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Abstract The development of small-scale efficient and low-cost Organic Rankine Cycle (ORC) units using low temperature waste heat for electricity production is attracting a lot of interest nowadays. This paper presents the thermodynamic simulation of a small scale regenerative ORC testing facility. The facility mainly consists of an electric steam generator to produce steam at 170oC and 7.5 bar as hot source, water at 20oC as cold sink and a scroll compressor converted to be used as expander. Simulation was performed by means of MATLAB, and CoolProp external library was used for the thermo-physical properties of the R245fa, the organic working fluid. The performance of the system in a certain range of working conditions has been calculated, obtaining maximum efficiency of 9.6% and net power of 17 kW. Simulations are used to understand the effect of different characteristics of main components on the performance of the system before running the test bench. Thus, allowing the future experimental campaign that will verify the validity of the model. [ABSTRACT FROM AUTHOR]

The development of low cost small scale Organic Rankine Cycle (ORC) has a very interesting potential in generating electricity using low temperature waste heat sources. Moreover, HVAC companies could significantly extend their market if a commercial scroll compressor can be converted into an expander using similar units. Therefore, this work reports experimental test funded by an Italian HVAC company on a scroll compressor modified to work as scroll expander in a non-regenerative cycle and a subcritical fluid regime, aimed at reducing system cost and complexity. The scroll expander has been tested with its fluid R410A in a ORC cycle in order to obtain the isentropic efficiency of the scroll expander (0.5) and the pump (0.4). On the basis of the experimental tests, a model accomplished by means of MATLAB/CoolProp has been set up to evaluate the performance of the ORC group to achieve 10 kWe as target power output. Four operative fluids have been simulated, i.e. R245fa, R134a, R1234yf, R1234ze, fixing 100°C as evaporating temperature and considering the condenser temperature in the range 20-50°C. The results have showed that R245fa is the most promising working fluid since there is a higher expansion ratio within lower pressure values. As a consequence, not only a lower mass flow rate is necessary, but overall a lower pump consumption is needed, reaching greater overall conversion efficiency (about 6.5% with condensing temperature of 20°C) and power. Thus, a commercial heat pump scroll compressor can be effectively converted into an expander. The fluid selection shows that the most common ORC fluid can be used with relative low performance but at low cost and easy management. [ABSTRACT FROM AUTHOR]

The development of low cost small scale Organic Rankine Cycle (ORC) has a very interesting potential in generating electricity using low temperature waste heat sources. Moreover, HVAC companies could significantly extend their market if a commercial scroll compressor can be converted into an expander using similar units. Therefore, this work reports experimental test funded by an Italian HVAC company on a scroll compressor modified to work as scroll expander in a non-regenerative cycle and a subcritical fluid regime, aimed at reducing system cost and complexity. The scroll expander has been tested with its fluid R410A in a ORC cycle in order to obtain the isentropic efficiency of the scroll expander (0.5) and the pump (0.4). On the basis of the experimental tests, a model accomplished by means of MATLAB/CoolProp has been set up to evaluate the performance of the ORC group to achieve 10 kWe as target power output. Four operative fluids have been simulated, i.e. R245fa, R134a, R1234yf, R1234ze, fixing 100°C as evaporating temperature and considering the condenser temperature in the range 20-50°C. The results have showed that R245fa is the most promising working fluid since there is a higher expansion ratio within lower pressure values. As a consequence, not only a lower mass flow rate is necessary, but overall a lower pump consumption is needed, reaching greater overall conversion efficiency (about 6.5% with condensing temperature of 20°C) and power. Thus, a commercial heat pump scroll compressor can be effectively converted into an expander. The fluid selection shows that the most common ORC fluid can be used with relative low performance but at low cost and easy management. [ABSTRACT FROM AUTHOR]

Concentrated solar technologies coupled with ORC system is a well-known topic in temperature ranges lower than 200°C. However, the integration to an efficient and economic working system is still a challenge especially at small scale. Efforts exist to achieve higher overall efficiencies but they are solely focused on thermal and electrical production while few of these is encompassing small-scale solar trigeneration systems. In the present article, the potential of a small scale concentrated solar Organic Rankine Cycle plant coupled with an absorber is investigated using a simulation analysis of a small scale 50 m2 CPC solar field, a 3.5 kWe ORC and a 17.6 kWc absorption chiller to satisfy respectively heating, electricity and cooling needs of a residential user. The simulation analysis of the overall system has been carried out in TRNSYS and an own model of the ORC system has been developed by the authors in Matlab thus improving the previous general model. The final aim of the proposed work is indeed the performance assessment of the small scale integrated system in order to evaluate the potential feasibility of such a system for residential applications. [ABSTRACT FROM AUTHOR]

Solar thermal collectors represent one of the most widely used technologies for heat production from renewable energy sources. To increase efficiency and to not increase too much cost different type of solar collectors, and in particular of evacuated tube collectors have been realized. In order to compare performance, tests at different conditions and in different configurations have to be performed. The aim of this paper is to establish the performance of a new prototype via an experimental evaluation of the performance in different conditions and configurations of three collectors. The prototype is particular owing to his new head configuration that permits an innovative parallel configuration way. Therefore, parallel and series configurations have been analyzed applying the UNI-EN 12975, in a steady-state regime. The efficiencies of the two configurations have been tested for different flow rates and different inflow water temperatures. The experimental results show that, with the same input flow rate to the single collector, the parallel configuration has higher performance than the series one, reaching 15% higher level of efficiency. Thus, it seems that these prototypes in optimized configuration can lead to a systems improvement, thereby increasing the overall energy production or giving the same energy production with smaller collector area. [ABSTRACT FROM AUTHOR]

