Analytical model of heat transfer in porous insulation around cold pipes

• Published in: International journal of heat and mass transfer Vol. 54; no. 1; pp. 288 - 292
• Main Authors: Guldbrandsen, Tom, Karlsson, Per W., Korsgaard, Vagn
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15-01-2011; Elsevier
• Subjects: Air conditioning systems; Air conditioning. Ventilation; Aircon; Applied sciences; Cloth; Condensation; Diffusion; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Foils (structural shapes); Heat transfer; Heating, air conditioning and ventilation; Insulation; Moisture; Piping; Retarding; Slits; Tubes; Vapour; Wicking; Wicking; Insulation; Piping; Condensation; Moisture; Aircon; Air conditioning; Chiller; Thermal insulation; Porous material; Modeling; Heat transfer
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2010.09.044

A thermal insulation system is analysed that consists of a cold tube insulated with a porous material faced with a vapour retarding foil.
Water vapour will diffuse through the vapour retarding foil and condense on the cold tube. To avoid build-up of water in the insulation a hydrophilic wicking cloth is wrapped around the cold tube and extended through a slit in the tubular insulation and a slot in the facing to the ambient so that condensed water can evaporate into the air. Some of the moisture in that part of the wicking cloth situated in the slit in the tubular insulation will diffuse backwards to the cold pipe and contribute to the heat uptake of the cold tube. This part is calculated for the stationary case and compared with the sensible heat transfer through the tubular shaped insulation material, using measured dry
λ values and measured fictitious moist
λ values.