Hot Start Conditions Research Articles

Supervisory control of a heavy-duty diesel engine with an electrified waste heat recovery system

This paper presents an integrated energy and emission management strategy, called Integrated Powertrain Control (IPC), for an Euro-VI diesel engine with an electrified waste heat recovery system. This strategy optimizes the CO2–NOx trade-off by minimizing the operational costs associated with fuel consumption, AdBlue dosage, and active particulate filter regeneration, while satisfying the tailpipe emission constraints. For comparison purposes, the proposed control strategy is applied to different powertrain configurations: with and without waste heat recovery (WHR) system and a WHR system equipped with a battery for energy storage. The potential of each studied configuration is evaluated over the World Harmonized Transient Cycle for cold-start and hot-start conditions. In comparison to the existing Euro VI engine without WHR system, it is shown in simulations that the optimal IPC strategy with an electrified WHR system and battery provides an additional 3.5% CO2 emission reduction and 19% particulate matter reduction, while satisfying the NOx emission constraint.

Chemical composition and source of fine and nanoparticles from recent direct injection gasoline passenger cars: Effects of fuel and ambient temperature

Particle number, mass, and chemical compositions (i.e., elemental carbon (EC), organic carbon (OC), elements, ions, and organic species) of fine particles emitted from four of the recent direct injection spark ignition (DISI) gasoline passenger cars and a port fuel injection (PFI) gasoline passenger car were measured under Japanese official transient mode (JC08 mode). Total carbon (TC = EC + OC) dominated the particulate mass (90% on average). EC dominated the TC for both hot and cold start conditions. The EC/TC ratios were 0.72 for PFI and 0.88–1.0 (average = 0.92) for DISI vehicles. A size-resolved chemical analysis of a DISI car revealed that the major organic components were the C20–C28 hydrocarbons for both the accumulation-mode particles and nanoparticles. Contribution of engine oil was estimated to be 10–30% for organics and the sum of the measured elements. The remaining major fraction likely originated from gasoline fuel. Therefore, it is suggested that soot (EC) also mainly originated from the gasoline. In experiments using four fuels at three ambient temperatures, the emission factors of particulate mass were consistently higher with regular gasoline than with premium gasoline. This result suggest that the high content of less-volatile compounds in fuel increase particulate emissions. These results suggest that focusing on reducing fuel-derived EC in the production process of new cars would effectively reduce particulate emission from DISI cars.

Two-phase plate-fin heat exchanger modeling for waste heat recovery systems in diesel engines

This paper presents the modeling and model validation for a modular two-phase heat exchanger that recovers energy in heavy-duty diesel engines. The model is developed for temperature and vapor quality prediction and for control design of the waste heat recovery system. In the studied waste heat recovery system, energy is recovered from both the exhaust gas recirculation line and the main exhaust line. Due to the similar design of these two heat exchangers, only the exhaust gas recirculation heat exchanger model is presented in this paper. Based on mass and energy conservation principles, the model describes the dynamics of two-phase fluid flow. Compared to other studies, the model is able to capture multiple phase transitions along the fluid flow by combining finite difference approach with moving boundary approaches. The developed model has low computational complexity, which makes it suitable for control design and real-time implementation.To validate the model, experiments are performed on a state-of-the-art Euro-VI heavy-duty diesel engine equipped with the waste heat recovery system. Simulation results show good accuracy, over the complete engine operating range, with average error below 4%. This is demonstrated on transitions between stationary operating points and on a dynamic response to a standard world harmonized transient cycle for both cold-start and hot-start conditions.

Characterization of nitromethane emission from automotive exhaust

We carried out time-resolved experiments using a proton-transfer-reaction mass spectrometer and a chassis dynamometer to characterize nitromethane emission from automotive exhaust. We performed experiments under both cold-start and hot-start conditions, and determined the dependence of nitromethane emission on vehicle velocity and acceleration/deceleration as well as the effect of various types of exhaust-gas treatment system. We found that nitromethane emission was much lower from a gasoline car than from diesel trucks, probably due to the reduction function of the three-way catalyst of the gasoline car. Diesel trucks without a NOx reduction catalyst using hydrocarbons produced high emissions of nitromethane, with emission factors generally increasing with increasing acceleration at low vehicle velocities.

Towards a Transient Simulation of Thermo-Acoustic Engines Using an Electrical Analogy

An electrical analogue of a looped-tube, thermoacoustic engine is presented and simulated using a graphical input, off-the-shelf network analysis tool called Tina™. The analyses are able to show both transient and non-linear behaviour. The recently documented phenomenon from the Score-Stove project of amplitude modulation of the pressure wave, called squegging has been simulated. By use of elements such as Zener diodes to simulate turbulent behaviour, non-linear effects can be seen. Thus the simulation shows the effect of many frequencies, not just the fundamental as is the case with conventional thermoacoustic simulations. Gradual cold start-up, and hot start conditions and a simple technique to ensure mathematical convergence on a non-zero solution are presented.

