Thermodynamic Principles Research Articles

The 4E emergy-based analysis of a novel multi-generation geothermal cycle using LNG cold energy recovery

Over the last decade, the increasing demand for sustainable energy sources has led to the development of innovative approaches in geothermal power plant cycles. In this study, a novel combined geothermal power plant cycle (GTPPC) that integrates the Kalina cycle, transcritical Carbon Dioxide (T-CO2) cycle, with the injections of the Liquid Natural Gas (LNG) stream and geothermal water (GTW) stream is proposed in order to provide cold and hot sources of the system. The performance of the system is evaluated using emergy analysis, an evaluation factor based on thermodynamic principle and solar energy with the aid of emergoeconomic and emergoenvironmental factors. The injection of LNG stream leads to significant improvements: enhancing the net output power and overall emergoeconomic and emergoenvironmental efficiencies of the cycle. By conducting improvement priority and parametric studies, crucial stream points and the system's performance's optimization is identified. Our results indicate that the Kalina sub-cycle has a greater impact on performance, and the exergy destruction in the LNG stream will be minimized. At the optimal point, the GTPPC achieves high thermal efficiency and emergy-based metrics, indicating its sustainability and viability as a geothermal power generation solution. By the injection of LNG stream, the net output power, and overall emergoeconomic and emergoenvironmental efficiencies of the cycle, improved by 1.79 MW, 14 %, and 16 %, respectively. According to the obtained results, the performance of the Kalina sub-cycle has more effect than the Carbon Dioxide sub-cycle, and destructing exergy in the LNG stream will have irreparable effects on the operation of the GTPPC. At the optimum point of the system performance, the GTPPC will operate with the thermal efficiency, ψ, and φ of 15.4 %, 94.3 %, and 98.5 %, respectively.

Cracking and thermal resistance in concrete: Coupled thermo-mechanics and phase-field modeling

Modeling damage and fracture in concrete accurately is crucial for a comprehensive analysis of structures under concurrent thermal and mechanical actions. This paper presents a novel coupled thermo-mechanical phase field model for concrete at high temperatures. Derived from principles of thermodynamics and unified phase field theory, the model integrates temperature-dependent thermal and mechanical properties, accounting for thermal expansion and transient creep. Mechanical damage, represented by the crack phase field, is augmented by a temperature-dependent thermal damage variable for heat-induced degradation. Addressing the impact of cracks on heat conduction and stress redistributions, the model introduces a novel approach to depict thermal resistance, seamlessly integrating mechanics, heat transfer, and crack propagation. Governing equations for damage evolution are derived, and the numerical implementation is detailed. Numerical illustrations showcase the model's ability to simulate diverse thermo-mechanical cracking patterns without explicit fracture path tracking or assumed criteria. Moreover, the model captures the influence of thermal actions on concrete cracking behavior and mechanical performance. This research is significant for predicting multi-field coupling damage in concrete and structures exposed to elevated temperatures.

Nonlinear constitutive model of CFRP composites under constant direct current: Combined effects of thermal damage and dielectric degradation

Prolonged exposure to low-density direct current (DC) can lead to mechanical degradation of carbon fiber-reinforced polymer (CFRP) composites, posing significant risks to material safety and reliability. This paper presents a nonlinear constitutive model to elucidate the mechanical degradation of CFRP composites when subjected to DC influences. Grounded in the principles of non-equilibrium thermodynamics, this model introduces two internal variables to account for the impact of thermal damage and dielectric degradation on the Helmholtz free energy. Furthermore, specialized dissipation functions are employed to derive the evolution equations governing these internal variables. Utilizing the model, we analyze the damage progression in carbon fiber–epoxy laminates subjected to constant DC loading. The theoretically projected resistivity and elastic modulus align closely with available experimental data in literature, thus confirming the rationality and accuracy of the proposed model. This model holds the potential to forecast the long-term evolution of mechanical properties in unidirectionally reinforced composite materials with varying carbon fiber contents under the influence of DC, thereby furnishing a theoretical foundation for enhancing the reliability design of CFRP composites in electrically-charged environments.

