Search

The article presents experimental research and calculations of spark ignition engine indicators, using hydrogen-containing H 2 /O 2 gas, when the engine is running at low power. The engine throttle was opened 8°, the amount of H 2 /O 2 gas was increased from 0 to 7.9 % of the mass of gasoline, the stoichiometric (λ = 1) air/fuel ratio was maintained. Research shows that the addition of the H 2 /O 2 gas leads a great influence on the energetic and ecologic indicators of the engine and this depends on the change in the combustion process and the change in the composition of the fuel. The calculation methodology of the combustion process when the engine is fuelled with pure gasoline and with additives of hydrogen-containing gas presented. Presented results how addition of H 2 /O 2 leads to a reduction in the duration of the combustion process and also has a significant effect on a faster rise of combustion pressure and temperature. Shorter combustion duration leads to a rise of the indicated efficiency of the engine, the heat utilisation factor and an increase in the indicated power. As a result of bench tests, an increase in the effective power and a decrease in the brake-specific fuel consumption of the engine were found. When assessing the influence of H 2 /O 2 on the concentration of CO 2 in the exhaust gas, no decreases was not observed, as hydrogen improves the combustion process. Only the concentration of incomplete combustion process products (e.g., HC) decreases, but the concentration of NO x increases at the same time. • Study of indicators of the engine operating at low power by changing the amount of H 2 /O 2 in a wide range. • Described method for calculating the indicated engine parameters, taking into account the addition of H 2 /O 2. • Determined indicators of the combustion process for the gasoline engine operating with the H2/O2 additive. • The addition of an H2/O2 (7.9% of mass) enhances heat usage efficiency and raises the indicated efficiency to 13.9%. • The H 2 /O 2 additive reduces BSFC but does not significantly affect the CO 2 emissions of the SI engine. [ABSTRACT FROM AUTHOR]

Road transport has a significant effect on air pollution. Therefore, the article focuses on the impact of addition of "oxyhydrogen", known as HHO, on selected vehicle features. These features, on which this study is focused, include the engine power and torque, composition of the exhaust gases and fuel consumption. There was also an impact of HHO on the value of pre-ignition as well as engine cleaning observed. HHO has been obtained from the generator designed and constructed for the purposes of this article. The measurements were performed under conditions of taking electric energy needed for HHO operation from the vehicle used in the measurements and also from the other source. The measurements were performed with vehicles of different kilometres driven, different technical conditions and different fuels and they were conducted under laboratory conditions to ensure a higher accuracy of the results. The results have shown a low impact of HHO addition of 2 dm3 min−1 on concentration of particular components of the exhaust gases. With HHO added, it was measured a mild decrease in the engine power and torque. Taking electric energy needed for HHO operation from the vehicle used in the measurement has evinced more considerably than addition of HHO into the engine. [Display omitted] • HHO addition slightly reduced the engine power and torque. • Taking electric energy for the HHO generator to be driven reduced the power on the wheels. • The fuel consumption at the idling speed with HHO decreased by 10%. • Taking electric energy for the HHO generator to be driven increased the fuel consumption by 20%. • HHO in the amount of 2 dm3 min−1 is considered very low for a common vehicle. [ABSTRACT FROM AUTHOR]

A significant jump in the development of machine building technologies requires the adjustment of environmental indicators. The main sources of air pollution are vehicles with internal combustion engines. According to research data, the main share of toxic emissions is accounted for by the engine idle mode and constant load mode. Studies carried out to improve fuel efficiency of diesel engines which have been in operation for some time show the potential for increasing the efficiency by deactivating a portion of the cylinders. At the same time, the improvement of efficiency indicators varies within a wide range - from 4 to 30%. The larger the number of deactivated cylinders, the higher the fuel economy effect, but as the effective power increases, it is advisable to reduce their number. The potential for increasing efficiency by deactivating a portion of the cylinders is incorporated in all diesel engines in operation. The efficiency of cylinder deactivation is confirmed by experimental data obtained on various types of engines, including automobile, tractor, diesel locomotive, and ship engines. This method is known in engine building primarily as a means of increasing the efficiency of diesel engines at idle speed and small loads. It has been established that there is a decrease in the hourly fuel consumption to 33% of the rated effective power when engine cylinders are deactivated compared to operation without cylinder deactivation. A diesel engine was tested on a running-brake stand fitted with the necessary measuring and recording equipment and instruments, allowing for a maximum torque of 363 N·m at the crankshaft speed within 1200–3000 min−1. Our studies covered three engine operation options. It has been established experimentally that the specific indicator fuel consumption in the second mode, as compared to the first mode, decreases to 9% due to a decrease in the hourly fuel consumption at the speeds from 1600 min−1 to 2350 min−1. In the third mode, fuel economy at idle speed with a shutdown of the fuel supply and the drive of the gas distribution mechanism of the 2nd and 3rd cylinders was about 24% at the engine shaft speed in the range from 1200 min−1 to 2350 min−1. Upgrading the diesel engine using an electromagnetic fuel valve will pay itself off in about a year. A comparison of the experimental and theoretical data shows that their discrepancy in the whole range of the engine crankshaft speeds does not exceed 7%. [ABSTRACT FROM AUTHOR]

