Search Results

Recently, a particle number (PN) limit was introduced in the European light-duty vehicles legislation. The legislation requires measurement of PN, and particulate mass (PM), from the full dilution tunnel with constant volume sampling (CVS). Furthermore, PN measurements will be introduced in the next stage of the European Heavy-Duty regulation. Heavy-duty engine certification can be done either from the CVS or from a partial flow dilution system (PFDS). For research and development purposes, though, measurements are often conducted from the raw exhaust, thereby avoiding the high installation costs of CVS and PFDS. Although for legislative measurements requirements exist regarding sampling and transport of the aerosol sample, such requirements do not necessarily apply for raw exhaust measurements. Thus, measurement differences are often observed depending on where in the experimental set up sampling occurs.

Particulate emissions cause adverse health effects and for this reason they are regulated since the 80s. Vehicle regulations cover particulate emission measurements of a model before its sale, known as type approval or homologation. For heavy-duty engines the emissions are measured on an engine dynamometer with steady state points and transient cycles. For light-duty vehicles (i.e. the full power train) the particulate emissions are assessed on a chassis dynamometer. The measurement of particulate emissions is conducted either by diluting the whole exhaust in a dilution tunnel with constant volume sampling or by extracting a small proportional part of the exhaust gas and diluting it. Particulate emissions are measured by passing part of the diluted exhaust aerosol through a filter paper. The increase of the weight of the filter is used to calculate the particulate matter mass (PM) emissions.

In our previous studies, a novel NOx aftertreatment system using adsorption and reduction by nonthermal plasma desorption is proposed. In the present study, application of the system to a real stationary diesel engine generator is investigated. The NOx is first removed by adsorption, then the adsorbent is regenerated by thermal desorption using waste heat of the exhaust gas. In the regeneration process, hot exhaust gas passes through the heat exchanger tubes surrounded by the adsorbent pellets. The desorbed NOx is subsequently reduced to N2 by nitrogen nonthermal plasma. This system reduces 245 ∼ 270 ppm NOx emitted by the generator to around 50% for 8 hours.

The purpose of this study is to formulate the degree of postural instability in working based on the data acquisition of center of pressure (COP) and surface electromyography (EMG). In the previous studies [1]-[4], the limits to which we could move the COP such as the functional stability limits and the balance limits were obtained. In this study experiments were carried out for ten male subjects to measure the COP displacements and EMG signals of leg muscles when the subjects leaned as far as possible while taking every four brief pauses in four directions. As a result, it was found that the muscle load increased exponentially with the COP displacement. Therefore we considered that postural instability also increased exponentially with the COP displacement. Finally we formulated the degree of postural instability. By installing the formulation into a digital human model Jack (Siemens), proactive evaluation of working postural stability could be conducted.

Different particulate mass (PM) portable emission measurement systems (PEMS) were evaluated in the lab with three heavy-duty diesel engines which cover a wide range of particle emission levels. For the two engines without Diesel Particulate Filters (DPF) the proportional partial flow dilution systems SPC-472, OBS-TRPM, and micro-PSS measured 15% lower PM than the full dilution tunnel (CVS). The micro soot sensor (MSS), which measures soot in real time, measured 35% lower. For the DPF-equipped engine, where the emissions were in the order of 2 mg/kWh, the systems had differences from the CVS higher than 50%. For on-board testing a real-time sensor is necessary to convert the gravimetric (filter)-based PM to second-by-second mass emissions. The detection limit of the sensor, the particle property it measures (e.g., number, surface area or mass, volatiles or non-volatiles) and its calibration affect the estimated real-time mass emissions.

In order to evaluate the crashworthiness of impact energy absorbing parts for automobiles, it is very important to obtain accurate stress-strain (s-s) relationships for steel sheets under various strain rates. However, at high strain rates over 10/s, stress wave interference in the load cell obstructs precise measurement of the s-s relationship with conventional tensile testing equipment. Various new tensile testing machines have been developed to obtain accurate s-s relationships at high strain rates. Six of these machines (coaxial Split Hopkinson Pressure Bar method, Non-coaxial Split Hopkinson Pressure Bar method, One Bar method, Sensing Block Testing System, and two types using the Hydraulic Servo method) were used to obtain s-s relationships for high strength steel sheets. In this paper, the s-s relationships are compared and the characteristic of the curves was discussed.

The efficiency and output of commercial agricultural as it exists today is greatly influenced by natural environmental conditions. Production under a controlled environment such as a Vegetable Factory concept may be considered to overcome these problems. The Modular Growing Component Salad Machine (MGCSM), which was built in 1992, has recently undergone major design changes. Use of red and blue LEDs are being considered to replace high-pressure sodium (HPS) lamps. This modification can reduce mass, weight and energy consumption. If this growing system can be manufactured at an affordable cost to be used for profitable agricultural production on Earth for growing flavorful, pesticide free, healthier vegetables with minimal labor requirements.

In contrast to the well-established “standard” log-law wall function, the analytical wall function (AWF) as an advanced modelling approach has not been extensively used in the industrial computational fluid dynamics (CFD) applications. As the model was originally developed aiming at computations on relatively coarse meshes, potential stability issues may arise due to the pressure-gradient sensitivity if employing locally inappropriate mesh layers, typically associated with the complex geometry details. This work evaluates performance of the thermal AWF, as proposed by Suga [4], in conjunction with the main flow field computed employing the k-ζ-f turbulence model and the hybrid wall treatment (denoted as AWF-e) within the Reynolds-averaged Navier-Stokes (RANS) framework.

In this study, the effects of equivalence ratio and nitrogen dilution on laminar burning velocity were studied for propane/air/nitrogen mixtures. The stretched laminar burning velocity of mixtures was determined from the measured pressure histories in a constant volume spherical chamber. The effect of stretch rate on the laminar burning velocity was analyzed using linear and nonlinear methods. The laminar burning velocities of the diluted mixtures decreased with an increase in volume percent of nitrogen dilution. The laminar burning velocity of diluted mixtures was lower than that of lean mixtures in the same propane concentration.

The proposed Euro 7 emission standard foresees that the emission behaviour of Euro 7 vehicles is monitored via an on-board monitoring (OBM) system. In Euro 7 vehicles, OBM systems will monitor the emissions of nitrogen oxides (NOX), ammonia (NH3) and particulate matter (PM) for every trip through a combination of measured and modelled data. Sensors employed to support on-board diagnostics (OBD) in current vehicles may be used to support OBM. According to the Euro 7 OBM concept presented in this paper, OBM will serve a dual purpose: the first is to warn the user of a vehicle about the need to perform repairs on the engine or the pollution control systems when these are needed. If these repairs are not performed in a timely manner, the OBM system will be able to ultimately prevent engine restart, akin to the existing low-reagent driver warning system in some compression ignition vehicles. The second purpose of OBM is to monitor the compliance of vehicle types with the emission limits.