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One of the proposals to increase the performance of the gas turbines is to improve chemical recuperated cycle. In this cycle, the heat in the turbine exhaust gases is used to heat and modify the chemical characteristics of the fuel. One mixture of natural gas and steam receives heat from the exhaust turbine gases; the mixture components react among themselves producing hot synthesis gas. In this work,...
Four different thermo-economic techniques for optimum design of hot water piping systems are presented. They are as follows: the first one is a sequential optimization of pipe diameter based on minimization of total cost without considering heat losses and then of insulation thickness based on minimization of cost of insulation and heat losses. The second is simultaneous optimization of pipe diameter...
This paper presents a study on selecting electricity contracts for a large-scale chemical production plant, which requires electricity importation, under demand uncertainty. Two common types of electricity contracts are considered, time zone (TZ) contract and loading curve (LC) contract. A multi-period linear probabilistic programming model is adopted for the contract selection and optimization. Hence,...
In the Croatian economy, the wood-processing industry is among the country's strategic export branches. The energy costs have a partial impact on the final price of wood products. The goal of this work paper is to minimize energy costs in this sector, using a mathematical formula that computes the lowest heat capacity as the cogeneration system starts to be more payable than a non-cogeneration system...
The liberalization of the electricity sector requires utilities to develop sound operation strategies for their power plants. In this paper, attention is focused on the problem of optimizing the management of the thermal power plants belonging to a strategic producer that competes with other strategic companies and a set of smaller non-strategic ones in the day-ahead market. The market model suggested...
The optimization of the heat recovery steam generator (HRSG) is one of the key elements for increasing the efficiency of combined plants. According to the current technical practice, it can be organized at different levels of complexity with objectives sequentially defined: operating parameters, geometrical details and technological elements.According to this point of view, in the paper a complete...
A decomposition methodology based on the concept of “thermoeconomic isolation” and applied to the synthesis/design and operational optimization of an advanced tactical fighter aircraft is the focus of this paper. The total system is composed of six sub-systems of which five participate with degrees of freedom (493) in the optimization. They are the propulsion sub-system (PS), the environmental control...
In this paper, the optimization of a hybrid solid oxide fuel cell–gas turbine (SOFC–GT) power plant is presented. The plant layout is based on an internal reforming SOFC stack; it also consists of a radial gas turbine, centrifugal compressors and plate-fin heat exchangers. In the first part of the paper, the bulk-flow model used to simulate the plant is presented. In the second part, a thermoeconomic...
We minimize the total entropy production of a process designed for dehydrogenation of propane. The process consists of 21 units, including a plug-flow reactor, a partial condenser, two tray distillation columns and a handful of heat exchangers and compressors. The units were modeled in a manner that made them relatively insensitive to changes in the molar flow rates, to make the optimization more...
The depletion of non-renewable natural exergy resources (the thermo-ecological cost) has been accepted as the objective function for thermo-ecological optimization. Its general formulation has been cited. A detailed form of the objective function has been formulated for a solar collector producing hot water for household needs. The following design parameters have been accepted as the decision variables:...
Long-term gas purchase contracts usually determine delivery and payment for gas on the regular hourly basis, independently of demand side consumption. In order to use fuel gas in an economically viable way, optimization of gas distribution for covering consumption must be introduced. In this paper, a mathematical model of the electric utility system which is used for optimization of gas distribution...
Most of the efforts to improve energy system configurations are directed towards the recovery of internal heat, which reduces the contribution of the external hot source and enhance system efficiency accordingly. This problem is strictly related to the synthesis of different components into system topology, i.e. with the definition of the optimal system configuration according to specified objectives...
Optimization studies along with optimum parameter correlations, using constant area mixing model are presented in this article for ejector-expansion transcritical CO 2 heat pump cycle with both conventional and modified layouts. Both the energetic and exergetic comparisons between valve, turbine and ejector-expansions-based transcritical CO 2 heat pump cycles are also studied for simultaneous...
Environmental decision support systems (EDSS) are recognized as valuable tools for environmental planning and management. In this paper, a geographic information system (GIS)-based EDSS for the optimal planning of forest biomass use for energy production is presented. A user-friendly interface allows the creation of Scenarios and the running of the developed decision and environmental models. In particular,...
Combined production of electricity, heat and cooling power in trigeneration represents a key option for the development of high-efficiency and cost-effective integrated energy systems. The complexity of the possible plant schemes calls for the adoption of general models handling multiple interconnected components and energy flows of various typologies. This paper presents a comprehensive input–output...
The increasing costs of fuel and operation of thermal power generating units warrant development of optimization methodologies for economic dispatch (ED) problems. Optimization methodologies that are based on meta-heuristic procedures could assist power generation policy analysts to achieve the goal of minimizing the generation costs. In this context, the objective of this study is to present a novel...
In this paper the second law analysis of thermodynamic irreversibilities in a coiled tube heat exchanger has been carried out for both laminar and turbulent flow conditions. The expression for the scaled non-dimensional entropy generation rate for such a system is derived in terms of four dimensionless parameters: Prandtl number, heat exchanger duty parameter, Dean number and coil to tube diameter...
In the present study, exergetic analyses and optimization of S-CO 2 recompression cycle have been performed to study the effect of operating parameters on the optimum pressure ratio, energetic and exergetic efficiencies and component irreversibilities. Effect of isentropic efficiency, recuperator effectiveness and component pressure drop on the second law efficiency is presented as well. Results...
This paper describes the development of a mathematical model to determine the optimized energy losses for a set of boilers (with a wide operating margin) supplying a common load. The model can be applied to steam systems that have a group of liquid- or gas-fired shell boilers available for use. The study shows that when the model is applied, the total energy losses of a few boilers working in unison...
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