Source Of Heat Generation Research Articles

Comparative studies on the combustion characters of the lithium-ion battery electrolytes with composite flame-retardant additives

Electrolytes are important parts of lithium-ion batteries, but traditional carbonate-based electrolytes have high flammability which could be an important source of heat generation in the thermal runaway process. The combustion characters of electrolyte and carbonate solvent based on three kinds of composite flame retardants are studied. The influence of lithium salt on the combustion process of carbonate mixed solvents is explored, and the flame-retardant effect of composite flame retardants on solvents is discussed. The results show that lithium salt has a great influence on the flame-retardant effect of carbonate mixed solvent, and changes the combustion rate and flame shape of carbonate mixed solvent. The combustion rate of carbonate solvents containing flame retardants decreases in varying degrees, and the flame state of the solvent samples changes greatly with the addition of flame retardants. Phenoxycyclophosphazene significantly reduces the peak value of the combustion rate of carbonate mixed solvent, reduces the flame height and fuel peak temperature, but has no significant effect on the flame temperature. Melamine phosphate reduces the combustion rate of the control stage of low boiling point component, reduces the flame height and fuel peak temperature, but does not change the peak temperature of carbonate mixed solvent flame. Tris (2-chloropropyl) phosphate has the best flame-retardant effect, because it not only greatly reduces the combustion rate of carbonate solvent, but also reduces the peak temperature of flame and fuel, which significantly improves the safety of carbonate solvent.

ProsNet – a Modelica library for prosumer-based heat networks: description and validation

Prosumer-based heat networks are a new concept in district heating systems that uses the ability of prosumers to operate as either producers or consumers. This type of networks allows for utilizing distributed heat generation and renewable energy sources. A broad range of individual operating modes, heat generation technologies, and topologies determine complex thermo-hydraulic behavior of such networks. Simulations help gain insights into their properties. In this paper, a Modelica library ProsNet is presented for such simulations. It is designed to set up models of prosumer-based heat networks to investigate their dynamic and steady-state performance in a user-friendly way. Important models of the library are described in more detail. Finally, a successful validation of the developed components was performed by comparing simulation results with another software for modeling bidirectional heat networks in steady-state.

A simplified thermal model for a lithium-ion battery pack with phase change material thermal management system

The present work is aimed at developing a simplified model for investigating numerically a Li-Ion battery pack storage with phase change material (PCM). The developed model is based on the energy balances for the battery cells and the PCM with a heat generation source. To simulate the phase transition phenomena in the PCM, the PCM specific heat capacity is expressed as a temperature-dependent function. The verification of the proposed model is carried out by comparing the numerical results with the experimental data from the literature and the maximum relative error obtained is approximately 6%. With the help of the validated model, the battery pack is explored during both charge and discharge cycles and the effect of various design and operating parameters on the battery temperature is reported and discussed. Results show that the use of PCM in the battery pack is appropriate and reduces the maximum battery temperature by up to 3 °C compared to a battery pack without PCM. Improving the airflow around the storage system can significantly increase the thermal management performance of the PCM and reduce the maximum temperature of the batteries by up to 2.5 °C. It has been also shown that PCM A-32 H is suitable for the battery pack than PCMs RT-31, RT-35 HC and A-36 due to its transition temperature and to its high latent heat of fusion. Eventually, the fast and simplified thermal model can be employed by battery pack designers to explore and optimize the thermal management system of the PCM with reasonable accuracy.

Modeling of the physical phenomenon of heat generation by using partial differential equations

The equations of mathematical physics are a natural environment for modeling physical phenomena, an example of the above is evidenced by the heat equation in relation to its use in a variety of applications; directly related to the equations of mathematical physics are the solution methods that are used to construct the predictive models. This paper describes step by step the analytical method of separation of variables to perform a complete description of the heat conduction phenomenon in the presence of a heat generation source. The investigation by using mathematical arguments allowed to calculate the temperature function as the addition of a Fourier series and a function which represents the steady state; by performing a computational simulation, it was possible to demonstrate the accuracy of the results achieved.

Eigenfunction expansion method for peristaltic flow of hybrid nanofluid flow having single-walled carbon nanotube and multi-walled carbon nanotube in a wavy rectangular duct.

