1,721,096 research outputs found
Numerical comparison of performance between traditional and alternative jet fans in tiled tunnel in emergency ventilation
No full textIn this paper a computational study was carried out to evaluate the performance of longitudinal ventilation
system equipped with an alternative jet fan with respect to traditional one in case of fire in tiled tunnel.
The alternative jet fan is equipped with inclined silencers (pitch angle a = 6) in order to reduce the
Coanda effect and consequently shear stress on the tunnel ceiling. The fire was simulated setting heat flux
on HGV surface. Computational fluid dynamic analysis was applied to simulate the ventilation in the unidirectional
tunnel through j–e model. The comparison conducted in terms of total thrust required to prevent
back-layering phenomena and numerical results were provided in terms of thrust of jet fan values,
average velocity values and temperature profiles, for different tunnel slope values. Furthermore the
authors have compared the critical velocity provided by CFD analysis with critical velocity provided in
the literature
The selective deficiency of immunoglobulin A: epidemiological, pathogenetic, clinical, therapeutic and medicolegal considerations
No full text
Assessment of domestic diaphragm gas meter service lifetime
No full textIn this paper are presented the experimental results of exhaustive metrological analysis aimed to correlate the percentage measurement errors performed by G4 diaphragm domestic gas meters and their in-service time period (service lifetime). The results are referred to diaphragm gas meters, with synthetic membrane (rubber-on-cloth), used for domestic metering (for cooking use only, or for both heating and cooking uses). The assessment of the average errors allows to obtain useful relations and indications in order to determine the “Operating Mean Lifetime” (OML) of this type of gas meters
A comparison among the new domestic smart static gas meters
No full textThis paper presents a comprehensive survey of the new emerging smart static gas measurement technologies that are available on the market today. New generations of thermal mass gas meters and ultrasonic gas meters for domestic (residential) applications have been studied and calibrated, by means of a traceable and accredited metrological laboratory. The main results of an experimental intercomparison among three different static gas meters are illustrated
Measurement of the compressed natural gas in automative application: a comparitive analysis between mass versus volumetric metering methods
No full textAlternative Gaseous Fuels are not new, but the fuel metering systems have become very sophisticated in order to control the flow of several products, such as Compressed Natural Gas (CNG), Liquefied Natural Gas (LNG), Liquefied Petroleum Gas (LPG), Hydrogen, Methanol and others. Alternative fuels and vehicles are now quite widespread, since they reduce emissions and dependence on foreign oil/energy supplies. In particular, CNG is currently being measured by means of a volumetric method when natural gas is supplied to a petrol pump, while is measured by a mass method when the gas is loaded into the vehicles. These different metering approaches can cause misalignments between the two metering systems, thereby causing arguments and disputes. In this paper, a metrological comparison between the two alternative CNG measurement approaches (volumetric vs. mass flow metering) is carried out.
In order to show and to stress the inconsistencies connected to these different measuring methods, the main results of a case study are presented and illustrated
- …