Abstract Single (α-Fe 2 O 3 and Fe 3 O 4) and composite iron oxides (α-Fe 2 O 3 @Fe 3 O 4) have been prepared by chemical vapor deposition for clean combustion. The physio-chemical properties of the obtained thin films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and the redox properties via temperature programmed reduction analyses. The catalytic performance for the oxidation of C 2 H 2 and CO and their mixtures as representatives of exhaust gases was performed at temperatures range of 100–400°C. The best performance, with respect to total oxidation of individual gas, was achieved by α-Fe 2 O 3 @Fe 3 O 4 composite that presented the highest amount of electrophilic oxygen on the surface (O-species) and the lowest reduction temperature. α-Fe 2 O 3 @Fe 3 O 4 also exhibited good performance towards the total abatement of the mixed gases at different gas hourly space velocities. Moreover, the catalysts were reusable and stable upon several consecutive runs and no obvious deactivation was observed after 11 h prolonged time-on-stream at 300 °C. The higher quantity of surface oxygen species, the low-temperature reducibility and the porous-like morphology are suggested to play decisive roles in the catalytic oxidation processes. The deep oxidation of individuals and mixed gases by the coexisting α-Fe 2 O 3 @Fe 3 O 4 is a promising strategy in energy utilization and environmental protection. [ABSTRACT FROM AUTHOR]

Hydrogen as potential engine fuel can appear either as a single gas or as a component in processing gases e.g. syngas, hythane and coke gas. The research in this paper investigates impact of combustible mixture dilution on abnormal combustion called knock in the reciprocating internal combustion engine. Dilution can be realized by either exhaust gas recirculation (EGR) or making the combustible mixture lean. Novelty of this work is a new metrics defined as dilution ratio, which makes it possible to compare knock reduction caused by either EGR or leaning the air-gas mixture to the engine. Two gaseous fuels were investigated: hydrogen and coke gas with 65% hydrogen. Conclusion based on the proposed dilution ratio states that, for hydrogen as the fuel, applying EGR is more effective in knock reduction than making the mixture lean. It was found that EGR strategy in the hydrogen fueled engine can reduce knock intensity from initial 40 kPa–20 kPa, whereas by leaning the mixture to the same dilution ratio, the knock is reduced to approximately 28 kPa. With respect to coke gas, it is proved that both EGR and lean mixtures influence on knock reduction at the same strength. • Combustible mixture dilution impact on combustion knock intensity. • Dilution ratio as a metrics for both exhaust gas recirculation and lambda. • Engine knock reduced more effectively by applying exhaust gases recirculation. • The correlation between dilution ratio and knock intensity is almost linear. [ABSTRACT FROM AUTHOR]

Highlights • An improved WSGG model suitable for the exhaust gases of aero engines is proposed. • The effects of temperature and pressure are included in the improved model. • Comparison between the improved model and existing models is conducted. Abstract Advanced aero engines operate at high temperatures and pressures to improve thermal efficiency and power output, thus thermal radiation becomes a significant mode of heat transfer for exhaust gases. The existing gaseous radiative models for atmosphere are not suitable for the application in aero engines due to the huge pressure variation of exhaust gases. In this work, an improved weighted sum of gray gases (WSGG) model for mixtures of H 2 O and CO 2 within broader ranges of temperature and pressure variations is proposed. The mole ratio of H 2 O and CO 2 is fixed at 1/1, which represents typical products of stoichiometric combustion of kerosene. The weighting factors, which only relate to the temperature in previous WSGG models, are modified by taking into account the effects of both temperatures and pressures. The coefficients of the improved WSGG model are obtained based on the up-to-date HITEMP-2010 database, and they are valid for the temperatures varying from 500 K to 2500 K, pressures ranging from 1 atm to 30 atm, and pressure path-lengths ranging from 0.0001 atm·m to10 atm·m. To access the accuracy of the coefficients, the improved WSGG model and other two traditional WSGG models are applied to the solution of the radiative heat transfer with the discrete ordinate method, and the comparison is conducted with the benchmark line-by-line calculations. The results indicate that the improved WSGG model has much higher accuracy in the simulation of gaseous radiative heat transfer for exhaust gases of aero engines. [ABSTRACT FROM AUTHOR]