Mutagenicity assessment of aerosols in emissions from wood combustion in Portugal

Polycyclic aromatic hydrocarbon (PAH) extracts of fine particles (PM2.5) collected from combustion of seven wood species and briquettes were tested for mutagenic activities using Ames test with Salmonella typhimurium TA98 and TA100. The woods were Pinus pinaster (maritime pine), Eucalyptus globulus (eucalypt), Quercus suber (cork oak), Acacia longifolia (golden wattle), Quercus faginea (Portuguese oak), Olea europea (olive), and Quercus ilex rotundifolia (Holm oak). Burning experiments were done using woodstove and fireplace, hot start and cold start conditions. A mutagenic response was recorded for all species except golden wattle, maritime pine, and briquettes. The mutagenic extracts were not correlated with high emission factors of carcinogenic PAHs. These extracts were obtained both from two burning appliances and start-up conditions. However, fireplace seemed to favour the occurrence of mutagenic emissions. The negative result recorded for golden wattle was interesting, in an ecological point of view, since after confirmation, this invasive species, can be recommended for domestic use.

Experimental Analysis of Exhaust Emissions from Transit Buses Fuelled with Biodiesel

This paper presents a real life data set that incorporates results from a Toledo Area Regional Transit Authority (TARTA) biodiesel project. The research is carried out to study the effect of biodiesel on the exhaust emissions from the public transport buses. A comprehensive exhaust emission testing protocol is developed to identify the emission variations of transit buses fuelled with blends of biodiesel under different operating modes. The study is divided into two groups: real-world on-road emission and idle-engine emission testing. Exhaust emissions of oxygen (O2), carbon monoxide (CO), sulfur dioxide (SO2), oxides of nitrogen (NOx), and carbon dioxide (CO2) have been reported in this study. The effects of biodiesel on vehicular emissions vary from pollutant to pollutant and are primarily dependent on engine characteristics and the concentration of biodiesel in the base fuel. The lower emissions are observed during the on-road test mode of CO, CO2, and SO2, with the increase in percentage of biodiesel in the base fuel. On the contrast, idle-engine emissions, except CO2, increase with the increase in percentage of biodiesel in the fuel. The emissions of NOx, SO2, and CO2 during cold-start are observed to be higher than that of the hot-start conditions.

Specificity-Enhanced Hot-Start PCR: Addition of Double-Stranded DNA Fragments Adapted to the Annealing Temperature

A new method to produce hot-start conditions in PCR is described. Short double-stranded DNA fragments were found to inhibit the activity of DNA polymerases from Thermus aquaticus and Thermus flavus. This inhibition is not sequence specific, but exclusively dependent on the melting temperature of the fragments as shown by its correlation to their melting curves as measured. This property is exploited by adding fragments of the appropriate length to the PCR mixture during the reaction setup and thereby preventing the DNA polymerases from extending primers annealed nonspecifically at lower than the optimal temperature. By amplifying ten copies of phage lambda DNA in the presence of 2 micrograms of nonspecific DNA, it is shown for three different primer pairs how the melting temperatures of the double-stranded DNA fragments have to be adapted to the cycle profiles to obtain predominantly specific products in the 0.5 microgram range.

Condiciones de desarrollo de un programa de reacción en cadena de la polimerasa-transcriptasa reversa para el estadiaje molecular del cáncer de próstata

ObjectiveTo determine accurately the conditions for the development of tests using RT-PCR for PSA in patients with prostate cancer. MethodGen amplification of PSA in cultures of the human prostate tumoral cell line LNCaP with RTPCR under hot-start conditions, and verification through enzyme restriction digestion of the PCR product. Also, calculation of the PCR test limit of detection through serial dilutions of LNCaP cells in peripheral blood mononucleate cells. ResultsA highly specific, easy to perform, reproducible RT-PCR protocol has been developed. The lowest limit of detection reached was 1 PSA synthesising cell per 106 peripheral blood mononucleate cells. ConclusionsRT-PCR is a highly sensitive technique that allows detection of small numbers of PSA producing cells in peripheral blood. This experience allows to establish with precision the conditions for the development of RT-PCR tests for PSA.

