Hot Water Boiler Research Articles

Исследование характеристик комбинированных устройств глубокого охлаждения дымовых газов на водогрейных котлах системы ЖКХ

One of the ways to increase the efficiency of hot water boilers of the housing and communal services system is the deep cooling of combustion products to temperatures below the dew point temperature. Currently, there are a number of studies on the use of condensation economizers and air heaters of various types to solve this problem. The use of such devices makes it possible to reduce the temperature of combustion products and, thus, increase the heat utilization coefficient, reduce fuel consumption. The use of combined flue gas cooling devices seems particularly promising, but the parameters of their operation have not yet been studied. In this regard, the development and study of the parameters of such devices are relevant. Using the techniques to design heat exchangers, a set of thermal calculations has been performed to study the characteristics of a combined deep cooling system for combustion products after a hot water boiler of the housing and communal services system, represented by an air heater and a condensation economizer. It is considered that one part of the flue gases after the air heater is sent to the economizer, and the other part goes through the bypass, bypassing the economizer, and then meets the combustion products coming out of it. The distribution of the combustion product flow before the economizer is based on the need to ensure the temperature of the mixed flow after the economizer at 70 °C. For the most common hot water boiler in the housing and communal services system of the TVG-8M type, the authors have been established the dependence of the heat transfer coefficients, the surface area of the heat exchangers and other parameters of the deep cooling system of the exhaust gases on the set value of the temperature of the combustion products after the air heater. It has been established that the proposed scheme of a combined deep cooling system for combustion products makes it possible to improve the technical and economic performance of the boiler by reducing fuel consumption. It is proved that the smoke temperature after the air heater for this type of the boiler should not be very low (not lower than 115–130 °C), since it dramatically increases the heat flow with a decrease in the average logarithmic temperature difference and leads to an increase not only in the temperature of the heated air, but also in the surface area of the air heater.

ВЛИЯНИЕ ТЕПЛОФИЗИЧЕСКИХ СВОЙСТВ ПРОДУКТОВ СГОРАНИЯ БИОГАЗА НА ТЕПЛОВЫЕ ПАРАМЕТРЫ ВОДОГРЕЙНЫХ КОТЛОВ

The combustion products of biogas and natural gas differ in the content of components, which affects their heat content and heat exchange in boilers. To determine the possibility of using biogas in boilers designed for burning natural gas, the work compares the thermophysical properties of the combustion products of natural gas and biogas and their influence on the results of boiler calculations. Methods were obtained for calculating the thermal conductivity and viscosity of a mixture of gases depending on their composition and temperature. The comparison showed that the calorimetric and thermophysical properties of biogas combustion products differ from the properties of natural gas combustion products by up to 4 %, and the difference from the reference properties of combustion products given in the standard method for calculating boiler units is on average 6 %. A comparison has been made of the results of verification thermal calculations of low-power hot water boilers KVMG-1.0 and KSV-1.0 using the properties of combustion products given in the standard method for calculating boiler units, and when calculating them using the proposed equations. Calculations have shown that the results of calculations based on reference data of the standard method lead to higher values of exhaust gas temperatures and fuel consumption. It can be concluded that natural gas in boilers can be replaced by biogas without the need to reconstruct the boiler, but for thermal calculations it is necessary to take into account changes in the composition and properties of fuel combustion products.

Оценка эффективности завихрения воздуха при распылении водоугольных суспензий пневматической форсункой