In this study, "peristaltic transport of hybrid nanofluid" inside a rectangular duct is examined. Water (base fluid) is used with two types of nanoparticles, namely, single-walled carbon nanotube (SWCNT) and multi-walled carbon nanotube (MWCNT). The viscous dissipation effect comes out as the prime heat generation source as compared to the conduction of molecules. After using some suitable dimensionless quantities, we obtained the nonlinear partial differential equations in a coupled form which are then solved exactly by the Eigenfunction expansion method. Velocity distribution, pressure gradient, and pressure rise phenomena are also discussed graphically through effective physical parameters. The heat transfer rate is high for the phase flow (single-walled carbon nanotube/water) model as compared to the hybrid (single-walled carbon nanotube + multi-walled carbon nanotube/water) model due to the enhanced thermal conductivity of the hybrid model.

Power Loss Estimation and Thermal Analysis of an Aero-Engine Cylindrical Roller Bearing

High-speed rolling element bearings for aircraft engines are custom-made components and operate under high temperature conditions owing to the elevated rotational speeds and loads. Therefore, assessing the various heat generation sources and mechanisms is worth investigating to accurately quantify the overall power loss within the bearing. In this context, a numerical parametric study was performed to determine and locate various power losses inside an aero-engine cylindrical roller bearing. Then, a thermal network model based on Ohm’s law was developed to estimate the operating temperatures of the bearing elements. A series of experiments was carried out on a high-speed rolling element bearing test rig to validate the numerical predictions, such as bearing component temperatures and overall power loss at specific operating conditions. The numerical predictions based on a hybrid approach showed good agreement with the experimental data.

Cooling of periodically heat-generated element under the convective-radiative heat transfer in a rotating domain with a thermally conducting base plate

Convective heat transfer under an influence of thermal radiation in a rotating chamber has been investigated numerically. The cavity has periodically heat-generating source, cooling vertical walls and heat-conducting bottom wall. Governing equations have been formulated using stream function, vorticity and temperature. The considered set of control equations has been worked out employing the finite difference procedures. Streamlines and isotherms for different angles of rotation have been shown and described in detail. The effects of emissivity, angular velocity and bottom wall thickness have been illustrated using the flow rate, average heater temperature, mean convective and radiative Nusselt numbers. The results demonstrate that lower wall thickness can significantly reduce the mean heater temperature.

MODELLING RAIL THERMAL DIFFERENTIALS DUE TO BENDING AND DEFECTS

Rail foot flaws have the potential to cause broken rails that can lead to derailment. This is not only an extremely costly issue for a rail operator in terms of damage to rolling stock, but has significant flow-on effects for network downtime and a safe working environment. In Australia, heavy haul operators run up to 42.5 t axle loads with trains in excess of 200 wagons and these long trains produce very large cyclic rail stresses. The early detection of foot flaws before a broken rail occurs is of high importance and there are currently no proven techniques for detecting rail foot flaws on trains at normal running speeds. This paper shall focus on the potential use of thermography as a detection technique and begin investigating the components of heat transfer in the rail to determine the viability of thermography for detecting rail foot flaws. The paper commences with an introduction to the sources of heat generation in the rail and modelling approaches for the effects of bending, natural environmental factors and transverse defects. It concludes with two theoretical case studies on heat generated due to these sources and discusses how they may inform the development of a practical thermography detection methodology.

Investigation of the Degree of Augmentation of the Mass Transfer Coefficient of the Heat Transfer Medium in a Vortex Heat Exchanger of a Gas Pressure Regulating and Metering Station Heating System

Purpose of research.is to investigate the degree of augmentation of the mass transfer coefficient of a heat transfer medium in contact with a "spot" of liquid on the surface of the vortex blade when it is bombarded with dispersed contaminants in a vortex heat exchanger in order to identify a pattern that allows obtaining design values of the heat transfer coefficient of the heat transfer medium that have the best agreement with the experimental values provided in previously published articles [4, 6, 7].Methods.A complex analysis of the degree of augmentation of the mass transfer coefficient of the heat transfer medium on the surface of the vortex blade in a vortex heat exchanger based on the known theoretical positions and equations of heat and mass transfer processes.Results.The dependence of the augmentation of the mass transfer coefficient of the heat transfer medium in contact with the "spot" of liquid on the surface of the vortex blade when it is bombarded with dispersed contaminants was obtained, which allows obtaining the best agreement of the design and experimental values of the heat transfer coefficient in the vortex heat exchanger of a gas pressure regulating and metering station.Conclusion.The values of the heat transfer coefficient of the heat transfer medium calculated using the obtained dependence of the augmentation of the mass transfer coefficient of the heat transfer medium have a satisfactory convergence with the experimental data, which allows us to use this dependence in engineering calculations of the design parameters of the vortex heat exchanger used as a heat exchanger for the heating system of the working area of the gas pressure regulating and metering station. This technical solution allows not only saving natural gas as a source of heat generation, but also reducing the negative impact on the environment, since there is no need to burn natural gas. In this case, the production of thermal energy is carried out due to a regulated pressure drop of natural gas coming from the main line to consumers.

