•A new generation of catalytic converters is presented.•Experimental and numerical investigations are carried out.•The thermal and fluid flow characteristics is evaluated.•Improvement in the thermal ...performance by 18% is achieved.•The uniformity index is improved by 5%
The need for improved fuel economy, while meeting more stringent global vehicle emission standards, continues to grow with the increasing demand for environmental protection and rising fuel prices. A new generation of catalytic converters, designed and patented by Vida Fresh Air Corp., offers emissions reduction while improving fuel economy. In this design, a thin layer of insulating material is placed inside the ceramic honeycomb channels, creating a multi-chamber catalytic converter. The improvement in performance of the catalytic converter is attributed to the change in both the flow distribution and the controlled heat diffusion from the inner to the outer chambers. On engine performance tests have shown significant improvements in both fuel economy and emissions, however, the theory of operation of this design needs to be validated for potential design improvements to achieve an optimum performance. In this study both experimental and numerical investigations are carried out in order to understand the flow through the catalytic converter, using different monolith cell densities. A dynamically scaled-down model for a typical flow through catalytic converter was utilized for this study. Detailed experiments were conducted using hot air as the working fluid in order to evaluate the thermal and fluid flow characteristics of the new catalytic converter technology without the effect of chemical reactions. The measurements were performed at a Reynolds number of 43,000 with a free stream temperature of 177 °C. These conditions were selected in order to achieve thermal and hydraulic similarity to actual flow conditions for a typical catalytic converter. Numerical modelling of the flow through the setup under investigation was found to adequately replicate the experimental measurements for temperature, velocity and turbulence intensity within ±3%, ±5% and ±8% respectively. The use of a new design of the catalytic converter found to improve the thermal performance by 18% and the hydraulic performance by 5% without a significant increase of the pressure drop across the catalytic converter.
•Combining the ejector nozzle model with turbofan engine model.•A prediction method of infrared radiation intensity is proposed.•Combining the infrared radiation intensity prediction model with the ...engine model.•The overall engine performance changes under different mission stages are studied.
In order to study the effect of ejector nozzle on the overall performance of turbofan engine, a turbofan engine model with ejector nozzle is established in this paper, which includes parameter cycle analysis module and performance cycle analysis module. A backward prediction method of infrared radiation intensity for exhaust system is proposed, which includes solid wall and gas infrared radiation intensity prediction. The infrared characteristics and overall performance of the turbofan engine with ejector nozzle are analyzed and calculated in the flight missions. Firstly, the simulation model of turbofan engine with ejector nozzle is established and the influence of ejector bypass ratio on thrust performance of engine is studied. Secondly, the prediction model of engine infrared radiation intensity is established based on the prediction method of infrared radiation intensity. Finally, numerical simulations were carried out for different bypass ratios and different flight missions.
Display omitted
•Catalysts were prepared by a two step process involving solid state synthesis and high energy milling.•Catalysts were able to simultaneously store NOx and oxidize soot.•The barium ...cerate sample co-doped with Zr and Co exhibited the highest catalytic performance.
A series of doped barium cerate perovskite catalysts (BaCeO3-δ, BaCe0.8Zr0.2O3-δ and BaCe0.8Zr0.1Co0.1O3-δ) were prepared by a two-step process consisting of solid-state synthesis followed by high-energy ball milling. X-ray diffraction studies showed that the dopants (Zr and Co) were incorporated into the perovskite lattice. TPR studies revealed that the high-energy ball milling process significantly enhanced the reducibility of the catalysts. XPS data indicated a shift in electron density away from the metal centres and an increase in defect oxides, for the high-energy ball milled catalysts, which led to enhanced activity of the catalysts. The catalytic performance was evaluated in a fixed bed reactor system under simulated diesel exhaust conditions, including water. The high-energy ball milled barium cerate sample co-doped with Zr and Co exhibited NOx storage of ∼228 μmol/g at 380 °C and a Tmax, at which the rate of soot oxidation reaction was maximum, of 436 °C.