Due to modern requirements for environmental protection, introduction of environmentally friendly power engineering technologies involves search and development of new energy sources. One of the ways to meet these requirements and maintain the same level of energy production by thermal power plants is to use multicomponent fuels. The most promising and affordable heavy fuel oil from the point of view of energy, ecology and economy are coal-water slurries (CWS). In this regard, the study of the properties and characteristics of such fuels is relevant. The coal-water slurries have been prepared in a rotary hydrodynamic cavitation generator. A pneumatic atomizer with external mixing is used to spray the coal-water slurries. Interferometric Particle Imaging method is used to determine the average size of fuel droplets after atomization. The authors have conducted experimental studies of the characteristics of atomization of coal-water slurries based on lignite and pyrogenetic liquid with a pneumatic atomizer with a tangential supply of a spraying agent. A three-stage method to prepare lignite-based slurries with pyrogenetic liquid has been tested. It has been established that when using this technique, the fluidity of coal-water fuel is maintained even with the introduction of 20 % by weight of pyrogenetic liquid into the composition of coal-water slurries when replacing both water and coal in equal proportions. The kinematic viscosity of coal-water suspensions increases when pyrogenetic liquid is added, despite a decrease in the concentration of the solid component. The change of suspension density is insignificant. The results of the study of atomization process have shown that the tangential air supply to the atomizer leads to an increase of the jet spraying angle by 6° compared with direct supply. At the same time, the average droplet size in the jet of a two-component CWS with direct air supply is 8 % smaller. The results of the study have made it possible to obtain completely new knowledge that can significantly advance domestic and world science and technology in the field of power engineering, namely the technology of coal-water fuels atomization. Experimental studies have determined the main patterns of influence of the CWS properties and the method of spraying agent supply on the formation of a gas-drop jet. Such patterns will provide conditions for the effective atomization of quite viscous CWS in the combustion chambers of energy boilers. The results obtained will enable designers and constructors to develop highly efficient designs of steam and hot water boilers and gasifiers fueled by CWS.

Investigation of the energy performance of thermal energy sharing for photovoltaic-thermal systems in a thermal prosumer network

This study analyzes the potential for energy saving through the integration of a photovoltaic-thermal (PVT) system with a heat pump (HP) in a community with a small-scale thermal network. An empirical study was conducted in a community to analyze and compare the performance of a HP and small-scale thermal network with hub thermal energy storage system that utilizes the surplus thermal energy produced by a PVT system installed in a residential house from other buildings with that of an existing electric hot water boiler. The energy saving analysis of the proposed system revealed that the energy consumption could be reduced by more than 70 % compared to the existing system. The HP exhibited a COP ranging between 4.2 and 4.7. Throughout the experiment, the integrated system collected an average of 23.77 kWh of heat energy daily from the PVT units. The annual domestic hot water load coverage from PVT through the thermal network was found to be 50.4 %. These results indicate that PVT systems combined with thermal networks and HPs can effectively reduce energy consumption in individual buildings and enhance energy efficiency within communities.

The result of the investigation of a new micromodule gas burner with a sudden expansion at the outlet

The object of the study is a new micromodule gas burner for small hot water boilers, in which, to stabilize combustion, the phenomena of flow disruption due to sudden expansion at the outlet of the burner are used. Today, there is an urgent task related to the development of new technical solutions for the most efficient and environmentally pure combustion of fuel in power plants, particularly, it is necessary to pay special attention to the stabilization of the flare. The combustion characteristics in this burner have been studied experimentally and theoretically, calculations are given for modeling a micromodule gas burner with a sudden expansion at the outlet, in particular, the model of a burner device for burning natural gas (propane) was modeled in the Ansys Fluent 2021 R1 software package. As a result of the experiment, the length of the torch was reduced, as well as the concentrations of harmful NOx emissions were reduced with improved indicators of combustion completeness and temperature uniformity of the field. The results of experiments with different nozzles are presented, namely nozzles with slots at the outlet d1 – 0.12 m and d2 – 0.15 m. The number of modes in each experiment is 5. Mathematical modeling of this burner with the possibility of evaluating the effectiveness of these measures will allow us to develop optimal operating modes of power plants and develop new technical solutions to reduce the emission of pollutants. Based on the experimental data obtained, graphs were constructed (completeness of combustion, temperature unevenness, concentration of substances), and the results were summarized. In general, these characteristics will increase the efficiency of using this burner in hot water boilers