• The experimental SCR system for Euro-6 diesel engine is established. • A reliable numerical model for SCR is established. • The chemical reaction kinetic parameters for SCR are obtained. The Selective catalytic reduction (SCR) technology is an effective and economical method for reducing NO x emissions from the heavy duty diesel engine. To ensure a reasonable design of the SCR system, it is critical to understand the effects of space velocity (GHSV), NO 2 /NO x ratio, NH 3 /NO x ratio and structural parameters of the SCR reactor on the NO x conversion efficiency. Using the experimental method to conduct all the investigations though the entire development cycle of SCR system is expensive and would cost a long time. Numerical method as a complementary tool to bench tests can help to optimize the design and shorten the development cycle of SCR system. In this paper, a mathematical model is developed to predict the NO x conversion efficiency over a Cu catalyst. The model is calculated in the MATLAB environment. The simulation results agree well with the experimental data, which indicates that the mathematical model is reliable and can effectively predict the performance of the SCR catalytic system. Then the effects of the parameters, such as space velocity, NO 2 /NO x ratio, NH 3 /NO x ratio, length, diameter and number of channels per square inch (CPSI) of the SCR reactor on the NO x conversion efficiency were studied. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract Models and computational schemes are presented to simulate the flow field and radiation in solid propellant rocket plumes at high altitude. Different models are developed to calculate plume radiation induced by both the gas and the dispersed phase of alumina particles. Simulations were made to reproduce a 110 km altitude rocket plume and comparisons with experimental data on the plume radiance are presented. Influence of different physical processes on the simulation of the plume flow field and radiation is discussed, such as alumina phase change, scattering and the coupling of radiation with the two-phase flow. Highlights • Models and numerical tools are developed to simulate high altitude rocket plumes. • The two-phase compressible flow field is coupled to gas and alumina particle radiation. • Specific radiative property models are implemented in Monte Carlo simulations. • Supercooling of alumina particles is crucial for accurate prediction of their radiation. • The Bow Shock Ultra-Violet II (BSUVII) experiment is satisfactorily reproduced. [ABSTRACT FROM AUTHOR]

Highlights • A novel design of self-cleaning heat exchangers based on two-phase flow optimization. • Uniform dropwise condensation facilitates self-cleaning mechanisms of the surfaces. • Moderate Jakob and capillary numbers as optimal flow conditions for self-cleaning. Abstract Fouling on heat exchanger surfaces significantly impedes heat recovery from exhaust gases in many industrial applications. An introduction of the process of self-cleaning possibly represents an efficient solution to this well-known problem. Even if special treatments of the surfaces can help to protect them from fouling, it is still not well understood how to properly design heat exchangers in order to promote the self-cleaning process. In the present study, we investigate by means of Lattice-Boltzmann-based simulations the pivotal role of two-phase flow patterns and condensation-related phenomena in understanding the mechanisms that promote the self-cleaning, and, consequently, a stable heat recovery. In particular, we identify optimal flow conditions and two-phase flow characteristics that allow a clean and efficient operation of compact heat exchangers. Our results indicate that low heat duties and flow rates, which induce the condensation of small and motile droplets able to collect gas impurities, are beneficial for provoking and sustaining self-cleaning mechanisms. We therefore suggest that an effective design of self-cleaning heat exchangers should primarily be governed by principles of two-phase flow, rather than by the heat transfer duty. This work thus represents a step forward in identifying and proposing a procedure for an optimal design of heat exchangers to facilitate an effective heat recovery process from a wider range of exhaust gas mixtures. [ABSTRACT FROM AUTHOR]