Towards a qualitative theory of the interruption of eating behavior change

The poor maintenance of eating behavior change is one of the main obstacles to minimizing weight regain after weight loss during diets for non-surgical care of obese or overweight patients. We start with a known informal explanation of interruption in eating behavior change during severe restriction and formalize it as a causal network involving psychological variables, which we extend with energetic variables governed by principles of thermodynamics. The three core phenomena of dietary behavior change, i.e., non-initiation, initiation followed by discontinuation and initiation followed by non-discontinuation, are expressed in terms of the value of the key variable representing mood or psychological energy, the fluctuation of which is the result of three causal relationships. Based on our experimental knowledge of the time evolution profile of the three causal input variables, we then proceed to a qualitative analysis of the resulting theory, i.e., we consider an over-approximation of it which, after discretization, can be expressed in the form of a finite integer-based model. Using Answer Set Programming, we show that our formal model faithfully reproduces the three phenomena and, under a certain assumption, is minimal. We generalize this result by providing all the minimal models reproducing these phenomena when the possible causal relationships exerted on mood are extended to all the other variables (not just those assumed in the informal explanation), with arbitrary causality signs. Finally, by a direct analytical resolution of an under-approximation of our theory, obtained by assuming linear causalities, as a system of linear ODEs, we find exactly the same minimal models, proving that they are also equal to the actual minimal models of our theory since these are framed below and above by the models of the under-approximation and the over-approximation. We determine which parameters need to be person-specific and which can be considered invariant, i.e., we explain inter-individual variability. Our approach could pave the way for universally accepted theories in the field of behavior change and, more broadly, in other areas of psychology.

Thermodynamics of Life as a Speculative Model for Planetary Technology

Originating from nineteenth century physics, the concept of entropy—a measure of disorder, randomness, and/or the dissipation of useful energy—underlay a cosmology where order and complexity were seen as highly improbable phenomena in a universe tending toward chaos and disorganisation. Nearly a century later, theoretical frameworks were developed for understanding the production of entropy as an enabling feature of self-organized complexity in the natural world. These ideas would contribute to establishing connections between the origins, development, and evolution of life and the principles of a thermodynamic universe. For some, they also supplied the conceptual foundations for theorizing about a universal natural tendency driving the development of increasingly complex and ordered systems which amplify processes of entropy production and energy dissipation and dispersal. In this paper I chart a path through the aforementioned ideas and present their relevance in framing a relationship between our technological civilization and the Earth system. I then speculate about the prospect of a technosphere whose constitution and activity are aligned with thermodynamic principles of dissipation and entropy-production, drawing on theoretical biology and recent developments in bioengineering to envision a paradigm where technology becomes living matter itself.

Laws of Thermodynamics and Their Applications in Heat Engine

Thermodynamics is a fundamental branch of physics that governs the behavior of energy and heat in various systems. This paper explores the key principles of thermodynamics and their applications in internal combustion engines and gas turbines. The first law of thermodynamics, which states that energy cannot be created or destroyed but can only change forms, is fundamental to understanding energy transfer in these machines. The second law of thermodynamics introduces the concept of entropy and explains the direction of heat flow. We have discussed the applications of the laws in design and operation, such as improving performance and efficiency. We look forward to the development of the applications in the future.

Structure-preserving spatial discretization of a coupled Heat-Wave system formulated as an irreversible port-Hamiltonian system.

The port-Hamiltonian (pH) framework allows one to properly model, interconnect, simulate and control various types of systems. Yet, properly modeling irreversibility remains a challenge as one has to include a nonlinear relation between flows and efforts, leading to a nonlinear Dirac structure. In this work, we will focus on the modelling of a distributed coupling of the heat and wave equations as pH systems. In particular, the representation of the coupled dynamics as an irreversible pH system is presented and its properties discussed. A discretization in space which preserves both the second and first principles of thermodynamics is detailed. Finally some numerical results are presented.

