Table of Contents
Regular Original Research Article
| Energy-Dependent Production Functions and the Optimization Model “PRISE” of Price-Induced Sectoral Evolution | |
| Dietmar Lindenberger, Reiner Kummel | 101-107 | In an attempt to integrate thermodynamics with economics, production functions are proposed that depend on capital, labor, energy and technological parameters associated with the energy conversion efficiency of the capital stock. Based on these production functions, which resolve most of the unexplained Solow residual of conventional economic growth theory, we develop the optimization model PRISE of PRice-Induced Sectoral Evolution. The model is designed to analyze potential changes of inputs, outputs and profits in differently energy- and labor-intensive sectors of an economy in response to changing factor prices. The model has been tested by comparing its predictions with the German sectoral economic evolution, 1968-1989. |
| Relationships Creating Functionalities of a Process System and Their Representation by Process Vectors | |
| Masaru Ishida | 109-117 | Understanding of the target functionalities is the origin of creating systems. Those functionalities can be generated by the system structure. To examine both those functionalities and the system structure, we introduced the concepts of successional relationships among processes and mediative relationships between processes. Also the relation between inputs and outputs of the entire system is demonstrated. Process vectors were used to represent the above three kinds of relationships. These concepts were applied for methanol production to verify their usefulness. |
| Exergy Analysis of the Process of Thermal Decomposition of Phosphogypsum to Lime and Sulfur Dioxide | |
| Lubka Atanasova | 119-126 | The wet process phosphoric acid is produced by decomposition of phosphate raw materials with sulfuric acid. This gives a large amount of waste product - phosphogypsum. The thermochemical decomposition of phosphogypsum to lime and sulfur dioxide provides possibilities to utilize its main components CaO and S and, at the same time, to solve some ecological problems. The main problem arising with this method is that it needs a large consumption of primary energy carrier - natural gas. The aim of the present work is to study the process with the exergy method and find new effective methods and technological schemes to reduce energy consumption. It is suggested to decompose phosphogypsum using the products from the incomplete combustion of the natural gas with oxygen enriched air and using a preliminarily prepared reducing gas mixture. |
| Effects of the Productive Structure on the Results of the Thermoeconomic Diagnosis of Energy Systems | |
| Vittorio Verda, Luis M. Serra, Antonio Valero | 127-137 | In engineering, the word diagnosis identifies procedures for detecting the presence of anomalies in systems, locating where they have occurred and quantifying them. Thermoeconomic diagnosis procedures are based on the productive representation of systems. This is a mathematical expression of the role played by each component in the whole plant, made by defining its fuels and products in terms of exergy flows. This is called the productive structure. The details of a productive structure are at two different levels, one with respect to the number of components and the other with respect to the number of productive flows. The first one is selected according to the accuracy desired in the location of the anomalies. The higher the number of components is, the higher is the accuracy. Once the components are identified, the number of productive flows can be increased by separating exergy into its components (Tsatsaronis et al., 1990) or by introducing fictitious flows (Frangopoulos 1987, Von Spakovsky and Evans 1990). This decision facilitates the assessment of the nature of the anomaly (thermal, mechanical or chemical), but also affects the results of the thermoeconomic analysis, even when it is adapted for diagnosis purposes. In this paper the effects of these decisions on the results of the thermoeconomic diagnosis is investigated. A particularly sensitive test, obtained by simulating an anomaly in the HRSG of a combined cycle plant, is considered. |
| Simulation of the Performance of a Variable Geometry Turbocharger for Diesel Engine Road Propulsion | |
| G. Decombes, J. F. Pichouron, F. Maroteaux, N. Moreno, J. Jullien | 139-149 | Advanced research work has lead to the development of a new simulation program and the thermodynamic parameters at engine inlet and exhaust of an engine-mounted variable-geometry turbine can thus be evaluated. The machine is divided into characteristic sub-blocks and resolution of thermomechanical flow equations is carried out using the necessary geometrical parameters. A detailed study of losses is conducted experimentally and numerically into the scroll, the vaned nozzle and the rotor in relation to nozzle opening angles. Simulation results made on the variable geometry turbine are analyzed in relation to main flow entry parameters and are compared systematically with experimental data gathered on turbocharger test equipment, and on a Diesel engine used for industrial applications. |
ISSN: 2146-1511