This article develops an analytical model for heat and water vapor transfer in flat-slab and round-pipe thermal insulations. The model is validated by comparing its predictions with available experimental data. The effective thermal conductivity of the insulation in the presence of condensation depends on seven design and operating variables. The effect of these variables is determined by a parametric study. The effective thermal conductivity increases with decreasing cold surface temperature until condensation begins to occur in the slab and then decreases gradually. For practical operating conditions, the effective thermal conductivity varies from about 1 5 to 15 times the dry-state value The computed data arc prc sented in the form of design curves which may be used to estimate the effective ther mal conductivity for flat-slab and round-pipe insulation systems
Jespersen, H.B.1953. "Thermal Conductivity of Moisture Materials and Its Measurements,"J. Inst Heat Vent. Engrs., 1.216-222.
2.
Woodside, W.1958"Probe for Thermal Conductivity Measurements of Dry and Moist Materials,"Heat Pipe. Air Cond , 30:163-170.
3.
Joy, F.A.1957"Symposium on Thermal Conductivity Measurements and Applications of Thermal Insulations," ASTM STP 217 , pp. 65-80.
4.
Bomberg, M. and C.J. Shirtliffe1978. "Influence of Moisture Gradients on Heat Transfer through Porous Building Materials, Thermal Transmission Mcasurcmcnt of Insulation," ASTM STP 660, R. P. Tyc, ed., American Society for Testing and Materials, pp. 211-233.
5.
Langlais, L.C. , M. Hydrien and S. Klarsfeld1983. "Influence of Moisture on Heat Transfer through Fibrous Insulating Materials, Thermal Insulation, Materials and Systems for Energy Conservation in the 80's," ASTM STP 789, F. A. Govan, D. M. Greason and J. D. McAllister, cds., American Society for Testing and Materials, pp. 563-581.
6.
Langlais, C. and S. Klarsfeld.1984. "Heat and Mass Transfer in Fibrous Insulation,"J Thermal Insulation , 8:49-80
7.
Thomas, W.C. , G.P. Bal and R.J. Onega1983"Hcat and Mass Transfer in Glass Fibre Roof Insulating Materials," ASTM STP 789, American Society for Testing and Materials, pp 582-601.
8.
Hedlin, C.P.1988. "Heat Transfer in a Wet Porous Thermal Insulation in a Flat Roof,"J of Thermal Insulation , 11:165-188.
9.
Craussc, P., C. Bacon and C. Langlais1985"Experimental and Theoretical Study of Simultaneous Heat and Moisture Transfer in a Fibrous Insulation,"J of Thermal Insulation, 9:46-67
10.
Kumaran, M.K.1987. "Moisture Transport through Glass-Fibre Insulation in the Presence of a Thermal Gradient,"J. of Thermal Insulation, 10:243-255
11.
Kumaran, M.K.1988. "Comparison of Simultaneous Heat and Moisture Transport through Glass-Fibre and Spray-Cellulose Insulations,"J of Thermal Insulation, 12.6-16.
12.
Modi, D.K. and S.M. Bcnncr1985. "Moisture Gain of Spray Applied Insulations and Its Effect on Effective Thermal Conductivity - Part I,"J. of Thermal Insulation, 8:259-277
13.
Benner, S.M. and D.K. Modi.1986. "Moisture Gain of Spray Applied Insulations and Its Effect on Effective Thermal Conductivity - Part II,"J. of Thermal Insulation, 9:211-223.
14.
Wijeysundera, N.E., M. N A. Hawladcr and Y.T. Tan1989"Water Vapour Diffusion and Condensation in Fibrous Insulations,"Int. J Heat Mass Transfer, 32(10):1865-1878.
15.
Wijcysundera, N.E., M.N.A. Hawlader and S.C. Lian.1989. "An Experimental Study of Condensation in Fiberglass Insulations,"Paper FE89-32 ASHRAE Far East Conf. on Air Conditioning in Hot Climates, Kuala Lumpur, Malaysia, October 25-28.
16.
Motakef, S. and M.A. El-Masri.1985. "Liquid Diffusion in Fibrous Insulation,"ASME, J. Heat Transfer , 107.229-306.
17.
Ogniewiez, Y. and C.L. Tien.1981. "Analysis of Condensation in Porous Insulation,"Int J. Heat Mass Transfer , 24:421-429.
18.
Motakcf, S. and M.A. El-Masri.1986"Simultaneous Heat and Mass Transfer with Phase Change in a Porous Slab,"Int. J Heat Mass Transfer, 29(10).1503-1512.
19.
Shapiro, A.P. and S. Motakef.1990. "Unsteady Heat and Mass Transfer with Phase Change in Porous Slab: Analytical Solutions and Experimental Results,"Int J. Heat Mass Transfer , 33(1):163-173.
20.
Vafai, K. and S. Witaker1986"Simultaneous Heat and Mass Transfer Accompanied by Phase Change in Porous Insulation,"Trans. ASME, J Heat Transfer , 108132-140
21.
Vafai, K. and H.C. Tien.1989. "A Numerical Investigation of Phase Change Effccts in Porous Materials,"Int J. Heat and Mass Transfer, 23(7):1261-1277.
22.
Tao, Y-X., R.W. Besant and K.S. Rczkallah.1991"Unsteady Heat and Mass Transfer with Phase Changes in an Insulation Slab Frosting Effects,"Int J Heat Mass Transfer, 34(7) 1593-1603
23.
Edwards, D.K. , D.E. Dcnny and A.F. Mills1976. Transfer Process. New York: McGraw-Hill.
