Friction and heat

Relations for transport properties such as viscosity and thermal conductivity are also required if wall friction and heat-transfer effects are considered. 

The material, inside diameter (ID) and wall thickness are the three primary considerations in the selection of lines for a particular fluid power system. The ID of the line is important because it determines how much fluid can pass through the line without loss of power due to excessive friction and heat. The velocity of a given flow is less through a large opening than through a small opening. If the ID of the line is too small for flow, excessive turbulence and friction will cause unnecessary power loss and overheat the hydraulic fluid. 

Cope, W.F. Ptvc. Inst. Mech. Engrs. 45 (1941) 99. The friction and heat transmission coefficients of rough pipes. 

Theoretical solutions have been verified by many researchers for flow friction and heat transfer in a single channel. Hence, these results provide a valuable guideline for devices that may employ many such channels in parallel. However, passage-... 

Trinitrophenol can only be stored safely in the form of a paste with water. Lead, mercury, copper, zinc, iron and nickel salts are sensitive to impact, friction and heat. Sodium, ammonium and amine salts give rise to explosions. When it was poured on to a cement floor, trinitrophenol formed a calcium salt that detonated when it came into contact with shoes. Trinitrophenol salts in the form of moist paste are stable. Aluminium salt is not explosive, but combusts spontaneously when in contact with water. 

The mathematical model describing the two-phase dynamic system consists of modeling of the flow and description of its boundary conditions. The description of the flow is based on the conservation equations as well as constitutive laws. The latter define the properties of the system with a certain degree of idealization, simplification, or empiricism, such as equation of state, steam table, friction, and heat transfer correlations (see Sec. 3.4). A typical set of six conservation equations is discussed by Boure (1975), together with the number and nature of the necessary constitutive laws. With only a few general assumptions, these equations can be written, for a one-dimensional (z) flow of constant cross section, without injection or suction at the wall, as follows. 

Sabersky, R. H., and H. E. Mulligan, 1955, On the Relationship between Fluid Friction and Heat Transfer in Nucleate Boiling, Jet Propulsion 25(9) 12. (5)... 

Reputedly the most explosive substance known, it is very sensitive to impact, friction and heat. It is readily formed from ethanol and perchloric acid. 

Griesbaum, K. et al., J. Amer. Chem. Soc., 1976, 98, 2880 A friction- and heat-sensitive viscous liquid, it exploded violently during attempted injection into a gas chromatograph. 

It is sensitive to friction and heat, often deflagrating on gentle warming. 

Mixtures of thiocyanates with chlorates (or nitrates) are friction- and heat-sensitive, and explode on rubbing, heating to 400°C, or initiation by spark or flame [1]. A violent explosion occurred when a little chlorate was ground in a mortar contaminated with ammonium thiocyanate. A similar larger-scale explosion involving traces of barium thiocyanate is also described [2],... 

An explosion in flour-bleaching operations was attributed to violent decomposition of the basic nitrate [1], which is an impact-, friction- and heat-sensitive explosive [2]. The instability is associated with the presence of reducant and oxidant functions in the same molecule. The previous formulation as tin(II) nitrate oxide is revised to that above. 

Action of alkalies on diazonium solutions, or of acids on alkali diazoates to give a final pH of 5-6, causes these compounds ( diazoanhydrides ) to separate as oils or solids. Many of these are violently explosive (some exceeding nitrogen trichloride in effect), sensitive to friction and heat or contact with aromatic hydrocarbons [1,2], Individually indexed compounds are ... 

A variety of these compounds were prepared (R = CN, CONH2, Me, Ph). Not surprisingly they were explosives very sensitive to shock, friction and heat. They were inclined to distillation during distillation. 

The following discussion on influence of hot spots in initiation of explosion by impact friction and heat is given in Dunkle s Syllabi (Refs 22 26) ... 

Accdg to Ref 66, p 135> the usual way of treating shocks is to idealize them to jump discontinuities, in this way taking into account the> effect of the irreversible process caused by friction and heat conditions. It is assumed that the flow involving such a discontinuous process is completely determin ed by the three lawstof conservation of mass, momentum and energy and the condition that the entropy does not decrease in the discontinuous process. Outside of the transition zone the flow is determined by the differential eqs 2.1.1, 2.2.2 2.2.3 listed on p 132 of Ref 66... 

Accdg to Daniel (Ref 1), when a sola of platiriic oxide in sulfuric acid was treated with an excess of aq ammonia. a black ppt of pla-tine fulminant was obtd. When dry it detonated violently by shock, friction and heat (at 160°). Some scientists consider it. as being identical with the nitride (azoture, in Fr)... 

Silver Salt, AgC7HsN402 solid, extremely sensitive to impact, friction and heat Note Salts of dinitrobenzami dine were prepd as early as 1899 by Lossen Mierav (Ref 2), but the parent substance was not isolated until later... 

In general, NS Dynamites are less sensitive to shock, friction and heat than are corresponding NG Dynamites, and, therefore, are less hazardous when subjected to transportation and handling. Truckloads of NS Dynamites have undergone accidental burning without detonation, while NG Dynamites usually detonate under such conditions (Ref... 

In short lines, nozzles, and orifices, friction and heat transfer may be neglected, which makes the flow essentially isentropic. Work transfer also is negligible in such equipment. The resulting theory is a basis of design of nozzles that will generate high velocity gases for... 

It is to be expected that the kind of phase distribution will affect such phenomena as heat transfer and friction in pipelines. For the most part, however, these operations have not been correlated yet with flow patterns, and the majority of calculations of two-phase flow are made without reference to them. A partial exception is annular flow which tends to exist at high gas flow rates and has been studied in some detail from the point of view of friction and heat transfer. 

The final state of the products when friction and heat transfer are taken into account is naturally achieved when the products are fully braked and cooled to the temperature of the walls. 

A friction- and heat-sensitive viscous liquid, it exploded violently during attempted injection into a gas chromatograph. 

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