Actual Exhaust Research Articles

Analysis of Non-Road Mobile Machinery Homologation Standards in Relation to Actual Exhaust Emissions

This article presents issues related to the current approval procedures in the group of off-road vehicles. Our research aimed to demonstrate significant differences between actual railway vehicle operation and stationary homologation tests regarding exhaust emissions. The research cycle consisted of analyzing emissions of toxic compounds from exhaust systems under real operating conditions, supplemented by a temporal share analysis based on the denormalized NRTC test upon which the tested object was homologated. Based on the conducted analyses, a significant difference was found between the actual operation of the tested railway vehicle and the stationary homologation test. By interpreting emission intensities within the parameter ranges of the propulsion unit’s operation, key areas with a significant impact on the vehicle’s overall emissions were identified. Based on the obtained results, a critical opinion is expressed regarding current homologation standards for the off-road vehicle group and the necessity for further empirical research in the area of actual operation of the tested vehicle group.

Flow Field Analysis and Performance Study of a Hydrogen Circulation Pump for Proten Exchange Membrane Fuel Cell Vehicles with Different Working Clearances

This study investigates the impact of working clearances on the internal flow field, pressure pulsations, flow pulsations, and radial forces experienced by a hydrogen circulation pump. Numerical calculations are conducted on seven sets of distinct working clearances for the pump. The research findings demonstrate that an increase in meshing clearance and radial clearance results in higher leakage flow rate during the compression exhaust process, leading to a decrease in hydrogen circulation pump's exhaust flow rate. When the meshing clearance increases from 0.15 to 0.21 mm, the actual exhaust flow rate of the pump decreases from 37.46 to 32.73 m3 h−1. Similarly, when the radial clearance increases from 0.18 to 0.24 mm, the actual exhaust flow rate of the pump decreases from 42.46 to 29.71 m3 h−1. Additionally, with an increase in meshing clearance, both the radial forces Fx and Fy of the active rotor exhibit a downward trend. Yet, as radial clearance grows, the radial force Fx slightly descends, while the change trend of radial force Fy is first positive decrease and then reverse increase.

Performance of Transition Metal Supported Al2O3 Coated on Honeycomb Catalysts and Its Segmentation on Exhaust Gasses Oxidation

The oxidation of carbon monoxide (CO) and unburnt hydrocarbons (HC) under segmented honeycomb catalysts was investigated using actual exhaust gas mixtures from a gasoline-fueled internal combustion engine of a motorcycle. The honeycomb catalysts were prepared through a wet process, resulting in four types coated with transition metals (Cu, Cr, Fe, and Ni) supported on Al2O3. The oxidation of CO and HC was monitored using an exhaust gas analyzer across a range of air-to-fuel ratios (AFR), from lean to rich, under stationary conditions. The results demonstrate that the honeycomb catalysts effectively decreased CO and HC concentrations in the exhaust gas. Among the transition metal oxide honeycomb catalysts, Cr and Ni exhibited high CO and HC conversion rates, surpassing those observed with Cu. The average CO and HC conversion calculations, spanning from lean to rich air-to-fuel ratios, were consistent with the actual conversion rates achieved. Furthermore, the study investigated the effect of honeycomb segmentation on CO and HC conversion. Surprisingly, the catalytic performance of Cr and Ni remained high even with longer gaps in the honeycomb. Interestingly, the conversion of CO and HC over the iron oxide honeycomb catalyst increased as the gap in the honeycomb became longer. This is likely due to an increase in the gap size and enhanced re-mixing of reactants (CO, HC, and O2) caused by recirculation. Thus, this study provides valuable elucidation on the potential application of segmented honeycomb catalysts for reducing CO and HC emissions in exhaust gases.

Performance evaluation of methane oxidation catalyst for marine gas-engine in actual exhaust and simulated gas

To reduce methane slip from marine gas engines installed in gas fuelled ships, it is necessary to understand the effects of exhaust composition and temperature on the activity of the methane oxidation catalysts in the marine gas engine exhaust. A comparative study was performed to evaluate catalyst performance in both actual engine exhaust and the simulated gas under the same flow conditions. The test using actual exhaust gas test showed that despite the lower exhaust temperatures during low load operation, the catalyst exhibited an extremely high performance, achieving approximately 100% CH4 conversion. In contrast, at high load, despite high exhaust temperatures, the CH4 conversion was decreased to 50-60%. In the simulated gas test showed that the catalyst’ activity was declined with increasing concentration of H2O and NO, whereas it was improved by CH4 and CO oxidation. The results showed that high CH4 concentrations under low load conditions enhanced catalyst activity owing to the exothermic reaction, which increased the catalyst temperature despite the low exhaust temperature and the presence of H2O vapour. Furthermore, during actual engine operation, the catalytic performance at a high load was improved by controlling the air excess ratio.

