Exhaust Gas Duct Research Articles

Comparison of methods for diagnosing marine IC engines based on working medium parameters including exhaust gas specific enthalpy

Article points out methods currently used to diagnose marine engines in operation. The development of tools and programs for implementing these methods was pointed out. The problem of unsatisfactory measurement susceptibility of marine engines was highlighted. Three methods of parametric diagnosis are presented: measurement of in-cylinder parameters and in exhaust gas duct, numerical simulation due to computer software and calculations based on Wibe function. Unfitness states that were analyzed during tests are presented: reduced injection pressure, obstructed intake air duct and reduced compression ratio. The specific enthalpy of the exhaust gas within one engine cycle was determined as a new diagnostic parameter. As a supplement, thermograms of the engine in various states of inoperability were presented. The obtained results were compared and a series of conclusions derived from them were presented. It was evaluated that numerical simulation is an excellent tool for planning experimental studies. Tests on the engine in operation were found to be the most diagnostically reliable.

Boosting diesel generators power with thermoelectric generators and integrated oil tank – Thermal modeling and parametric study

In this paper, a unique method for using thermoelectric generators (TEGs) to generate electricity is introduced, a technique that makes use of a cold oil tank and hot exhaust gases from generators. A set of TEGs and an integrated cold oil tank are connected to the diesel generator as part of the suggested design. A pertinent thermal modeling was designed and a thorough parametric study was carried out to show the validity of this innovative concept. The parametric study has demonstrated that when the generator power and the thickness to thermal conductivity ratio of each TEG in the system are increased, the temperature differential in each TEG module and the power produced by the assembly of TEGs both exhibit linear increases. The length of the TEG plate and the height of the exhaust gas duct cause an exponential increase in the temperature differential across each TEG module. The TEG assembly's power output increases linearly with TEG surface length and decreases exponentially with exhaust gas duct height. Using an exhaust gas duct height of 0.05 m, and a TEGs plate length of 1 m, the parametric study showed that power generation of up to 2778 W is feasible under the predetermined circumstances of a diesel generator with an output of 125 kW. When compared to a conventional setup, the new hybrid generator in this scenario may be able to increase power generation by up to 2.22 %.

ANALYSIS OF THE CORRECTNESS APPROACHES TO DETERMINING THE SPECIFIC IMPULSE OF THRUST GENERATED BY THE WORKING FLUID OF A GAS GENERATOR CYCLE ROCKET ENGINE TURBINE

For liquid rocket engines (LREs) utilizing the gas generator cycle, the resulting engine thrust is composed of two components: the thrust of the engine chamber and the thrust of the turbine exhaust nozzle. Over the years of LRE utilization, methodologies for calculating ideal thermo gas dynamic parameters of the chamber have been developed, large volumes of statistical data regarding specific impulse losses in engine chambers have been obtained, and approaches for predicting specific impulse and, consequently, thrust of the main chambers have been refined. A much more complex situation arises with determining the specific impulse of the thrust generated by the working fluid of an autonomous turbine: significant limitations in information regarding methods for calculating this parameter have been found during literature analysis, and the available statistics exhibit contradictory characteristics. Accurate prediction of the specific impulse of the thrust from turbine exhaust nozzles allows for a more rational selection of design parameters (e.g., combustion chamber pressure) during the development of a new engine and is particularly important in cases where the spent gas generator gas is used to create control efforts. As the rocket and space industry historically developed under conditions of increased secrecy, many approaches and design methods for LREs remain known only to design bureaus and research institutes that were founded and developed during the heyday of rocket and space technology. This complicates the situation for new, young aerospace companies, as they must either conduct physical tests, which require expensive specific test equipment and increase the time and cost of engine development, or use numerical modeling, which, although to some extent allows for the replacement of physical experimentation, requires model verification and confirmation of the assumptions made. Furthermore, considering the military focus of rocket-related topics in the past, it cannot be excluded that intentionally distorted information may be present in open sources. Thus, considering the global trend of increasing the number of startups in the rocket and space industry, the identification of reliable and open sources of information becomes an important task. In this work, data from open sources regarding the specific impulse of the thrust from turbine exhaust nozzles of existing LREs were analyzed, revealing significant inconsistencies in the declared energy parameters. Numerical modeling of generator gas leakage from the nozzle of the exhaust gas duct of the RD-111 engine turbine has been conducted, and the results were compared with the calculations carried out by other methods. As a result of the work, various approaches to evaluating the thrust of exhaust nozzles during the design of an engine utilizing the gas generator cycle were analyzed, and conclusions were drawn regarding the correctness of their application.

