The calculation of specific heats for some important solid components in hydrogen production process based on CuCl cycle

Hydrogen is one of the most promising energy sources of the future enabling direct production of power and heat in fuel cells, hydrogen engines or furnaces with hydrogen burners. One of the last remainder problems in hydrogen technology is how to produce a sufficient amount of cheap hydrogen. One of the best options is large scale thermochemical production of hydrogen in combination with nuclear power plant. copper-chlorine (CuCl) cycle is the most promissible thermochemical cycle to produce cheap hydrogen.This paper focuses on a CuCl cycle, and the describes the models how to calculate thermodynamic properties. Unfortunately, for many components in CuCl cycle the thermochemical functions of state have never been measured. This is the reason that we have tried to calculate some very important thermophysical properties. This paper discusses the mathematical model for computing the thermodynamic properties for pure substances and their mixtures such as CuCl, HCl, Cu2OCl2 important in CuCl hydrogen production in their fluid and solid phase with an aid of statistical thermodynamics. For the solid phase, we have developed the mathematical model for the calculation of thermodynamic properties for polyatomic crystals. In this way, we have used Debye functions and Einstein function for acoustical modes and optical modes of vibrations to take into account vibration of atoms. The influence of intermolecular energy we have solved on the basis of Murnaghan equation of state and statistical thermodynamics

Application of Alternative Technologies in Combination with Nuclear Energy

Studies show that the developed world will need even more energy in the future. At the same time, the reserves of fossil fuels are rapidly running out. Due to ecological and demographic impacts, there is a high probability of a series of changes occurring on our planet over the next fifty to seventy years. One of the best ways how to avoid global warming effect is the use of hydrogen technologies. Hydrogen is used widely by petrochemical, agricultural, manufacturing, food processing, electronics, plastics, metallurgical, aerospace and other industries. The consumption of hydrogen is possibly in many ways but most perspective is the use of fuel cells. One of the biggest problems in hydrogen technology is to produce enough hydrogen for use in all technical applications. One of the most optimistic procedures is hybrid thermochemical decomposition of water and solar photochemical production of hydrogen. In the presented article, we have tried to develop energy analysis which model shows the best results regarding Slovenia regio

Evaluation of System for Economically Viable Thermal Power Plant Operation

Taking into consideration the impacts of global warming and strict European Union policy 2030 climate & energy framework, it is imminent for conventional thermal power plants to modernize their infrastructure for achieving economically viable operation on demanding electricity market. In the scope of the paper is presented author’s individual research work - economic evaluation of conventional thermal power plant operation with solar central receiver system and flue gas desulphurization installation. The goal of research work is to determine whether the designed model is profitable on current European electricity market or not. Based on analytical calculations and gathered numerical data for the designed model, a program code was generated in mathematical environment Matlab, that enables simulation of operation for the designed model in the annual time period. Positive and pessimistic scenarios were analyzed. Results are presented numerically and also graphically and show a positive contribution to the economically viable operation of conventional thermal power plants

Exergoeconomic Analysis of the Potential Exploitation of Condensation Water Vapor Waste Heat in a Thermal Power Plant Using Heat Pumps

This paper deals with the possibilities for the reduction of thermal environmental pollution and increases in the efficiency of the condensate system of a turbine by installing an inverter heat pump system. The inverter heat pump system will use the heat energy of the turbine exhaust steam that would otherwise be rejected. The operation of a condenser cooling system in a heating plant will be presented, and the possibilities of an inverter heat pump system installation will be analysed. The envisaged waste heat recovery system will be presented and analysed. The analysis will involve an evaluation of exergy and anergy efficiency of the system to minimize the generation of entropy, thus reducing the irreversibility of the system. Some guidelines regarding the utilization of heat energy generated by the inverter heat pump system and the impact of the utilization of heat on turbine efficiency will be indicated

