anaerobic digestion of the algae biomass to produce hydrogen. However with a more integrated process a higher e ency and value could be achieved. The goal will be addressed through the following objectives: Analysis of various production processes Keyparametersforthee ciency Alternative use of intermediate products in the process Potentialofaselectedprocess The extends of this subject corresponds to the work of one student. Stefanie Van Damme, Ph.D. student stefvdam@vub.ac.be

2 Dynamic model of a micro humid air turbine, Department of Mechanical Engineering (MECH). Micro Gas Turbine (µgt) o ers new perspective in decentralised Combined Heat and Power (CHP) production. The profitability of the investment however strongly depends on the yearly amount of running hours. The non-continuous heat demand often leads to a forced shut down of the unit, resulting in bad eco- Thermal Power 352 kw 166 kw 25 kw Average power demand Nominal power T100 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Figure 1: In the summer, the heat demand is decreasing in domestic applications. Therefore, the µgt has to be shutted down (source : De Paepe, 2013). nomic performance. An alternative is to recuperate the lost thermal power through the injection of heated water in the µgt. This will increase the electric e - ciency and will allow to run the unit during periods with low heat demand. While the steady state performances have been characterised, the dynamic behaviour should be investigated before this machine is completely implemented in heating system. This Master thesis will address three main objectives: the existing dynamic model for dry operation will be adapted to humidified conditions; this model will be validated with experimental data; improvements of the µgt control system will be formulated to increase dynamic performances. The students (up to two) taking this subject should have a good track record in thermodynamics. Moreover, they should have a good knowledge of Matlab Simulink programming. Ward De Paepe, Ph. D. Student wdepaepe@vub.ac.be

3 Second law analysis of a steam cycle in the context of Waste-to-Energy, Department of Mechanical Engineering (MECH). Prof. Svend Bram, Department of Engineering Technology (INDU). Within the EU, municipal solid waste (MSW) is (partially) recognised as a source of renewable energy. Therefore, in addition to the objectives related to waste, European waste policy imposes energy recovery targets. In the Waste Framework Directive, there is therefore an e ciency criterion (R1 value) to be met in order to obtain the incentives related to renewable energy. For a limited number of Waste-to-Energy (WtE) plants, conceived as combined heat & power (CHP) sources, the presence of external steam/electricity consumers as such allows to exceed by far the R1 requirements. For new WtE plants of the stand-alone type (i.e. without neighbouring energy clients, as in most cases), the e ciency target is achievable too with state-of-the-art equipment and well-considered engineering practice. In most of the existing WtE plants however, it is required to remediate critical spots in the process or to execute major refurbishments in order to raise the net energy output above the imposed threshold. The EUs waste policy has become a tangible driver for the entire field of WtE to increase the net yield of energy per ton of MSW combusted. The objective of this Master thesis is to perform the second law analysis of an existing Waste-to-Energy cycle in collaboration with Keppel Seghers Belgium. The output will provide the key parameters of the cycle to improve the R1 value. The students (up to two) taking this subject should have demonstrated a very good track record in thermodynamics. They should also have a informal interview with the company involved. Prof. Svend Bram sbram@vub.ac.be This Master thesis will be performed in collaboration with Johan De Greef (Johan De Greef@keppelseghers.com) from Keppel Seghers Belgium.

4 The age of GPU: using graphical display card to accelerate combustion simulations, Department of Mechanical Engineering (MECH). Combustion simulations that include detailed kinetic mechanisms require solving a very large system of non-linear sti ordinary di erential equations (ODE). The combustion of practical fuels involves hundreds of chemical species and thousands of reactions, which render such problems computationally una ordable, at least on classical computing architectures... Enter modern graphics processing units (GPU); they rely on a multithreaded and many-core architecture which is highly scalable for computeintensive tasks. These features make them very appealing for the integration of large ODE systems such as those encountered in combustion chemistry. Moreover in the context of CFD simulations, they can be used within a hybrid paradigm where the classical multicore CPU handles the data management and the more complex parts of the algorithm, such as the fluid dynamics computation. The objective of this Master thesis is to develop the tools to simulate a combustion test case using a GPU within the OpenFOAM library and to compare the e ciency with the CPU simulations. The students (up to two) taking this subject should have followed a course on combustion and CFD. Moreover, they should have a good knowledge of programming and UNIX system. This Master thesis will be performed in collaboration with the group of Prof. Chatelain at UCL.