АНАЛИЗ ТЕХНИЧЕСКИХ РЕШЕНИЙ ДЛЯ ПОВЫШЕНИЯ ЭФФЕКТИВНОСТИ РАБОТЫ ВОДОГРЕЙНЫХ КОТЛОВ ДЛЯ СЖИГАНИЯ ОТХОДОВ В НЕПОДВИЖНОМ СЛОЕ И ВЫБОР КОНСТРУКЦИИ ГАЗОХОДА ДЛЯ РАЗРУШЕНИЯ ВРЕДНЫХ ВЕЩЕСТВ В ПРОДУКТАХ СГОРАНИЯ

The purpose of the work is to analyze technical solutions used to improve the efficiency of hot water boilers for waste combustion. As a result of the analysis of available design solutions for low-power water heating boilers, in which waste is burned in a fixed bed, their main disadvantages were identified: low combustion temperature; ineffective heat transfer from combustion products to the coolant; contamination of flues and heating surfaces; incomplete combustion of fuel; the impossibility of accurately regulating the combustion process, which leads to the formation of a large amount of harmful emissions and a decrease in the heat output and efficiency of the boiler. It is proposed to install a flue after firing the boiler, in which the gases will remain for more than 2 seconds and the organic harmful substances contained in the combustion products will be completely destroyed. To determine the passage time and select the optimal design of the gas duct, a numerical simulation of the movement of the gas flow was carried out using the developed numerical model implemented in the ANSYS Fluent software package. To ensure uniformity of the gas flow in the gas duct, options with different heights of the window between the firebox and the gas duct and the installation of a dividing partition in the gas duct to organize two-pass gas movement were considered. The best results were obtained for a horizontal flue. For further design development and search for ways to increase the residence time of gas in the gas duct, the most effective option with a horizontal gas duct was chosen.

Numerical investigation of double-flame hot-water boilers under steady-state operation

This study investigates the optimal arrangement of combustion chambers in double-flame hot-water boilers using computational fluid dynamics (CFD) under steady-state and laminar conditions. The study considers two arrangements: horizontal and vertical. In the horizontal layout, the study tests three vertical distances of Y*=-0.25, 0, and 0.25 from the center of the boiler and three horizontal gap spaces of S*=0.05, 0.1, and 0.15 between two chambers. In the vertical layout, the study examines three vertical distances of S*=0.1, 0.2, and 0.3. The computations for both layouts are conducted for Richardson numbers ranging from 0.1 to 10 under a constant Reynolds number of 50. The Navier–Stokes equations along with the energy equation are implicitly computed based on the finite volume approach for single-phase water flow inside a simplified two-dimensional model. The results are validated for a single-flame hot-water boiler in terms of the Nusselt number and non-dimensional pressure drop, and a good agreement has been achieved. The study shows that the geometric parameters considered in the study, as well as the Richardson number, have significant impacts on the boiler performance. The study finds that the horizontal arrangement with S*=0.05 and Y*=-0.25 offers the highest thermal-hydraulic performance, regardless of the Richardson number.

Reconstruction of production and heating boiler plant JSC "NP NC KBK IM. S.P. Titov" with building expansion

RELEVANCE. In Russia there are a large number of large and small boiler houses that supply steam and hot water to industrial enterprises. Today, more than 70% of boiler houses require serious modernization, the options for which can be different. Research into the area of modernization and reconstruction of boiler houses in the country is important, since most of the equipment has exhausted its service life, and the need for heat supply is increasing due to the increase in industrial output. TARGET. Consideration of one of the options for modernization and reconstruction of a specific boiler house. METHODS. When considering the option, the steam-water heating boiler developed by the Taganrog Boiler Plant and well-known methods for expanding energy enterprises were taken as the basis. RESULTS. The article describes the relevance of the topic, presents an option for modernizing a hot water boiler, which makes it possible to operate the boiler in a combined mode, which allows solving steam reserve issues in the short term, and also presents an option for expanding the boiler room. CONCLUSIONS. The option of reconstructing and modernizing an industrial heating boiler house with its expansion and transfer of hot water boilers to steam mode is an opportunity to solve the growing production need for process steam.

