Marco Astolfi

• PhD in Energy Engineering
• Researcher at Politecnico di Milano

This two-part paper investigates the potential of ORC (Organic Rankine Cycles) for the exploitation of low-medium enthalpy geothermal brines. Part A deals with thermodynamic analysis and optimization, while Part B focuses on economic optimization. In this part, an economic model was defined and implemented in the Matlab® code previously developed....

Solar thermal plants are among the most promising technologies to replace fossil fuel stationary applications, and within solar thermal technologies, parabolic troughs are considered the most mature application in the market. This paper compares different solar field technologies, in terms of both performance at design conditions and annual energy...

A combined concentrating solar power system and a geothermal binary plant based on an Organic Rankine Cycle (ORC) is analyzed. Given a supercritical ORC, designed for the optimal utilization of an intermediate enthalpy geothermal source, a solar parabolic trough field was included in the plant, introducing an additional high temperature heat source...

This study investigates the potential of trigeneration systems utilizing CO2-based power cycles to harness high-temperature excess heat. Various CO2-based cycles are proposed, comprising pure CO2 and CO2-mixture, emphasizing integration into district heating and cooling networks. Given the non-isothermal heat rejection of CO2-based cycles, performa...

The waste heat potentially available from a wide range of industrial processes still represents a significant fraction of the primary energy consumption related to the processes. Some of the most energy intensive processes can be categorized in the iron, steel and glass production, the fine chemical industry, and the production of non-ferrous mater...

The present work deals with the study of the part-load performance and operating strategies of a coal-fired sCO 2 power plant. In sCO 2 cycles the compression phase generally starts very close to the fluid critical point in a region characterized by significant real gas effects, so that depressurization, that is the typical operating strategy adopt...

The present work aims to investigate the potential advantages in using a novel wet and dry configuration for heat rejection units in ORC power plants. The reference case is a geothermal power plant that exploits a low temperature brine and uses a closed loop of cooling water to release the condensation heat to the ambient. In the calculations, the...

Low-medium temperature heat sources in the range 5–50 MWth are made available by many industrial fields but they may also be of interest for biomass, geothermal and solar energy applications. ORC has been proposed in the last 20 years as a reliable solution for the exploitation of these energy sources since the alternative represented by steam cycl...

The calculation of the performance of an ORC (Organic Rankine Cycle) and its components (in particularly the turbine) is generally not a trivial task because of the lack of a proper instrumentation, the inaccuracy of the available measurements and the uncertainty on fluid thermodynamic properties calculation. These limitations can greatly affect th...

In this study, we investigated the possible synergies between desalination technologies and solar energy in a remote energy system modelled as a small-size island with the goal to increase system sustainability. The solar systems implemented are photovoltaic panels (PV) and a Concentrating Solar Power system coupled with an Organic Rankine Cycle (C...

This study investigates the use of an ORC as heat recovery unit in a natural gas pipeline compression station powered by a gas turbine with the aim of increasing the process energy efficiency. A flexible Matlab® suite, able to investigate both subcritical and supercritical cycle, has been developed for the plant sizing and for the part-load simulat...

The present work aims to investigate the potential advantages in using a novel wet and dry configuration for heat rejection units in ORC power plants. The reference case is a geothermal power plant that exploits a medium temperature brine and uses a closed loop of cooling water to release the condensation heat. In the calculations, the off-design o...

This paper focuses on the design and the optimization of Organic Rankine Cycle (ORC) for LNG regasification plants. This technology is a promising solution with large benefits attainable in terms of primary energy savings compared to both Open Rack Vaporizer (ORV) and Submerged Combustion Vaporizer (SCV) technologies. Different cycle configurations...

This paper, after a brief description of the radial outflow turbine and of its main features, discloses the field performances evaluation of two operating geothermal ORC (Organic Rankine Cycle) plants installed by Exergy Spa in Turkey. The work describes the test procedure, the measurements and calculation methods used to obtain the turbine efficie...

Low-medium temperature heat sources in the range 5 - 50 MWth are made available by many industrial fields but they may also be of interest for biomass and solar energy applications. ORC has been proposed in the last 20 years as a reliable solution for the exploitation of these energy sources since the alternative represented by steam cycles leads t...