Energy and exergy diagnostics of an industrial annular shaft limekiln working with producer gas as renewable biofuel

Quicklime, a globally significant commodity used in various industrial applications, is produced in limekilns requiring substantial energy, traditionally, from fossil fuels. However, due to escalating emission constraints and depletion of fossil fuel deposits, the quicklime industry explores alternative fuels, like biomass. The literature lacks feasibility diagnostic studies on limekilns using alternative biomass fuels. Thus, this article aims to conduct energy and exergy diagnostics on an industrial limekiln using producer gas derived from eucalyptus wood as renewable biofuel. Employing industrial data and thermodynamics principles, the equipment was characterized, and results were compared with literature findings for similar limekilns using fossil fuels. The Specific Energy Consumption (??????) for the producer gas-operated limekiln was 4.8 GJ/tquicklime, with energy (??????) and exergy (??????) efficiencies of 54.6% and 42.2%. Overall energy (?????????????????????) and exergy (?????????????????????) efficiencies were 42.0% and 23.6%, respectively, lower than literature values. ???????????????????? was 7.6 GJ/tquicklime, higher than literature results. Identified enhancements for both renewable and fossil fuel-powered limekilns involve recovering energy and exergy, including heat recovery from exhaust gases, minimizing thermal losses, and optimizing operational variables. These findings offer valuable insights for researchers exploring renewable biofuel adoption, like producer gas derived from eucalyptus wood, as alternatives to conventional fossil fuels in limekilns.

Non-ideal nernstian behavior in organic electrochemical transistors: fundamental processes and theory.

Despite the successful implementation of organic electrochemical based devices (OEDs), fundamental processes that regulate their operations and sensing capabilities, specifically those related to ion-to-electron transduction, remain unclear. Indeed, there is still a lack of fundamental models to explain the steady-state and transient characteristics of OEDs, associating fundamentals of the physical-chemistry of the pair polymer-electrolyte with the output performance of such devices. In this study, we bring new highlights to a thermodynamic-based model that qualitatively and quantitatively describes OEDs operation, with a special focus on the organic electrochemical transistor (OECT). In this context, we introduce novel interpretations for traditional drain current models, grounded in thermodynamic and electrochemical principles. The model fitting parameters are correlated to the physical and chemical properties of the polymer-electrolyte pair, and it has been shown to explain trends observed in experimental results from the literature. Moreover, our model reveals that a non-Nerstian electrochemical behavior dominates OECT operation. Also, by analyzing experimental data, we are able to generate guidelines for material design and device development, targeting highly sensitive electrochemical biosensors and devices.

Differences in phytoplankton population vulnerability in response to chemical activity of mixtures.

Hydrophobic organic contaminants (HOCs) affect phytoplankton at cellular to population levels, ultimately impacting communities and ecosystems. Baseline toxicants, such as some HOCs, predominantly partition to biological membranes and storage lipids. Predicting their toxic effects on phytoplankton populations therefore requires consideration beyond cell uptake and diffusion. Functional traits like lipid content and profile can offer insights into the diverse responses of phytoplankton populations exposed to HOCs. Our study investigated the vulnerability of five phytoplankton species populations to varying chemical activities of a mixture of polycyclic aromatic hydrocarbons (PAHs). Population vulnerability was assessed based on intrinsic sensitivities (toxicokinetic and toxicodynamic), and demography. Despite similar chemical activities in biota within the exposed algae, effects varied significantly. According to the chemical activity causing 50% of the growth inhibition (Ea50), we found that the diatom Phaeodactylum tricornutum (Ea50 = 0.203) was the least affected by the chemical exposure and was also a species with low lipid content. In contrast, Prymnesium parvum (Ea50 = 0.072) and Rhodomonas salina (Ea50 = 0.08), both with high lipid content and high diversity of fatty acids in non-exposed samples, were more vulnerable to the chemical mixture. Moreover, the species P. parvum, P. tricornutum, and Nannochloris sp., displayed increased lipid production, evidenced as 5-10% increase in lipid fluorescence, after exposure to the chemical mixture. This lipid increase has the potential to alter the intrinsic sensitivity of the populations because storage lipids facilitate membrane repair, reconstitution and may, in the short-term, dilute contaminants within cells. Our study integrated principles of thermodynamics through the assessment of membrane saturation (i.e. chemical activity), and a lipid trait-based assessment to elucidate the differences in population vulnerability among phytoplankton species exposed to HOC mixtures.

