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Modelling the combustion in a dual fuel HCCI engine. Investigation of knock, compression ratio, equivalence ratio and timing in a Homogeneous Charge Compression Ignition (HCCI) engine with natural gas and diesel fuels using modelling and simulation.Ghomashi, Hossein January 2013 (has links)
This thesis is about modelling of the combustion and emissions of dual fuel HCCI engines for design of “engine combustion system”. For modelling the combustion first the laminar flamelet model and a hybrid Lagrangian / Eulerian method are developed and implemented to provide a framework for incorporating detailed chemical kinetics. This model can be applied to an engine for the validation of the chemical kinetic mechanism. The chemical kinetics, reaction rates and their equations lead to a certain formula for which the coefficients can be obtained from different sources, such as NASA polynomials [1]. This is followed by study of the simulation results and significant findings. Finally, for investigation of the knock phenomenon some characteristics such as compression ratio, fuel equivalence ratio, spark timing and their effects on the performance of an engine are examined and discussed. The OH radical concentration (which is the main factor for production of knock) is evaluated with regard to adjustment of the above mentioned characteristic parameters. In the second part of this work the specification of the sample engine is given and the results obtained from simulation are compared with experimental results for this sample engine, in order to validate the method applied in AVL Fire software. This method is used to investigate and optimize the effects of parameters such as inlet temperature, fuels ratio, diesel fuel injection timing, engine RPM and EGR on combustion in a dual fuel HCCI engine. For modelling the dual fuel HCCI engine AVL FIRE software is applied to simulate the combustion and study the optimization of a combustion chamber design. The findings for the dual fuel HCCI engine show that the mixture of methane and diesel fuel has a great influence on an engine's power and emissions. Inlet air temperature has also a significant role in the start of combustion so that inlet temperature is a factor in auto-ignition. With an increase of methane fuel, the burning process will be more rapid and oxidation becomes more complete. As a result, the amounts of CO and HC emissions decrease remarkably. With an increase of premixed ratio beyond a certain amount, NOX emissions decrease. With pressure increases markedly and at high RPM, knock phenomenon is observed in HCCI combustion.
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A Comparative Study of Diesel Ignited Methane and Propane Dual Fuel Low Temperature Combustion in a Single Cylinder Research EngineRaihan, Mostafa Shameem 13 December 2014 (has links)
The objective of this thesis is to investigate and compare the performance and emissions characteristics of diesel-ignited methane and diesel-ignited propane dual fuel LTC in a single cylinder research engine (SCRE) at a constant engine load of 5.1 bar net indicated mean effective pressure (IMEP) and at a constant engine speed of 1500 RPM. Percentage of energy substitution of propane or methane (0 - 90 percent), diesel injection timing (SOI: 355 CAD – 280 CAD), rail pressure (200 bar – 1300 bar) and boost pressure (1.1 bar – 1.8 bar) were varied to quantify their impact on engine performance and engine-out ISNOx, ISHC, ISCO, and smoke emissions. Advancing SOI to 310 CAD and beyond yielded simultaneous ISNOx and smoke emissions. A rail pressure of 500 bar was the optimal one for both fueling combinations while increasing boost pressure over 1.2 bar had a very little effect on ISNOx and smoke emissions.
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Simulating the Influence of Injection Timing, Premixed Ratio, and Inlet Temperature on Natural Gas / Diesel Dual-Fuel HCCI Combustion in a Diesel EngineGhomashi, Hossein, Olley, Peter, Mason, Byron A., Ebrahimi, Kambiz M. 01 1900 (has links)
Yes / Dual-fuel HCCI engines allow a relatively small quantity of diesel fuel to be used to ignite a variety of fuels such as natural gas or methane in HCCI mode. The gaseous fuel is mixed with the incoming air, and diesel fuel is sprayed into the cylinder by direct injection. Mathematical modelling is used to investigate the effects of parameters such as premixed ratio (fuel ratio) and pilot fuel injection timing on combustion of a dual-fuel HCCI engines. A CFD package is used with AVL FIRE software to simulate dual-fuel HCCI combustion in detail. The results establish a suitable range of premixed ratio and liquid fuel injection timing for low levels of NOx, CO and HC emissions along with a reliable and efficient combustion. Dual-fuel HCCI mode can increase NOx emission with lower premixed ratios in comparison to normal HCCI engines, but it is shown that the NOx emission reduces above a certain level of the premixed ratio. Due to the requirement of homogenous mixing of liquid fuel with air, the liquid fuel injection is earlier than for diesel engines. It is shown that, with careful control of parameters, dual-fuel HCCI engines have lower emissions in comparison with conventional engines.
