Papers by Christos Frangopoulos
Design and off-design models of single and two-stage ORC systems on board a LNG carrier for the search of the optimal performance and control strategy
Applied Energy, 2017
A diesel-electric propulsion system is generally used in large scale ships to allow a free placem... more A diesel-electric propulsion system is generally used in large scale ships to allow a free placement of Internal Combustion Engines (ICEs), to acoustically decouple engines and hull, and reduce total weight and volume. On long voyages, the speed of a vessel can be more or less constant. Thus, to a first approximation, it can be considered that the engines operate most of the time at steady-state conditions. On this basis, Organic Rankine Cycle (ORC) systems can be conveniently installed aboard to generate additional electric power by recovering ICEs waste heat and increase in turn the overall system efficiency. The ICEs-ORC combined cycle system has to be designed properly to maximize the work production and guarantee at the same time a stable operation during both transient and steady-state working conditions.
Conceptual development and optimization of the main absorption systems configurations
Renewable Energy, 2021
On Professor Jan Szargut's 80th birthday
ENERGY, 2004
CrossRef is an independent membership association, founded and directed by publishers. CrossRef&a... more CrossRef is an independent membership association, founded and directed by publishers. CrossRef's mandate is to connect users to primary research content, by enabling publishers to do collectively what they can't do individually. CrossRef is also the official DOI registration agency for scholarly and professional publications. It operates a cross-publisher citation linking system that allows a researcher to click on a reference citation on one publisher's platform and link directly to the cited content on another publisher's platform, subject to the ...
Synthesis, design and operation optimization of a combined cycle integrated energy system including optimization of the seasonal speed of a VLCC
Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment, 2020
The study of an integrated energy system is presented in this article that will cover all types o... more The study of an integrated energy system is presented in this article that will cover all types of energy loads (mechanical, electrical, thermal) on a Very Large Crude Carrier (VLCC) with the maximum technically possible and economically feasible exploitation of fuel energy, thus reducing the operating cost and environmental footprint of the ship. There may be a large variety of configurations, design specifications and operating states that can cover the loads, making it necessary to apply synthesis, design and operation optimization of the system. The net present value of the system is selected as the objective function. For this purpose, a superconfiguration of the system is considered, which includes a number of Diesel engines adapted for possible operation in a combined Diesel and Rankine cycle, heat recovery steam generators producing high and low pressure steam, steam turbines that can contribute to propulsion and/or to the electricity production, an exhaust gas boiler and au...
Thermoeconomic functional analysis :a method for optimal design or improvement of complex thermal systems
Ph.D.Robert B. Evan
Thermodynamic analysis
Cogeneration: Technologies, Optimization and Implementation
Research and development on cogeneration
Cogeneration: Technologies, Optimization and Implementation
Cogeneration has been applied for more than a century and, consequently, it can be considered a m... more Cogeneration has been applied for more than a century and, consequently, it can be considered a mature technology. However, new challenges, such as increased awareness of the depletion of fuels and other natural resources, the pollution of the environment beyond acceptable limits and the scarcity of water in many areas on earth, give the impetus for a continuous research and development (RD it is indicative only.
Economic analysis of cogeneration systems
Cogeneration: Technologies, Optimization and Implementation
Cogeneration systems are capital-intensive installations. Even if a cogeneration system has high-... more Cogeneration systems are capital-intensive installations. Even if a cogeneration system has high-energy efficiency, it will not be possible to proceed with the investment unless it is also economically viable. The procedure for evaluation of the economic performance of cogeneration systems is presented in this chapter, supported with information about the various types of costs, definition of the most important of the economic parameters and measures used for evaluation, as well as examples of economic analysis. Two additional issues are also tackled: (a) the distribution of costs of a cogeneration system among its energy products and (b) the effect of the internalization of environmental externalities on the cost of covering energy needs either by a cogeneration system or by the conventional approach, that is separate production of work and heat. Care has been exercised so that the values of costs given here to be realistic. However, they can be considered indicative only, as they change with place and time. Consequently, the economic performance evaluation of any cogeneration project should be based on cost information obtained for the particular project.
Cogeneration: Technologies, Optimization and Implementation
Cogeneration: Technologies, Optimization and Implementation
This section of the Developer's Assessment Report (DAR) provides a summary of the main elements o... more This section of the Developer's Assessment Report (DAR) provides a summary of the main elements of the Jay Project (Project) and predictions of the environmental assessment of the Project. For the human environment, the Project is expected to have overall positive effects on the socioeconomic environment, maximizing economic, employment, and educational benefits, while minimizing the negative impacts on well-being, physical infrastructure and non-traditional land use. Impacts to cultural aspects are predicted to be not significant. The Project is expected to have no significant negative effects on the biophysical environment (i.e., air quality, water quality and quantity, fish and fish habitat, vegetation, caribou, and wildlife and wildlife habitat).