Quantum Dissipative Adaptation with Cascaded Photons

Classical dissipative adaptation is a hypothetical non-equilibrium thermodynamic principle of self-organization in driven matter, and it relates transition probabilities with the non-equilibrium work performed by an external drive on dissipative matter. Recently, the dissipative adaptation hypothesis was extended to a quantum regime with a theoretical model where only one single-photon pulse drives each atom of an ensemble. Here, we further generalize that quantum model by analytically showing that N cascaded single-photon pulses driving each atom still fulfill a quantum dissipative adaptation. Interestingly, we find that the level of self-organization achieved with two pulses can be matched with a single effective pulse only up to a threshold, above which the presence of more photons provides unparalleled degrees of self-organization.

Homeostasis and information processing: The key frames for the thermodynamics of biological systems

Life is a natural phenomenon ineluctably subject to the laws and principles of physics. In this framework, thermodynamics has a crucial role, since living beings are structured on a molecular and cellular basis that can only be maintained with extensive energy consumption. This imposes that living beings are necessarily open systems. But the survival of each type of organism depends on the relative stability of certain essential variables, even in the presence of the disturbances to which they are subjected. The stability of these variables is relative in the sense that they have a narrow range of variation. This stability of the essential variables is a consequence of refined control mechanisms developed in the course of evolution, that lead to the condition called homeostasis. This homeostasis requires that control mechanisms process the various types of information related to the internal structure of the organism and its environment. Consequently, a biological system, through information processing aimed at guiding the mechanisms that maintain its homeostasis, manages the conditions imposed by the principles of thermodynamics, obtaining the most efficient use of energy possible and keeping entropic degradation controlled. In this article, we discuss the close links between thermodynamics, homeostasis and the information processing necessary to maintain homeostasis.

Thermodynamic Modelling, Technical and Operational Issues of Supercritical Carbon Dioxide Power Generation Cycles for Industrial Applications: A Literature Review

Future electricity production systems will be able to harness the power of supercritical carbon dioxide (S-CO<sub>2</sub>) as it moves through thermal cycles. It serves the same goal as sources of energy such as fossil fuels, nuclear power, solar power, and the recovery of waste heat (or surplus heat from industrial processes). When the heat source temperature is between 350°C and 800°C, CO<sub>2</sub> as a working fluid exhibits excellent thermal efficiency. Its novel technological benefits over conventional steam Rankine cycles, such as the use of small turbo gear and compact heat exchangers, have captured the attention of scientists. It has excellent operational flexibility and may induce significantly cheaper energy costs. Aligned with these goals, this paper presents a panoramic work, exploring the current state of the art of S-CO<sub>2</sub> power generation, with a particular emphasis on the technical and operational perplexities. After providing a comprehensive overview of the thermodynamic principles that underpin this study, the foundation is established for an engaging discourse on the continuous research and development of supercritical carbon dioxide (S-CO<sub>2</sub>) cycles in power generation. Upon delving into the thermodynamic facets of CO<sub>2</sub> that propel this investigation, the spotlight is cast upon dissecting the existing state of research and development of S-CO<sub>2</sub> cycles in power generation before transitioning into encapsulating the principal domains of application and noteworthy thermodynamic modelling inquiries of S-CO<sub>2</sub> cycles. The present advancements and hurdles within the primary application areas are succinctly summarized, while future research trends are identified.

Coupled chemical reactions: Effects of electric field, diffusion, and boundary control.