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[en] REACTIVITY CONTROLLED COMPRESSION IGNITION OF DIESEL FUEL AND ETHANOL IN RAPID COMPRESSION MACHINE / [pt] IGNIÇÃO POR COMPRESSÃO COM REATIVIDADE CONTROLADA DE ÓLEO DIESEL E ETANOL EM MÁQUINA DE COMPRESSÃO RÁPIDAJUAN CARLOS VALDEZ LOAIZA 09 November 2018 (has links)
[pt] Serão necessários muitos anos para que os biocombustíveis sejam capazes de substituir integralmente os derivados fósseis. Este trabalho visa estudar formas alternativas de conversão de energia contida nos combustíveis utilizados em motores de combustão interna. Maiores eficiências na conversão da energia
contida no combustível e uma menor emissão dos gases de exaustão são benefícios associados à ignição por compressão de reatividade controlada, RCCI, onde dois fluidos com diferentes reatividades são introduzidos na câmara de combustão em instantes diferentes. Optou-se pelo uso de uma máquina de
compressão rápida, MCR, capaz de controlar parâmetros relevantes, como taxa de compressão, pressões, tempos de injeção, que foi adaptada para receber dois sistemas de injeção direta na câmara de combustão. Como segundo combustível, que substitui parcialmente o óleo diesel, que é empregado tradicionalmente em motores de ignição por compressão, optou-se pelo etanol hidratado. Os estudos
revelaram que diferentes formas de injeção dos dois combustíveis produzem processos muito diferentes, para as mesmas quantidades de combustíveis injetados. Os resultados são apresentados na forma de pressão indicada como função do ângulo equivalente, bem como calor liberado e atraso de ignição.
Experiências foram conduzidas para uma ou duas injeções de etanol por ciclo, em diferentes tempos. Altas razões de substituição do combustível fóssil foram obtidas, quando comparadas com a técnica de fumigação, onde o segundo combustível é misturado externamente ao ar de combustão. / [en] Many years will be needed for biofuels or other renewable sources to be able to fully replace fossil fuels. This work aims to study alternative ways of converting energy contained in fuels used in internal combustion engines. Higher efficiencies in converting the energy contained in the fuel and lower emission of harmful exhaust gases are benefits associated with the Reactivity Controlled Compression Ignition, known for RCCI. In this type of combustion, two fluids with different ignition-reactivity characteristics are introduced into the combustion chamber at different times. To better understand this phenomenon, it was used a RCM, that is able to control, more easily, relevant parameters such as compression ratio, temperatures, pressures, injection times etc. As a second fuel, which partially replaces the diesel, which is traditionally used in compression ignition engines, it was used the ethanol. The RCM was then adapted to receive two systems for direct injection into the combustion chamber. Studies have shown that different forms of injection of the two fuels produce very different processes to the same amount of fuel injected. The results are presented in the form of indicated pressure as a function of position. Heat released and ignition delay are also presented. Experiments were conducted for one or two injections of ethanol per
cycle at different times. High substitution rates of the fossil fuel were obtained when compared to injections of external mixtures of diesel and ethanol or fumigation technique, where the second fuel is mixed externally with the combustion air.
