An adiabatic calorimeter for the range 30-degrees-C to 500-degrees-C

Abstract

An adiabatic calor imeter accur ate t o 0.1 percent and suitable for heat capacity measurements of solids and liq uids over the the temper atur e range 39 0 to 500 0 C is d~scribed . Factors affecting the design and accuracy are di scussed. AutomatIc controls pen mt one-man operaion of the apparatus. Measurements of th.e heat capacity of ~1 203 agree to 0.1 percent with earlier measurements made with other calorI meters at the N atlOnal Bureau of Standard s.

Heat capacity of the reference material synthetic sapphire (α-Al2O3) at temperatures from 298.15 K to 1000 K by adiabatic calorimetry. Increased accuracy and precision through improved instrumentation and computer control

“…Figure 11 shows the deviation of the present experimental determinations from the recommended values, (4) as well as those by other authors. (5)(6)(7)(8)(25)(26)(27)(28)(29)(30)(31) Our earlier results (8) were obtained on IPTS-48. Recalculation of the heat capacities show that the change to ITS-90 implies a correction varying within 20.03 per cent in the region T = 300 K to T = 800 K. It decreases to −0.16 per cent at T = 860 K, −0.19 per cent at T = 900 K, −0.33 per cent at T = 950 K, and −0.40 per cent at T = 1000 K. These correction values differ slightly in the T = 300 K to T = 900 K FIGURE 7.…”

“…The results by West and Ginnings (7) were obtained with an approximately 120 g Calorimetry Conference sample in a stepwise heated adiabatic calorimeter, filled with CO 2 . Each value represented the mean of usually three determinations with standard deviation from (20.019 to 20.065) per cent.…”

“…(2) and by Ditmars et al (3) Only a few sets of experimental determinations for 298.15 K Q T Q 1000 K were included in the re-evaluation. (4) Those extending to significantly higher temperatures than 300 K are by Andrews et al (300 K Q T Q 548 K), (5) Inaba (70 K Q T Q 700 K), (6) West and Ginnings (312 K Q T Q 689 K), (7) Ditmars and Douglas (273 K Q T Q 1173 K), (2) and Ditmars et al (1173 K Q T Q 2257 K). (3) Hence, at temperatures above 700 K, only the dropcalorimetric determinations by Ditmars and Douglas (2) and by Ditmars et al (3) were considered.…”

Measurement of the relative enthalpy of pure a-Al2O3 (NBS heat capacity and enthalpy Standard Reference Material No. 720) from 273 to 1173 K

“…Th e mean heat ca pac it y va lu es ca lc ul a ted fro m th e prese nt e nth al py meas ure m e nts a t adj ace nt te mpe ra tures a nd co rrecte d fo r c ur vature (so li d circ les) s ho w a n ave rage devia ti o n of 0 .23 pe rce nt fr o m th e base lin e. Th e d ata of Martin a nd S nowd o n [1 8, 40J . whi c h co m p ri se 157 indi vidu al hea t ca pac iti es in th e ra nge 295 to 473 K a nd for whi c h th e a uth o rs claim 0.1 pe rce nt acc uracy, a re s ho wn in fi g ure 6 in their s moo th rep re s e nt a ti o n. The d ev ia ti o n of th ese heat capac it y d a ta of Ma rtin a nd S no wd o n fr o m th e N BS d a ta of ta bl e 4 (so li d c urv e) is less th a n 0.1 pe rce nt be lo w 330 K a nd s li g htl y more th a n 0 .1 pe r· ce nt above 330 K. [t is pre do min a ntl y pos itive but ca n ~+.66 be considered as being within the individual uncertainties of both sets of data_ The heat capacity data of West and Ginnings [16]. who used painstaking care to avoid heat-leak errors and to analyze all unavoidable errors.…”

Thermodynamic behaviour of polyethylene single crystals

“…13 The calorimeter vessel (a cylinder of chromium copper having many blind holes drilled in it parallel to the cylinder axis) could be sealed with a reduced pressure of helium inside by means of an O-ring and lid. 13 The calorimeter vessel (a cylinder of chromium copper having many blind holes drilled in it parallel to the cylinder axis) could be sealed with a reduced pressure of helium inside by means of an O-ring and lid.…”