Particle Counter Design Upgrade for Euro 7

This research article presents an optimized approach to enhance the performance of the APC exhaust gas particle analyzer, a significant instrument used for exhaust emission evaluation in diesel-powered vehicles considering EU regulations on pollutant emissions. The study aimed to address the challenge of particle counter contamination that often occurs during frequent exhaust gas measurements and leads to measurement interruptions until maintenance is conducted. To achieve this, a preparatory unit that extends the operational duration of the measurement system between maintenance intervals while preserving measurement accuracy was developed based on actual exhaust gas experiments. The preparatory unit comprises a condensate drainage system, cooling fan, HEPA filter, membrane pump, and interconnecting pipelines to prevent moisture and larger particle deposition, ensuring uninterrupted and accurate exhaust gas measurements. The research findings underscore the significance of reliable and precise exhaust gas emission measurements, contributing to advancements in particle counting technology and facilitating compliance with emissions regulations in various scientific and industrial applications. This study provides an objective representation of the proposed preparatory unit’s effectiveness in mitigating particle contamination with only 1.9% measurement variance, offering promising implications for the improvement of exhaust gas analysis methods.

Correlation between zeolitic particle size and the low-temperature NOx storage capacity of Pd/ZSM-11 passive NOx adsorber

The effect of zeolitic particle size on the NOx adsorption and desorption was investigated by synthesizing ZSM-11 zeolites with different particle sizes (0.5∼0.8, 1∼2, and 5∼6 μm) for doping Pd as passive NOx adsorbers (PNAs). Several characteristic techniques of XRD, HAADF-STEM, H2-TPR, CO-DRIFT, XPS and NH3-TPD were applied to clarify the essential association of the PNAs performance of Pd/ZSM-11 zeolites with the support zeolite properties and Pd active species. It was found that both the efficient Pd(II) species for assisting NOx adsorption-release and the acid amount (especially the strong acid sites) for facilitating Pd dispersion have positive correlation with the decrease of zeolite particle size. Differently, in addition to the active Pd species, meso-macroporosity properties are another key factors to determine the NOx adsorption ability of PNAs. The meso-macroporosity properties of Pd/Z11-1.5 show a negative correlation with the decrease of zeolite particle size while Pd/Z11-0.7's show the positive correlation with the decrease of zeolite particle size. As a consequence, Pd/Z11-1.5 with higher Pd(II) content but weaker meso-macroporosity properties than Pd/Z11-5.0 shows comparable adsorption capacity to Pd/Z11-5.0, while Pd/Z11-0.7 with both high Pd(II) content and good meso-macroporosity properties not only exhibits the highest NOx storage capacity, but also can release the NOx at the lowest temperature of less than 300 °C, indicating to be a good candidate for purifying NOx at the actual exhaust temperature of diesel vehicles.