Analysis of the Occurrence of Combustion Failure in the Steam Boiler at KM. Nggapulu

The availability of steam is crucial for the smooth operation of devices requiring hot steam. The operational activities of a ship can be hindered if the production of hot steam is insufficient due to problems arising from inadequate maintenance or other reasons, leading to the failure of combustion in the steam boiler. This research aims to identify the factors influencing the failure of combustion in the steam boiler on KM Nggapulu, to understand the consequences of the combustion failure in the steam boiler on KM Nggapulu, and to ascertain the measures taken in the event of combustion failure in the steam boiler on KM Nggapulu. The research method employed in this thesis is qualitative. The data sources include primary and secondary data. Data collection techniques encompass observation, interviews, and documentation, ensuring the validity of the data. Based on the research conducted, the following conclusions can be drawn: The causes of combustion failure include irregular implementation of the Planned Maintenance System (PMS), contamination of main burner components (automizer, electrode, solenoid valve), clogged exhaust gas pipes due to soot, excessive air composition in the furnace due to exhaust gas pipe blockage, poor fuel quality, and irregular cleaning practices. The impacts of boiler combustion failure involve operational difficulties for systems dependent on hot steam, inadequate hot steam supply for passenger or crew accommodation, and viscosity issues in MFO (Marine Fuel Oil) due to inadequate hot steam. Remedial actions that can be taken include checking and maintaining the automizer, inspecting and maintaining the main burner (electrode and nozzle), cleaning the fuel heater, replacing the solenoid valve, reducing fuel viscosity, and cleaning the steam boiler exhaust gas duct.

Thermal modeling and parametric study of TEG power generation from the exhaust gas of boilers and cold oil tank

A new concept of power generation from thermoelectric generators TEGs using the hot exhaust gas of boilers and a cold oil tank is proposed. The suggested concept consists of a flow of exhaust gas of boilers and cold oil in a tank separated by a plate comprising several TEGs in series. The oil tank at the bottom of the system constitutes the cold convection condition for the TEG plate and the upper hot exhaust gas flow constitutes the hot convection condition. Accordingly, a temperature gradient is created across the thickness of the TEGs, which play the role of a separation plate, and converted to an electrical power. To justify the feasibility of this new concept, a suitable thermal modeling is developed and the associated parametric analysis is carried out. The parametric analysis reveals that powers up to 622 W can be generated with a system having a space heating load of 200 kW, an exhaust gas duct height of 0.05 m, and a TEG plate length of 1 m. The temperature difference across each TEG module decreases exponentially when the TEGs plate length increases and decreases exponentially when the exhaust gas duct height increases.

Determination of the Conversion and Efficiency for CO2 in an Atmospheric Pressure Microwave Plasma Torch

AbstractIn a 2.45 GHz plasma torch, carbon dioxide (CO2) has been converted into carbon monoxide (CO) and oxygen (O2) at atmospheric pressure. The conversion and the efficiency of the plasma have been determined using two independent measuring methods: mass spectrometry and Fourier transform infrared absorption spectroscopy. The conversion depends on the measurement position in the exhaust gas duct. The conversion values at the beginning of the exhaust gas duct are significantly higher (maximum conversion is 22 %) than in the thermalized state at the end of the duct. In the cold, thermalized state of the gas, the maximum conversion rate is 8 % at 1.5 eV molecule−1. The maximum efficiency of 25 % is achieved at approximatively 0.6 eV molecule−1 operating at a microwave power of 0.48 kW and a mass flow of 12 slm CO2.