With the growth of the economy, the number of automobiles on the road is fast growing, resulting in substantial environmental pollution from exhaust gas emissions. In the automobile factory, some ...improvements have been achieved by constructing devices to degrade automobile exhaust. However, although most of the vehicle exhaust emissions have met the national standards, the exhaust gas is superimposed at the same time period due to the increasing traffic volume, making the exhaust emissions seriously reduce the air quality. Therefore, the scholars in the road field began to study new road materials to degrade vehicle exhaust, which has gradually become one of the effective ways to reduce automobile exhaust. Photocatalyst materials have been widely concerned because of their ability to oxidize harmful gases by solar photocatalysis. Yet, the effect has been not satisfactory because of the small light response range of photocatalyst material, which restricts the catalytic effect. In this study, this paper attempts to use Fe3+ to modify the TiO2, which is one of the main photocatalytic materials, to expand the range of light reaction band and to improve the degradation effect of automobile exhaust. The degradation effects of ordinary TiO2 and modified TiO2 on automobile exhaust were compared by test system in the laboratory. The results show that the modified TiO2 can effectively improve the performance of vehicle exhaust degradation. Moreover, the molecular dynamics method was used to establish the channel model of TiO2, and the dynamic process of automobile exhaust diffusion and absorption was simulated. The diffusion law and adsorption process of different types of automobile exhaust gas such as NO, CO, and CO2 in the TiO2 channel were analyzed from the molecular scale through the radial concentration distribution and adsorption energy.
► The PGMs are mostly located on the inner surface of the cells. ► Hydrogen thermal pre-treatment does not improve the recovery significantly. ► The addition of H
2O
2 as oxidant agent implies the ...reduction of the pollutant gases. ► The different compositions of reagents studied recover more than 95% of PGMs.
The car industry is one of the technological applications which more platinum-group metals (PGM) employs. Therefore, the recovery of the PGMs from the car catalytic converters could be an important source to obtain these precious metals, with economic and environmental consequences.
In this work, the car catalytic converters were characterized through different techniques as X-ray diffraction, scanning electron microscopy and inductively coupled plasma.
In order to suggest an environmentally friendly method for the recovery of PGMs, some conditions such as the reagents concentration and composition, energy optimization, pre-treatment in hydrogen atmosphere and a thermal pre-treatment were studied.
In addition, a new alternative to recover at least the 95% of the PGMs present in the car catalytic converters by the application of lees aggressive, corrosive or expensive reagents and conditions is proposed.
We present a highly active CeO2‐based catalyst for oxidizing CO in automobile exhaust. This catalyst was systemically designed by co‐doping with transition metals (TMs). First, we used density ...functional theory (DFT) calculations to screen Mn and 13 dopant TMs (periods 4∼6 in groups VIII∼XI) and their 91 binary combinations for co‐doping. As a result, Cu and (Cu, Ag) were found to be the best candidates among the single and binary dopants, respectively. Next, we synthesized CeO2 nanoparticles doped with Cu or (Cu, Ag), then experimentally confirmed that the predicted (Cu, Ag) co‐doped CeO2 showed higher activity than pure CeO2 and other TM‐doped CeO2. This was attributed to the easy formation of oxygen vacancies in the lattice of CeO2. Our study demonstrates that the use of a rational design of CeO2‐based catalyst through theoretical calculations and experimental validation can effectively improve the low‐temperature catalytic activity of CO oxidation.
Finding the CEO of CeO2: Transition metal (TM) co‐doped CeO2 catalyst for CO oxidation reaction was rationally designed by exploiting the relationship between DFT‐calculated oxygen vacancy formation energy and catalytic activity. Among the 91 binary combinations for co‐doping, DFT calculations predicted that (Cu, Ag) co‐doped CeO2 would have the best catalytic activity for CO oxidation. The following experiments successfully proved that the (Cu, Ag) co‐doped CeO2 indeed had higher activity than pure CeO2 and other TM‐doped CeO2.
Very simple and economical SiO 2 supported ionic liquid phase (SILP) materials are efficient catalysts for the addition of CO 2 to epoxides, producing cyclic carbonates in high yields (up to 99%) and ...selectivities (up to 99%). A range of ionic liquid (IL) concentrations (5–100 wt%), SiO 2 -supported 1- n -butyl-3-methylimidazolium halides (SBMIm·X: X = Cl, Br and I) ( 1–7 ) and 1-ethyl-3-(3-(trimethoxysilyl)propyl)-imidazolium halides (SEPIm·X) ( 8 , 9 ), were prepared and fully characterised. These hybrid materials are very active catalysts under mild reaction conditions (low temperature and atmospheric pressure or adsorbed CO 2 ). Under the optimal reaction conditions (S = 3.34 mmol, cat/S = 0.50, P CO2 = 5 bar, T = 80 °C), the best SILP system yields maximum conversion in just 30 min and can be reused at least five times without a noticeable decrease in activity and selectivity. The catalytic system is also active when using a CO 2 gas mixture from an industrial exhaust in both batch and continuous flow systems. A detailed structural and electronic analysis indicates that increasing the IL and water concentrations induces a solvation effect through the contact ion pair of the IL that drives the anions (Cl, Br and I) to the deeper regions of the confined space of SiO 2 . The catalytic performance is directly related to the presence of the nucleophilic Br anion on the outermost exposed layer of the hybrid material.