Numerical Simulation of a Gas Burner Using Mixed Propane/Ammonia Fuel

In recent years, ammonia has received more and more interest to be used as carbon-free energy. In the present study, a computational model of a burner for the domestic hot water boiler in the building has been developed. The combustion characteristics of propane/ammonia-mixed fuel in the burner were investigated by numerical simulation under different ammonia blending ratios and equivalence ratios. Based on the flue gas concentration distribution of the numerical simulation results, the baseline carbon emission of hot water supply in a community was calculated. The results show that as the ammonia blending ratio increases, the overall combustion temperature decreases. At the outlet of the burner, when the ammonia blending ratio is 0.5, the emission concentration of carbon dioxide can be reduced by 31.4% compared to pure propane combustion. When the ammonia blending ratio increases from 0 to 50%, the carbon baseline emission decreases from 9.89 kg/GJ to 6.87 kg/GJ, and the carbon emission under the baseline decreases from 17.20 T to 11.94 T. The emission of NO pollutants remains basically unchanged due to the decrease of combustion temperature. It indicates that the mixed fuels can effectively reduce carbon emissions in domestic water heaters and have good potential for future application.

THE PARTICIPATION OF RESIDENTIAL CONSUMERS IN ENERGY MARKETS THROUGH DEMAND RESPONSE

Abstract. The article considers the approach to the interaction of the transmission system operator with consumers - the demand management mechanism, as well as its role and place in the energy markets. The tools and experience of implementation of demand management are described. With the help of a natural experiment, the possibility and effectiveness of the participation of consumers with household storage hot water boilers in the balancing market was evaluated. Optimizing the participation of large numbers of consumers in energy markets is a challenging problem, especially for portfolios with thousands or millions of flexible resources. One of the aggregator's tasks is to transform the functionality of automation technologies, such as a consumer's "smart" home, into products that could be traded on energy markets. The task of optimization consists in the effective and timely management of a large number of flexible resources. A key feature of demand management is the sale of managed load on a par with generating capacity. This is explained by the fact that, from the point of view of the balance, in the energy system, one kWh not consumed equals one kWh produced. As a result, the financial benefits of managing consumer electricity demand are equivalent to the prices of balancing services and the provision of capacity reserves from other market participants. The sale of a demand-side management resource can be implemented through balancing market (BM) and ancillary service market (SMS) instruments, which use TSOs to balance the power system. Attracting additional participants in RDP and BR should stimulate competition and allow TSOs to meet their needs for auxiliary and balancing services, which will positively affect the reliability of the energy system and increase competition. In general, the level of provision of the power system with reserves depends on a wide range of factors, including: different hours of the day, weather conditions or trading strategies of market participants, etc. The optimal way to involve household consumers in responding to demand is to use the services of aggregators. But this does not mean the simple accumulation of a certain resulting power of consumers. The quantitative and qualitative composition of the aggregator's portfolio should ensure the execution of OSP commands in full, even in conditions of unavailability of part of the boilers or other aggregated units. For this, it is necessary to have a certain reserve of regulating power, for example, other boilers or energy storage units for the possibility of their prompt replacement (reconfiguration) within the portfolio. Demand management in the power system can effectively reduce the peak load of the system and delay the necessary capital investment in additional generating capacity and transmission lines. In addition, demand management facilitates the integration of renewable energy sources and reduces the costs of setting up, starting or shutting down thermal power units during peak load periods. Consumer participation in demand management requires bidirectional communication infrastructure, advanced metering, efficient economic tariffs and energy management algorithms. With the rise of smart grid technologies and automated demand response systems, demand management systems are a key element expected to provide a cost-effective alternative to traditional generation-side solutions to meet increasing demand for electricity during peak load or high prices. Demand management competes with auxiliary services provided by "traditional" providers - power plants and is used by TSOs to stabilize UES parameters when the power grid faces unforeseen situations, accordingly, the development of this sector is an important component of energy security.