A review of safety considerations for batteries in aircraft with electric propulsion

Modern aircraft designs for “more electric” and “fully electric” aircraft have large battery packs ranging from tens of kWh for urban aviation to hundreds or thousands of kWh for commercial aviation. Such large battery packs require careful consideration of the safety concerns unique to aviation. The most pertinent safety concerns related to batteries can be categorized into two broad areas: exothermic heat related events (thermal issues) and partial or complete loss of safety–critical power supply (functional issues). Degradation during operation of a battery can contribute to capacity fade, increased internal resistance, power fade, and internal short circuits, which lead to the loss of or decrease in propulsive power. When batteries are the primary source of onboard power and energy, it is crucial to be able to estimate their state-of-health in terms of capacity and power capability. Internal short circuits and other sources of excessive heat generation can lead to high temperatures within the cells of a battery pack leading to safety concerns and thermal events. One of the biggest risk factors for batteries used in aviation is the potential for thermal runaway where temperatures reach the flashpoint of one of the cell components, eventually cascading over multiple cells leading to system-wide battery pack failure and a fire hazard. This article reviews the current understanding of the safety concerns related to batteries in the context of urban and regional electric aviation.

Research and operating experience of long-burning boilers in the North-East of Russia

In Yakutia, there is a tendency to build individual houses in rural areas. Due to the complex geographical location, economic problems and transport and logistics difficulties, it is not possible to connect many settlements to centralized sources of energy supply. Therefore, the demand for efficient autonomous sources of thermal generation due to the use of local solid fuels has recently increased. Practice shows that heat generators of imported and national manufacturers are not adapted to work at low outdoor temperatures. In the climatic conditions of the North-East of Russia, one of the important tasks is to increase the reliability and efficiency of heat generation sources; this is a necessary condition for ensuring comfortable working and living conditions for a person.

Improvement of methods of comprehensive assessment of the operation efficiency of centralized heat supply systems in municipal heat power engineering

The possibility of a comprehensive assessment of the efficiency of the operation of a district heating system based on the indicator of the overall efficiency of the equipment OEE (overall equipment efficiency) and its extension to the system as a whole is considered. The disunity of the direction of existing approaches in assessing the efficiency of operation of district heating systems does not allow a comprehensive assessment of the overall efficiency of the functioning of the technological sequence of the entire system. It is proposed to consider efficiency as the probability of full functioning of all elements of the heat supply system. It is shown that the heat output of the boiler house is proportional to the power consumption of the boiler house and is approximated by a periodic function. It is shown that the main element of the heat supply system, which determines its efficiency, is the heat-generating source. As a result of the study, it is determined that the efficiency of the heat-generating source functioning increases as the maximum value of its efficiency is reached. Numerical modeling has shown that the flexible use of the installed heat generator capacity contributes to an increase in the efficiency factor from 0.53 to 0.70 and the overall efficiency of the heat supply system can be increased by more than 30 %. When designing a boiler house, it was recommended to provide for the installation of capacities with gradation 1; 0.5; 0.25. It is shown that the OEE indicator allows one to characterize the efficiency of both the heat supply system as a whole and its individual components, and can be used in the design and analysis of the operation of systems

Forced convection in 3D Maxwell nanofluid flow via Cattaneo–Christov theory with Joule heating

In this article, an investigation of the thermal and solutal energy transport in the 3 D flow of Maxwell nanofluid through a porous medium under the influence of the magnetic field is performed. The heat generation source and chemical reaction are also taken in account as a controlling agent for the heat and mass transport in the Maxwell liquid. A novel idea of Cattaneo-Christov theory and Buongiorno model for nanofluid is employed under the impact of Joule heating for the present analysis. The governing partial differential equations (PDEs) are transformed into a non-linear system of ordinary differential equations (ODEs) by using flow similarities. The solution of similar ODEs is constructed through a well known semi-analytical technique which is the homotopy analysis method. The results of the investigation are explored in the form of graphs. It is observed that higher values of magnetic field decline the flow field. The temperature and concentration distributions decrease with the higher magnitude of thermal and solutal relaxation time phenomena, respectively. Moreover, the temperature field enhances when the Brownian motion of nanoparticles increases in flow while the concentration profile decreases. Also, it is found that the increase in resistive heating boosts up the thermal energy transport in the fluid motion.