Challenges and feasibility of a six-stroke engine using water direct injection

As fuel efficiency and exhaust regulations have become more stringent, many studies have been conducted to improve fuel efficiency. One interesting proposal is to develop a six-stroke engine using water injection. However, there is a lack of research on this concept, and existing studies have only taken a theoretical approach or did not involve comparisons with a four-stroke engine, obscuring the feasibility of a six-stroke engine using water injection. So, in this study, we performed experiments and simulations of a six-stroke engine using water injection and compared the results with those of a four-stroke engine. We optimized the exhaust valve lift profile through simulation for an actual exhaust cam of the six-stroke engine, and modified a four-stroke port fuel injection engine to a six-stroke engine. Then, through experiments and simulations, we evaluated the feasibility and the challenges of building a six-stroke engine using water injection. We used the CONVERGE v2.4 software application and validated the simulation models through the results of experiments. Using these models, we conducted simulations with various injection timings, masses, and water temperatures. The results indicate that the cylinder wall is cooled due to continuous water injection making evaporation unstable and that wall-temperature control is required in order to realize a six-stroke engine using water injection. In a simulation assuming the constant temperature of the wall, as additional strokes are added, the indicated mean effective pressure (IMEP) decreases by about 0.4 bar compared to that of the four-stroke engine, and only about 40% of this loss is recovered through water injection. The wall evaporation ratio is more critical to the feasibility of the six-stroke engine using water injection than other parameters. We show that it is very difficult to achieve a six-stroke engine using water injection unless a significant amount of heat energy for evaporation is brought from sources other than the mixture in the cylinder. The challenges of a six-stroke engine using water injection were cylinder temperature control and latent heat of water. If excessive cooling does not occur, such as in steam injection, IMEP can increase due to an increase in mass. However, this is very ideal case. It is difficult to obtain energy elsewhere for evaporation, and due to the latent heat of water, the mixture is inevitably cooled down making it difficult to realize this concept of six-stroke engine.

Catalytic degradation of chlorinated volatile organic compounds (CVOCs) over Ce-Mn-Ti composite oxide catalysts

Developing industrially moldable catalysts with harmonized redox performance and acidity is of great significance for the efficient disposal of chlorinated volatile organic compounds (CVOCs) in actual exhaust gasses. Here, commercial TiO2, typically used for molding catalysts, was chosen as the carrier to fabricate a series of Ce0.02Mn0–0.24TiOx materials with different Mn doping ratios and employed for chlorobenzene (CB) destruction. The introduction of Mn remarkedly facilitated the synergistic effect of each element via the electron transfer processes: Ce3++Mn4+/3+↔Ce4++Mn3+/2+ and Mn4+/3++Ti4+↔Mn3+/2++Ti3+. These synergistic interactions in Ce0.02Mn0.04–0.24TiOx, especially Ce0.02Mn0.16TiOx, significantly elevated the active oxygen species, oxygen vacancies and redox properties, endowing the superior catalytic oxidation of CB. When the Mn doping amount increased to 0.24, a separate Mn3O4 phase appeared, which in turn might weaken the synergistic effect. Furthermore, the acidity of Ce0.02Mn0.04–0.24TiOx was decreased with the Mn doping, regulating the balance of redox property and acidity. Notably, Ce0.02Mn0.16TiOx featured relatively abundant B-acid sites. Its coordinating redox ability and moderate acidity promoted the deep oxidation of CB and RCOOH- intermediates, as well as the rapid desorption of Cl species, thus obtaining sustainable reactivity. In comparison, CeTiOx owned the strongest acidity, however, its poor redox property was not sufficient for the timely oxidative decomposition of the easier adsorbed CB, resulting in its rapid deactivation. This finding provides a promising strategy for the construction of efficient commercial molding catalysts to decompose the industrial-scale CVOCs.

The Impact of Thermochemical Exhaust Energy Recovery Using Ethanol-Gasoline Blend on Gasoline Direct Injection Engine Performance

Thermochemical exhaust energy recovery in a modern gasoline direct injection engine is investigated using ethanol-gasoline blend (E25) and gasoline, as base fuel. The primary objectives of this research are focused on reducing carbonaceous emissions as well as improving thermal efficiency and fuel economy in combustion engines. These are consistent with the global commitment to lessen carbon emissions and meet environmental regulations and agreements.The possibility of hydrogen production through catalytic reforming of mentioned fuels using actual exhaust composition is investigated on full-scale Rh (Rhodium)—Pt (Platinum) catalysts. ANSYS-Chemkin is utilized for thermodynamic equilibrium analyses based on the Gibbs energy minimization method to explore the key reaction pathways for E25 reforming. Main reforming parameters including steam to carbon molar ratios and reforming temperatures are selected to investigate the feasibility of ethanol-gasoline blend reforming as well as to identify the reformate composition and evaluate the whole process efficiency. The results revealed that the presence of ethanol in reforming fuel mixture facilitates endothermic reactions and improves hydrogen-rich mixture, particularly at high engine load conditions where maximum heat recovery is obtained. Furthermore, E25 fuel reforming helped achieving up to 16% greater CO2 compared to gasoline fuel reforming under the same engine condition. Overall, the experimental results of full-scale reforming tests using E25 can be accredited for effective implementation of the reforming technique in practical application.