COMPARATIVE CFD BASED PARAMETRIC ANALYSIS OF GAS FLOW IN TWO CONTER-FLOW WET SCRUBBER SYSTEMS

" In this study, gas flow field were simulated using ANSYS 2020R2, Fluid Flow Fluent computational fluids dynamic (CFD) software based on the continuity, velocity, temperature, energy and k -  turbulence. The overall objective of the study is to compare the pressure and velocity maps inside the wet scrubber system for two different scrubber designs. I have choose to analyse an In-Line scrubber bottom inlet, type I, and In-Line scrubber side inlet, type L. Bottom entry or side entry designs to allow a direct up-flow configuration and simplify engine exhaust gas duct routing for any type of vessel. The flow in a wet scrubber is very complex due to the interaction between dust particles, water droplets, and bulk water and flue gas. The flue gas flow is turbulent and there are multiple phases (gas, liquid and solid). CFD codes that predict gas flow patterns are based on conservation equations for mass, momentum and energy. The results show that the residuals have a very good job of converging at minimum flow contours and vectors at the inlet across the scrubbing chamber and outlet shows a distributed flow. The velocity profiles have fully conformed to the recommended profile for turbulent flow in pipes. As can be seen in the figures above, the velocity flow contour inside the scrubber is higher in the scrubber side inlet. Even though I choose to study the simplified scrubber model without taking into account that spray nozzle improve mixing between the scrubbing liquid and waste gas; from the results obtained, it can be deduced that the numerical simulation using CFD is an effective method to study the flow characteristics of a counter-flow wet scrubber system. "

Analysis of Energy Balance for a Steel Electric Arc Furnace

A process and energy analysis was performed for an Electric Arc Furnace for steel production in order to determine the energy efficiency defined as losses contribution in the total energy input. Process analysis was performed during operation for one batch, measuring the relevant process parameters. Energy balance revealed that a significant potential for improvement exists, the main directions being reducing the cooling water loss (for example, by implementing a heat recovery system), reducing the loss during loading and adjustment by implementing technology changes and automation and reducing the loss through exhaust gas. Although implementation of heat recovery systems on the cooling water circuit and exhaust gas duct will not influence the actual process energy efficiency, it is expected to improve the overall energy expenditure by integrating other heat consuming equipment.

The Emission and Combustion Characteristics of Marine Diesel Engine with Extreme Throttled of Air or Exhaust Ducts

Abstract Presented paper shows the results of the laboratory tests on the relationship between the extreme throttling of both air intake duct and exhaust gas duct and gaseous emission from the marine engine. The object of research is a laboratory, 4-stroke, DI diesel engine, operated at loads from 50 kW to 250 kW at a constant speed equal to 750 rpm. During the laboratory tests the thermodynamic and exhaust gas emission characteristics of the engine were measured with technical condition recognized as “working properly” and with simulated throttling of both air intake duct and exhaust gas duct. Air intake duct throttling by 60% causes visible changes at both gas temperature and pressure behind the intercooler. The study results show significant changes of NOx and CO2 emission for considered air intake duct throttling. The best indicator of exhaust gas duct throttling among considered thermodynamic parameters of the engine is mean in-cylinder pressure. In the case of measuring the composition of exhaust gas, the throttling of the exhaust gas duct causes visible changes in CO2 and NOx emission. The conclusion is that the results of measurements of the composition of the exhaust gas may contain valuable diagnostic information about the technical condition of air intake and exhaust gas duct of the marine engine.