Applied Sciences
A review of developments, trends, and challenges in synthesis, design, and operation optimization... more A review of developments, trends, and challenges in synthesis, design, and operation optimization of ship energy systems is presented in this article. For better understanding of the context of this review, pertinent terms are defined, including the three levels of optimization: synthesis, design, and operation (SDO). The static and dynamic optimization problems are stated mathematically in single- and multiobjective form. The need for intertemporal optimization is highlighted. The developments in ship energy systems optimization throughout the years is clearly presented by means of journal articles, giving the main characteristics of each article. After the review of what has been done up to now, ideas for future work are given. Further research needs for optimization of ship energy systems are mentioned: further development of methodology for synthesis optimization and SDO optimization, including transients, uncertainty, reliability, and maintenance scheduling. Hints are given for...
Special issue dedicated to MOSES2019: 2nd international conference on modelling and optimisation of ship energy systems
Energy
Dynamic optimization of synthesis, design and operation of marine energy systems
Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment
In order to cover the overall energy demands of a vessel (e.g. mechanical, electrical and thermal... more In order to cover the overall energy demands of a vessel (e.g. mechanical, electrical and thermal), energy systems onboard ships are required to produce energy of several forms while at the same time being completely autonomous and cost effective. Optimization of the ship’s energy system, as a whole, in terms of synthesis, design and operation, is nowadays an unavoidable aspect of the marine industry. Furthermore, once time dependencies (e.g. time-varying loads and weather conditions) are introduced, the optimization problem is imperatively characterized as dynamic and its complexity increases dramatically. This study is focused on the dynamic optimization of synthesis, design and operation of a marine energy system. The general method, based on differential-algebraic equation formalism combined with mixed-integer nonlinear programming, along with solution procedures is presented first. The three optimization levels (synthesis, design and operation) are tackled simultaneously, with ...
Recent developments and trends in optimization of energy systems
Energy
Intertemporal optimization of synthesis, design and operation of integrated energy systems of ships: General method and application on a system with Diesel main engines
Applied Energy
Thermo-economic optimization of synthesis, design and operation of a marine organic Rankine cycle system
Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment, 2017
The recovery of high temperature thermal energy released by propulsion engines in order to cover ... more The recovery of high temperature thermal energy released by propulsion engines in order to cover thermal loads is commonplace in contemporary ships. However, the medium- and low-temperature thermal energy is only partially exploited or not exploited at all. In the present work, an organic Rankine cycle system driving an electric generator is considered, in addition to the exhaust gas boiler, in order to recover available heat and produce electrical energy. The specifications of the system are determined by an optimization procedure taking economic criteria into consideration, apart from the technical criteria usually used in this kind of studies. More specifically, with the net present value as the objective function and by application of optimization algorithms, the optimal synthesis, design and operation of the organic Rankine cycle system are determined. For the particular vessel considered, the installation of the organic Rankine cycle is technically feasible and economically pr...
Simulation and optimisation of synthesis, design and operation of cogeneration systems
Cogeneration: Technologies, Optimization and Implementation, 2000
Synthesis, Design and Operation Optimization of the Marine Energy System for a Liquefied Natural Gas Carrier
International Journal of Applied Thermodynamics, 2008
... George G. Dimopoulos* and Christos A. Frangopoulos ... 1. INTRODUCTION Many studies of LNG pr... more ... George G. Dimopoulos* and Christos A. Frangopoulos ... 1. INTRODUCTION Many studies of LNG propulsion systems in the literature focus on the techno-economic evaluation of predetermined configurations (Andrianos, 2006; Levander and Hannula, 2004; MAN-B&W, 2004). ...
Optimal Synthesis and Operation of Thermal Systems by the Thermoeconomic Functional Approach
Journal of Engineering For Gas Turbines and Power, Oct 1, 1992
Methods developed for optimization of thermal systems usually work on a predetermined configurati... more Methods developed for optimization of thermal systems usually work on a predetermined configuration of the system. Consequently, in order to select the best system, it is necessary to apply the method separately for each possible configuration and compare the results. The designer’s work would be significantly facilitated, if the optimization method could synthesize the optimal configuration of the system automatically. Such a method is presented here, based on the Thermoeconomic Functional Approach (TFA). TFA is a method developed for optimal design or improvement of complex thermal systems. It combines thermodynamic concepts with economic considerations in a systems approach. A thermal system is considered as a set of interrelated units; each unit has one particular function (purpose, or product). The documented determination of the function of the system as a whole and of each unit individually is achieved by functional analysis. The problem is mathematically formulated (objective function, constraints) at two levels: (A) optimization of operation, (B) optimization of the configuration and the design of the system. The solution is obtained by a two-level algorithm. As an example, the method is used to optimize a cogeneration system supplying a process plant with heat and electricity, which are known functions of time.
Multi-criteria selection and thermo-economic optimization of Organic Rankine Cycle system for a marine application
International Journal of Thermodynamics, 2015
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Papers by Christos Frangopoulos