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Utformning av avgaskatalysator / Designing Exhaust Gas CatalystsASTORSDOTTER, JENNIFER, RICKNELL, JONAS, YU, FIONA, Forsgren, Axel January 2015 (has links)
Naturgas är ett alternativ till oljebaserade bränslen. Ur ett miljöperspektiv är naturgasen fördelaktig eftersom den vid förbränning ger mindre utsläpp av miljöfarliga ämnen än olja. I en diesel dual-fuel motor används diesel och naturgas som bränsle. Naturgas består till största delen av metan. För att oskadliggöra den del av metangasen som inte förbränns i motorn krävs en avgaskatalysator som kan bryta ned det relativt stabila metanet vid låga temperaturer. Målet med det här kandidatexamensarbetet är att tillverka och testa tre olika avgaskatalysatorer för nedbrytning av metan. De tre katalysatorer som valdes för tillverkning och testning var Pd/Al2O3, Pd/SnO2 och In2O3/SnO2 (ITO). Valen baserade sig på att katalysatorerna som tillverkades skulle vara aktiva för nedbrytning av metan vid låga temperaturer. ITO sågs som en extra intressant kandidat eftersom In är billigare än ädelmetallen Pd. Pd/Al2O3 tillverkades med en kommersiell support och impregnering av Pd genom ”incipient wetness” (IW). Pd/SnO2 tillverkades på samma sätt. ITO tillverkades genom ”forward co-precipitation”. En monolit testades för varje katalysator. Vid ungefär 315 °C kunde 10 % omsättning av metan detekteras för alla tre katalysatorer. Pd/Al2O3 var den katalysator vars aktivitet förbättrades som mest då temperaturen ökade ytterligare. Katalysatorerna testades bara en gång. För att statistiskt säkerställa resultaten behöver upprepade tester göras. Resultaten överensstämmer delvis med tidigare studier. Slutsatsen av arbetet är att alla tre katalysatorer fungerar och att ITO skulle kunna vara en billigare men i övrigt likvärdig avgaskatalysator för en diesel dual-fuel lean burn motor vid 315 °C. Fler tester måste dock göras för att ta reda på om ITO verkligen är ett mer fördelaktigt alternativ.
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[en] ANALYSIS OF A SYSTEM FOR THE SIMULTANEOUS PRODUCTION OF ELECTRICAL ENERGY, HEAT AND COLD / [pt] ANÁLISE DE UM SISTEMA DE PRODUÇÃO SIMULTÂNEA DE ELETRICIDADE, FRIO E CALORFRANK CHAVIANO PRUZAESKY 23 March 2006 (has links)
[pt] A produção simultânea de energia elétrica, calor e frio, a
partir da
queima de combustível primário (trigeração), pode se
mostrar como
estratégia promissora do ponto de vista energético e de
projeto,
principalmente em indústrias como a química e a de
alimentos. No
presente trabalho descreve-se o estudo experimental de um
sistema de
produção de água gelada (chiller) com compressor hermético
acionado
eletricamente. Um motor a combustão interna, do tipo
Diesel, foi
convertido para operar com gás natural veicular (Diesel-
gás) e aciona um
gerador de eletricidade que supre a energia elétrica
necessária ao
funcionamento do chiller e ao atendimento de demanda
elétrica préestabelecida.
O resultante sistema de trigeração é, portanto, composto
por dois sub-sistemas: a bomba de calor (chiller) e o
conjunto motorgerador.
Calor de rejeito, do condensador do chiller e do sistema de
arrefecimento e gases de exaustão do motor, é recuperado
para a
produção de água quente. O sistema é analisado à luz da 1ª
e 2ª leis da
Termodinâmica. As razões entre as demandas de frio, calor
e eletricidade,
as temperaturas de evaporação e de condensação da bomba de
calor, e
a razão de substituição de óleo Diesel por gás natural
veicular são os
principais parâmetros de controle dos resultados
apresentados.
