Total pressure

About: Total pressure is a research topic. Over the lifetime, 5199 publications have been published within this topic receiving 66658 citations.

Toluene LIF at elevated temperatures: implications for fuel-air ratio measurements

Abstract: Toluene laser-induced fluorescence (LIF) was investigated for 266- and 248-nm excitation in the temp. range of 300-650 K in a nitrogen/oxygen bath gas of 1 bar total pressure with oxygen partial pressure in the range 0-400 mbar. Contrary to a popular assumption, the toluene LIF signal is not directly proportional to the fuel-air ratio (termed the FAR-LIF assumption) for many conditions relevant to reciprocating IC engines. With increasing temp., a higher oxygen partial pressure is required to justify the FAR-LIF assumption. The required oxygen pressure becomes unrealistic (>5 bar) for T>670 K at 266-nm excitation and for T>625 K at 248-nm excitation.

Kinetics of Char Gasification with CO2 under Regime II Conditions: Effects of Temperature, Reactant, and Total Pressure

Abstract: There are relatively few studies reported in the literature characterizing the kinetics of high-pressure, high-temperature char gasification reactions. Of particular interest to the application of kinetic data to gasification models are studies that provide links between reaction rate data relevant to high-temperature conditions, where some extent of pore diffusion limitation may apply, and lower-temperature, intrinsic gasification reactivity data. This work describes the effects of temperature, reactant partial pressure, and total pressure on the kinetics of the char−CO2 reaction under conditions where reactant diffusion through the pores of the reacting char has been shown to impact the overall conversion rate. A global nth-order rate equation was used to describe these kinetics, in particular, the effect of temperature (via the activation energy) and reactant pressure (via the reaction order). As expected, activation energies at high temperatures (≥∼1300 K) were consistently less than those obtained un...

Potential Vorticity in a Moist Atmosphere

Abstract: The potential vorticity principle for a nonhydrostatic, moist, precipitating atmosphere is derived. An appropriate generalization of the well-known (dry) Ertel potential vorticity is found to be P 5 r21(2 V1 = 3 u )· =ur, where r is the total density, consisting of the sum of the densities of dry air, airborne moisture (vapor and cloud condensate), and precipitation; u is the velocity of the dry air and airborne moisture; and ur 5 Tr is the virtual potential R /c aP a (p /p) 0 temperature, with Tr 5 p/(rRa) the virtual temperature, p the total pressure (the sum of the partial pressures of dry air and water vapor), p0 the constant reference pressure, Ra the gas constant for dry air, and cPa the specific heat at constant pressure for dry air. Since ur is a function of total density and total pressure only, its use as the thermodynamic variable in P leads to the annihilation of the solenoidal term, that is, =ur ·( =r 3 =p) 5 0. In the special case of an absolutely dry atmosphere, P reduces to the usual (dry) Ertel potential vorticity. For balanced flows, there exists an invertibility principle that determines the balanced mass and wind fields from the spatial distribution of P. It is the existence of this invertibility principle that makes P such a fundamentally important dynamical variable. In other words, P (in conjunction with the boundary conditions associated with the invertibility principle) carries all the essential dynamical information about the slowly evolving balanced part of the flow.