Domestic hot-water boilers harbour active thermophilic bacterial communities distinctly different from those in the cold-water supply

Running cold and hot water in buildings is a widely established commodity. However, interests regarding hygiene and microbiological aspects had so far been focussed on cold water. Little attention has been given to the microbiology of domestic hot-water installations (DHWIs), except for aspects of pathogenic Legionella. World-wide, regulations consider hot (or warm) water as ‘heated drinking water’ that must comply (cold) drinking water (DW) standards. However, the few reports that exist indicate presence and growth of microbial flora in DHWIs, even when supplied with water with disinfectant residual. Using flow cytometric (FCM) total cell counting (TCC), FCM-fingerprinting, and 16S rRNA-gene-based metagenomic analysis, the characteristics and composition of bacterial communities in cold drinking water (DW) and hot water from associated boilers (operating at 50 – 60 °C) was studied in 14 selected inhouse DW installations located in Switzerland and Austria. A sampling strategy was applied that ensured access to the bulk water phase of both, supplied cold DW and produced hot boiler water. Generally, 1.3- to 8-fold enhanced TCCs were recorded in hot water compared to those in the supplied cold DW. FCM-fingerprints of cold and corresponding hot water from individual buildings indicated different composition of cold- and hot-water microbial floras. Also, hot waters from each of the boilers sampled had its own individual FCM-fingerprint. 16S rRNA-gene-based metagenomic analysis confirmed the marked differences in composition of microbiomes. E.g., in three neighbouring houses supplied from the same public network pipe each hot-water boiler contained its own thermophilic bacterial flora. Generally, bacterial diversity in cold DW was broad, that in hot water was restricted, with mostly thermophilic strains from the families Hydrogenophilaceae, Nitrosomonadaceae and Thermaceae dominating. Batch growth assays, consisting of cold DW heated up to 50 – 60 °C and inoculated with hot water, resulted in immediate cell growth with doubling times between 5 and 10 h. When cold DW was used as an inoculum no significant growth was observed. Even boilers supplied with UVC-treated cold DW contained an actively growing microbial flora, suggesting such hot-water systems as autonomously operating, thermophilic bioreactors. The generation of assimilable organic carbon from dissolved organic carbon due to heating appears to be the driver for growth of thermophilic microbial communities. Our report suggests that a man-made microbial ecosystem, very close to us all and of potential hygienic importance, may have been overlooked so far. Despite consumers having been exposed to microbial hot-water flora for a long time, with no major pathogens so far been associated specifically with hot-water usage (except for Legionella), the role of harmless thermophiles and their interaction with potential human pathogens able to grow at elevated temperatures in DHWIs remains to be investigated.

Methanol-based fuel boiler: Design, process, emission, energy consumption, and techno-economic analysis

Methanol-based alternative energy sources are critical to maintaining energy security, reducing the need for oil imports, and safeguarding the environment in China. However, the use of methanol-based fuels in the field of thermal combustion has not been thoroughly investigated. Therefore, an evaluation of the costs, emissions, and usage of methanol boilers is necessary. The study finds that methanol heaters and air source heat pumps have comparable annual cost values. Methanol heating furnaces emit the least amount of NOx and produce no SO2. After the refurbishment, the boiler's emissions and energy consumption have significantly decreased upon conversion of coal-fired steam boilers to methanol-based fuel hot water boilers. Nevertheless, the economy has also somewhat declined. Additionally, 5499 tce (standard coal) less energy will be used during the heating season, and 1.8 million CNY less will be spent on dust removal and desulfurization. Unfortunately, the economic benefits of methanol are only apparent when the cost of methanol fuel is less than 1900 CNY/t. The research presented in this paper provides an essential technological foundation for the development of methanol-fueled fuel burners and for the renovation of small and medium-sized coal-fired boilers.