Determinou-se, para o sistema em questão, uma taxa de
substituição
energética ótima do óleo Diesel por GNV de aproximadamente
25%, com
uma economia de 11% a 15% (para geração de potência
elétrica acima
de 4,0 kW), fundamentada na diferença de preços entre os
dois
combustíveis e numa melhora do rendimento do motor para
estas condições de operação. Obteve-se a contribuição
percentual de cada um
dos produtos energéticos (frio, calor e eletricidade), em
função do
consumo de combustível, para as diferentes potências
testadas, em
função da taxa de substituição energética do óleo Diesel
por GNV.
Determinou-se, experimentalmente, a vazão de água nos
diferentes
componentes, para a qual se obtém uma máxima eficiência do
sistema,
quando analisado do ponto de vista exergético. / [en] The simultaneous production of electric energy, heat and
cooling
capacity from the primary fuel burning on a heat engine
(trigeneration) can
emerge as a promising strategy, from the energy and
project points of
view, mostly, in food and chemistry industries. The
present work describes
the experimental study of a vapor compression system for
chilled water
production. A Diesel internal combustion engine was
converted to operate
with natural gas (Diesel-gas) and drives an electric
generator that supplies
the necessary electric energy for the chiller`s
functioning and to attend the
pre-established electric demand. The resultant system of
trigeneration is,
therefore, composed of two subsystems: the heat pump
(chiller) and the
engine-generator group. Heat rejected from the condenser
of chiller and
from the cooling system and exhaust gases of the engine,
is recovered for
hot water production. The system is analyzed under the
light of first and
second laws of the Thermodynamics. The ratio between the
cooling,
heating and electricity demands, the temperatures of
evaporation and
condensation of the heat pump, and the Diesel-natural gas
substitution
ratio are main parameters of control of the presented
results. The
percentile contribution of cold, heat and electricity (on
energetic fuel
consumption basis), for the different electric energy
generation rates, was
obtained as a function of the energy substitution rate of
the Diesel oil for
natural gas. An optimal energy substitution rate of Diesel
oil for natural gas
of approximately 25% was determined with an economy rated
between
11% and 15% (for electric energy generation rates above
4,0 kW), based
both on the difference between prices of the two fuels and
on the engine`s performance improvement for these
operational conditions. An optimum
water flow rate, from the exergetic point of view, was
found for each
component.
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Experimental investigation of DME assisted gasoline CAI combustion with re-breathing valve strategySeo, Kangwoo January 2015 (has links)
Controlled auto-ignition (CAI), also known as HCCI combustion in a gasoline engine has been extensively researched due to their potential of improved engine efficiency and low NOx emission. However, the combustion timing and the phasing of conventional CAI combustion depend on the in-cylinder condition, such as temperature and combustible mixture strength and thus cannot be directly controlled. In this study, direct DME (Dimethyl Ether) injection was adopted to increase the ignitability of premixed gasoline/air charge and to trigger the auto ignition of premixed charge. Re-breathing valve strategies were used to obtain hot internal EGR to eliminate a need of intake heating. Firstly, the pilot valve opening event, including its opening and closing timing, valve lift and dwell duration between the main valve event, was analysed by the WAVE simulation. Based on the analysis a re-breathing cam lobe was manufactured and installed on a Ricardo E6 engine to achieve the intake rebreathing and exhaust rebreathing operations. The intake re-breathing was realised by the pilot intake valve opening during the exhaust stroke and the exhaust re-breathing was achieved by the secondary exhaust valve opening during the intake stroke. Effects of the pilot intake valve open timing, 2nd DME injection timing, split DME injection ratio, air/fuel ratio and compression ratio were examined during the intake rebreathing operation. Then the performance and emission characteristics of DME assisted gasoline CAI combustion were examined during the exhaust re-breathing operation. Finally, results of the intake and exhaust re-rebreathing operations were compared to the conventional SI operation. The experimental study found that both the intake and the exhaust re-breathing operations provided enough heat to initiate DME assisted gasoline CAI combustion. The direct DME injection enabled to control the start of combustion and phasing. The quantity of the first DME injection showed greater effect than its timing, whereas the injection timing of 2nd DME injection had more dominant effect than its quantity. The exhaust re-breathing strategy provided stratified and hotter internal EGR that does not impact negatively on the volumetric efficiency because exhaust gas was re-breathed from the exhaust port during the intake stroke. High load of both CAI and SI baseline operations were limited by knocking combustion and their low load were limited by incomplete combustion. Exhaust re-breathing operation extended substantially the operational range of the DME assisted gasoline CAI combustion. Extremely low NOx emissions were obtained by DME/gasoline CAI operations. Most importantly, the exhaust rebreathing method produced dramatically improved overall efficiency of 43% compared to 28% of SI operation at a typical part-load operation of 4.0-5.0bar IMEP. It was also found that slightly improved efficiency and the extended operation range could be obtained by 33%:67% split DME injection ratio at higher load, while 67%:33% split DME injection ratio at lower load.
