Development and verification of an in-flow water condensation model for 3D-CFD simulations of humid air streams mixing

In recent years, many engine manufacturers have turned to downsizing and boosting of gasoline engines in order to meet the ever more stringent fuel economy and emissions regulations. With an increase in the number of turbocharged gasoline engines, solutions are required to manage knock under a range of operating conditions. The charge air cooler has been introduced to mitigate knock. Moreover, the engine is required to operate with spark retard and/or boost reduction to provide knock reduction leading to reduced fuel economy. Under some operating conditions water can condense in the charge air cooler (CAC). Corrugated plate separators have been widely used in gas-water separation and oil-water separation in many industries including marine diesel engines. However, this sort of separator has not been applied to gasoline engines in vehicles to separate the condensation in the charged air. In this paper, a 1-D condensation model to estimate the potential amount of water condensation and entrainment from the charge air coolers is presented. An approach to designing a unit to separate condensation in the flow from the charge air cooler while maintaining a low pressure drop is described. The design approach provides correlations of separator geometries versus separation and pressure drop performance. The study is developed using a 3-D computational model for analyzing charge air and condensation flow. The model results of the 1-D condensation model and the 3-D computational model have been validated by experiments on an engine-dynamometer based test cell. The set-up incorporates a 4 cylinder gasoline direct injection (GDI) turbocharged engine. An air-to-air charge air cooler is mounted under the engine. The intake air for the engine is supplied using a combustion air unit which enables the operators to control the temperature and humidity. Test conditions have been identified to demonstrate the phenomenon of CAC water condensation. Measurements of water condensation and motion through the system confirm the results of models. A separator has been designed that achieves high separation efficiency and low pressure drop.

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Accurate measurements of carbon monoxide in humid air using the cavity ring-down spectroscopy (CRDS) technique

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-5-6493-2012 ◽

2012 ◽

Vol 5 (5) ◽

pp. 6493-6517 ◽

Cited By ~ 4

Author(s):

H. Chen ◽

A. Karion ◽

C. W. Rella ◽

J. Winderlich ◽

C. Gerbig ◽

...

Keyword(s):

Carbon Monoxide ◽

Water Vapor ◽

Near Infrared ◽

Infrared Region ◽

Humid Air ◽

Cavity Ring Down Spectroscopy ◽

Carbon Dioxide Co2 ◽

Air Streams ◽

Line Interference ◽

Cavity Ring Down

Abstract. Accurate measurements of carbon monoxide (CO) in humid air have been made using the cavity ring-down spectroscopy (CRDS) technique. The measurements of CO mole fractions are determined from the strength of its spectral absorption in the near infrared region (∼1.57 μm) after removing interferences from adjacent carbon dioxide (CO2) and water vapor (H2O) absorption lines. Water correction functions that account for the dilution and pressure-broadening effects as well as absorption line interferences from adjacent CO2 and H2O lines have been derived for CO2 mole fractions between 360–390 ppm. The line interference corrections are independent of CO mole fractions. The dependence of the line interference correction on CO2 abundance is estimated to be approximately −0.3 ppb/100 ppm CO2 for dry mole fractions of CO. Comparisons of water correction functions from different analyzers of the same type show significant differences, making it necessary to perform instrument-specific water tests for each individual analyzer. The CRDS analyzer was flown on an aircraft in Alaska from April to November in 2011, and the accuracy of the CO measurements by the CRDS analyzer has been validated against discrete NOAA/ESRL flask sample measurements made on board the same aircraft, with a mean difference between integrated in situ and flask measurements of −0.6 ppb and a standard deviation of 2.8 ppb. Preliminary testing of CRDS instrumentation that employs new spectroscopic analysis (available since the beginning of 2012) indicates a smaller water vapor dependence than the models discussed here, but more work is necessary to fully validate the performance. The CRDS technique provides an accurate and low-maintenance method of monitoring the atmospheric dry mole fractions of CO in humid air streams.

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Preconditioning Method for Very-Slow Flows With Heterogeneous Condensation in a Mixing T-Junction Channel

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2005-77073 ◽

2005 ◽

Author(s):

Kei Sakakura ◽

Yasuhiro Sasao ◽

Satoru Yamamoto

Keyword(s):

Industrial Processes ◽

Jet Flows ◽

Wall Jet ◽

Moist Air ◽

Flow Problems ◽

Heterogeneous Condensation ◽

Slow Flows ◽

Preconditioning Method ◽

Condensation Model ◽

Air Streams

The purpose of this study is to develop a numerical method for simulating condensate flow problems observed in industrial processes. The preconditioning method developed by our group is applied to the calculations of very-slow flows assuming heterogeneous condensation in a mixing T-junction channel which dry and moist air streams flowing into the channel are mixed together. A classical condensation model simplified by our group is used for evaluating condensation with heterogeneous nucleation. As shown in the calculated results, condensation in a T-junction pipe was variously influenced by the mixing type, such as stratified, turned jet, and wall jet flows. A notable difference in temperature distributions was also found with and without condensation due to the release of latent heat when condensation occurs.

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