The results of the research in the field of benzene, toluene, ethylbenzene and xylene isomers (BTEX) concentrations in exhaust gases of spark ignition engines under different operating conditions are presented in this paper. The aim of this paper is to gain a clearer insight into the impact of different engine working parameters on the concentrations of BTEX. The experimental investigation has been performed on the SCHENCK 230 W test stand with the controlled IC engine. The engine operating points have been chosen based on the results of a simulation and they are considered as the typical driving conditions according to the New European Driving Cycle. Concentration levels of BTEX compounds in exhaust gas mixtures have been determined by gas chromatography technique by using the combination of Supelcowax 10-Polyethylene glycol column and the PID detector. Based on the experimental research results, the emission model of BTEX compounds has been defined by the simulation of movement of a Fiat Punto Classic passenger car in accordance with the NEDC cycle. Using the results obtained within the simulation, the official statistics on the number of gasoline-powered cars on the territory of the Republic of Serbia and the European Commission data on the annual distance traveled by car, the amounts of BTEX compounds emitted annually per car have been estimated, as well as the emissions of the entire Serbian car fleet. [ABSTRACT FROM AUTHOR]

In a vehicle with a CI (compression ignition) engine, the power of the latter rotates an electric generator to produce a mixture of hydrogen (H 2 ) and oxygen (O 2 ) gas (hydrooxile – HHO, later just HHO) by water electrolysis. Low HHO content levels in air (0.14–0.18% of the volume) combined with air in cylinders of the CI engine affect the energy and environmental performance of the engine. It was found through stand tests and numerical modeling that chemically active hydrogen starts to ignite at the end of the compression stroke when the pressure and temperature rise prior to fuel injection into the cylinder. Early hydrogen ignition and supplemental energy consumption for HHO gas production worsen the energy performance of the engine and increase concentrations of carbon dioxide (CO 2 ) and nitrogen oxide (NO x ) in the exhaust gas. However, H 2 and O 2 additives reduce concentrations of incomplete combustion products (carbon monoxide (CO) and hydrocarbons (HC)) as well as the smokiness of the exhaust. When diesel fuel is replaced with biodiesel and when HHO gas is added, the indicated efficiency of the engine changes insignificantly; however, concentrations of CO and HC in the exhaust gas and smoke levels are reduced markedly. [ABSTRACT FROM AUTHOR]

In this study, a novel aerated surface flow constructed wetland (SFCW) using exhaust gas from biological wastewater treatment was investigated. Compared with un-aerated SFCW, the introduction of exhaust gas into SFCW significantly improved NH 4 + -N, TN and COD removal efficiencies by 68.30 ± 2.06%, 24.92 ± 1.13% and 73.92 ± 2.36%, respectively. The pollutants removal mechanism was related to the microbial abundance and the highest microbial abundance was observed in the SFCW with exhaust gas because of the introduction of exhaust gas from sequencing batch reactor (SBR), and thereby optimizing nitrogen transformation processes. Moreover, SFCW would significantly mitigate the risk of exhaust gas pollution. SFCW removed 20.00 ± 1.23%, 34.78 ± 1.39%, and 59.50 ± 2.33% of H 2 S, NH 3 and N 2 O in the exhaust gas, respectively. And 31.32 ± 2.23% and 32.02 ± 2.86% of bacterial and fungal aerosols in exhaust gas were also removed through passing SFCW, respectively. [ABSTRACT FROM AUTHOR]

We present experimental data on the line pressure broadening and shift coefficients in the first vibrational overtone band of HCl in mixtures with CO and CO 2 gas at room temperature. CO-broadening coefficients are published for the first time. The CO 2 -broadening coefficients and shifts for both systems are in very good agreement with the literature data and have better accuracy than earlier results. Collisions with CO 2 lead to stronger broadening for the most lines than collisions with CO. Similar to the broadening coefficients, the absolute values of CO 2 -induced shift coefficients are larger than those for HCl-CO system. However, the asymmetric shifts are very similar for both systems except for R 2 (0) and P 2 (1) lines, where the interaction anisotropy has the strongest influence. [ABSTRACT FROM AUTHOR]

The article outlines the results of comparative assessment of characteristics of the diesel 4ChN13/15 working process with exhaust gases recirculation and their cooling in the vortex tube. It is shown that the presence of cooling on the most exploited mode of work of the engine (n=1250 min -1 , loading 75%), with the share of recycled gases in the fresh charge equal to 18% and their cooling on 60K, gives an observable temperature difference of the fresh charge on the input to cylinder, the maximum and average gases temperature in the head-end volume. Moreover, a lower fresh charge temperature in case of cooling the recycled gases provides the increase of oxygen mass fraction in the head-end space, and, consequently, it allows boosting the fuel combustion which leads to a more intensive heat generation. [ABSTRACT FROM AUTHOR]