The use of biomass waste in high efficient low pollutants emissions micro-cogeneration plants overpasses the main biomass barriers: competition with the food and material uses, dispersion of a low energy density fuel and high emissions. Evaluations of present technical aspects, economic benefits and their future projections are very important to bring into focus the needs of the technological development of this energy application. This paper is focused on a small (250 kWth) steam gasification fluidized bed and hot gas conditioning system, contextualized in the case study of a farm situated near Rome. Since most of usable biomass waste comes from agriculture, appraisal of applicability to real rural contexts deserves closer examination, considering the necessity of a small size solution as well. A feasibility study of an actual employment of this energy system has included: biomass availability and energy consumption analysis, biomass and gasification tests, power plant sizing, using experimental data and chemicad simulation. Finally an economic analysis has been carried out by varying the main economic parameters. Olive pruning are confirmed as very suitable, and in this case, able to satisfy the farm energy consumption. Global electrical efficiency of 25% can be achieved without any auxiliary fuel consumption. Consumption of 60% of the heat generated are required, meanwhile investment and biomass costs up to 8000 €/kW and 100 €/t can be sustained, especially if the farm electricity cost are higher than 0.15 €/kWh. [ABSTRACT FROM AUTHOR]

Solar thermal collectors represent one of the most widely used technologies for heat production from renewable energy sources. To increase efficiency and to not increase too much cost different type of solar collectors, and in particular of evacuated tube collectors have been realized. In order to compare performance, tests at different conditions and in different configurations have to be performed. The aim of this paper is to establish the performance of a new prototype via an experimental evaluation of the performance in different conditions and configurations of three collectors. The prototype is particular owing to his new head configuration that permits an innovative parallel configuration way. Therefore, parallel and series configurations have been analyzed applying the UNI-EN 12975, in a steady-state regime. The efficiencies of the two configurations have been tested for different flow rates and different inflow water temperatures. The experimental results show that, with the same input flow rate to the single collector, the parallel configuration has higher performance than the series one, reaching 15% higher level of efficiency. Thus, it seems that these prototypes in optimized configuration can lead to a systems improvement, thereby increasing the overall energy production or giving the same energy production with smaller collector area. [ABSTRACT FROM AUTHOR]

The use of biomass waste in high efficient low pollutants emissions micro-cogeneration plants overpasses the main biomass barriers: competition with the food and material uses, dispersion of a low energy density fuel and high emissions. Evaluations of present technical aspects, economic benefits and their future projections are very important to bring into focus the needs of the technological development of this energy application. This paper is focused on a small (250 kWth) steam gasification fluidized bed and hot gas conditioning system, contextualized in the case study of a farm situated near Rome. Since most of usable biomass waste comes from agriculture, appraisal of applicability to real rural contexts deserves closer examination, considering the necessity of a small size solution as well. A feasibility study of an actual employment of this energy system has included: biomass availability and energy consumption analysis, biomass and gasification tests, power plant sizing, using experimental data and chemcad simulation. Finally an economic analysis has been carried out by varying the main economic parameters. Olive pruning are confirmed as very suitable, and in this case, able to satisfy the farm energy consumption. Global electrical efficiency of 25% can be achieved without any auxiliary fuel consumption. Consumption of 60% of the heat generated are required, meanwhile investment and biomass costs up to 8000 €/kW and 100 €/t can be sustained, especially if the farm electricity cost are higher than 0.15 €/kWh. [ABSTRACT FROM AUTHOR]

Today, in the grid there are more and more installation of renewable energy plants. The renewable sources are so discontinues and they may affect the stability and efficiency of the grid. Many distribution service operators are experimenting the battery energy storage systems (BESSs) to integrate them on the grid and resolve these problems. This paper analyses the energy performance under real conditions of a BESS prototype. The real BESS under focus has made by a lithium battery pack of 16 kWh, a DC/DC converter of 20 kW and an IGBT inverter of 30 kVA with a direct voltage bus of 600 V. The energy analysis has been performed through an integrated data acquisition system that take data from on-board electronic diagnostic measurements and from smart metering data. This latter using remote devices. The tests have been carried out on the system to monitor the following characteristic parameters: current and voltage of the batteries, current and voltage of the grid and current and voltage of the auxiliaries. The system energy performances have been analyzed in dynamic and real conditions with particular reference to the following quantities: energy consumption for the auxiliary system and overall efficiency of the system in a distributed energy resources microgrid. The entire system has been analyzed until twenty-four hours. [ABSTRACT FROM AUTHOR]

Today, in the grid there are more and more installation of renewable energy plants. The renewable sources are so discontinues and they may affect the stability and efficiency of the grid. Many distribution service operators are experimenting the battery energy storage systems (BESSs) to integrate them on the grid and resolve these problems. This paper analyses the energy performance under real conditions of a BESS prototype. The real BESS under focus has made by a lithium battery pack of 16 kWh, a DC/DC converter of 20 kW and an IGBT inverter of 30 kVA with a direct voltage bus of 600 V. The energy analysis has been performed through an integrated data acquisition system that take data from on-board electronic diagnostic measurements and from smart metering data. This latter using remote devices. The tests have been carried out on the system to monitor the following characteristic parameters: current and voltage of the batteries, current and voltage of the grid and current and voltage of the auxiliaries. The system energy performances have been analyzed in dynamic and real conditions with particular reference to the following quantities: energy consumption for the auxiliary system and overall efficiency of the system in a distributed energy resources microgrid. The entire system has been analyzed until twenty-four hours. [ABSTRACT FROM AUTHOR]