International Journal of Heat and Mass Transfer, Vol.129, 144-151, 2019
Measuring moisture content in a porous insulation package with finite thickness
Porous insulation materials may acquire moisture, and the moisture content must be accurately measured for appropriate maintenance of the materials. Current thermal methods for measuring moisture are applicable only to an infinite test domain. This paper used computational fluid dynamics (CFD) to investigate the effects of a finite test domain and the associated boundary heat loss on moisture measurement. Insulation material of various thicknesses, bounded by two solid plates, was modeled. The convective heat loss to the air from both solid plates was considered. The over-measured moisture content due to a finite geometric domain was regressed into formulas, by means of which the excessive amount could subsequently be deduced. The corrected moisture content was then compared with that obtained by gravimetric weighing using a digital precision balance. The results show that significant over measurement of moisture content can occur for the tested insulation material with a thickness less than 4.5 cm. The remedial strategy is quite effective and can provide moisture content results that are close to the gravimetric values. (C) 2018 Elsevier Ltd. All rights reserved.