•Fuel-saving effect of ORC-WHR facilities on trucks are comprehensively evaluated.•Fuel-saving effect degradation due to existing components’ limitations is examined.•Fuel-saving effect degradation ...due to interactions in system integration is studied.•Effects of system dynamics and control strategies are explored.•It is suggested the system power density should be greater than 70 W/kg.
Recovering and converting the waste heat within the exhaust gas of high-density diesel engines to mechanical or electrical energy using an organic Rankine cycle is a hotspot in recent years, and many optimistic views towards the fuel-saving capacity of this technology have been reported. But considering the off-the-shelf components’ limitations, system integration, dynamics, and other attached penalties, there lacks a comprehensive evaluation yet, especially in driving cycle scenarios. For this, a heavy truck co-simulation platform is built, embedded with organic-Rankine-cycle-based exhaust heat recovery models. Based on that the fuel-saving performance of organic Rankine cycle facilities are evaluated and main losses due to limiting factors are also discussed. It is found that an ideal subcritical organic Rankine cycle system improves the truck’s fuel economy by 4.48–7.52% when it is fully loaded. But due to the performance limitations of existing components and system interactions, the fuel-saving effect is reduced from 7.52% to 3.5%. Further considering organic Rankine cycle system dynamics and control operations, this value degrades to 2.07–2.24%, and it continues to decline with the attached weight. It is suggested that the system power density should be greater than 70 W/kg at least. At this point, its fuel-saving effect is just 1.75%.
Providing the population with high-quality drinking water is one of the main state tasks. Rural water supply systems and water supply systems of small settlements in the region require special ...attention, namely, the development of technologies for individual, small-sized water treatment equipment, as well as equipment for collective use, designed to purify groundwater for drinking purposes. In many areas, there are groundwaters containing excess levels of several pollutants, which makes their purification much more difficult. Elimination of shortcomings in the known methods of water iron removal is possible by reconstructing existing water supply systems from underground sources in small settlements. A rational solution is to search for groundwater treatment technologies that make it possible to provide the population with high-quality drinking water at a lower cost. The result of increasing the concentration of oxygen in water was obtained in the process of modifying the filter by changing the excess air exhaust system, which was made in the form of a perforated pipeline located in the lower half of the granular filter layer connected to the upper branch pipe. At the same time, high-quality groundwater treatment, sufficient simplicity and reliability in operation are ensured, local conditions and the inaccessibility of many objects and settlements in the region are taken into account as much as possible. After the filter was upgraded, the concentration of iron decreased from 4.4 to 0.27 mg/L and ammonium nitrogen from 3.5 to 1.5 mg/L.
The Organic Rankine Cycle (ORC) is a thermal engine, which is used to convert low temperature heat to electrical power using organic working fluids. It is an established technique for waste heat ...recovery and for the utilization of renewable heat. This study presents a novel operational strategy of an ORC, which allows for reliable control of process parameters while simultaneously ensuring high power output. Preheated liquid working fluid is injected directly into a volumetric screw expander at an intermediate pressure level. The injected mass flow bypasses the evaporator and can be controlled by a valve. Thus, direct liquid injection into the expander reduces the exhaust temperature, leading to a lower risk of thermal damages in case of a hermetic or semi-hermetic expander. This strategy is analyzed experimentally and compared with a system simulation. The experimental and simulation results show that the exhaust vapor temperature can be reduced by approx. 40 K for the investigated operational conditions. This enables the expander to run at higher live vapor conditions by simultaneously ensuring sufficient cooling of the generator and thus allows for up to 40% higher power production depending on the operational conditions.
•Analysis of direct liquid injection (DLI) into a twin-screw expander.•The DLI is able to reduce the exhaust vapor temperature by up to 40 K.•Reduced exhaust vapor temperature enables operation with higher live vapor states.•Increased live vapor state, can lead to up to 40% higher power production.
PDF