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[en] EXPERIMENTAL INVESTIGATION OF A DIESEL CYCLE ENGINE OPERATING ON DUAL-FUEL MODE: DIESEL / ETHANOL AND DIESEL / GAS / [pt] AVALIAÇÃO EXPERIMENTAL DE UM MOTOR DO CICLO DIESEL OPERANDO NO MODO BICOMBUSTÍVEL: DIESEL/ETANOL E DIESEL/GÁSJULIO CESAR CUISANO EGUSQUIZA 21 March 2011 (has links)
[pt] No presente trabalho, ensaios experimentais de um motor do ciclo Diesel consumindo etanol hidratado ou gás natural em substituição parcial ao óleo diesel, foram realizados. Os objetivos principais foram verificar as influências dos combustíveis alternativos e avaliar as técnicas do avanço da injeção do diesel e da restrição parcial do ar de admissão, em relação aos parâmetros característicos da combustão, desempenho e emissões. Com base nos dados do diagrama pressão-ângulo de virabrequim, foi possível analisar alguns parâmetros característicos da combustão, tais como o início da combustão, a máxima taxa de elevação de pressão e o pico de pressão. Os parâmetros do desempenho e emissões do motor foram analisados através do rendimento térmico e as concentrações de monóxido de carbono, hidrocarbonetos, material particulado e óxidos de nitrogênio. Os resultados obtidos mostraram que as técnicas avaliadas no modo bicombustível junto com as elevadas taxas de substituição do óleo diesel favoreceram a melhor queima dos combustíveis alternativos, refletindo-se favoravelmente em menores emissões de CO e MP, além de um pequeno aumento no rendimento térmico do motor. No entanto, houve também um acréscimo nas emissões de NOX e, no caso específico do avanço da injeção, foi notado um maior ruído gerado pelo motor. / [en] In this report, experimental tests of a Diesel cycle engine running with hydrous ethanol or natural gas with partial substitution for diesel fuel were performed. The main objectives were to verify the influence of alternative fuels and evaluate the advancing of diesel injection timing and the air partial restriction, regarding the characteristic parameters of combustion, performance and emissions. Based on data from the pressure-crank angle diagram, it was possible to analyze some characteristic parameters of combustion, such as the start of combustion, the maximum rate of pressure rise and peak pressure. The parameters of the engine performance and emissions were analyzed through the thermal efficiency and the concentrations of carbon monoxide, hydrocarbons, particulate matter and nitrogen oxides. The results showed that the techniques evaluated in dual fuel mode with higher rates of substitution of diesel fuel favored a better burning of the alternative fuels, reflecting favorably in lower emissions of CO and PM, and also in a small increase in the engine thermal efficiency. However, there was also an increase in NOX emissions and, in the specific case of the advanced injection timing, it was noted a louder noise generated by the engine.