The Organic Rankine Cycle (ORC) technology is a reliable way to convert heat into electricity, either for renewable energy applications (biomass, geothermal, solar), or industrial energy efficiency. ORC systems range from micro-scale (a few kW) for domestic cogeneration to large multi-megawatt geothermal power plants. After a slow initial start, th...

This work discusses a preliminary thermodynamic assessment of three different supercritical CO2 (sCO2) power cycles applied to a high temperature solar tower system, with maximum temperatures up to 800 °C. The thermal power is transferred from the solar receiver to the power block through KCl-MgCl2 molten salts as heat transfer fluid, therefore an...

This work presents a preliminary thermodynamic assessment of three different supercritical CO2 (sCO2) power cycles integrated in a high temperature solar tower system, working up to 800 °C. An indirect cycle configuration is considered with KCl-MgCl2 molten salt as heat transfer fluid (HTF) in the solar receiver and a two tanks thermal energy stora...

Hybrid microgrids are expected to play an important role in the expansion of access to electricity in developing countries. While most of these systems are operated with dispatch strategies which do not make use of predictions about the load or about the availability of renewable energy resources, forecast-based strategies have recently gained atte...

The optimization of an organic Rankine cycle is a challenging task that cannot be tackled without the aid of numerical tools for plant simulation and optimization. The large availability of various working fluids, the possibility of adopting several plant layouts, and the need to consider many thermodynamic, technological, and economical aspects le...

This chapter aims to define a set of general correlations for the estimation of axial-flow turbine efficiency in the Organic Rankine Cycle (ORC) field. A dedicated numerical tool is used for the optimization of several hundreds of turbines and the results are presented in terms of specific parameters (SP, Vr, and Ns) according to similarity rules....

The plant components and the plant configurations adopted in the Organic Rankine Cycle (ORC) field differ appreciably from the solutions used in large steam cycles because of the different nature of the working fluid and the type of heat source. ORCs are rarely fueled by fossil fuels, they usually work at relatively low temperatures, and they are s...

Organic Rankine Cycle (ORC) Power Systems: Technologies and Applications provides a systematic and detailed description of organic Rankine cycle technologies and the way they are increasingly of interest for cost-effective sustainable energy generation. Popular applications include cogeneration from biomass and electricity generation from geotherma...

This paper focuses on the design optimization of a stand-alone hybrid microgrid serving a 2000 inhabitants community located in a rural area of Bihar (India) and it investigates the potential of the use of wood biomass for electricity generation. The economic performance of the different power generation configurations is evaluated simulating the...

Reduction of peak fluxes on solar receiver is an important research topic because peak minimization can lead to lower receiver temperatures with advantages in terms of thermal efficiency and mechanical stresses. This work proposes different approaches for the minimization of the heat flux on external tower receiver with surround field. The mathemat...

Similar to a difference in elevation, potential energy is also associated with a difference in salt concentration so that electric power can eventually be produced by exploiting the salinity gradient between freshwater of rivers and seawater. Unfortunately, exploiting the salinity gradient for power production is not so easy as waterfalls. The pote...

This paper is focused on the design of a stand-alone microgrid for rural electrification. The aim of this work is to define the best mix of energy sources and the optimal size of the energy storage for a small isolated village on the Ghana seaside. We obtain the optimal solution by simulating one year of operation for several different combinations...

Small Organic Rankine Cycles (ORC) coupled with low temperature parabolic collectors can be an affordable solution for the rural electrification of many remote areas worldwide. The aim of this work is to investigate the feasibility of this concept investigating the capabilities of different plant layouts and the use of volumetric screw devices as e...

This work presents innovative cogenerative Organic Rankine Cycles operating with fluids at high temperature (up to 400 °C) coupled with a biomass-fired molten salts boiler, that allow to obtain an electrical efficiency over the threshold of 20 %. Two fluids have been considered in this study, namely PP9 and TiCl4. The power plants are modeled with...

l presente documento descrive le attività di ricerca svolte all’interno dell’Accordo di collaborazione “Definizione e studio di fluidi organici o loro miscele in grado di operare a temperature massime superiori a quelle attualmente in uso e valutazione dei cicli termodinamici” Responsabile scientifico ENEA: Roberta Roberto Responsabile scientifico...