A modular dynamic mathematical model of thermoelectric elements for marine applications

This paper presents a modular, dynamic and spatially distributed model of thermoelectric elements for marine applications intended to assess the low-grade waste heat recovery potential of thermoelectric devices on-board seagoing vessels. The model describes the dynamic behaviour of marine thermoelectric components and captures the detailed thermodynamic and thermoelectric process phenomena. Validation against experimental data from the literature indicates good model predictive ability. Two marine applications are examined using the model: (a) a scavenge air cooler, and (b) an auxiliary engine exhaust gas duct section integrated with thermoelectric generators. For each case, a parametric analysis is conducted to identify the designs that yield maximum thermoelectric efficiency and power output. The study concludes that thermoelectrics can recover low-grade waste heat on-board ships. Systems engineering modelling and simulation techniques can successfully determine the best system design, to achieve maximum energy harvesting, satisfying the weight, space and operational constraints on-board.

An Experimental Study of Emission and Combustion Characteristics of Marine Diesel Engine in Case of Cylinder Valves Leakage

Abstract Presented paper shows the results of the laboratory tests on the relationship between throttling of both air intake duct and exhaust gas duct and a gaseous emission from the marine engine. The object of research is a laboratory, four-stroke, DI diesel engine, operated at loads from 50 kW to 250 kW at a constant speed equal to 750 rpm. During the laboratory tests over 50 parameters of the engine were measured with its technical condition recognized as a „working properly” and with simulated leakage of both air intake valve and exhaust gas valve on the second cylinder. The results of this laboratory research confirm that the leakage of cylinder valves causes no significant changes of the thermodynamic parameters of the engine. Simulated leakages through the inlet and exhaust valve caused a significant increase in fuel consumption of the engine. Valve leakages cause an increase of the exhaust gas temperature behind the cylinder with leakage and behind other cylinders. The exhaust gas temperature increase is relatively small and clearly visible only at low loads of the engine. The increase of the temperature and pressure of the charging air behind the intercooler were observed too. Charging air temperature is significantly higher during the engine operation with inlet valve leakage. The study results show significant increases of the CO, NOx and CO2 emission for all the mentioned malfunctions. The conclusion is that the results of measurements of the composition of the exhaust gas may contain valuable diagnostic information about the technical condition of the air intake duct and the exhaust gas duct of the marine engine.

INFLUENCE OF THE MARINE 4-STROKE DIESEL ENGINE MALFUNCTIONS ON THE NITRIC OXIDES EMISSION

The article presents the results of the laboratory study on nitric oxides (NOx) emission level from marine fourstroke diesel engine. The object of the study was laboratory piston engine, operating at constant speed. Measured engine parameters were necessary to determine the NOx emission in accordance of the requirements of the Annex VI to MARPOL 73/78 Convention. The study consisted of tests during the engine operation without malfunctions and engine operation with simulated malfunctions. Malfunctions of the charge gas exchange in the form of throttling of the air intake duct and the throttling of the exhaust gas duct were taken into account in the simulations. Measurements during the engine operation with simulated malfunctions of the fuel pump on one of the cylinders were also carried out. Mentioned malfunctions were delay of the fuel injection by 5° of the crankshaft angle position and the leakage of the fuel pump of the second engine cylinder. The simulated malfunctions decrease the total weighted NOx emission in all considered the engine loads. All simulated malfunctions resulted in an increase of the NOx emissions during engine operation at low the engine loads and a decrease of the mentioned emission at maximum the engine loads operation. The calculations of the weighted specific fuel consumption present a little change in engine efficiency which are within the range of measuring error of the used method.

107 ボイラ排ガスダクトで発生した異音の原因と対策について(騒音抑制技術)

107 ボイラ排ガスダクトで発生した異音の原因と対策について(騒音抑制技術)

Thermodynamic and experimental studies on condensation behavior of low-boiling-point elements volatilized in the melting process