The results of experimental and theoretical research that indicate the improvement of the environmental performance of the petrol vehicle of class M1 are shown. The fuel and air channels of engine are equipped with permanent magnets. Studies were carried out at slow and fast idling of a crankshaft engine. Permanent magnets are installed in such a way that the magnetic field lines pass through the fuel and air in the perpendicular plane relative to the direction of flow of the material. It creates a magnetic flux of different configurations and intensity. As a result of such influence, the composition of the exhaust gas is changed. The toxic components are reduced in such exhaust gases. The results of experimental studies were approximated by polynomials of the second degree. As a result, the optimal combination of flow on the criterion of a minimum total toxicity was identified. [ABSTRACT FROM AUTHOR]

The properties of tin containing MFI type zeolite nanocrystals (Sn-MFI) synthesized under hydrothermal conditions from colloidal suspensions, and further application for selective detection of automotive exhaust gases (CO, CO 2 , NO x ) are reported. The properties of the Sn-MFI nanosized zeolite are compared with the pure silicalite-1 nanocrystals (Si-MFI) synthesized under identical conditions, and used as a reference. Additionally, both samples (Si-MFI and Sn-MFI) with high crystallinity and high porosity were stabilized in coating suspensions and deposited in films by spin-coating approach. The Si-MFI and Sn-MFI samples as self-supported pellets and thin films were exposed to different concentrations of exhaust gases in the presence of 100 ppm of water. The sorption behavior of the Sn-MFI and the Si-MFI towards CO, CO 2 , NO and NO 2 gases was followed by in situ IR spectroscopy. The influence of the tin concentration in the zeolite nanocrystals and the type of assembly (self-supported pellets and films) on the gas detection was studied. The fast detection of NO 2 with the Sn-MFI sample in comparison to the other gases implies that the tin containing zeolite could be considered for further use a selective material for detection of low concentrations of NO 2 (0–20 ppm). [ABSTRACT FROM AUTHOR]

The article outlines the results of the research of influence characteristics of heat-storage material on thermodynamic process in heat storage, installed in system of waste-heat recovery of internal combustion engines. It is shown that the highest average temperature and dampening effect among 4 analyzed heat-storage materials is reached by means of utilization of tripartite eutectic mixture 7NaNO 3 /40, NaNO 2 /53 КNO 3 and LiNO 3 , due to appropriate thermophysical properties. [ABSTRACT FROM AUTHOR]

In order to address road traffic emissions, studies need to be performed under realistic driving conditions where the input from other sources is minimised. Measurements in traffic tunnels have been used for quantifying emissions, but so far no study has established emission factors (EFs) for Southern Europe. To fill this gap, a sampling campaign was carried out for one week in the Liberdade Avenue tunnel (Braga, Portugal). The campaign included the monitoring of gaseous pollutants (CO 2 , CO, NO x ) and suspended particulate matter (PM) at two sites, one in the tunnel and another in an urban background location. Organic and elemental carbon (OC and EC) in size-segregated particles (PM 0.5, PM 0.5–1 , PM 1–2.5 and PM 2.5–10 ) were determined by a thermal–optical system, whereas major and trace elements were analysed by ICP-MS and ICP-AES. PM 0.5 accounted for 56% of the PM 10 mass, while PM 2.5–10 represented only 12%. The carbonaceous fraction was concentrated in PM 0.5 , encompassing 88% of the EC and 67% of the OC present in PM 10 . Elements attributable to non-exhaust emissions could be divided into two groups. Fe, Ba, Cu, Sb, Sn and Zn, from tyre and brake wear, were more abundant in particles between 1 and 2 μm. Ca, Al, K, Sr and Ti, associated with soil resuspension, were mainly present in particles > 2 μm. The average EFs of CO, CO 2 and NO x were 212, 4.02 and 1.22 g veh − 1 km − 1 , respectively, while values of 152 mg PM 10 veh − 1 km − 1 and 133 mg PM 2.5 veh − 1 km − 1 were obtained for the particles. OC and EC emission factor was 39 mg veh − 1 km − 1 for PM 10 . The corresponding OC and EC values for PM 2.5 were 34 and 38 mg veh − 1 km − 1 . The EFs are slightly lower than those found for other tunnels, but within the ranges presented by the EMEP/EEA inventory. [ABSTRACT FROM AUTHOR]