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Advancing the Limits of Dual Fuel CombustionKönigsson, Fredrik January 2012 (has links)
There is a growing interest in alternative transport fuels. There are two underlying reasons for this interest; the desire to decrease the environmental impact of transports and the need to compensate for the declining availability of petroleum. In the light of both these factors the Diesel Dual Fuel, DDF, engine is an attractive concept. The primary fuel of the DDF engine is methane, which can be derived both from renewables and from fossil sources. Methane from organic waste; commonly referred to as biomethane, can provide a reduction in greenhouse gases unmatched by any other fuel. The DDF engine is from a combustion point of view a hybrid between the diesel and the otto engine and it shares characteristics with both. This work identifies the main challenges of DDF operation and suggests methods to overcome them. Injector tip temperature and pre-ignitions have been found to limit performance in addition to the restrictions known from literature such as knock and emissions of NOx and HC. HC emissions are especially challenging at light load where throttling is required to promote flame propagation. For this reason it is desired to increase the lean limit in the light load range in order to reduce pumping losses and increase efficiency. It is shown that the best results in this area are achieved by using early diesel injection to achieve HCCI/RCCI combustion where combustion phasing is controlled by the ratio between diesel and methane. However, even without committing to HCCI/RCCI combustion and the difficult control issues associated with it, substantial gains are accomplished by splitting the diesel injection into two and allocating most of the diesel fuel to the early injection. HCCI/RCCI and PPCI combustion can be used with great effect to reduce the emissions of unburned hydrocarbons at light load. At high load, the challenges that need to be overcome are mostly related to heat. Injector tip temperatures need to be observed since the cooling effect of diesel flow through the nozzle is largely removed. Through investigation and modeling it is shown that the cooling effect of the diesel fuel occurs as the fuel resides injector between injections and not during the actual injection event. For this reason; fuel residing close to the tip absorbs more heat and as a result the dependence of tip temperature on diesel substitution rate is highly non-linear. The problem can be reduced greatly by improved cooling around the diesel injector. Knock and preignitions are limiting the performance of the engine and the behavior of each and how they are affected by gas quality needs to be determined. Based on experiences from this project where pure methane has been used as fuel; preignitions impose a stricter limit on engine operation than knock. / QC 20120626 / Diesel Dual Fuel
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[en] CRITICAL EVALUATION OF TECHNICAL-ECONOMIC POTENTIAL OF ELECTRIC ENERGY SELFGENERATION IN BRAZIL / [pt] AVALIAÇÃO CRÍTICA DO POTENCIAL TÉCNICO-ECONÔMICO DA AUTOGERAÇÃO DE ENERGIA ELÉTRICA NO BRASILBRUNO DE QUEIROZ LIMA 10 March 2005 (has links)
[pt] O objetivo desse trabalho é avaliar o potencial técnico-
econômico nacional
da autogeração de energia elétrica. O levantamento desse
potencial é realizado a
partir do desenvolvimento de uma metodologia determinística
para os clientes de
alta tensão da concessionária LIGHT no estado do Rio de
Janeiro, extrapolando-a
para a estimativa do potencial brasileiro, através dos
dados de consumo nacional.
A geração distribuída é analisada a partir do atual estado
da arte da tecnologia
disponível para motores alternativos de combustão interna,
ciclos Diesel e Otto.
Os motores alternativos possuem tecnologia amplamente
difundida, alta escala de
produção, alta eficiência e baixo custo de investimento de
aquisição,
principalmente quando comparado a outras tecnologias de
geração elétrica de
pequeno e médio porte. Dessa forma, optou-se pela
tecnologia dos motores
alternativos como o mais adequado para a autogeração. Os
motores alternativos
têm grande potencial para servir de base para expansão da
geração distribuída
nacional. São considerados como alternativas de fontes
energéticas para a
autogeração, o óleo diesel e o gás natural. Para a operação
dos motores ciclo
Diesel foi considerada, além da hipótese de funcionamento
pelo modo tradicional
a óleo diesel, sua operação com um kit de conversão para
combustível dual.
