1,721,535 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
ORC technology for waste-wood to energy conversion in the furniture manufacturing industry
No full textExploitation of low and medium temperature thermal sources, in particular those based on biomass combustion and on industrial residual heat recovery, has been increasingly investigated in the last decades, accordingly to the growing interest towards reduction in primary energy consumption and environmental issues. Organic Rankine Cycle (ORC) technology allows designing power plants that are less demanding in terms of auxiliaries, safety systems, maintenance and operating costs when compared to conventional water steam power plants.
To support the preliminary technical and economic design of this kind of plants in different contexts, a simulation code of part load and off-design operation of an ORC unit for Combined Heat and Power (CHP) has been developed. In the paper, taking the real situation of a furniture manufacturing factory as a starting point, it is shown how all energy flows occurring all year long inside the CHP plant, can be estimated on the basis of the thermal user duty time profile, the available biomass flow rate and the adopted operation strategy. This information is the basis in order to correctly evaluate the energetic, economic and environmental advantages of the proposed technical solution, with respect to a particular context, as it is shown in the concluding part of the paper
Replication Data for: The political drivers of information exchange Explaining interactions in the European Migration Network
No full textReplication data for: The political drivers of information exchange
Explaining interactions in the European Migration Networ
Replication Data for: Swift, brokered and broad-based information exchange: How network structure facilitates stakeholders to monitor EU policy implementation
No full textMonitoring the implementation process in domestic settings of multi-level policies like the EU gender directives is dependent on interactions among a diverse set of policy stakeholders. However, there is no clear understanding what factors determine the structure of these monitoring networks and what benefits effective exchange. Drawing on insights from social network theory, literature on information politics in transnational networks and policy network analysis, this study analyses what drives information exchange among actors in the monitoring network of women’s groups in the Netherlands. Using Exponential Random Graph Models, the analysis reveals distinctive structural features facilitating efficient information exchange and significant brokerage in the monitoring network. Moreover, the results demonstrate that interactions that serve the purpose of monitoring EU policy implementation occur among a diverse set of actors in a multi-level structure. These findings indicate that effective monitoring requires resourceful and broad-based information exchange to increase transparency in the implementation process
Replication Data for: Temporal dynamics of interactions in European Administrative Networks: The case of SOLVIT
No full textDataset, script and codebook for replication of analysi
Replication Data for: Swift, brokered and broad-based information exchange: How network structure facilitates stakeholders to monitor EU policy implementation
No full textMonitoring the implementation process in domestic settings of multi-level policies like the EU gender directives is dependent on interactions among a diverse set of policy stakeholders. However, there is no clear understanding what factors determine the structure of these monitoring networks and what benefits effective exchange. Drawing on insights from social network theory, literature on information politics in transnational networks and policy network analysis, this study analyses what drives information exchange among actors in the monitoring network of women’s groups in the Netherlands. Using Exponential Random Graph Models, the analysis reveals distinctive structural features facilitating efficient information exchange and significant brokerage in the monitoring network. Moreover, the results demonstrate that interactions that serve the purpose of monitoring EU policy implementation occur among a diverse set of actors in a multi-level structure. These findings indicate that effective monitoring requires resourceful and broad-based information exchange to increase transparency in the implementation process
Optimization of a distributed Cogeneratio System with solar District Heting
No full textThe aim of the paper is to identify the optimal energy production system and its optimal operation strategy required to satisfy the energy demand of a set of users in an industrial area. A distributed energy supply system is made up of a district heating network, a solar thermal plant with long term heat storage, a set of Combined Heat and Power units and conventional components also, such as boilers and compression chillers. In this way the required heat can be produced by solar thermal modules, by natural gas cogenerators, or by conventional boilers. The decision variable set of the optimization procedure includes the sizes of various components, the solar field extension and the thermal energy recovered in the heat storage, while additional binary decision variables describe the existence/absence of each considered component and its on/off operation status.
The optimization algorithm is based on a Mixed Integer Linear Programming (MILP) model that minimizes the total annual cost for owning, maintaining and operating the whole energy supply system. It allows to calculate both the economic and the environmental benefits of the solar thermal plant, cooperating with the cogeneration units, as well as the share of the thermal demand covered by renewable energy, in the optimal solutions.
The results obtained analyzing different system configurations show that the minimum value of the average useful heat costs is achieved when cogenerators, district heating network, solar field and heat storage are all included in the energy supply system and optimized consistently. Thus, the integrated solution turns out to be the best from both the economic and environmental points of view. (C) 2014 Published by Elsevier Ltd
On bottoming a micro turbine with a micro ORC section: Part a) preliminary design of the ORC expander
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