Gas exchange stability of linear engine generator under fuel injection quantity fluctuation

Gas exchange instability is an important issue that affects the stability of the linear engine generator (LEG). Fuel injection quantity fluctuation is a potential disturbance factor that induces LEG gas exchange instability. In order to grasp the impact of fuel injection quantity changes on LEG under the action of multi-field coupling the effect of gas exchange stability, a numerical model of the coupling of motion-combustion-gas exchange multiprocessing is constructed, and the calculation method of cyclic iteration of the simulation results of each process is adopted to simulate and study the performance characteristics of the LEG gas exchange process under the fluctuation of fuel injection. The results demonstrate that the reciprocating frequency, movement stroke of LEG, and the fluctuation of fuel injection quantity present positive correlation characteristics. The increase of fuel injection quantity causes the piston to move faster near the reciprocating dead point, so the time provided for the gas exchange flow is compressed. Moreover, the increase in fuel injection quantity means that more fuel participates in the combustion process, releases more heat, and enhances the pressure and temperature of the gas in the cylinder. Although this is conducive to the rapid discharge of more combustion exhaust gas in the free exhaust phase, due to the shortening of the gas exchange flow time. The actual exhaust gas scavenging efficiency decreases with the increase of the fuel injection quantity and the corresponding fresh charge trapping efficiency shows an increasing trend.

Performance Evaluation of Methane Oxidation Catalyst for Marine Gas-Engine in Actual Exhaust and Simulated Gas

Performance Evaluation of Methane Oxidation Catalyst for Marine Gas-Engine in Actual Exhaust and Simulated Gas

Influences of inner surface of pipe on deposit formation

Engine deposits in exhaust gas passages cause the increase of the pumping loss and the failing of the valve action. Deposits also affect EGR gas temperature in cooled EGR system because their thermal conductivity is low. Therefore, it is necessary to reduce engine deposits in order to improve engine performance. In this study, the influences of the inner surfaces of pipe on deposit formation are investigated by comparing the deposition on SUS304 and two kinds of fluorocarbon polymer, PTFE(polytetrafluoroethylene) and PFA(copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether). Deposits are experimentally formed by smoke produced when diesel fuel is burning in an alcohol lamp or actual exhaust gas emitted from a gasoline engine. The results indicate that different surfaces make difference to the amount and shape of deposits. In addition, it is suggested that small Van der waals force and non-wettability contribute to deposit reduction.

Analysis of pollutant emissions and fuel consumption for the use of a multi-storey carpark

In Poland, the number of vehicles owned per capita is systematically increasing. There is also a noticeable increase in traffic in large urban agglomerations. This creates a number of problems, such as difficulties in finding a parking spot. Then it becomes necessary to search for a long time to stop, which is correlated with higher emission of harmful substances and energy consumption. The aim of the work is a multi-criteria analysis of the selection of a parking spot at a shopping center focused on travel times, pollutant emissions and fuel consumption. In addition, consideration was given to the selection of the optimal parking spot. The tests were carried out in Real Driving Conditions similar to Real Driving Emissions testing. The procedure, currently used as an extension of the type-approval tests, reflects the actual exhaust emissions from vehicles more accurately than tests under laboratory conditions. Specialized PEMS (Portable Emissions Measurement System) apparatus was used for the measurements.

A mathematical model for VOCs removal in a treatment process coupling absorption and biodegradation

Biological treatments are used in gas treatment when containing Volatile Organic Compounds (VOC). Key factor to enhance treatment efficiency is to maximize mass transfer from gas to liquid. VOCs can be removed from the gas flow by absorption in a separate gas–liquid contactor before entering a Two-Phase Partitioning Bioreactor (TPPB) (Two-stage unit). The Non-Aqueous Phase Liquid (NAPL), a silicone oil in this study, is able to solubilize large amounts of hydrophobic VOCs while avoiding toxicity effects on the microorganisms.The aim of this study is to provide a designing tool for the degradation process occurring in the TPPB. Simulations considering mass transfer coupled with biodegradation kinetics were considered when investigating the TPPB mechanisms. A single VOC (toluene) was first taken as a reference to assess the accuracy of the model in comparison with experimental results. A mixture of seven VOCs (toluene, m-xylene, 1,3,5 trimethylbenzene, n-heptane, ethyl acetate, methyisobutylketone and isopropyl alcohol) presenting a wide range of hydrophobicity was then implemented in the model considering no interaction regarding their biodegradation. Degradation kinetics of the mixture (representing an actual exhaust gas from an industrial plant) were compared with experimental results. The developed model tends to highlight that modeling results are closed to experimental results. The results delivered by the model shows that mass transfer, through the “kLa” value, is a key parameter to enhance efficiency of NAPL renewal by biological regeneration.