In this study, a novel dual selective Pt/SnO 2 sensor to carbon monoxide and propane in exhaust gases of a gasoline engine, using a Pt/LaFeO 3 perovskite catalytic filter, is presented. SnO 2 was prepared by a sol–gel method and LaFeO 3 by a combustion synthesis method. The samples were impregnated with aqueous solutions of H 2 PtCl 6 to get 1.0 wt% Pt/SnO 2 and 1.0 wt% Pt/LaFeO 3 . BET surface area measurement, XRD, EDS, TEM, HR-TEM, temperature programmed methods of reduction (TPR) and O 2 -desorption (TPD) analyses were carried out to investigate surface and bulk properties of the samples. In a mixture of 10,000 ppm carbon monoxide, 1000 ppm nitric oxide and 1000 ppm propane in 1.0% oxygen, Pt/LaFeO 3 catalytic filter-Pt/SnO 2 sensor combination is selective to CO and C 3 H 8 at the temperature ranges of 150–250 and 350–400 °C, respectively. In the temperature range of 150–250 °C, the filter-sensor combination has a significant response to CO, whereas negligible response to C 3 H 8 and NO is observed. On the other hand, at temperatures higher than 350 °C, CO and NO in the mixture are completely converted to almost inert products on the filter and the sensor shows a response only to C 3 H 8 . [ABSTRACT FROM AUTHOR]

The ceaseless search for renewable sources of energy puts biodiesel as a great alternative to replace oil-based fuels. This work aimed to assess the specific consumption of fuel, thermal efficiency and emission of exhaust gases when crambe biodiesel and diesel oil are used in a diesel-cycle internal combustion engine-generator, with different levels of resistive loads. A diesel-cycle engine generator was used, with 7.36kW (10cv) of power and 5.5kVA/5.0kW of nominal power, with monophasic output tension of 120/240V. The used fuels were crambe biodiesel (B100) and diesel oil (B0). Nominal resistive loads applied ranged between 1.0kW and 5.0kW. In order to quantify the emission of gases, fuel quality and emission analyzer were used. Crambe biodiesel׳s data for specific consumption and efficiency of energetic conversion proved to be statistically equal to those of diesel. With the usage of crambe biodiesel there was a significant reduction in the analyzed exhausted gases. [ABSTRACT FROM AUTHOR]

Abstract: With the aim to investigate the main pollution characteristics of exhaust gases emitted from plastic waste recycling granulation plants, mainly volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) and phthalate esters (PAEs) were analyzed in Xingtan Town, the largest distribution center of plastic waste recycling in China. Both inside and outside the plants, the total concentrations of volatile monocyclic aromatic hydrocarbons (MAHs), PAHs and PAEs ranged from 2000 to 3000 μg m−3, 450 to 1200 ng m−3, and 200 to 1200 ng m−3, respectively. Their concentration levels inside the plants were higher than those outside the plants, and PAHs and PAEs were mainly distributed in the gas-phase. Notably, highly toxic benzo[a]pyrene (BaP) could be detected inside the plants, and harmful PAEs could be detected not only inside but also outside the plants, although PAEs are non-volatile. The exhaust gas composition and concentration were related to the plastic feedstock and granulation temperature. [Copyright &y& Elsevier]

Abstract: Polyvinylidene chloride (PVDC; polymer of 1,1-dichloroethylene) was combusted with paper in a well-controlled, small-scale incinerator at an average grate temperature of 700°C, and then dioxins (PCDDs, PCDFs, and coplanar-PCBs) formed in the exhaust gases were analyzed by gas chromatography/mass spectrometry. PVDC lowered the combustion temperature due to its less flammable character. The amount of total dioxins (PCDDs+PCDFs+coplanar-PCBs) formed in the exhaust gas was 58.0ng/g of a combustion sample and its toxicity equivalency quantity (TEQ) value was 0.64ng-TEQ/g. The amount of PCDDs formed in the sample ranged from 2.33ng/g (Cl8-isomer) to 0.048ng/g (Cl1-isomer). The lower the number of chloride, the less production of PCDDs. On the other hand, there was no relation between the number of chloride and PCDF formation. The amount of PCDFs formed in the sample ranged from 8.02ng/g (Cl2-isomer) to 4.46ng/g (Cl8-isomer). A polyvinylchloride (PVC) sample produced 207ng/g of total dioxins and a PVDC sample produced 57.4ng/g of total dioxins when they were combusted under the same conditions. An approximately equal composition of dioxin isomers was formed from PVDC and PVC samples. Paper was found to contribute to PCDF formation when it was combusted with plastics. [Copyright &y& Elsevier]

