Specific heat of superheated ammonia vapor

Abstract

Measurements of the specific heat at constant pressure of superheated ammonia vapor were made within the range of temperature and pressure ordinarily used in refrigeration, namely, in the temperature interval -15 to +150°C . and at various pressures ranging from 0.5 to 20 atmospheres.Incidentally a few meas urements of the Joule-Thomson effect were made in order to evaluate certain small correction terms.The method employed is a familiar one in calorimetry, that of continuous flow combined with electric heating of the vapor. The principle of this method is to observe the rise in temperature produced by a measured electric power added as heat to a steady stream of vapor flowing through the instrument at a measured rate. ♦ A flow calorimeter, which was developed for the particular purpose of making these measurements on ammonia, is briefly described.

Thermodynamic properties of 1,3-butadiene in the solid, liquid, and vapor states

“…The true heat capacity, dQ/d T, is the limit of this fraction as AT approaches zero. This limit, dQ/dT=[(Jb, may be calculated from the finite measured quanti ties by means of a relation given by Osborne, Stimson, Sligh, and Cragoe [10] . (1) where AQ is the heat added, AT is the temperature rise, and Ta is the average temperature of the heating.…”

Thermal properties of aluminum oxide from 0 to 1200 K

“…, Because it has long been the custom in the applications of chemical thermo· dynamics to express energies in calories, it was recommended by the Eighth Calori metry Conference (at Chicago, Dlinolli, September [11][12]1953) ~he~' r~gularity in this tempera ture ran ge pr obably ]ustlfymg th e shor t extrapolation . In order t o m a k e t h e val ues of table 5 in ternally consis~ent, except for small discrepa n cies caused by roundmg, on e more significan t fig ure is given th an is justified by t h e accm acy of th e measurem en ts.…”

Calorimetric properties of diphenyl ether from 0-degrees to 570-degrees-K

“…Six serie of experiments were made on the empty container , and the temperature ranges wer e 13° Lo 35° K , 15° to 31° Ie, 28° to 60° K , 90° to 370° K , 50° to 119° K , and 279° to 342° K . Curvature correc tions were applied to thes~ measurement wh erever significant, using the r elatIOn gIven by 0 borne, et al [4] : (1) ZTon is the corrected heat capacity at the mean temperature, T"" of the interval Ll T; Q is the electrical energy added; and (o2Z/oT2)7' is the second derivative of the h eat capacity with ;espect to temperature at T",. The observed results (corrected for CUl'vature) were plotted on a large scale as deviations from an approximate empirical equation and a smooth curve was drawn through the deviation points.…”