Biogas for partial substitution of diesel in power generators

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.In recent years, agricultural farms in Peru have started to implement equipment for anaerobic digestion of the organic residues of their production. At first, the main objective of the implementation was to obtain bio-fertilizers, but in this process, biogas was also obtained. Farms in Peru did not use this biofuel in any process, which is why they freed it or burnt it in torches, polluting the environment in both ways, due to the biogas content of methane. This last fuel has a high global warming potential (GWP) and carbon dioxide, result of the biogas burning is also a pollutant. In this context, an experimental device was designed and built to evaluate the performance of a Diesel cycle engine generator set of 40 kW using diesel and biogas as fuels. The generator set had a fixed speed of 1800 RPM. The tests were initially carried out using only diesel as fuel to obtain comparable parameters. The tests were made simulating an electric load of 62.5%. After this, a conversion kit was installed to allow the use of biogas in the engine. This equipment controls the Duty Cycle, which is a value between 0 and 1 that indicates the percentage of time the injectors are opened. The kit used as input signals the generated power, the electronic governor signal and the exhaust gases temperature. Then, tests were carried out partially substituting diesel for biogas. The biogas used for the test contained approximately 40% of methane. The results indicated that for higher Duty Cycles (higher quantities of biogas), the exhaust temperatures increased, due to the superior temperature of biogas combustion. With the percentage of methane available in the biogas, the substitution rates reached 17,9% and 36,7%, maintaining the generated power and reducing significantly the consumption of diesel. This technology makes possible the modular production of electric energy in agricultural farms, usually isolated, allowing the use of biogas commonly produced in the same place with the organic residues they manage, diminishing pollution, reducing costs and using the energy for useful purposes.dc201

Combined production of electricity and heat in a microcogeneration unit

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.Diesel engines are widely used in industrial activities in Peru for electricity generation and heat production. The requirement of different types of energy and its separate generation represent a higher demand for fossil fuels, when the equipment used are internal combustion engines, and higher emission of high-temperature pollutant gases to the environment; all of this, with a deficient utilization of the energy supplied by the fuel. In this context, a Diesel cycle generator of 40 kW was evaluated for the production of electricity and heat. The engine was mapped with different electrical charges (5 kW, 10 kW, 15 kW, 20 kW, 25 kW and 30 kW) simulated by a copper resistance submerged in a tank with salty water. A regenerator was used for the recovery of the exhaust gases heat to allow cogeneration. The experimental device was monitored and instrumented with K type thermocouples, differential pressure sensors, power meters, flow meters, among others; all the signals were received and stored by a data acquisition system for its processing and interpretation. The electrical power, thermal power, specific fuel consumption, thermal efficiency and electric efficiency were evaluated for conventional electricity generation and for combined production of electricity and heatdc201

Semitoric integrable systems on symplectic 4-manifolds

Let M be a symplectic 4-manifold. A semitoric integrable system on M is a pair of real-valued smooth functions J, H on M for which J generates a Hamiltonian S^1-action and the Poisson brackets {J,H} vanish. We shall introduce new global symplectic invariants for these systems; some of these invariants encode topological or geometric aspects, while others encode analytical information about the singularities and how they stand with respect to the system. Our goal is to prove that a semitoric system is completely determined by the invariants we introduce