5 Particle matter measurement in the exhaust of a diesel engine, Department of Mechanical Engineering (MECH). Prof. Svend Bram, Department of Engineering Technology (INDU). In addition to the concerns for CO 2 emissions, pollutant emissions such as CO, NO x, unburned hydrocarbons and particle matter are of primary importance for human health. In particular, emissions of particles from car engines are considered as very harmful. In order to determine the amount and type of particles, we are using an impactor that measures the number of particles in di erent size ranges in real time (see Figure 1). Figure 1: The ELPI+ impactor can measure particle in the range of nm to µm (image from dekati.com). The objective of this Master thesis is to determine the link between the operating parameters of a diesel engine installed on a test bench and the particle emissions from the engine. The students (up to two) taking this subject should have followed a course on combustion engines. Moreover, they should have good experimental skills. Prof. Svend Bram sbram@vub.ac.be This Master thesis will be performed in the lab of the VUB located at Nijverheidskaai 170, 1070 Brussel.

6 Numerical simulations of new generation biofuels in a HCCI engine, Department of Mechanical Engineering (MECH). The second generation of biofuels mainly focus on converting non-food resources into fuels. One of the main processes involves the conversion of lignocellulose into ethanol. Converting lignocellulose to biofuels is a real challenge because of its internal structure. It therefore requires advanced and complex processes. Instead of using those processes, lignocellulose can be more easily processed into valeric biofuels through levulinic acid. These biofuels consist of methyl to pentyl valerate (or pentanoate) in proportions that depend on the process parameters. Limited data are available on these fuels. To have a better description of their combustion behaviour, we have performed experiments using the homogeneous charge compression ignition (HCCI) engine. This engine does not intrinsically rely on specific fuel properties as it is the case for traditional engines (spark ignition, SI and compression ignition, CI). Given that the air-fuel mixture is prepared properly, it can be operated on a large range of fuels. Its main working principle is between SI and CI engines. Like in conventional SI engines, the fuel and air are mixed together to obtain an homogeneous charge at the beginning of the compression stroke. Then, the mixture heats up when the piston compresses the charge and auto-ignites close to the top dead center (TDC), similarly to conventional CI engines. The objective of this Master thesis is to use the OpenFOAM library to perform CFD simulations of a HCCI engine operated with valerate esters. After the validation of the numerical model with the experimental data, further analysis will be performed on mixture of esters and di erent engine regimes. The students (up to two) taking this subject should have followed a course on combustion and CFD. Moreover, they should have a good knowledge of programming and UNIX system.

7 Modelling of a rapid compression machine to predict the ignition delay of advanced fuels When developing new generation (bio)fuels, we have to analyse their combustion behaviour. In addition to physicochemical properties, other information related to the kinetics of combustion should be investigated. Rapid compression machines (RCM) are used to study the auto-ignition delay Figure 1: The RCM compresses a air/fuel mixture at high speed to study the ignition delay of fuels. RCM are made of a piston that compresses a of fuels (image from Di Sante, 2013). gas mixture at high velocity (see Figure 1). This mixture is then very rapidly at high temperature and pressure (conditions similar to the engine combustion chamber). Then the ignition delay is obtained by measuring the pressure rise rate in the chamber while the fuel starts burning. This ignition delay is used to develop combustion mechanisms by comparing experimental results with simulation results. Current models describing the RCM are generally 0D, i.e. averaging all the values in the combustion chamber. However, some e ects may be underestimated through this averaging. Therefore, the objective of this Master thesis is to use the OpenFOAM library to develop the CFD model of a RCM and to compare it with a 0D model. The students (up to two) taking this subject should have followed a course on combustion and CFD. Moreover, they should have a good knowledge of programming and UNIX system. This Master thesis will be performed in collaboration with the group of Prof. Jeanmart at UCL.