M.K. Kumaran

Moisture Diffusivity of Building Materials from Water Absorption Measurements

Moisture diffusivity is a transport property that is frequently used in the hygrothermal analysis of building envelope components. This property is de pendent on the local moisture content. The experiments that lead to the detailed in formation on the dependence of diffusivity on moisture content are often very so phisticated. However, two recent exercises, as a part of the activities of an International Energy Agency Annex, have shown that a correct estimate of the mag nitude of the moisture diffusivity can provide useful information with regard to its application in hygrothermal analysis. This technical note presents results from a sim ple moisture absorption measurement that led to a good estimate of the moisture diffusivity of building materials. Results from measurements on a sample of spruce are presented.

Excess enthalpies of decan-1-ol +n-pentane, +n-hexane, +n-heptane, +n-octane, +n-nonane, +n-decane, and +n-undecane at 298.15 K

Abstract Excess molar enthalpies H m E of (decan-1-ol + n -alkane) at 298.15 K are reported for the n -alkanes C 5 to C 11 . The H m E curves are skewed towards low mole fractions of alcohol and exhibit a regular progression in the values for the homologous series. Two methods of correlating the results are examined.

Excess enthalpies and excess volumes of each of the mixtures: (n-dodecane+an isomer of hexane) at 298.15 K☆

Abstract Calorimetric measurements of excess enthalpies and dilatometric measurements of excess volumes were carried out for each of the five mixtures: ( n -dodecane + an isomer of hexane) at 298.15 K. The Flory theory of mixtures provides a reasonable correlation of the results.

Moisture Transport Through Glass-Fibre Insulation in the Presence of a Thermal Gradient

A heat flow meter apparatus is used to monitor the heat flux across a moist speci men of a low density glass-fibre insulation. The results indicate that moisture is transported through the specimen predominately by vapour diffusion. A thermo dynamic model is suggested to represent the transport process. This model leads to two moisture transport coefficients characteristic of the specimen.

Thermal Performance of Sprayed Polyurethane Foam Insulation with Alternative Blowing Agents

A test methodology that uses thermal resistance-time curves deter mined on thin shces of the foam and the scaling technique to relate aging time to the specimen thickness, was applied to evaluate long-term thermal performance of six polyurethane foams manufactured with the same polymer but different blowing agents. The blowing agents employed were: CFC-11 with 0, 0 5, 1 0 or 1.5% water and HCFC-123 or HCFC-141b.

Excess enthalpies of binary mixtures of n-octane with each of the hexane isomers at 298.15 K☆

Abstract Excess molar enthalpies, measured at 298.15 K in a flow microcalorimeter, are reported for the five binary systems formed by mixing n-octane with n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane and 2,3-dimethylbutane. The results for equimolar mixtures, together with similar data for other n-alkane + hexane isomer mixtures, are correlated in terms of the acentric factors of the n-alkanes.

Ultrasonic speeds and isentropic compressibilities of n-heptane +each of the hexane isomers at 298.15 K

Abstract Measurements of ultrasonic speed were carried out for n-heptane + each of the five isomeric hexanes at 298.15 K. The results were combined with excess volumes reported previously to obtain isentropic compressibilities and excess isentropic compressibilities. Values of the latter are in reasonable agreement with estimates from the Flory theory of mixtures.

Limiting partial molar volumes of ethanol, propan-1-ol, butan-1-ol, pentan-1-ol, and hexan-1-ol in n-heptane at 298.15 K

Abstract Excess molar volumes of { x C A H 2 A +1 OH + (1− x )C 7 H 16 } have been measured for values of x less than about 0.04 by means of a specially designed tilting dilution dilatometer. Values of the limiting excess partial molar volumes V 1 E, ∞ , and thence of the limiting partial molar volumes V 1 ∞ , of the alcohols in n -heptane have been derived.

Thermodynamic properties for 2, 5, 8, 11-tetraoxadodecane + n-dodecane mixtures at 298.15 K

Abstract Flow calorimetric measurements of the excess molar enthalpy and excess molar isobaric heat capacity, dilatometric measurement of the excess molar volume, and pulse-echo-overlap determinations of the speed of sound were carried out over the whole composition range for mixtures of 2,5,8,11-tetraoxadodecane with n -dodecane at 298.15 K. The excess molar enthalpy and excess molar volume are positive at all mole fractions. The speed of sound shows negative deviations from linearity on a mole fraction basis. The excess molar isobaric heat capacity exhibits a maximum and two minima.

Excess enthalpies of some binary mixtures: (a C5-alkanol + n-heptane) at 298.15 K

Excess enthalpies, determined at 298.15 K in a flow microcalorimeter, are reported for n-heptane + each of the C5-alkanols: pentan-1-ol, cyclopentanol, and 2-methylbutan-2-ol. Results for dilute alkanol mixtures were obtained from measurements of enthalpies of dilution, and were used to estimate the limiting values of the excess partial molar enthalpies of the alkanols at infinite dilution.