To measure traffic pollutants with high temporal and spatial resolution under real conditions a mobile laboratory was designed and built in Helsinki Polytechnic in close co-operation with the University of Helsinki. The equipment of the van provides gas phase measurements of CO and NOx, number size distribution measurements of fine and ultrafine particles by an electrical low pressure impactor, an ultrafine condensation particle counter and a scanning mobility particle sizer. Two inlet systems, one above the windshield and the other above the bumper, enable chasing of different type of vehicles. Also, meteorological and geographical parameters are recorded. This paper introduces the construction and technical details of the van, and presents data from the measurements performed during an LIPIKA campaign on the highway in Helsinki. Approximately 90% of the total particle number concentration was due to particles smaller than 50 nm on the highway in Helsinki. The peak concentrations exceeded often 200,000 particles cm-3 and reached sometimes a value of 106 cm-3. Typical size distribution of fine particles possessed bimodal structure with the modal mean diameters of 15–20 nm and ∼150 nm. Atmospheric dispersion of traffic pollutions were measured by moving away from the highway along the wind direction. At a distance of 120–140 m from the source the concentrations were diluted to one-tenth from the values at 9 m from the source. [Copyright &y& Elsevier]

Although combustion is essential in most energy generation processes, it is one of the major causes of air pollution. Spiral fin exhaust pipes were designed to study the effect of cooling the recirculated exhaust gases (EGR) of Diesel engines on the chemical composition of the exhaust gases and the reduction in the percentages of pollutant emissions. The gases examined in this study were oxides of nitrogen (NOx), carbon dioxide (CO2) and carbon monoxide (CO). In addition, O2 concentration in the exhaust was measured. The two designs adopted in this study were exhaust pipes with solid and hollow fins around them. The first type uses air flow around the fins to cool the exhaust gases. The second type consists of hollow fins around the exhaust pipe to allow cooling water to flow in the hollow passage. Different combinations and arrangements of the solid and hollow fins exhaust pipes were used. It was found that decreasing the temperature of the EGR resulted in reductions in the oxides of nitrogen (NOx) and carbon dioxide (CO2) but increased the carbon monoxide (CO) in the exhaust gases. In addition, the oxygen (O2) concentration in the exhaust was decreased. As a general trend, the percentages of reduction in the NOx gas concentrations were lower than the percentages of increase in the CO emissions as a result of cooling the EGR of a Diesel engine by a heat exchanger. Using water as a cooling medium decreased the exhaust gases temperature and the amount of pollutants more than did air as a cooling medium. In a separate series of tests, increasing the cooled EGR ratios decreased the exhaust NOx but increased the particulate matter concentrations in the exhaust gases. [Copyright &y& Elsevier]

As a consequence of the formation of water droplets in the car engine at cold start, the fragile ZrO2 λ sensor cannot be heated until the engine is sufficiently warm. A possibility to shorten the time before closed loop λ control would decrease the exhaust emission. As a solution to this problem, the metal insulator silicon carbide field effect transistor (MISiCFET) sensor, which presumably is more thermo shock resistant than the ZrO2 sensor, could be used at cold start. The requirements for a cold start sensor are, among others, sensitivity to λ (air to fuel ratio) close to stochiometry, selectivity to λ and high speed of response. In this communication, the possibility of using the MISiCFET sensor at cold start is treated. The sensor consists of a SiC based MOSFET device with a buried channel design and a catalytic gate metal of 10 nm TaSix and 100 nm Pt. The response depends linearly on λ at 500 °C. The sensitivity of the device has been tested both in artificial atmospheres and in an engine. Two-level factorial designed experiments showed a high selectivity to λ compared to other gases such as CO, hydrocarbons, NOx and H2. The response time was found to be <10 ms at 500 °C when changing from an oxidizing to a reducing atmosphere. The MISiCFET sensor response showed interesting differences in λ stairs when the λ-value was varied by changing the oxygen, hydrogen or CO concentration. The results show that the MISiCFET sensor is a promising choice as a future cold start sensor. [Copyright &y& Elsevier]