Detection of circulating prostate cells by reverse transcriptase-polymerase chain reaction of human glandular kallikrein (hK2) and prostate-specific antigen (PSA) Messages

Objectives To investigate the clinical value of human glandular kallikrein (hK2) reverse transcriptase-polymerase chain reaction (RT-PCR) for detection of prostate cells in circulation and to compare the results with those obtained from prostate-specific antigen (PSA) RT-PCR. Methods We examined peripheral blood (PB) and bone marrow (BM) samples of 13 patients with advanced-stage prostate cancer and 63 patients with clinically localized disease for the presence of circulating prostate cells. An RT-PCR protocol with a two-step amplification cycle and hot-start conditions was used. Results The limit of detection of the PCR portion is similar for PSA and hK2 (5 to 10 copies of the plasmid containing the cDNA). The RT-PCR limit of detection is one LNCaP cell in 10 8 peripheral blood mononuclear cells (PMBC) for PSA, and one LNCaP cell in 10 7 PMBC for hK2. Of the BM samples obtained prior to radical prostatectomy, 71.4% were positive for PSA mRNA and 41.3% were positive for hK2 mRNA. In PB, the PSA positivity was 19% and hK2 positivity 12.7%. In advanced-stage patients, there were 76.9% PSA-positive samples in BM versus 38.5% hK2-positive samples; 46.2% of patients were positive in PB for PSA versus 30.8% for hK2. Conclusions We have developed a sensitive RT-PCR protocol for detection of hK2 mRNA and evaluated the suitability of hK2 mRNA in comparison with PSA mRNA as an additional marker for detection of prostate cells in circulation. Combining results of these two tests increased the sensitivity of detection. UROLOGY

A solar cooker using vacuum-tube collectors with integrated heat pipes

A solar cooking system is described which consists of a vacuum-tube collector with integrated long heat pipes directly leading to the oven plate. The cooker was tested during several clear days in Marburg (latitude 51°). The heat-up times were measured under cold- and hot-start conditions. Detailed temperature distributions and their time dependences were measured. The maximum temperature obtained in a pot containing 51 of edible oil was 252°C.

Impact des conditions de conduite sur l'efficacite des pots catalytiques de véhicules a essence et diésel

Various driving conditions determine major changes in IC-engined vehicles polluting emissions. The generalized use of three-way catalysts on gasoline-engined vehicles and, in the near future, oxidation catalysts on diesel-engined vehicles, is likely to enable the control of such changes. Thus, the influence of driving conditions on the efficiency of such devices was studied in a research program proposed by RENAULT and carried out in collaboration with LHVP and UTAC. This study was performed using a chassis dynamometer with the measurement of both regulated (CO, HC, NOx) and some non-regulated pollutants (sulphur oxides, aldehydes, monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, nitrated or otherwise). Simultaneously, the mutagenous properties of such emissions were assessed using the Ames test. Test vehicles were operated under urban cold or hot start conditions (a sub-unit of the European cycle) and under extra-urban hot start conditions( another sub-unit of the European cycle). For the two engine types, the extra-urban cycle raises catalyst efficiency to a maximum: >95% for gasoline cars and ∼ 90% for organic compounds of diesel cars. Conversely, for cold start in the urban cycle, the catalyst-related decrease in pollution levels is less significant. It is of the order of 85% for gasoline-engined vehicles and <40% for diesel-engined vehicles. Finally, for the hot urban cycle, the performances of the catalysts installed on gasoline-engined vehicles are similar to those obtained for the extra-urban cycle. But with diesel-engined vehicles, the efficiency of such a device is close to that obtained for cold conditions. Catalytic post-combustion seems to be an efficient system for reducing the mutageneous effect of emissions, in particular on diesel-engined vehicles.

Evolution des émissions de polluants des voitures particulières lors du départ à froid

Evolution of pollutant emissions from passenger cars under cold start conditions. CO, CO2, HC, CH4, NOx and N2O emissions were measured on ten conventional petrol-engined passenger cars, ten vehicles equipped with a three-way catalyst, and five diesel-engined vehicles over a great number of driving cycles under hot or cold start conditions: two standardized European and American cycles, four hot cycles representative of real-world driving conditions, and three representative mini-cycles, which were repeated 15 times after a cold-start. Simultaneously, water and oil temperatures were measured to assess engine temperatures. The analysis of the results enabled the follow up of emission and temperature changes with time for various kinematic types. The limit of hot temperature, the duration of cold-start emissions (over about 6 km) and excess emission rates under cold start conditions could be thus determined. These parameters significantly vary a lot according to vehicle technology, driving behaviour and pollutant type. These results should allow an accurate modeling of excess emissions under cold start conditions.

Increased PCR sensitivity by using paraffin wax as a reaction mix overlay

The use of mineral oil as a reaction mix overlay in conventional PCR may lead to problems. In addition to more difficult handling, traces of mineral oil in amplicon suspensions have been shown to decrease the efficiency of post-PCR manipulations. Commercial alternatives aimed at resolving the problem more than double the cost of an amplification. This is an important drawback when dealing with a large number of clinical samples. The use of inexpensive paraffin wax as a reaction mix overlay eliminated problems associated with the presence of mineral oil while being more practical and safer in handling potentially contaminated clinical samples. Moreover, when used in conjunction with a modified hot start technique, the use of paraffin wax increased the specificity and sensitivity of PCR amplifications over mineral oil in similar hot start conditions. Using the aforementioned method, the increase in specificity and sensitivity has enabled specific detection of viral DNA in clinical samples which the conventional PCR method failed to detect.