To study the volatilization and condensation behaviors of low-boiling-point elements in the waste melting process, experiments were conducted to collect the dust from a coke-type incineration residue melting furnace. Then, a comparison was made between the experimental results and the calculated values obtained from a thermodynamic equilibrium model in terms of the chemical composition of the dust. The composition of the dust collected from a cylindrical filter in the exhaust gas duct was determined by chemical methods, scanning electron microscopy/energy-dispersive X-ray spectroscopy, and X-ray analysis. As a result, the sampled dust was classified into two different types: fine particles mainly containing Na, K, Pb, and Zn collected from the side face of the cylindrical filter, and large particles containing Ca, Si, and Al collected from the bottom face of the cylindrical filter. From X-ray analysis of the sampled dust, NaCl, KCl, PbS, and ZnS were identified in the fine-particle dust, while CaO, SiO2, Al2O3 were detected in the large-particle dust. From the results of the thermodynamic equilibrium calculation in the gas cooling process from 2000 to 600 K, it was found that Na, K, Pb, and Zn volatilized as metals in the melting furnace were condensed as alkali chlorides such as NaCl and KCl and heavy metal sulfides such as PbS and ZnS. These computational results were in good agreement with the X-ray diffraction results of the sampled dust at a gas temperature of 823 K for the formation of NaCl, KCl, PbS, and ZnS.

500MW 발전소에서 협소 공간 내 대형 덕트 설계의 최적화

Some sections of the exhaust system to determine the shape of the duct is to suffer the difficulties by space constraints to install new equipment of the environment post-treatment for existing operation of the power plants. In this paper the large duct in flue gas desulfurization equipments of the 500MW coal-fired power plant on the current operation is numerically analyzed from induced draft fan exit to booster up fan inlet section which is in the narrow space of the exhaust system with four times bending and is connected to emergency duct to bypass the exhaust gas on the emergency operation. The procedure and method using computational fluid dynamics are proposed to maintain the stability of the guide vane with the uniform flow and a minimum pressure loss of exhaust gas in the case of normal and emergency operation between the direction of the flow of exhaust gas duct at different.

Modelling of EAF Off‐Gas Post Combustion in Dedusting Systems using CFD Methods

To comply with the increasingly strict environmental regulations, the poisonous off‐gas species, e. g. carbon monoxide (CO), produced in the electric arc furnace (EAF) must be treated in the dedusting system. In this work, gas flow patterns of the off‐gas post combustion in three different dedusting system units were simulated with a computational fluid dynamics (CFD) code: (1) post combustion in a horizontal off‐gas duct, (2) post combustion in a water cooled post combustion chamber without additional energy supply (no gas or air/oxygen injectors) and (3) post combustion in a post combustion chamber with additional energy input (gas, air injectors and ignition burner, case study of VAI‐Fuchs GmbH).All computational results are illustrated with gas velocity, temperature distribution and chemical species concentration fields for the above three cases. In case 1, the effect of different false air volume flow rates at the gap between EAF elbow and exhaust gas duct on the external post combustion of the off‐gas was investigated. For case 2, the computed temperature and chemical composition (CO, CO2 and O2) of the off‐gas at the post chamber exit are in good agreement with additional measurements. Various operating conditions for case 3 have been studied, including different EAF off‐gas temperatures and compositions, i. e. CO content, in order to optimize oxygen and burner gas flow rates. Residence time distributions in the external post combustion chambers have been calculated for cases 2 and 3. Derived temperature fields of the water cooled walls yield valuable information on thermally stressed parts of post combustion units.The results obtained in this work may also gain insight to future investigation of combustion of volatile organic components (VOC) or formation of nitrogenoxide (NOx) and permit the optimization of the operation and design of the off‐gas dedusting system units.

The Development and First Commercial Application of an Innovative Diesel Engine Based Cogeneration System

This paper covers the development of a cogeneration (combined heat and power) system based upon a compression ignition, reciprocating, internal combustion engine and a standard three-pass economic shell-and-tube industrial boiler as well as the first commercial application of the system. An innovative feature of this cogeneration system is that additional fuel is burnt to utilize the free oxygen in the engine exhaust gas (a practice common with gas turbines but rarely attempted with reciprocating engines) to provide a significant, fuel-efficient and easily variable increase in the high-quality heat, that is steam, output from the system. The initial development work was done in 1983 using heavy fuel oil as the fuel to both engine and burner, while the first commercial application in 1988 utilizes a dual-fuel engine (gas and diesel oil pilot or diesel oil) and dual firing of the exhaust gas duct burner with gas or diesel oil.