Laboratory measurements of vehicle exhaust emissions in conditions reproducing real traffic

The measurement of exhaust emissions is an important element of the vehicle type-approval. The tests in this area are carried out mainly under laboratory conditions, and the obligatory road tests in force since 2017 supplement them. One of the most important requirements in relation to the laboratory tests is the best possible representation of real traffic conditions, as well as ensuring the reliability of the results obtained. Laboratory measurement cycles carried out nowadays assume an unchangeable way of recreating the trip under specific measurement conditions. This is conducive to misuse and, in many cases, obtaining the results that do not reflect the actual exhaust emission. Therefore, it is necessary to develop an alternative test method that would ensure a better representation of the road traffic conditions and allow the test to be individualized according to the type of vehicle or the professional group that uses it. This is possible owing to the proposed, differentiated speed profile during the exhaust emission tests under the laboratory conditions, with simultaneous reliable reconstruction of the road traffic conditions during bench measurements. The article describes a new measurement method that meets these requirements, based on a random selection of measurement sections. It was also validated by comparing the obtained results with the actual exhaust emission recorded during road tests. It has been proven that the method developed corresponds to the random nature of road traffic conditions, while maintaining the similarity of the emissions of toxic exhaust components, and therefore constitutes an effective and expected alternative to the currently used type-approval procedures.

Numerical and experimental investigation of an exhaust air energy recovery Savonius wind turbine for power production

World energy consumption is continuously increasing due to rising industrialization and demands especially in developing countries. The crisis of power outage is a common occurrence in many developing countries. To meet the demand of world energy more emphasis is given on all available energy resources such as exhaust air energy. The main aim of this research was utilizing industrial exhaust air energy as source of electric power with the help of savonius wind turbine to convert exhaust air energy to electrical energy. The actual exhaust air data at the fan outlet were collected from central air conditioning station of a composite textile mill (Kombolcha Textile Share Company). The measured exhaust air speed in the outlet of exhaust air fans using anemometer varied between 6 and 12 m/s. When an enclosure with a drag force blocker plate was attached at the outlet side of the exhaust air fans, the turbine speed doubled than the initial speed. An enclosure with a drag force blocker plate hads the ability to improve the overall efficiency of the system by 86.83%. In addition to this, using the collected data, the turbine blades were analyzed and simulated using Solid-work-2015 and Ansys-2019 software. As a result, the minimum and maximum generated power output from the system was 10kWs and 140kWs, respectively.

Evaluation of ecological extremes of vehicles in road emission tests

New testing procedures for determining road emissions of exhaust pollutants for passenger vehicles were established in 2018. New road testing procedures are designed to determine actual exhaust emissions, which may not always reflect laboratory emissions. Test procedures for the emission of pollutants in real traffic conditions are divided into four stages. The latest research on the emission of pollutants from motor vehicles in road traffic conditions, carried out using mobile measuring systems, reflects the actual ecological state of vehicles. The article compares the results of exhaust emissions obtained in road tests using the latest legislative proposals for passenger cars. Then, an attempt was made to determine the engine operating parameters in which exhaust road emission would be the lowest. Solution scenarios were defined as part of permissible changes to dynamic parameters that are included in European legislation on RDE testing. For this purpose, an optimization tool was used, allowing on the basis of given input data to determine the minimum objective function, defined as the smallest emission value of individual harmful compounds. The results of the exhaust gas emissions in the RDE test were used to determine the road emissions of individual harmful compounds. A thorough analysis of the emission intensity of individual compounds has shown that it is possible to approximate such values using functional relationships or adopting them as a constant value. This division was used to determine the extremes (in this case the minima) of the objective function (minimum road emissions of harmful exhaust compo-nents). This task resulted in obtaining (within the permissible tolerances of all driving parameters and durations of individual road test sections) the value of exhaust emissions in the range from 26% to 81% lower than in the actual road test. This means that there is a tolerance range, where you can obtain the value of emissions in road tests. As a result, you can use the process of determining the minimum emissions tests RDE calibration of the drive units already at the stage of preparation so that in the real traffic conditions characterized by the lowest exhaust emissions.