Chemical reactions involve the movement of charges, and this paper presents a mathematical model for describing chemical reactions in electrolytes. The model is developed using an energy variational method that aligns with classical thermodynamics principles. It encompasses both electrostatics and chemical reactions within consistently defined energetic and dissipative functionals. Furthermore, the energy variation method is extended to account for open systems that involve the input and output of charge and mass. Such open systems have the capability to convert one form of input energy into another form of output energy. In particular, a two-domain model is developed to study a reaction system with self-regulation and internal switching, which plays a vital role in the electron transport chain of mitochondria responsible for ATP generation-a crucial process for sustaining life. Simulations are conducted to explore the influence of electric potential on reaction rates and switching dynamics within the two-domain system. It shows that the electric potential inhibits the oxidation reaction while accelerating the reduction reaction.

The evolution of the concept of time in modern physics

The main object of this article is to contribute to a synthesis study of the notion of time through the physical theories. In detail, we focus on the evolution of the concept of time from Newton's classical theory to various modern theories such as relativity and quantum mechanics and more modern ones such as string theory and quantum computing. We are also interested in the notion of the arrow of time, which according to thermodynamic principles cannot be reversed. However, in the context of quantum computing, we show an interesting work in which it has been demonstrated that one can reverse the arrow of time.

Production of Light Naphtha by Flash Distillation of Crude Oil

The escalating global demand for sustainable, renewable energy sources has catalyzed research into advanced refining processes, particularly focusing on the generation of essential raw materials like light naphtha. This paper delves into the production of light naphtha via the flash distillation of crude oil, underlining its critical role in fulfilling the petrochemical industry's requirements. The research delineates the fundamentals of flash distillation, incorporating both physical and mathematical models, with a specific emphasis on Raoult's Law, to demystify the hydrocarbon separation process in crude oil. The mathematical framework encompasses material and energy balances, coupled with the application of liquid-vapor equilibrium equations, thereby shedding light on the thermodynamic principles steering this procedure. The progression of this study involved analyzing the distillation curve of the referenced crude oil and identifying the pseudo-components representative of the involved hydrocarbons. Utilizing the DWSIM commercial simulator, the flash distillation process of Nemba crude oil was simulated, taking into account diverse operational conditions and thermodynamic models. The outcomes were juxtaposed with industrial datasets, demonstrating a significant alignment and affirming the simulation's predictive efficacy. A parametric sensitivity analysis was conducted to refine light naphtha yield, elucidating the effect of variables like the temperature of crude oil feed and naphtha separator feed on the process efficiency. The response surface methodology underscored the feasibility of augmenting naphtha production under certain conditions. Furthermore, this study assessed the impacts of employing two distinct thermodynamic models – the Soave-Redlich-Kwong (SRK) and Peng-Robinson (PR) equations of state. This analysis revealed minimal discrepancies in physical parameters, confirming the simulation's robustness and the reliability of both models. The findings of this paper validate the efficacy of flash distillation in light naphtha production, with numerical simulation emerging as a potent tool for enhancing process optimization and predictive analysis. These insights not only contribute to a deeper understanding of environmental sustainability but also offer strategies for maximizing light naphtha production in the oil industry. In conclusion, the results from this investigation significantly advance our comprehension of phase equilibrium profiles and their relationship with the applied thermodynamic state equations, thereby enriching the quality of the results.

(General Student Poster Award Winner, 3rd Place) Corrosion Electrochemistry in Molten Flinak Salts