Modeling the relationship between outdoor meteorological data and energy consumptions at heating and cooling periods: Application in a university building

<p style='text-indent:20px;'>In this study regression modeling is proposed for calculating the heating and cooling load of the buildings by considering the outdoor meteorological data. For this pupose, Balikesir University Rectorate Building is selected as the case building. In the winter months, measurements were made in the hot water boiler in the basement of the building for the heating energy load. For the cooling energy load, measurements were made in the chiller groups near the building. As climate data, eight variables were considered: outdoor temperature, solar radiation, relative humidity, wind speed, atmospheric pressure, sunshine duration, steam pressure, and 1 m underground temperature. The Minitab statistical analysis program was used to perform the modeling. 55 samples were used for mathematically modeling the heating load, while 37 samples are used for modeling the cooling load. The R<inline-formula><tex-math id="M1">\begin{document}$ {}^{2\ } $\end{document}</tex-math></inline-formula>(coefficient of determination) values are calculated as 96.2% and 98.94% for cooling load and heating load, respectively. In addition to these findings, ANOVA results for both models were examined and both models were found to be significant.</p>

STUDY OF A DISTRICT HEATING SYSTEM WATER BOILER AS A OBJECT OF CONTROL


 
 The analysis of the operating conditions of a typical district heating system, in particular, a hot water gas boiler, was carried out. It is shown that the boiler, as the main control object, operates under conditions of constant change in external heat load, which, due to their random nature, leads to a number of uncertainties. The expediency of the mathematical description of uncertainties using the stochastic method as the most tested in practical conditions is substantiated. According to the results of the passive experiment on the hot water gas boiler KVG6.5-150 of the district heating system of one of the districts of Kharkov, an array of hourly experimental data was obtained, reflecting the main performance indicators of the hot water boiler. As a result of data processing by the least squares method, a mathematical model of the boiler was obtained in the form of a linear regression equation, reflecting the relationship between the temperature of the coolant at the boiler outlet and the ambient air temperature, the temperature of the coolant at the inlet to the boiler and with the flow rates of natural gas and coolant to the boiler. The obtained regression equation was verified by Student's t-test, which confirmed the significance of all coefficients of the regression model. The practical significance of the multiple regression equation was assessed using the coefficient of determination. The quality of the multiple regression equation as a whole was assessed using Fisher's F-test. Since parallel surveys were not conducted, instead of checking the adequacy, the quality of the approximation of the experimental points by the accepted regression equation was assessed, that is, it was checked whether this equation makes sense. Such a test was carried out by comparing the residual variance and the variance relative to the mean. The calculation results showed that the value of the coefficient of determination significantly exceeds the allowable value, and the actual value of the Fisher criterion significantly exceeds the table value. The obtained indicators led to the conclusion that the relationship between the variables in the regression model is significant, and the proposed stochastic method and the multiple linear regression equation can be used to make decisions in the process of synthesizing the technical structure of a computer-integrated control system for objects of a district heating system.
 
 
 
 
 

Calculation of reconstruction volumes of hot-water boilers during the transition to a methane-hydrogen fuel

The ongoing research provides for the development of general technical solutions for the creation of a methane-hydrogen water-heating boiler unit. The advantages of this source of thermal energy over similar units is the reduction in specific carbon dioxide emissions per unit of thermal energy produced, which is relevant for the decarbonization of the Russian heat and power industry. As part of the work, a mathematical model was created for the mixed thermal calculation of a hot water boiler unit (calibration for the furnace and constructive for the convective part) in the Python programming language. The calculation in the model is carried out on the basis of the normative method. Implemented the ability to calculate the conversion of the most popular standard sizes of hot water boilers to another gas composition: KVGM-10, KVGM-20, KVGM-30, KVGM-50, KVGM-100, KVGM-180, PTVM-30, PTVM-50, PTVM-100 and PTVM-180. The result of the calculation of the reconstruction of the convective part is the required area of the heat-receiving surface, which makes it possible to estimate the volume of reconstruction. The paper analyzes the volume of reconstruction of burners RGMG-10, RGMG-20 and RGMG-30 when switching to a methane-hydrogen mixture.