Este permite uma substituição do óleo diesel pelo gás
natural em torno de 80 por cento. Já
para os motores alternativos ciclo Otto foi apenas
considerada a utilização do
energético gás natural. A viabilidade econômica do
investimento em centrais de
geração distribuída, é obtida quando traçado um paralelo
entre o atual custo da
energia elétrica que é fornecida pela concessionária e o
custo da aquisição e
operação do sistema de autogeração. O cálculo de
viabilidade será dado por uma
ótica estritamente econômica. Considerando-se que a
atratividade do
empreendimento seja dada por uma taxa interna de retorno do
investimento mínima de 15 por cento a.a para um horizonte de 15
anos, é estimado que a geração
distribuída possa representar 2,6 por cento da energia elétrica
gerada nacionalmente ou
cerca de 7.173 GWh/ano, concentrada principalmente para
geração de horário de
ponta. Os geradores a diesel representam 44,6 por cento desse total,
os geradores dieselgás
55,2 por cento e os geradores a gás cerca de 0,2 por cento. Isto significa um
consumo diário
de 2,2 MMm3 de gás natural e 2.800 m3 de óleo diesel. De
uma maneira geral a
autogeração não se viabiliza economicamente para geração
fora de ponta, em
virtude do baixo custo da energia elétrica neste período.
Em função da penetração
do gás natural no mercado nacional, é realizada uma análise
de sensibilidade entre
custo desse energético e o aumento do potencial de geração
distribuída nacional.
Conclui-se, que a queda do preço do gás natural pode
aumentar ainda mais o
potencial de geração distribuída baseado nos geradores
diesel-gás, além de
também viabilizar os geradores gás. Finalmente são
abordados e analisados os
impactos e benefícios trazidos pela geração distribuída ao
sistema atual de geração
e transmissão nacional. / [en] The objective of this work is to evaluate the technical-
economic potential
of electric energy self-generation in Brazil. A
deterministic methodology will be
built for market evaluation. It will be based on a
developed model for high voltage
customers from LIGHT, located in state of Rio de Janeiro
and extrapolated to
establish the national market. The extrapolation will be
made through the national
consumption data. The distributed generation is analyzed
from the state of the art
of reciprocating internal combustion engines, Diesel and
Otto cycles. These
engines have widespread technology, high efficiency and
offer low acquisition
cost when compared with other small and medium scale
gensets technologies. In
that way, they were chosen, to be the alternatives for the
distributed generation.
The reciprocating engines have great potential to support
the expansion of the
distributed generation in Brazil. Diesel oil and natural
gas are considered as the
fuel alternatives for the gensets. Besides the usual diesel
oil, used as fuel for diesel
engines, it was considered the mix between diesel oil and
natural gas. The mix is
handled with an auxiliary conversion kit. It allows diesel
oil being substituted
around 80% by natural gas. It was only considered natural
gas fuel for the gas
engines. The economic feasibility of the investment in
distributed generation is
achieved when a comparison is made between the current cost
of the electric
energy, which is supplied by the local utility company, and
the cost of acquisition
and operation of the self generation system. The
feasibility will be given by a
strict economic aspect. Considering the attractiveness for
the enterprise, it is given
by a minimum internal rate of return of 15 percent per year in a
horizon of 15 years. It is
estimated that the national distributed generation can
represent 2.6 percent of all
national electric generation or 7,173 GWh/year. Mainly for
generation at peak
hours. The diesel oil gensets represents 44.6 percent of that
total, the diesel-gas gensets 55.2 percent and the gas gensets
around 0.2 percent. Meaning a daily consumption of 2.2
MMm3 of natural gas and 2,800 m3 of oil diesel. Self
generation isn`t economic
feasible at off-peak hours, because the low tariff value.
For the perspective of
expansion of the natural gas net distribution in Brazil, a
sensibility analysis was
accomplished between the natural gas cost and increase of
the national distributed
generation market. It is concluded that if the natural gas
cost less, the national
distributed generation market would grow, based mainly in
diesel-gas and gas
gensets. Finally, the impacts and benefits brought by
distributed generation in the
current scenery of national generation and transmission
systems were analyzed.
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