An attempt has been made to arrive at a better characterizing dimensionless group for steady isothermal ow of Newtonian uids in helically coiled circular tubes. Pressure drop versus ow rate data has been experimentally obtained for helical coils made from thick-walled polyethylene tubing. Generalized pressure drop correlations have been developed in terms of Euler number, Eu, Reynolds number, Re, and the obtained geometrical group, G rhc = (d 0:85 D 0:15 eq =Lc), where d is the inside diameter of the tube, Deq is the equivalent diameter which accounts for the torsion e ect, and Lc is the length of the coil. The Fanning friction factor for helical coil tube is found to depend on Reynolds number and a geometrical number, d=D eq , separately both, and not by a dimensionless number obtained by any combination of Reynolds number and some geometrical number as is the case of Dean number, De = Re √ (d=D), where D is the diameter of the coil. There exist four regimes of ow for the ow through helical-coiled circular tubes. The obtained pressure drop correlations are simple to use.

As the need for petroleum products is increasing, it has led to increased crude oil prices. For an alternative approach, much research has been done in the field of catalytic conversion of methanol-to-hydrocarbon (MTH). The MTH process is suitable, which converts methanol directly into gasoline and other valuable hydrocarbons. The review provides information about methanol to olefins (MTO), methanol to aromatics (MTA), and MTH processes involved in converting oxygenates into hydrocarbons and information regarding methanol synthesis. It reviews the effect of physicochemical properties such as acidity, pore diameter, surface area, the catalyst’s lifetime, and process conditions on MTH transformation. The article shows different methods that are employed to change the zeolite’s acidic properties. These methods include acidic, alkaline, and steam heat treatment, which are also discussed. The results obtained after catalytic cracking of methanol were also validated by using several kinetic models proposed worldwide.

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A fuel with parameters such as high energy density, lower viscosity, and freezing point is desirable to be used in missile aircrafts jets at higher altitudes. In this regard, exotetrahydrodicyclopentadiene, a major constituent of JP-10 fuel, has ideal properties to be used as missile fuel and can be produced from its endoisomeric form known as endotetrahydrodicyclopentadiene. Dicyclopentadiene is used as a feedstock to produce endo or exotetrahydrodicyclopentadiene either in one or two steps. This brief review is a compilation of the research so far, conducted by various research groups, and provides knowledge on the dicyclopentadiene transformation to endo and exotetrahydrodicyclopentadiene over various hydrogenation−isomerization catalysts at various reaction conditions. The role of the catalyst and its deactivation is discussed, and the use of a catalytic reactor is also mentioned.