Preheating and Humidification of the Combustion Air to Increase the Hot Water Boiler Efficiency

Energy efficiency is one of the most pressing topics now. Energy consumption in-creases as living standards rise. Efficient heat production, i.e. efficient use of energy, is achieved with optimal boiler load. The second pressing issue is the protection of the environment from pollution. The process of burning different types of fuels to produce heat or energy results in emissions that can have negative impacts on the environment. One of the solutions to improve air quality is to reduce emissions from heating plants during their production. The scientific paper considers the possibility of a preheating and humidification for combustion air system to increase the efficiency of the boiler and reduce the amount of harmful emissions in flue gases. The boiler efficiency values were calculated before and after the installation of the preheating and humidification system for the combustion air, and measurements of the flue gas analysis were carried out using a Testo 350 flue gas analyzer. Calculations and measurements for flue gas analysis have shown that the combustion air preheating and humidification system increases the boiler house efficiency by 15 % and re-duces nitrogen oxide emissions by 70 %.

Thermohydraulic Analysis of Ocean Thermal Energy Conversion

Thermohydraulic analysis is a mandatory analysis for power plants, including in this case marine thermal power plants (OTEC = ocens thermal energy conversion). The application to OTEC shows that temperature and pressure are things that must be considered, the higher the surface temperature, the greater the output power. Calculation of heat flow is a variable that is determined before a plant is built. This study aims to make a mathematical analysis of heat flow or thermohydraulic. The study uses the study of the heritage of Mendalan so that modeling and determination of design variables are formed, including heat flow in the pipe, diameter, hot and cold water discharge and boiler variables

CFD simulation study of a biomass pellet-fuelled boiler

Biomass energy is an important substitute for fossil energy. Direct combustion of biomass in the boiler has the problem of high emissions. In this paper, a 0.1 t/h biomass atmospheric pressure hot water boiler is used for CFD modeling, aiming at providing a low-cost and high-efficiency way for the study of biomass boilers. In this paper, the biomass pyrolysis process is divided into three processes: water evaporation, devolatilization, and coke combustion. Using the UDF function combined with a porous medium model to write code, the gas-solid combustion process in the boiler is realized, and the grate is used to split the air. The calculation results show that the model can accurately restore the temperature, velocity, and composition changes in the boiler. Compared with the actual results, the temperature difference between the furnace and the outlet is less than 20 K, and the modeling has achieved good results.

Experimental Study of Heat Transfer in Bundles of Wavy Pipes of a Hot-water Boiler

The possibility of intensifying heat exchange by using wavy pipes and a membrane between them is considered. It is known that heat exchange in curved pipes and channels of the coil type proceeds more intensively than in straight ones. Increasing the intensity of heat exchange and the use of double-light screens will reduce the dimensions of the boiler unit, which will improve its technical characteristics. For this purpose, experimental studies of heat transfer and resistance in bundles of wavy pipes have been carried out in two flow directions: in the plane of bending of pipes and in the plane perpendicular to the bending of pipes. So, for the flow in the direction of bending pipes, heat transfer and resistance are 9% higher than in bundles of straight pipes. And for a flow perpendicular to the bending plane of wavy pipes, the heat exchange is 13%, and the resistance is 20% higher than in bundles of straight pipes. To further increase heat transfer, it is proposed to use finning by installing membranes between wavy pipes.

Simplified finite volume-based dynamic modeling, experimental validation, and data-driven simulation of a fire-tube hot-water boiler

This paper proposes and implements a novel approach to simulate the dynamic behavior of hot-water fire-tube boilers, in which physical phenomena-based and data-driven modeling methodologies have both been employed. The first model, which includes a reduced one-dimensional finite volume method to simulate the flue-gas side’s behavior, can be employed for accurate sizing of the unit considering end-users’ dynamic consumption profile. In the data-driven model instead, machine learning algorithms are used to estimate hot water’s supply temperature, which makes it a suitable tool for real-time prediction and model predictive control. Utilizing the latter model in combination with an advanced management system allows reducing the plant’s energy consumption and enhancing its controllability. Employing the measurements performed in an Italian industrial firm, the developed model is validated and is demonstrated to have a limited thermal efficiency estimation bias of 1.2%. Furthermore, the data-driven model achieves a mean absolute relative difference error lower than 6%, demonstrating its acceptable accuracy for various prediction horizons.