Part One
The thermal decomposition of n-butane was investigated in aflow reactor at a pressure of 1 atm, in a temperature range of460° to 560°C, and at low conversion levels, i.e. 0.06 - 0.68%for the 460° runs, 0.5 - 2.3% for the 510° runs, and 3.5 to8.2% for the 560°C runs. Temperature, velocity, and concentrationprofiles at the exit end of the reactor were measuredto study the effects of energy, momentum, and mass transportson chemical reaction. It was found after analysis of datathat the reactor could be treated as an isothermal reactorwith plug flow under the prevailing operating conditions.
Two rate expressions were determined for the reaction; onecorresponding to a first-order and the other to a second-orderrate. They are
First-order rate = 3.34 x 10^(12) e -54,600/RT(C_4H_(10)lb/ft^3 sec
Second-order rate = 2.55 x 10^(14)e-56,800/RT(C_4H_(10)^2lb/ft^3 sec
These two expressions equally well represent the experimentaldata.
On the basis of the products formed and the rates observed, aRice-type, free-radical mechanism was proposed for the thermaldecomposition of n-butane. The mechanism, which is presentedin the section on correlation of data, quantitatively describesthe reaction. One major feature of the mechanism is the considerationof secondary reactions at very low conversions.
Part Two
Flow of an incompressible fluid at the entrance section ofparallel plates under isothermal, laminar conditions was investigatedby solving the two-dimensional Navier-Stokesequations numerically. The Navier-Stokes equations were transformedinto finite-difference equations in terms of streamfunctions ψ and vorticities ω with a technique developed byde G. Allen. The finite-difference equations were thensolved by an iterative procedure on digital computers. Fromthe solution, point velocities and pressure gradients werecomputed.
Two cases were studied, both with a Reynolds number of 300.Case I had a flat velocity distribution at the entrance to theplates. Case II assumed that potential-flow conditions existedonly far upstream from the entrance. For both cases, largevelocity and pressure gradients were found near the leadingedges of the plates, although they were comparatively smallerin Case II. Also the velocity profiles for small distancesfrom the entrance were found to be slightly concave in thecentral portion between the plates.
Schlichting and others have solved the boundary layer equationfor Case I. Their solutions agree well with the present workat large distances from the entrance but deviate considerablynear the leading edges as the boundary-layer equation doesnot describe the behavior of fluid flow near singular points.