Comparison of the evolution of the COVID-19 disease between Romania and Italy

After the outbreak of COVID-19 in Italy, thousands of Romanian citizens who worked in Northern Italy, Spain or Germany returned to Romania. Based on the time-dependent susceptible–infected–recovered—SIR model, this paper compares the evolution of the COVID-19 disease between Romania and Italy, assuming that the parameter value of R0 in the time-dependent SIR model decreases to R1 < R0 after publicly announced restrictions by the government, and increases to a value of R2 < R1 when the restrictions are lifted. Among other things, we answer the questions about the date and extent of the second peak in Italy and Romania with respect to different values of R2 and the duration of the restrictions

Thermodynamic and transport properties of fluids and solids in a Cu–Cl solar hydrogen cycle

Sustainable methods of clean fuel production are needed in the face of depleting oil reserves and to reduce carbon dioxide emissions. The technology of fuel cells for electricity production or the transport sector is already developed. However, a key missing element is a large-scale economical method of hydrogen production. The Cu–Cl thermochemical cycle is a promising thermochemical cycle to produce hydrogen. This paper focuses on a copper–chlorine (Cu–Cl) cycle and solar hydrogen production technology and describes the models how to calculate thermodynamic and transport properties. This paper discusses the mathematical model for computing the thermodynamic properties for pure substances and their mixtures such as CuCl in the solid phase with an aid of statistical thermodynamics and kinetic theory. The developed mathematical model takes into account vibrations of atoms in molecules and intermolecular forces. This mathematical model can be used for the calculation of thermodynamic properties of polyatomic crystals on the basis of the Einstein and Debye equations. We developed the model in the low-temperature and high-temperature region. All analytical data are compared with experimental results, and these show good agreement. For the transport properties, we have used kinetic theory. For fluid phase, we have calculated viscosity and thermal conductivity on the basis of the Chung–Lee–Starling kinetic model; for the solid phase, we have developed a model for calculations of thermal conductivity on the basis of electron and phonon contributions

Exergy analysis of a Brayton cycle with variable physical properties and variable composition of working substance

U radu je provedena eksergijska analiza Braytonovog ciklusa. Četiri ulazne varijable, omjer tlakova na izlazu i ulazu u kompresor, omjer temperature na ulazu u turbinu i temperature na ulazu u kompresor, te izentropski stupnjevi djelovanja kompresora i turbine su uzeti u analizu. Omjer temperatura je variran tako da je temperatura zraka na ulazu u kompresor držana konstantnom, a temperatura dimnih plinova na ulazu u turbinu je varirana od 900 °C do 1200 °C. U komori za izgaranje potpuno izgara metan s pretičkom zraka koji je određen temperaturom dimnih plinova na ulazu u turbinu. Analiza nadalje uključuje promjenjivost molarnih toplinskih kapaciteta zraka i dimnih plinova s temperaturom i promjenjivost njihovih izentropskih eksponenata. Eksergijska destrukcija u komori za izgaranje, turbini i kompresoru kao i ukupna eksergijska efikasnost su uzete u analizu

Application of Gas Condensing Boilers in Domestic Heating

A growing number of households have had condensing boilers built in to be used for the heating of spaces and for the hot water supply. The use of condensing boilers is justified from the point of view of energy because they achieve higher thermal efficiency than traditional boilers. Condensation of water vapour occurs in the flue gases, whereby the heat released by condensation is used to heat the water in the boiler. How much water vapour will condense depends on the temperature to which the flue gases are cooled. In this paper, a thermodynamic analysis of thirteen built-in gas condensing boilers was performed; data on the flue gas composition and temperature, as well as on the excess air required for combustion were obtained for that purpose. The calculation results consisting of the amount of condensed water, the thermal efficiency of the boiler, and the volume flow rates of the air and fuel are presented in tables. The analysis identified the cases in which the water vapour condensation occurred and determined the amount of the condensed water. The cases without water vapour condensation were also identified