Effects of Rapid Cooling on Properties of Aluminum-Steel Friction Stir Welded Joint.

In this study, dissimilar sheets including AA3003 aluminum and A441 AISI steel were welded via cooling-assisted friction stir welding (FSW). Three different cooling mediums including forced CO2, forced water, and forced air were employed, and a non-cooled sample was processed to compare the cooling-assisted condition with the traditional FSW condition. The highest cooling rate belongs to CO2 and the lowest cooling rate belongs to the non-cooled sample as FSW. The best macrograph without any segregation at interface belongs to the water-cooled sample and the poorest joint with notable segregation belongs to the CO2 cooling FSW sample. The CO2 cooling FSW sample exhibits the smallest grain size due to the suppression of grain growth during dynamic recrystallization (DRX). The intermetallic compound (IMC) thickening was suppressed by a higher cooling rate in CO2 cooling sample and just Al-rich phase was formed in this joint. The lowest cooling rate in the FSW sample exhibits formation of the Fe rich phase. The IMC layers were thicker at the top of the weld due to closeness with the heat generation source. The water cooling sample exhibits the highest tensile strength due to proper mechanical bonding simultaneously with optimum IMC thickness to provide appropriate metallurgical bonding. Fractography observation indicates that there is a semi-ductile fracture in the water cooling sample and CO2 cooling sample exhibits more brittle fracture. Hardness evaluation reveals that the higher the cooling rate formed, the higher the hardness in stir zone, and hardness changes in the aluminum side were higher than the steel side.

MHD Convection of an Al2O3–Cu/Water Hybrid Nanofluid in an Inclined Porous Cavity with Internal Heat Generation/Absorption

In Present communication, the transference of the hybrid nanofluids due to the natural propulsive like shrinkage and relaxation of the flexible walls and the motion has serious applications in several embryonic technologies. Stimulated by the multi-disciplinary development and study in this trend, a mathematical model is suggested to explore the numerical simulation of the hybrid nanofluid flow inside a slant porous cavity to determine the impact of volume fraction, Rayleigh number, heat generation and heat source length and location on magneto-free convective with entropy analysis. The governing nonlinear problem is converted into non-dimensional partial equations via suitably adjusted transformations. Successive Under-Relaxation (SUR) technique has been incorporated to find the solutions of the non-linear problem. Variation in entropy generation and heat transfer characteristic and thermal performance criteria has been noted for various fluid parameters. The results are plotted graphically. The outcomes indicate that the thermal performance reduces more in the case of high volume fraction in comparison with low concentration. The addition of nanoparticles for several Rayleigh numbers causes the thermal performance to be declined.

Project specifics for the construction of a municipal solid waste treatment plant

Environmental trends and growing tendency to think about ecology play an important role in the development of modern industry. Significant role in this field takes a construction of plants for the processing of municipal solid waste, contributing to the neutralization of the harmful effects by different waste. This article represents development and stages of project implementation for the plant OOO «Kamskoye» that works with solid municipal waste in the city of Chaykovsky, Perm Territory. Investment efficiency of the construction of this facility was calculated. A model of interaction between business and government bodies, which regulate investment to waste disposal projects, is presented. The main structural elements of construction of a plant for processing municipal solid waste are shown. The project was developed using a public-private partnership model. The implementation of the project will ensure the production of secondary raw materials for its further use as an alternative source of heat and electricity generation, as well as the use of products necessary for the market in the production process. The main feature and advantage of the project is the possibility of using a principle «waste to income», which allows to provide your production with energy resources from reusable waste.

Forecasting the impact on the environment of generating sources in agricultural production

The development of rural electrification is aimed at distributed energy, i.e. availability of autonomous sources of electricity and heat generation. Generation sources can use coal, fuel oil, gas, local and alternative energy sources as fuel and energy resources. This causes additional emissions of pollutants. Prediction of negative impact on the environment depends on the quantity and quality of emissions during the operation of various types of installations that generate electric and thermal energy. The purpose of the study is to select and substantiate the most attractive method for predicting the impact on the environment of generating sources in agricultural production. The widespread introduction of distributed energy using local and renewable energy sources will significantly reduce emissions of pollutants due to a decrease in energy intensity, matching the required load with the capacity of generation sources, using the most energy efficient sources, and widespread introduction of renewable energy sources. In this regard, it is advisable to forecast the impacts by the scenario method considering the implementation of the proposed distributed power supply system. The implementation of measures developed considering the analysis of the forecast of the negative impact on the environment of generating plants in agricultural enterprises will reduce the negative impact on the environment by introducing energy-efficient technologies into the energy balance of the enterprise, as well as increase production by up to 20% and increase sustainability. rural areas.

