SEDL / STP / STP1116-EB / STP16348S

Thermal Performance of HCFC-22 Blown Extruded Polystyrene Insulation

Yarbrough, DW
Chairman and Professor of Chemical EngineeringAdjunct Research ParticipantSenior Research AssociateResearch Staff Membermanager, Tennessee TechOak Ridge National LaboratoryOak Ridge National LaboratoryOak Ridge National Laboratory,

Graves, RS
Chairman and Professor of Chemical EngineeringAdjunct Research ParticipantSenior Research AssociateResearch Staff Membermanager, Tennessee TechOak Ridge National LaboratoryOak Ridge National LaboratoryOak Ridge National Laboratory,

Christian, JE
Chairman and Professor of Chemical EngineeringAdjunct Research ParticipantSenior Research AssociateResearch Staff Membermanager, Tennessee TechOak Ridge National LaboratoryOak Ridge National LaboratoryOak Ridge National Laboratory,

Pages: 15    Published: Jan 1991

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Abstract

A closed-cell foamboard insulation containing chlorodifluoromethane (HCFC-22) has been monitored in the laboratory and in the field for about three years. Experimental data for this developmental extruded polystyrene insulation has been obtained in two laboratories using three apparatuses. A correlation of apparent thermal conductivity with time gives the thermal resistivity of the two-inch-thick unfaced foamboards to within 3% with 95% confidence. A thermal resistivity of 30.2 m∙K/W (4.36 ft²∙h∙°F/Btu∙in) was calculated from the correlation for time equal 180 days after manufacture. Based on three years of data, the predicted thermal resistivity is 27.6 m∙K/W (3.98 ft²∙h∙°F/Btu∙in) as time since manufacture becomes large. Field measurements confirm the decrease with time of the thermal resistivity that was observed in the laboratory.

A three-dimensional model for heat transfer through foamboard was used to predict thermal resistivity as a function of time. A comparison of the experimental results with the model shows a radiative contribution to the total heat flux of about 30%. A one-dimensional model was used to show the effect of initial foamgas pressure and thickness on thermal performance.