energetic investigation of organic rankine cycles orcs for the exploitation of low temperature geothermal sources a possible application in slovakia

Abstract: The paper aims at analysing the energetic performances of Organic Rankine Cycles (ORCs) for the exploitation of low temperature heat sources. Specifically, the attention has been focused on low-enthalpy geothermal energy for small-scale applications. To this purpose a thermodynamic model has been developed and a parametric investigation has been performed considering different organic fluids (isobutane, isopentane, and R245ca). Saturated conditions at the expander inlet have been adopted and the effect of the internal regenerator on the system performances has been evaluated. The investigation highlights the large impact of the evaporation temperature on the ORC behaviour and the positive influence of the internal regenerator at the highest temperatures. Conversely, the effect of the internal heat exchanger reduces when the evaporation temperature decreases. Furthermore, a possible application in the Kosice Basin (Slovakia) has been analysed. The investigation demonstrates that the organic Rankine cycle represents an interesting option for efficient valorisation of low-enthalpy geothermal resources and electricity production in small-scale applications

Energetic Investigation of Organic Rankine Cycles (ORCs) for the Exploitation of Low-Temperature Geothermal Sources – A possible application in Slovakia

Abstract: The paper aims at analysing the energetic performances of Organic Rankine Cycles (ORCs) for the exploitation of low temperature heat sources. Specifically, the attention has been focused on low-enthalpy geothermal energy for small-scale applications. To this purpose a thermodynamic model has been developed and a parametric investigation has been performed considering different organic fluids (isobutane, isopentane, and R245ca). Saturated conditions at the expander inlet have been adopted and the effect of the internal regenerator on the system performances has been evaluated. The investigation highlights the large impact of the evaporation temperature on the ORC behaviour and the positive influence of the internal regenerator at the highest temperatures. Conversely, the effect of the internal heat exchanger reduces when the evaporation temperature decreases. Furthermore, a possible application in the Kosice Basin (Slovakia) has been analysed. The investigation demonstrates that the organic Rankine cycle represents an interesting option for efficient valorisation of low-enthalpy geothermal resources and electricity production in small-scale applications

Diseño de un sistema híbrido de generación en un huerto de moringa oleifera

Resumen (Español): En la actualidad, más de 1300 millones de personas no cuentan con acceso a la electricidad en el mundo y otras 1000 millones cuentan con un acceso poco fiable. Este proyecto se traslada a Gambia, país en el que el ralentizado progreso en la ampliación del grid y la pobreza energética imposibilitan el abastecimiento de las zonas rurales, viéndose obligados a la utilización desmesurada e insegura de combustibles fósiles. Bajo este contexto, la generación energética descentralizada parece significar una oportunidad de transición hacia la electrificación del país, partiendo desde las principales actividades nacionales. Un huerto de 0.25ha en Muritabeh, un pequeño pueblo de Gambia, resulta en una interesante localización para implantar un sistema autoabastecido de generación, estimando un consumo local aproximado de 1263kWh al año para el tratamiento de Moringa oleifera. La energía solar fotovoltaica se selecciona como fuente de generación principal, con una potencia mínima a instalar de 4.5kW. Las alternativas para su generación auxiliar son, por un lado, la utilización de baterías de litio, que logra abastecer un 80% del consumo con la incorporación de 2kWh sobre una potencia fotovoltaica de 4.5kW, y, por el otro lado, un sistema ORC de aprovechamiento de biomasa que, dada su limitada producción, apenas consigue un 87% de abastecimiento con su soporte al sistema fotovoltaico. Las condiciones locales son entonces valoradas para concluir que para un completo abastecimiento es necesario reemplazar la etapa de deshidratación artificial y reducir el consumo local, o bien incorporar la tecnología ORC sobre el sistema solar de 4.5kW de capacidad fotovoltaica y 2kWh en baterías. De esta manera, el sistema consigue alcanzar un abastecimiento del 121% respecto al consumo, con una hibridación que permite además una mayor flexibilidad y proporcionalidad respecto a la producción local.Gaur egun 1300 milloi pertsona baino gehiagok ez dauka elektrizitatehornikuntzariketa beste 1000 milloi pertsonek segurtasun murritzekoa daukate. Proiektu hau Gambian ezartzen da, non grid-aren hedapenmotelaketa energia pobreziakarazo bat adierazten dutenisolaturiko zonaldeentzat, seguruak ez diren erregaiak erabiltzera derrigortuz. Horren ondorioz, deszentralizaturiko energia distribuzioa Gambiaren elektrifikaziorako trantsiziozko pausuan bihurtu daiteke, herrialdean ohikoenak diren jardueretatik hasita. Gambiankokaturiko 0.25ha-ko ortu bat, Muritabeh izeneko herri txiki batean, autohornikuntzarako sistema bat diseinatzeko leku aproposmoduanerabaki da, urtero 1263kWh-kokontsumoa egonik bertako Moringa oleiferalandarea tratatzeko.Energia sorrerarakooinarri moduan, eguzki-energia fotovoltaikoa erabiltzea erabaki da, gutxieneko 4.5kW-ko potentziadun sistema aukeratuz.Honen atzetik, euskarri moduan lan egin dezan, bi aukeraaztertudira. Alde batetik litio baterien erabilera, 2kWh-ko edukiera duen bateria 4.5kW-ko potentziadun sistema fotovoltaikoan ezarriz kontsumoaren %80-ko hornidura lortuz. Beste aldetik, bertan sortutako biomasa aprobetxatzeko tenperatura baxuko ORC sistema ezarriz, eguzki-energiarekin bat egin eta %87-ko hornidura lortuz.Bertako baldintzak hartzen dira orduan kontutan eta erabateko hornidura lotzeko artifizialki ezarritako lehorketa etapa ordezkatu egin behar dela edo ORC sistema eta fotovoltaiko-bateria sistema bat egin behar direla ondorioztatu da. Modu honetan, kontsumoarekiko %121-ko ahalmena duen sistema lortu da, flexibilitate eta proportzionaltasun handiagoa errazten dituen sistemaren hibridazioaren bidez.Currently, more than 1.3 billion people in the world do not have access to electricity and and 1 billion more have unreliable access. This project moves to the Gambia, a country where slow progress in expanding the grid and energy poverty make it impossible to supply rural areas, being forced to use fossil fuelsunrulyand riskily. In this context, decentralized energy generation seems to represent a transition optiontowards the electrification of the country, starting from the main national activities. A0.25haMoringa oleiferacultivationin Muritabeh, a small town in the Gambia, is an interesting location to implement a self-sufficient generation system, estimating an approximate local consumption of 1263kWh per year. Photovoltaic solar energy isthenselected as the main generation source, with a minimum installed powerof 4.5kW. The alternatives for its auxiliary generation are, on the one hand, the use of lithium batteries, which manages to supply 80% of the consumption with the incorporation of 2kWh on a photovoltaic power of 4.5kW, and, on the other hand, an ORC system usinglocally producedbiomass which, due toits limited production, barely achieves an 87% supply with its support to the photovoltaic system. The local conditions are then evaluated to conclude that for a complete supply it is necessaryeitherto replace the artificial dehydration stepand reduce local consumption, or to incorporate ORC technology on the solar system of 4.5kW of photovoltaic capacity and 2kWh in batteries. In this way, the system achieves a supply of 121% with respect to consumption, stimulatinga hybridization that also allows greater flexibility and proportionality with respect to local production