Waste heat recovery using an (organic) Rankine cycle is an important and promising technology for improving engine efficiency and thereby reducing the CO 2 emissions due to heavy-duty transport. Experiments were performed using a Rankine cycle with water for waste heat recovery from the exhaust gases of a heavy-duty Diesel engine. The experimental results were used to calibrate and validate steady-state models of the main components in the cycle: the pump, pump bypass valve, evaporator, expander, and condenser. Simulations were performed to evaluate the cycle performance over a wide range of engine operating conditions using three working fluids: water, cyclopentane, and ethanol. Additionally, cycle simulations were performed for these working fluids over a typical long haul truck driving cycle. The predicted net power output with water as the working fluid varied between 0.5 and 5.7 kW, where the optimal expander speed was dependent on the engine operating point. The net power output for simulations with cyclopentane was between 1.8 and 9.6 kW and that for ethanol was between 1.0 and 7.8 kW. Over the driving cycle, the total recovered energy was 11.2, 8.2, and 5.2 MJ for cyclopentane, ethanol, and water, respectively. These values correspond to energy recoveries of 3.4, 2.5, and 1.6%, respectively, relative to the total energy requirement of the engine. The main contribution of this paper is the presentation of experimental data on a complete Rankine cycle-based WHR system coupled to a heavy-duty engine. These results were used to validate component models for simulations, allowing for a realistic estimation of the steady-state performance under a wide range of operating conditions for this type of system. [ABSTRACT FROM AUTHOR]

Working fluid selection is critical for the system design of an organic Rankine cycle (ORC). Computer-aided molecular design (CAMD) provides a new approach to search novel working fluids. In this study, the possibility of using molecular properties to predict the optimal system performance of an ORC is investigated. First, for a heat source of high-temperature exhaust gases, the influences of the molecular properties including the critical temperature and the specific heat capacity on the exergy efficiency of an ORC using 10 alkanes as working fluid are estimated. Then, the possibility of using the parameters of PC-SAFT to assess the optimal efficiency of the ORC is explored. The relation of the optimal temperature difference between the heat source and the molecular properties is determined. The prediction precision of PC-SAFT method is compared with the other four different molecular property methods. The results indicate that the parameters of PC-SAFT can be used to predict the optimal exergy efficiency of ORC system and the corresponding optimal heat source temperature. The average deviations of the exergy efficiency predicted is only 1.44% for the PC-SAFT method. The search range of the optimal working fluid can be decreased and the computation load is reduced significantly. • Molecular property method is used to predict ORC efficiency for exhaust gases. • A method based on the parameters of PC-SAFT is proposed. • A comparison among the PC-SAFT, Joback-Reid, Marrero-Pardillo is performed. • This method can be integrated with CAMD to reduce computation load. [ABSTRACT FROM AUTHOR]

By this study; it has been aimed to determine the design parameters and to manufacture a heat recovery unit using "heat pipe technology" in order to recover the energy of high temperature waste flue gases which are the exhaust product of a water-tube steam boiler, fire-tube steam boiler, superheated water boiler, hot water boiler, incinerator, any equipment producing heat energy or any power unit and machine. After having determined the scope of the Project, it has been decided that the system to be designed shall be a prototype "Heat Pipe Air Recuperator". Thus, the heat energy of the high temperature waste flue gases which are the exhaust product of a boiler or of an equipment producing heat energy shall be recovered through the use of the "Heat Pipe Air Recuperator" to be designed. A heat exchange between the exhaust gases and the fresh air shall realize, and so, the air shall be heated as free of charge. As well as this is a new technical profit, by the technical application of the Project, by implementing waste heat recovery in such a way, an important energy efficiency and great profit shall be provided for the companies, industrial plants and also for the country economy by saving energy and fuel. • "Heat pipe" sytem, a novel technique can efficiently recover the waste heat energy. • A prototype "Heat Pipe Air Recuperator" has been produced. • Capacity rate for heat pipe air recuperator depends on the limitation values. • Hydrodynamic -thermal inlet -outlet lengths must provide fully developed flow condition. • Fin structure, dimensions and fin configuration are important for the calculations. [ABSTRACT FROM AUTHOR]

In this paper, we describe an autopsy case in which death was due to accidental carbon monoxide poisoning occurring in a stationary vehicle idling in an open space. To investigate the source of the fatal fumes, the death scene situation was reconstructed using the vehicle. Exhaust gases were found to invade the interior through the floor from a defective exhaust system. CO gas was detected while idling and the level in the cabin gradually rose to 1.5% over a 2-h period. Since the 8-year-old motor vehicle seemed to have been defective for some months, it was concluded that stationary idling overnight caused an accumulation of toxic gases in the interior. [Copyright &y& Elsevier]