An existing knowledge gap in the field of molten salt (MS) corrosion is the lack of in situ, diagnostical and instantaneous measurements of the underlying corrosion system. Numerous investigations comparing the corrosion behavior of commercial alloys with complex microstructures and compositions in molten fluoride salts have been conducted during the past five years. A few of these have been expanded from exposure studies to those using electrochemical methods[1,2]. In essence, electrochemical techniques offer an in situ and diagnostical way to analyze the corrosion behavior of potential materials in real-time, either in open-circuit (static immersion) or polarized conditions. Investigations on MS corrosion have found few mechanistic insights that elucidate the fundamentals of electrode reactions and characteristics of the electrode-salt interface. However, fate of elements oxidized are not tracked. Nonetheless can be difficult to understand the electrochemical corrosion behavior of structural alloys in non-aqueous, aggressive media, such as molten LiF-NaF-KF (FLiNaK) salts, as they may be influenced by a wide range of parameters (such as microstructure, impurity, and potential).Understanding the mechanism of an alloy's most susceptible alloying constituent's dissolution and describing the rate-determining steps (RDS) of this process using the principles of thermodynamics, kinetics, and electrochemistry are fundamental initial steps in understanding the complexities of alloy corrosion. Chromium (Cr) is frequently referred to in molten fluorides research as an essential yet harmful alloying element in candidate molten salt reactor structural alloys (i.e.Ni-based superalloys and stainless steels) due to its high thermodynamic driving force to dissolve relative to other alloying elements. Because of that Cr is a crucial material for research because it serves as the basis for work on Fe-Cr, Ni-Cr, and Fe-Ni-Cr alloys as well as other alloys. However, published research does not consistently describe the mechanism relating to Cr corrosion in FLiNaK.The objective of this work was to explore the electrochemical corrosion behavior of pure Cr in molten FLiNaK salts at 600oC using electrochemical methods. In this study, we describe and clarify the regimes of Cr corrosion in FLiNaK at 600 oC that are potential-dependent, rate-limiting charge-transfer and mass-transport regulated.A range of measurements based on electrochemistry and material characterization, such as linear, cyclic, and potentiostatic polarization techniques, is presented. A key finding in this work was the attempt to establish a connection between the reactivity of Cr in an aggressive, non-aqueous electrolyte such as molten FLiNaK to electrochemical potentials and corrosion morphology predicted thermodynamically. It was found, that the corrosion mechanism of Cr in FLiNaK was dependent upon mixed potentials established by the anodic Cr/Cr(II) and/or Cr(II) /Cr(III) oxidations coupled with cathodic reactions by multiple oxidizer candidates whose predominance is a function of salt impurity level and Cr exposure times. Results suggest that the early stage of Cr dissolution is regulated by charge-transfer (or activation-controlled) in FLiNaK at 600oC. This type of mechanism can occur at low overpotential (i.e. lower driving force) and can be interrupted by the oversaturation of Cr at the surface. Its presence may be eliminated if the salt film is present. The electrochemical potential in which mass transport regime is rate-limiting falls within the phase stability field where CrF6 3- species dominates, and leading to the formation of a K3CrF6 salt film. The post-exposure SEM analysis revealed that Cr dissolution in this regime involves volume transport within each grain, resulting in the revelation of surface facets containing crystallographic features of cubic crystals.The application of electrochemistry enables a more straightforward way to identify potential RDS that control the rate of Cr corrosion and offers a temporal description of the corrosion mechanism. Such fundamental understanding, especially on the nature of cathodic and anodic reactions of Cr, can provide a baseline to understand the corrosion mechanism of complex alloys. The post-corrosion microstructure investigation, the XRD of the solidified salt combination, and the thermodynamic analysis of the stable phases present in each corrosion regime all corroborated these conclusions. Acknowledgments Research is primarily supported as part of the fundamental understanding of transport under reactor extremes (FUTURE), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. Wang, Y. L., et al. Corrosion Science 109, 43–49 (2016).Chan, H.L., et al. NPJ Materials Degradation 6(1), 46 (2022).

