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Mathematical modelling of heat transfer, condensation, and capillary flow in porous insulation on a cold pipe.

Author(s) : CHOUDHARY M. K., KARKI K. C., PATANKAR S. V.

Type of article: Article

Summary

Porous insulation used on pipes carrying cold fluids suffers thermal degradation due to condensation of water vapour and the build up of water in the insulation. Recently, it has been suggested that the thermal degradation can be significantly reduced by wrapping a hydrophilic wick fabric on the cold pipe. The capillary action of the fabric, aided by gravity, allows the condensed moisture to move to the outer surface of the insulation, from where, if ambient conditions are right, it evaporates. The article presents the details of a mathematical model for condensation in the insulation in the presence of the wick fabric. The model is based on the volume-averaged equations for unsteady transport of heat, water vapour, and liquid water in a porous medium. The wick is modelled as an anisotropic porous medium. The model also allows for the presence of a vapour retarder jacket that is used to reduce the ingress of water vapour into the insulation. The model has been applied to an insulation layer around a horizontal pipe. The presence of the wick is shown to significantly reduce the amount of liquid water in the insulation. The results of the model have been verified using laboratory experiments and field tests.

Details

  • Original title: Mathematical modelling of heat transfer, condensation, and capillary flow in porous insulation on a cold pipe.
  • Record ID : 2005-0623
  • Languages: English
  • Source: International Journal of Heat and Mass Transfer - vol. 47 - n. 26
  • Publication date: 2004/12

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