Diseño de un sistema híbrido de generación en un huerto de moringa oleifera

Resumen (Español): En la actualidad, más de 1300 millones de personas no cuentan con acceso a la electricidad en el mundo y otras 1000 millones cuentan con un acceso poco fiable. Este proyecto se traslada a Gambia, país en el que el ralentizado progreso en la ampliación del grid y la pobreza energética imposibilitan el abastecimiento de las zonas rurales, viéndose obligados a la utilización desmesurada e insegura de combustibles fósiles. Bajo este contexto, la generación energética descentralizada parece significar una oportunidad de transición hacia la electrificación del país, partiendo desde las principales actividades nacionales. Un huerto de 0.25ha en Muritabeh, un pequeño pueblo de Gambia, resulta en una interesante localización para implantar un sistema autoabastecido de generación, estimando un consumo local aproximado de 1263kWh al año para el tratamiento de Moringa oleifera. La energía solar fotovoltaica se selecciona como fuente de generación principal, con una potencia mínima a instalar de 4.5kW. Las alternativas para su generación auxiliar son, por un lado, la utilización de baterías de litio, que logra abastecer un 80% del consumo con la incorporación de 2kWh sobre una potencia fotovoltaica de 4.5kW, y, por el otro lado, un sistema ORC de aprovechamiento de biomasa que, dada su limitada producción, apenas consigue un 87% de abastecimiento con su soporte al sistema fotovoltaico. Las condiciones locales son entonces valoradas para concluir que para un completo abastecimiento es necesario reemplazar la etapa de deshidratación artificial y reducir el consumo local, o bien incorporar la tecnología ORC sobre el sistema solar de 4.5kW de capacidad fotovoltaica y 2kWh en baterías. De esta manera, el sistema consigue alcanzar un abastecimiento del 121% respecto al consumo, con una hibridación que permite además una mayor flexibilidad y proporcionalidad respecto a la producción local.Gaur egun 1300 milloi pertsona baino gehiagok ez dauka elektrizitatehornikuntzariketa beste 1000 milloi pertsonek segurtasun murritzekoa daukate. Proiektu hau Gambian ezartzen da, non grid-aren hedapenmotelaketa energia pobreziakarazo bat adierazten dutenisolaturiko zonaldeentzat, seguruak ez diren erregaiak erabiltzera derrigortuz. Horren ondorioz, deszentralizaturiko energia distribuzioa Gambiaren elektrifikaziorako trantsiziozko pausuan bihurtu daiteke, herrialdean ohikoenak diren jardueretatik hasita. Gambiankokaturiko 0.25ha-ko ortu bat, Muritabeh izeneko herri txiki batean, autohornikuntzarako sistema bat diseinatzeko leku aproposmoduanerabaki da, urtero 1263kWh-kokontsumoa egonik bertako Moringa oleiferalandarea tratatzeko.Energia sorrerarakooinarri moduan, eguzki-energia fotovoltaikoa erabiltzea erabaki da, gutxieneko 4.5kW-ko potentziadun sistema aukeratuz.Honen atzetik, euskarri moduan lan egin dezan, bi aukeraaztertudira. Alde batetik litio baterien erabilera, 2kWh-ko edukiera duen bateria 4.5kW-ko potentziadun sistema fotovoltaikoan ezarriz kontsumoaren %80-ko hornidura lortuz. Beste aldetik, bertan sortutako biomasa aprobetxatzeko tenperatura baxuko ORC sistema ezarriz, eguzki-energiarekin bat egin eta %87-ko hornidura lortuz.Bertako baldintzak hartzen dira orduan kontutan eta erabateko hornidura lotzeko artifizialki ezarritako lehorketa etapa ordezkatu egin behar dela edo ORC sistema eta fotovoltaiko-bateria sistema bat egin behar direla ondorioztatu da. Modu honetan, kontsumoarekiko %121-ko ahalmena duen sistema lortu da, flexibilitate eta proportzionaltasun handiagoa errazten dituen sistemaren hibridazioaren bidez.Currently, more than 1.3 billion people in the world do not have access to electricity and and 1 billion more have unreliable access. This project moves to the Gambia, a country where slow progress in expanding the grid and energy poverty make it impossible to supply rural areas, being forced to use fossil fuelsunrulyand riskily. In this context, decentralized energy generation seems to represent a transition optiontowards the electrification of the country, starting from the main national