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Experimental flow rate data are presented for saturated liquid, saturated vapor, and two-phase liquid-vapor carbon dioxide through a convergent nozzle and a square-edged orifice. The data cover the range from the triple-point pressure to the critical pressure. Charts have been prepared for this complete range at critical flow. Results are also presented for subcritical flow.The tests at various back pressures indicate that the saturated liquid behaved as a cold liquid without evaporation ahead of the throat.Saturated vapor became supersaturated in the nozzle, and the vapor behaved as if no condensation occurred.Equations are presented for the flow rates of saturated vapor, and two-phase mixtures in the critical flow region.A Mollier (pressure-enthalpy) diagram is used to determine the flow rates of saturated vapor and two-phase mixtures where supersaturation takes place. In these cases, the lines of constant specific volume or density are extrapolated from the superheated region into the normal two-phase region to obtain values corrected for supersaturation.flows through a pipeline, the drop in pressure, caused by.the flow friction loss, is accompanied by a drop in temperature, and the boiling or evaporation of the liquid to convert a fraction of it to vapor in order to maintain thermodynamic equilibrium. If the liquid is colder than the pipeline, the heat transferred to the liquid also causes the evaporation of part of the liquid. This formation of vapor results in a two-phase mixture of liquid and vapor. Such a flow of a two-phase mixture of liquid and vapor occurs when liquid carbon dioxide is used for fire extinguishing purposes or for industrial work such as cooling cold chambers or material which is being processed. HISTORICALThe flow of saturated liquid and satuCritical flow nozzles or orifices are used atmosphere. This investigation was rated vapor carbon dioxide through nozzles at a back pressure of 142 lb./ sq. in. abs. was recently investigated (10).in many cases to discharge two-phase carbon dioxide from piping systems to the undertaken in order to predict the effect of nozzle or orifice design and operating conditions on the f l o~ rate. The flow rates were determined by e v a p rating and metering, at low pressure, the carbon dioxide which \vaa discharged by the nozzle or orifice. The metering was done by orifice plates which werc calibrrttcd by weighing carbon dioxide.For water at room temperature the discharge coefficient of the nozzle was 1.00. BASIC EQUATIONSThe following are the basic equations used to compute the flow rates through an ideal nozzle for negligible appro:wli velocity C1 (22). For criticd flow, P2 = P,, U? = L7r, and V2 = VI. For subcritical flow, I', = Pa. SATURATED VAPORPrevious investigators have found that saturated stcam can flow through a nozzle or orificc in a supersaturated condition (4, 18, %).In this investigation it was found that saturated carbon dioxide vapor can flow through a nozzle or orifice in a supersaturrttetl condition. Khcn floiving in R supersaturated condit...

ARLIER studies of hydrocarbon pyrolysis (12, 14, 4 6 ) were E usually conducted at temperatures below 650" C. (1202" F.), or, when higher temperatures were used, at extremely short reaction times, t o obtain data suitable for kinetic interpretation. Because of the emphasis given to these relatively mild pyrolysis conditions, the interpretation of results generally stressed dissimilarity in the behavior of individual or groups of hydrocarbons. However, except in the production of acetylene, practical operating conditions for hydrocarbon pyrolysis fall in the temperature range of 1200" t o 2000" F. at reaction time well above 0.1 second.In this range of pyrolysis conditions the gaseous product distribution for most feed hydrocarbons other than methane shows a striking similarity, only slightly affected by the composition, structure, or molecular weight of the feed hydrocarbon when cracked at equivalent temperatures, reaction times, and partial pressures (14, 28).I n the first part of this study, empirical relationships for the prediction of gaseous product distribution are developed for a wide range of feed hydrocarbons by the use of a simple and general approach t o the analysis of the behavior of the complex gaseous reaction systems encountered in high-temperature, vapor-phase cracking. Pyrolysis data show similiar gaseous product distributionsPrevious studies have shown that hydrocarbons of equal carbon-hydrogen weight (C/H) ratio will yield approximately equal quantities of gas of similar composition (26-28, $3) independently of their molecular weight or structure as long as the severity of cracking is sufficient to eliminate the effects of the primary decornnosition reactions. The composition, although not the total yield, of the nongaseous products was shown to be affected by feed hydrocarbon properties other than carbon-hydrogen ratio because of the tendency of feed hydrocarbons of higher molecular weight t o form nongaseous cracking products through primary reactions-that is, those specific to the feed hydrocarbons, such as dehydrogenation, cyclization and dehydrocyclization, and polymerization.As illustrated in Table I, the influence of carbonhydrogen ratio on gaseous product distribution is small for natural gas liquids, and for petroleum and shale oils, so that only minor changes in cracking conditions will compensate for the tendency of hydrocarbons of higher carbon-hydrogen ratio to form gases of higher hydrogen content and higher paraffinolefin ratio (26, 28). This similarity in gaseous product distribution tends to be masked by the relatively slow rates of the primary cracking reactions for hydrocarbons of low molecular weight such as methane, ethane, and ethylene.From the data on pyrolysis obtained in this and earlier studies, any reaction schemes attempting t o interpret gaseous product distributions-by the assumption of dehydrogenation or carbon-carbon bond scission reactions specific to a given hydrocarbon (14, 38) did not appear applicable for reaction temperatures above 1300' F. and reaction ti...