New Insight into the In Situ SO2 Poisoning Mechanism over Cu-SSZ-13 for the Selective Catalytic Reduction of NOx with NH3

To reveal the nature of SO2 poisoning over Cu-SSZ-13 catalyst under actual exhaust conditions, the catalyst was pretreated at 200 and 500 °C in a flow containing NH3, NO, O2, SO2, and H2O. Brunner−Emmet−Teller (BET), X-ray diffraction(XRD), thermo gravimetric analyzer (TGA), ultraviolet Raman spectroscopy (UV Raman), temperature-programmed reduction with H2 (H2-TPR), temperature-programmed desorption of NO+O2 (NO+O2-TPD), NH3-TPD, in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS), and an activity test were utilized to monitor the changes of Cu-SSZ-13 before and after in situ SO2 poisoning. According to the characterization results, the types and generated amount of sulfated species were directly related to poisoning temperature. Three sulfate species, including (NH4)2SO4, CuSO4, and Al2(SO4)3, were found to form on CZ-S-200, while only the latter two sulfate species were observed over CZ-S-500. Furthermore, SO2 poisoning had a negative effect on low-temperature selective catalytic reduction (SCR) activity, which was mainly due to the sulfation of active sites, including Z2Cu, ZCuOH, and Si-O(H)-Al. In contrast, SO2 poisoning had a positive effect on high-temperature SCR activity, owing to the inhibition of the NH3 oxidation reaction. The above findings may be a useful guideline to design excellent SO2-resistant Cu-based zeolite catalysts.

Experimental verification of hydrodynamic similarity in hot flows

This paper examines a common hypothesis in the design of internal combustion engine exhaust lines, namely that the ratio of the total pressure drop across the line to the inlet dynamic head should be a function only of the Reynolds number. While incompressible flow theory, provided that some simplifications are considered, is often used in support of this hypothesis, detailed experimental verification in actual exhaust lines is absent from the literature. Production exhaust lines contain non-trivial flow complexities such as muffler devices and catalytic converters and, in the case of high-performance engines, often operate at high temperature and high mass flow conditions, thereby rendering the usual theoretical simplifications doubtful. In this work, a production exhaust line composed of cold and hot ends, featuring a muffler and a catalytic converter, is tested at a variety of conditions. Analysis of the results shows that compressibility corrections must be factored in at certain conditions routinely found in actual high-performance engines, and that for hot ends, laminar flow at the converter monolith channels may pose a challenge to the hydrodynamic similarity hypothesis.

Designing Regenerators of Thermoacoustic Engines for Automotive Waste Heat Recovery

<div class="section abstract"><div class="htmlview paragraph">Extraction and utilization of automotive waste exhaust heat is an effective way to save fuel and protect the environment. One promising technology for this purpose is the thermoacoustic engine, where thermal energy is converted to mechanical energy in terms of high amplitude oscillations. The core component in a travelling-wave thermoacoustic engine is its regenerator where the process of energy conversion is mainly realized. This paper introduces a strategy for the design of the regenerator for applications in typical light- and heavy-duty vehicles. Starting from 1-D linear thermoacoustic theory, the nonlinear effects (given by the high amplitude oscillations) are modelled as acoustic resistances and introduced into the basic linear equations to estimate the nonlinear dissipations in the regenerator. Then, a few dimensionless parameters are derived by normalizing these thermoacoustic equations. This yields a good overview of how different design parameters such as the geometrical dimensions, operating temperature, and thermal boundary conditions influence the performance of the regenerator. For the application of automotive waste heat recovery, the thermal properties of the actual exhaust gas are accepted to be the boundary condition for the heat matching. The results obtained in the current work show that the optimum designs for the regenerators in travelling-wave thermoacoustic engines aimed at light- and heavy-duty applications widely differ due to the different thermal properties of their exhaust gas. Finally, two possible optimal designs of the regenerators in travelling-wave thermoacoustic engines for the typical light- and heavy-duty applications are presented. The designs are based on heat matching between the required heat by the regenerators and the available heat from the exhaust gases.</div></div>