2017
Cavazzini, Giovanna; Bari, Serena; Pavesi, Giorgio; Ardizzon, Guido
A multi-fluid PSO-based algorithm for the search of the best performance of sub-critical Organic Rankine Cycles Journal Article
In: Energy, vol. 129, pp. 42-58, 2017, ISSN: 03605442.
Abstract | Links | BibTeX | Tags: Critical temperature, Organic Rankine Cycles, PSO, System efficiency, waste heat, Working fluid
@article{Cavazzini2017a,
title = {A multi-fluid PSO-based algorithm for the search of the best performance of sub-critical Organic Rankine Cycles},
author = {Giovanna Cavazzini and Serena Bari and Giorgio Pavesi and Guido Ardizzon},
doi = {10.1016/j.energy.2017.04.090},
issn = {03605442},
year = {2017},
date = {2017-01-01},
urldate = {2017-01-01},
journal = {Energy},
volume = {129},
pages = {42-58},
abstract = {The present paper focuses on the thermodynamic optimization of a sub-critical ORC for heat source temperatures in the range between 80 and 150 °C. The most significant novelty of the optimization procedure is that the optimization algorithm was modified for this particular application in order to allow the swarm particles to dynamically choose the working fluid among a list of 37 candidates during their heuristic movement, by continuously and dynamically modifying the search domain of each particle iteration-by-iteration due to the different vapour saturation lines of the chosen working fluid. The significant amount of data obtained by the optimization procedure highlighted the dependency of the system efficiency on two main parameters: the Jakob number related to the optimized cycle (Jaopt) and the ratio between the critical temperature of the working fluid and the inlet heat source temperature. At closer inspection, a third new parameter Ω was identified, resulting from the combination of the previous two, whose minimization is correlated to the maximization of system efficiency. A procedure for the preliminary estimation of the optimal cycle allowing to estimate with good accuracy the Jakob number Jaopt and the corresponding value of Ω was also developed.},
keywords = {Critical temperature, Organic Rankine Cycles, PSO, System efficiency, waste heat, Working fluid},
pubstate = {published},
tppubtype = {article}
}
The present paper focuses on the thermodynamic optimization of a sub-critical ORC for heat source temperatures in the range between 80 and 150 °C. The most significant novelty of the optimization procedure is that the optimization algorithm was modified for this particular application in order to allow the swarm particles to dynamically choose the working fluid among a list of 37 candidates during their heuristic movement, by continuously and dynamically modifying the search domain of each particle iteration-by-iteration due to the different vapour saturation lines of the chosen working fluid. The significant amount of data obtained by the optimization procedure highlighted the dependency of the system efficiency on two main parameters: the Jakob number related to the optimized cycle (Jaopt) and the ratio between the critical temperature of the working fluid and the inlet heat source temperature. At closer inspection, a third new parameter Ω was identified, resulting from the combination of the previous two, whose minimization is correlated to the maximization of system efficiency. A procedure for the preliminary estimation of the optimal cycle allowing to estimate with good accuracy the Jakob number Jaopt and the corresponding value of Ω was also developed.
2015
Cavazzini, Giovanna; Toso, Paolo Dal
Techno-economic feasibility study of the integration of a commercial small-scale ORC in a real case study Journal Article
In: Energy Conversion and Management, vol. 99, pp. 161-175, 2015, ISSN: 01968904.
Abstract | Links | BibTeX | Tags: Business model, Energy efficiency, Organic Rankine Cycles, Real case study, Simulation model, Waste heat recovery
@article{Cavazzini2015a,
title = {Techno-economic feasibility study of the integration of a commercial small-scale ORC in a real case study},
author = {Giovanna Cavazzini and Paolo Dal Toso},
url = {http://linkinghub.elsevier.com/retrieve/pii/S0196890415003970},
doi = {10.1016/j.enconman.2015.04.043},
issn = {01968904},
year = {2015},
date = {2015-01-01},
journal = {Energy Conversion and Management},
volume = {99},
pages = {161-175},
abstract = {© 2015 Elsevier Ltd. The ORC certainly represents a promising solution for recovering low-grade waste heat in industries. However, the efficiency of commercial small-scale ORC solutions is still too low in comparison with the high initial costs of the machine and the lack of simulation models specifically developed for commercial ORC systems prevents industries from defining an accurate business model to correctly evaluate the ORC integration in real industrial processes. This paper presents a techno-economic feasibility analysis of the integration of a small-scale commercial ORC in a real case study, represented by a highly-efficient industrial distillery. The integration is aimed at maximizing the electricity auto-production by exploiting the heat produced by an internal combustion engine, already partially recovered in internal thermal processes. To analyze the influence of the ORC integration on the industrial processes, a semi-empirical steady-state model of the commercial small scale ORC was created. The model made it possible to simulate the performance of the commercial ORC within a hypothetical scenario involving the use of the heat from the cooling water and from the exhaust gases of the internal combustion engine. A detailed thermo-dynamic analysis has been carried out to study the effects of the ORC integration on the plant's energy system with particular focus on the two processes directly affected by ORC integration, namely vapor production and the drying process of the grape marc. The analysis highlighted the great importance in the business model of considering not only the direct costs (unit costs, engineering, etc.), but mainly the indirect ones and hence the need of an appropriate business model, based on the simulation of the commercial ORC behavior, to evaluate its introduction in real industrial processes. In particular, in the specific case of a highly-efficient distillery plant, the ORC integration resulted to cause an increase in inner fuel consumption, represented by dried grape marc, with a consequent economic loss not offset by a significant increase in electricity auto-production. As a consequence, the ORC integration was not economically feasible in the considered case study due to the great value in the market of the dried grape marc.},
keywords = {Business model, Energy efficiency, Organic Rankine Cycles, Real case study, Simulation model, Waste heat recovery},
pubstate = {published},
tppubtype = {article}
}
© 2015 Elsevier Ltd. The ORC certainly represents a promising solution for recovering low-grade waste heat in industries. However, the efficiency of commercial small-scale ORC solutions is still too low in comparison with the high initial costs of the machine and the lack of simulation models specifically developed for commercial ORC systems prevents industries from defining an accurate business model to correctly evaluate the ORC integration in real industrial processes. This paper presents a techno-economic feasibility analysis of the integration of a small-scale commercial ORC in a real case study, represented by a highly-efficient industrial distillery. The integration is aimed at maximizing the electricity auto-production by exploiting the heat produced by an internal combustion engine, already partially recovered in internal thermal processes. To analyze the influence of the ORC integration on the industrial processes, a semi-empirical steady-state model of the commercial small scale ORC was created. The model made it possible to simulate the performance of the commercial ORC within a hypothetical scenario involving the use of the heat from the cooling water and from the exhaust gases of the internal combustion engine. A detailed thermo-dynamic analysis has been carried out to study the effects of the ORC integration on the plant's energy system with particular focus on the two processes directly affected by ORC integration, namely vapor production and the drying process of the grape marc. The analysis highlighted the great importance in the business model of considering not only the direct costs (unit costs, engineering, etc.), but mainly the indirect ones and hence the need of an appropriate business model, based on the simulation of the commercial ORC behavior, to evaluate its introduction in real industrial processes. In particular, in the specific case of a highly-efficient distillery plant, the ORC integration resulted to cause an increase in inner fuel consumption, represented by dried grape marc, with a consequent economic loss not offset by a significant increase in electricity auto-production. As a consequence, the ORC integration was not economically feasible in the considered case study due to the great value in the market of the dried grape marc.
