• Home
• Preliminary Program
• Presentations
• Gala dinner
• Authors Centre
• Presentation Guidelines
• Program at a Glance
• Keynote speakers
• Technical tours
• Publications
• ORC 2017 awards
• Pictures
• Important Dates
• Sponsors, Exhibitors & Industry Day
• Committees
• Conference Venue
• Hotels in Milan
• Registration Information
• Contact

16:30   Session 5B: Solar Energy 16:30 20 mins A retrofit for geothermal Organic Rankine Cycles based on concentrated solar thermal systems Florian Heberle, Markus Hofer, Dieter Brüggemann Abstract: Countries with a great potential for geothermal power generation like Turkey, Italy or the United States also have a high solar radiation level. In general, Organic Rankine Cycle (ORC) systems are used for the exploitation of geothermal low- and medium-enthalpy resources. Such air-cooled ORC lead to a notable reduction of power output for high ambient temperatures. In this context, a retrofit solution is examined in order to weaken the decrease of performance by coupling a concentrated solar thermal (CST) system to an existing ORC. A case study is performed based on a recuperated ORC using the working fluid n-butane. For the geothermal fluid, typical parameters of the Menderes Basin (Turkey) are chosen. In contrast to Ghasemi et al. [1], the retrofit is realized by superheating the ORC working fluid. This allows a simple and robust upgrade. Therefore, the ORC is coupled with a CST system by a shell-and-tube heat exchanger. Both components are modelled in MATLAB. The performance of the CST unit is estimated on the basis of hourly data for solar radiation and ambient temperature. For the simulation of the ORC module the software CYCLE TEMPO is used. Off-design calculations are performed to determine the operational parameter of the ORC, depending on ambient temperature and degree of superheating. Finally, the submodels (ORC, superheater and CST system) are linked on the basis of energy and mass balances. The described procedure leads to characteristic maps which provide the electrical power output as a function of the present climatic data. These maps enable fast simulations over the period of one year. The results show that the examined retrofit is applicable to existing geothermal power plants, due to operational parameters which are below the auto ignition and the decomposition temperature of the working fluid. However, the solar input is limited according to the maximum capacity of the rotating equipment. For a CST unit of 21.6 MW, the generated electricity per year is increased up to 5 %. This improvement is mainly due to an increase in turbine efficiency, which is raised up to 22 % by the retrofit depending on off-design conditions. [1] H. Ghasemi, E. Sheu, A. Tizzanini, M. Paci, A. Mitsos, Hybrid solar–geothermal power generation: Optimal retrofitting, Applied Energy. 131 (2014) 158–170. 16:50 20 mins Small-scale CSP plant coupled with a ORC system for providing dispatchable power: the Ottana Solar Facility Mario Petrollese, Daniele Cocco, Giorgio Cau Abstract: This paper is focused on the ongoing studies at the Ottana Solar Facility, a new experimental power plant located in Sardinia (Italy). The facility consists of a 630 kW CSP plant and a 400 kW CPV plant. The CSP section includes a solar field based on linear Fresnel collectors using thermal oil as heat transfer fluid and a two-tank direct thermal storage system with a storage capacity of about 15 MWht. The electricity generation is carried out in the Turboden 6HR Special ORC unit. This paper presents a description of the CSP plant characteristics and an analysis of its expected performance. In particular, the results of the simulation activities aimed at assessing the influence of different operational strategies on the CSP plant behavior and, particularly, on the ORC performance are explained and discussed. The simulation models of the main sections of the CSP plant were developed in accordance with literature data and specific information given by the manufacturers. The results provide a useful basis for the future development of the management schemes during the experimental campaigns on the CSP plant. 17:10 20 mins Thermodynamic comparison and dynamic simulation of direct and indirect solar Organic Rankine Cycle systems with PCM storage Jahan Zeb Alvi, Muhammad Imran, Gang Pei, Jing Li, Guangtao Gao, Junaid Alvi Abstract: A thermodynamic comparison between a novel direct solar ORC system (DSOS) and indirect solar ORC system (ISOS) is carried out in this study. A phase change material (PCM) heat storage unit is integrated with both systems to ensure the stability of power generation. Water and R245fa are selected as a heat transfer fluids (HTFs) for ISOS and DSOS respectively. However, R245fa is used as working fluid for both systems. Weekly, monthly and annual dynamic simulations are carried out to compare the performance of both systems using hourly weather data of Islamabad, Pakistan. ISOS has shown 1.71% system efficiency and able to provide 34.02 kW/day power while DSOS has shown 4.5 times higher system efficiency and 2.8 times higher power on annual basis. Numerical model for the PCM storage is developed and validated with the previous experimental data. Average annual amount of energy stored by PCM during charging phase for ISOS is 4.24 MW/day higher than DSOS. However, in comparison with ISOS, DSOS has delivered 33.80 kW/day more power to HTF during discharging phase of the PCM on annual basis. Maximum benefits of PCM storage are observed during the summer season compared to the winter season at selected operating conditions. Furthermore, average annual increment in capacity factor by using PCM storage are found to be 21.71% and 17% for DSOS and ISOS respectively. 17:30 20 mins Solar/biomass hybrid cycles with thermal storage and bottoming ORC: System integration and economic analysis Antonio Pantaleo, Sergio Camporeale, Arianna Sorrentino, Adio Miliozzi, Nilay Prof Shah, Christos Markides Abstract: This paper focuses on the thermodynamic modelling and thermo-economic assessment of a novel arrangement of a combined cycle composed of an externally fired gas-turbine (EFGT) and a bottoming organic Rankine cycle (ORC). The main novelty is that the heat of the exhaust gas exiting from the gas turbine is recovered in a thermal energy storage from which heat is extracted to feed a bottoming ORC cycle. The thermal storage can receive heat also from parabolic-trough concentrators (PTCs) with molten salts as heat-transfer fluid (HTF). The presence of the thermal storage between topping and bottoming cycle facilitates a flexible operation of the system, and in particular allows to compensate solar energy input fluctuations and increase capacity factor, increase the dispatchability of the renewable energy generated and potentially operate in load following mode A thermal-energy storage (TES) with two molten-salt tanks (one cold and one hot) is selected since it is well suited for operation in the temperature range useful to recover heat from the exhaust gas of the EFGT as topping cycle and supply heat to the ORC as a bottoming cycle. The gas turbine exhaust gas that cannot be recovered in the TES can be delivered to thermal users for cogeneration. The selected bottoming ORC is a superheated recuperative cycle suitable to recover heat in the temperature range of the TES with good cycle efficiency. On the basis of the results of the thermodynamic simulations, upfront and operational costs assessments, and subsidized energy framework (feed-in tariffs for renewable electricity), the global energy conversion efficiency and investment profitability are estimated.