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Pipe Diameter (pipe + diameter)

Distribution by Scientific Domains

Chemistry	80%

Selected Abstracts

Parametric studies for heating performance of an earth to air heat exchanger coupled with a greenhouse

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 11 2005
M. K. Ghosal
Abstract A thermal model has been developed to investigate the potential of using the stored thermal energy of the ground for greenhouse heating with the help of an earth to air heat exchanger (EAHE) system integrated with the greenhouse located in the premises of IIT, Delhi, India. Experiments were conducted extensively during the winter period from November 2002 to March 2003, but the model developed was validated against the clear and sunny days. Parametric studies performed for EAHE coupled with the greenhouse illustrate the effects of buried pipe length, pipe diameter, mass flow rate of air, depth of ground and soil types on greenhouse air temperatures. Temperatures of greenhouse air with the experimental parameters of EAHE were found to be on an average 7,8°C more in the winter than the same greenhouse without EAHE. Greenhouse air temperatures increase in the winter with increasing pipe length, decreasing pipe diameter, decreasing mass flow rate of flowing air inside buried pipe and increasing depth of ground up to 4 m. Predicted and measured values of greenhouse air temperature, which were verified in terms of root mean square of percent deviation and correlation coefficient, exhibited fair agreement. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Dynamics of particles suspended in a yield stress fluid flowing in a pipe

AICHE JOURNAL, Issue 5 2008
Othmane Merkak
Abstract This study seeks to understand the basic mechanisms governing the dynamics of a solid particle in a Poiseuille flow field of a viscoplastic fluid. An experimental set-up to create flows with a prescribed flow rate and enable the particles to be visualized in three dimensions was designed and validated. The absence of slip at the interfaces between flows and particles was characterized. The Reynolds numbers are low, gravity effects negligible and plastic effects significant. The ratio of pipe diameter to particle diameter is 8. The dynamics of a particle in a velocity field depends strongly on its position in the sheared wall zone or in the moving rigid zone. The effect of rigid and sheared zones on particle behavior was examined. Changes in particle translation and rotation velocities were quantified. © 2008 American Institute of Chemical Engineers AIChE J, 2008 [source]

Mesomixing in semi-batch reaction crystallization and influence of reactor size

AICHE JOURNAL, Issue 12 2004
Marika Torbacke
Abstract Experiments on semibatch reaction crystallization of benzoic acid are reported, in which hydrochloric acid was fed into an agitated solution of sodium benzoate. The influence of mixing and the influence of reactor size are examined on the product crystal mean size. The product mean size increases with increasing stirring rate and with decreasing feed rate. At low feed rates, the mean size increases at decreasing feed pipe diameter. At high feed rates the influence of the feed pipe diameter is more complex. Micromixing is of some importance in most experiments, but the rate of mesomixing especially governs the process. Mesomixing seems to be adequately described by the inertial-convective disintegration mechanism. In many aspects experimental results cannot be described by the turbulent-dispersion mechanism. The product mean size does not exhibit a clear dependence on reactor size, but depends more strongly on other parameters. Results from experiments from 1 L scale to 200 L scale can be correlated fairly well against a dimensionless number defined as the ratio of the total time of reactant feeding to the time constant of mixing. The best representation of the mixing time constant is obtained by making it directly proportional to the ratio of the feed pipe diameter and the linear velocity of the bulk flow passing the feed pipe. The proportionality constant can be calculated from turbulence data over the bulk flow at the feed point. © 2004 American Institute of Chemical Engineers AIChE J, 50: 3107,3119, 2004 [source]

Deflagration and detonation of ethylene oxide vapor in pipelines

PROCESS SAFETY PROGRESS, Issue 3 2000
Paul Thibault
Pure ethylene oxide (EO) vapor may propagate decomposition flames through pipe above certain minimum conditions of temperature, pressure and pipe diameter. Flame propagation was studied in both closed and vented 5 cm (2-inch) pipe and closed 30 cm (12-inch) pipe. Flame progression in closed pipe was irregular and proceeded in pulsed stages. A possible mechanism involves preferential flame propagation at the pipe roof accompanied by periodic autodecomposition of EO accumulated in hot products behind the flame front, such accumulation probably being augmented by liquid EO condensed on the pipe walls ahead of the expanding flame system. Flames propagated 15 m (50 ft) through horizontal 5 cm pipe at 70°C and initial pressures , 4.3 bar (62 psia). In a series of 30 cm pipe tests employing low-energy ignition and otherwise increasingly severe conditions, a deflagration-to-detonation transition (DDT) occurred, partially destroying the test equipment. A new test facility was set up to confirm the ability of EO to propagate detonations in 30 cm pipe and to further investigate the phenomenon. Two EO detonations at 2.9 bar and one at 3.5 bar were directly initiated via the strong shocks from hydrogen-oxygen detonations. Based on a spectrum analysis of the pressure histories, the two detonations at 2.9 bar were probably marginal and propagated in a single spin detonation mode. At 3.5 bar, the pressure history suggests that the detonation propagated in a two-head detonation mode near the end of the 24 m test section. [source]

Effect of various parameters on the solid circulation rate in a liquid,solid circulating fluidized bed

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2008
P. Natarajan
Abstract A liquid,solid circulating fluidized bed (LSCFB) is operated at high liquid velocity, where particle entrainment is highly significant, and between the conventional liquid fluidized bed and the dilute-phase liquid transport regimes. In the present work, systematic experiments were carried out in a 0.094 m i.d. and 2.4 m height laboratory-scale LSCFB apparatus by using various solid particles and tap water as fluidizing medium to study the hydrodynamics. The effects of operating parameters, i.e. primary liquid flow rate in the riser (jf), auxiliary liquid flow rate (ja), total liquid flow rate (jl), particle density (,s), particle diameter (dp) and solid feed pipe diameter (do) on the solid circulation rate were analyzed from the experimental data. Finally, a correlation was developed from the experimental data to estimate solid velocity (solid circulation rate), and was compared with the present experimental and available data in the literature. They agree well with a maximum root mean-square (RMS) deviation of 12%. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd. [source]