activities. A0.25haMoringa oleiferacultivationin Muritabeh, a small town in the Gambia, is an interesting location to implement a self-sufficient generation system, estimating an approximate local consumption of 1263kWh per year. Photovoltaic solar energy isthenselected as the main generation source, with a minimum installed powerof 4.5kW. The alternatives for its auxiliary generation are, on the one hand, the use of lithium batteries, which manages to supply 80% of the consumption with the incorporation of 2kWh on a photovoltaic power of 4.5kW, and, on the other hand, an ORC system usinglocally producedbiomass which, due toits limited production, barely achieves an 87% supply with its support to the photovoltaic system. The local conditions are then evaluated to conclude that for a complete supply it is necessaryeitherto replace the artificial dehydration stepand reduce local consumption, or to incorporate ORC technology on the solar system of 4.5kW of photovoltaic capacity and 2kWh in batteries. In this way, the system achieves a supply of 121% with respect to consumption, stimulatinga hybridization that also allows greater flexibility and proportionality with respect to local production

Simulação off-design de um sistema ORC para recuperação de calor residual de um motor de combustão interna

The exhaust gases of an internal combustion engine (MCI) leave the equipment still with sufficient temperature to generate more electrical power, if a system is used for this purpose. Therefore, due to this scenario of the possibility of increasing the efficiency of the energy plant, thus reducing the emission of pollutants and fuel consumption, in this work a study was made on the use of the residual energy existing in the combustion gases of an engine diesel stationary internal combustion. For this, the ORC (Organic Rankine Cycle) was used, a thermodynamic cycle that uses an organic fluid as the working fluid. The analyzes are evaluated in three parts: 1) parametric analysis of an ORC system in permanent on-design regime (within the design conditions) to ascertain the influence of the variation of thermodynamic parameters, both in power and in the flow of working fluid , with the objective of determining the optimum point of operation of the cycle, determined “design point”; 2) parametric analysis of the same cycle, now in a permanent off-design regime (outside the design conditions), to check the influences when they are varied as a characteristic of the heat source (flow and temperature), now without varying the geometric design of the equipment constituents of the cycle, which brings the functioning of the cycle closer to reality; 3) an economic analysis of the feasibility of implantation for such an ORC plant, based on the model based on CEPCI. From the thermodynamic analyzes regarding the cycle efficiency, the system design was determined for a working fluid flow of 0.09 kg / s, evaporation and condensation pressure of 3.870 kPa and 25 kPa, respectively and with the exhaust gas (heat source) at 420 ° C and 0.1697 kg / s. From that point of operation, the geometries of the basic components of the ORC were determined: evaporator, turbine, condenser and pump. For the off-design simulations, performed with the aid of the ASPEN HYSYS® V.11 software, the evaporation pressure, the working fluid flow and the heat source inlet conditions were varied. From such simulations in different conditions, a minimum, average and maximum net power production of 8.56 kW, 15.59 kW and 26.29 kW, respectively, was observed, while in the design condition of 14.72 kW. The informative economic analysis that the initial investment for the implementation of the system is R$93,502.22 and the financial return and the rate of return reach an average of 1.5 years and 90$ 93.502,22 e o retorno financeiro e a taxa de retorno de chegam a uma média de 1,5 anos e 90%, respectivamente, a depender dos valores de juros tomados para o investimento. O estudo revela o sistema não requer grandes investimentos de capital e pode trazer retorno do investimento em pouco tempo e com ganhos satisfatórios a partir de então