DESIGN AND INVESTIGATION OF WEIGHT BUNDLE SIMULATOR FOR INDIAN PHWR USING APDL - A THERMAL ASPECT

Under a postulated scenario of Loss of Coolant Accident (LOCA) with un-availability of emergency core cooling system (ECCS) for Indian Pressurized Heavy Water Reactor (IPHWR), the channel integrity needs to be assured. An experimental facility is presently being developed at Indian Institute of Technology Roorkee (IIT R) India to study such a severe event. In this study a CFD simulation of fuel bundle weight simulator is being carried out using ANSYS 19.0 in transient thermal analysis using ANSYS Parametric Design Language (APDL) solver. The test facility aims to estimate the thermal aspect of weight bundle simulator which is the source of heat generation for pressure tube. Thermo-mechanical deformation of pressure tube will depend on the heat source, therefore it is of great importance to check the thermal integrity of weight bundle fuel simulator. Power requirement, weight, and dimensions of weight bundle fuel simulator is similar to the actual fuel bundle used in 700 MWe IPHWR. Simulation was done for 3 % and 2% decay heat. From analysis it was found that the rate of temperature rise in pressure tube with 3 % decay heat reached a maximum of 2 0C/sec and average rate of temperature rise was around 1 0C/sec whereas with 2% decay heat, pressure tube maximum temperature rise was 1.5 0C/sec and average rate 0.8 0C/sec. Results obtained will be further used for designing of 700 MWe full length channel set-up.

Selection of the structure of thermal generation in cities of the russian federation when actualizing the heat supply schemes

THE PURPOSE. To analyze the materials of heat supply schemes for large cities of Russia, to consider the impact of an increase in the number of boiler houses in cities when planning the development and modernization of heat supply sources. To develop a methodology for choosing the structure of thermal generation in cities, which is distinguished by the use of an additional criterion for energy efficiency and a system of taken into account restrictions on the energy balances of the region. The weakening of attention to the overall energy efficiency of the aggregates of heat generation sources is shown, an additional reserve for increasing the energy efficiency of heat supply of cities is identified. METHODS. When solving this problem, methods of comparative analysis of the heat supply schemes of large cities of the Russian Federation over the past 7-10 years is used. RESULTS. The article describes the relevance of the topic, created a methodological base aimed at increasing the energy efficiency of heat supply systems in the city. A criterion is proposed that takes into account the different efficiency of sources and structural effects that are realized when choosing the composition of working heat sources for the prospective of urban development. The basic provisions, the relations used, the features of the developed methodology are given. A conclusion is drawn on the appropriateness and effectiveness of these proposals when testing this method. CONCLUSION. The developed method for choosing the structure of thermal generation was tested in the analysis of schemes of large cities of the Russian Federation. Efficiency on the example of the districts of Nizhny Novgorod ranged from 16.5 million to 180.0 million rubles per year.

–1 MV DC Filter and High-Voltage DC Measurement System for ITER Neutral Beam Injector System

This article proposes the one-package structure of –1 MV direct current (dc) filter circuit and dc measurement system composed of dc voltage dividers and dc current transducers (DCCTs). These apparatuses are becoming more important for the expansion of high-voltage dc (HVDC) power grids. However, at present, they are separately installed keeping a huge distance for air insulation, and an increase in equipment size and footprint has become a major issue. We succeeded in reducing the footprint to 1/100 by storing the aforementioned HVDC vital parts in one package of a pressure vessel. Our developed configuration uses sulfur hexafluoride (SF6) gas not only for insulation purpose but also as a refrigerant to forcibly ventilate vertically in order to allow the dc filter circuit, which is heat generation source, and the dc measuring instruments, which need to minimize the effect of temperature drift, to coexist. We also addressed another issue caused by the limited space in the one-package structure, where the stray capacitance of the dc voltage divider tends to become large and then lowers the measurement accuracy for transient voltage variation. As a countermeasure, the dc voltage divider is composed of much larger capacitance than the stray capacitance and additional damping resistance to avoid LC resonance with wiring inductance. The actual-product tests demonstrated the followings; the dc measurement system has satisfied high measurement accuracy of 0.5% and fast responsivity of 3.3 μ s retaining decay rate within −3 dB; the temperature rise of the dc voltage dividers and the DCCTs is reasonably suppressed; the dc measurement system and the dc filter circuit withstood DC −1.2 MV.