108 research outputs found
Constructal law & thermoeconomics
No full textIn spite of evident differences, Constructal Theory and Thermoeconomics (in particular thermoeconomic optimization) have also some similarities. For instance, they both suggest the optimal allocation of two different types of losses: high permeability vs. low permeability flow losses in the Constructal Theory, while local losses inside the process vs. external losses for making available all resources actually consumed, at local level, by a component or a process in the thermoeconomic optimization. The paper discusses this one and related aspects, highlighting how the optimal criterion of minimum energy cost of the product can be derived from the Constructal Law, when the flow of useful product through the productive structure is considered as the characteristic flow of the system. In this context, the evolution of energy systems toward highly interrelated productive structures, with recycling flows, can be regarded as a consequence of the Constructal Law
A.R.T. (Associated Reversible Transformations) as a basis for thermodynamic cycles analysis
No full textThis paper tries to give a general description of a thermodynamic cycle (whatever kind and number of transformations) as a function of a set of independent parameters characterising thermodynamic transformations, as well as of constraints imposed on the cycle by plant physical nature, lay-out and controls. An ‘Associated Reversible Transformation’ (A.R.T.), defined in the paper, is used to describe each real thermodynamic
transformation of working fluid, similarly to well-known description of ideal gas adiabatic compression by means of a polytropic transformation, so that A.R.T. may be regarded as polytropics generalised.
A simple gas cycle is used to present an application of A.R.T. in the field of energy Diagnosis, underlining usefulness of a complete set of independent parameters for cycle description. Further pplication in the fields of second law analysis and thermoeconomics are outlined in the concluding part of the paper
On bottoming a micro turbine with a micro ORC section: Part a) preliminary design of the ORC expander
No full textPanel I: Connecting 2nd Law Analysis with Economics, Ecology and Energy Policy
No full textThe present paper is a review of several papers from the Proceedings of the Joint European Thermodynamics Conference, held in Brescia, Italy, 1–5 July 2013, namely papers introduced by their authors at Panel I of the conference. Panel I was devoted to applications of the Second Law of Thermodynamics to social issues—economics, ecology, sustainability, and energy policy. The concept called Available Energy which goes back to mid-nineteenth century work of Kelvin, Rankine, Maxwell and Gibbs, is relevant to all of the papers. Various names have been applied to the concept when interactions between the system of interest and an environment are involved. Today, the name exergy is generally accepted. The scope of the papers being reviewed is wide and they complement one another well
Simulation of a Combined Heat and Power plant based on diesel engines using the Aspen Plus shell
No full textIs the Evolution of Energy System Productive Structures Driven by a Physical Principle?
No full textThe aim of the paper is to identify the consequence of the Constructal Principle in the field of Thermoeconomics of (energy) production systems. This Principle has been recently formulated as an extension of the Maximum Entropy Production Principle and it has been used in literature to explain the shape and structure of all kind of flowing systems. First, the concept of Thermoeconomic Environment is defined consistently with the consumption of environmental resources and residual emissions, which inherently characterize every kind of production system. This approach allows to infer that the evolution of any energy system is strictly related to the exploitation of resources from the Thermoeconomic Environment. Moreover, the widely accepted assumption that energy systems have to be optimized by minimizing the specific resource (exergy) cost of products, has to be regarded as a consequence of a physical principle that tells us which energy systems can persist in time (to survive) and which others would be selected for extinction. The paper shows how the creation of a recycle may allow a reduction of the unit exergy cost of the product, obtaining a more sustainable behavior of the macro-system, made up by the production process together with its supply chains, consistently with the Constructal Principle. Finally, the definition of the Thermoeconomic Environment allows (at least in principle) to properly identify the resource (exergy) cost of disposing off residues and sub-products directly in the environment, without any kind of additional operation. As a consequence, residues and sub-products have to be generally converted into some kind of product by different (new) production processes, supporting the paradigm of the Circular Economy and highlighting the importance of recycling not only for system efficiency, but for system surviving. More generally, the results obtained may be regarded as the physical justifications of the evolutionary tendency toward the more and more complex and highly circular pathways that can be observed in both natural and artificial (energy) production systems
On bottoming a micro turbine with a micro ORC section: Part b) micro-combined-cycle plant performance evaluation
No full textOn Energy Diagnosis of Steam Power Plants: A Comparison Among Three Global Losses Formulations
No full textApplicazione della simulazione termoeconomica allo studio dei parametri di progetto della sezione a vapore di un impianto combinato. Parte B: Influenza della valorizzazione dell’energia elettrica sul costo di produzionedell’ energia termica
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