Assessment of heat and entropy balance of an OWC wave energy converter

This paper deals with the thermodynamic processes governing an Oscillating Water Column (OWC) device, focusing on the entropy variation and the energy and heat budgets over the expansion–compression cycles. The influence of the thermodynamic performance on the Levelized Cost of Energy (LCOE) and the carbon footprint is analysed. The research deals with an experimental research on a simple OWC off-shore model for the purpose, with the open gas system inside the chamber formulated by a real gas model, and conceptually represented by an equivalent closed one in order to apply the First Principle of Thermodynamics appropriately. Analysed results show that the compression process is an active process, while the expansion process is a passive one. In addition, the observed non-adiabatic performance of the complete cycle implies a efficiency reduction, with consequences on the LCOE. Furthermore, an approach to emergy (embodied energy) analysis is considered, providing with concluding remarks on OWC renewability and possible impacts on the biosphere and GHG emissions. An utter approach on OWC energy and emergy assessment will be develop on future researches.

REDUCING THE СО2 ATMOSPHERIC EMISSION BY NATURAL GAS “OXY-FUEL COMBUSTION”, AS A MEANS OF PREVENTION THE GREENHOUSE IMPACT

At present, the relation to the fuel-energy complex as the main source of climatic changes of a planetary scale (global warming) has been formed. In view of the corresponding forecasts related to the greenhouse effect, mostly associated with emissions of carbon-containing combustion products (carbonization of the environment), the following ways of countering the climate threat are considered the last time: a — rejection of use of the organic fuel with a gradual transfer to using (burning) of carbon-free fuels (primarily hydrogen and hydrogen-containing mixtures); b — increasing an efficiency of use the organic fuel, first of all is the natural gas, which can provide a 2-times (sometimes more) reduction of total CO2 emissions in the industry; c — reducing the consumption of C-containing technological substances in the treatment of thermal and chemical-thermal processing of metallic materials (steel); d — ferrous recycling and maximum scrap using by iron and steel production. In the paper under consideration the methodology, based upon application the specific greenhouse (CʺСO2) and harmful (CʺNOx) substances issue per unit of useful energy as the determinative parameters, has been advanced for the first time from the standpoint of environment’s decarbonization and pollution. The proper solution for lowering СО2 issue is especially suitable by provision the high temperature processes with utilization the systems of gently oxygen-enriched combustion air. In contrast to traditional assessment of harmful (primarily NOx) and greenhouse (СО2) emissions per unit of generated or supplied energy (the corresponding indicators are C'NOx and C'СO2), application of more adequate values have been proposed by performing the relevant calculations per unit of useful energy Quse. The proper values of relevant indicators CʺNOx and CʺСO2 are objective characteristics by option the most suitable composition of fuel-oxidant mixture. This is approach makes the decisive solution by conditions of mutual substitution the fuels with purpose of account the energy utilization of exhaust gases. Thermodynamic principles and a methodology for calculation the relevant indicators of pollution the exhaust gases CʺNOx and CʺСO2 have been developed. Numerical calculations have been performed and the values of specific emissions of CʺNOx and CʺСO2 have been and determined in dependence on degree of enrichment an oxidizing air-oxidant with oxygen [O2], % (vol.), by account the operating temperature of the process. The possibility of reducing the CʺСO2 emissions by 2 to 3 times or more compared to natural gas with atmospheric air burning has been established even by the cases of a slight (till 30 % vol.) enrichment of the air with oxygen. Bibl. 33, Fig. 11, Tab. 1.

ANALYSIS OF EXISTING CALCULATION METHODS FOR PREDICTING PARAFFIN PRECIPITATION AND DETERMINATION OF CRITICAL PARAMETERS

pecially during the production, transportation and refining of crude oil. This problem is related to changes in temperature and pressure, crude oil composition, and flow conditions. Research in the petroleum industry is actively focused on developing improved models and correlations to accurately predict wax deposition. The authors of the paper consider approaches based on thermodynamic principles to develop a model capable of predicting the conditions under which wax deposition occurs. The model takes into account the chemical and physical interactions in the system, and also includes parameters determined from laboratory experiments and data on the characteristics of crude oil. This article presents an analysis of scientific research literature and publications on calculation methods for predicting paraffin precipitation, and a comparative analysis of existing current correlations is carried out. Also shown is the calculation of the critical parameters (PVT) from the obtained data, which is the first step towards a model for calculating the precipitated wax.