Measuring moisture content in a porous insulation package with finite thickness. (February 2019)

• Record Type: Journal Article
• Authors: Zhang, Tengfei (Tim); Xu, Yiheng; Lin, Chao-Hsin; Wei, Zhigang (Daniel); Wang, Shugang
• Is Part Of: International journal of heat and mass transfer. Volume 129(2019)
• Page Start: 144
• Page End: 151
• Publication Date: 2019-02
• Subjects: Moisture content -- Measurement -- Finite thickness -- Boundary heat loss -- Compensation -- CFD; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2018.09.106
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Moisture content in non-hygroscopic insulation materials was measured by a heating needle. Test domain was released from the required infinite dimension to a finite thickness. CFD modeling was adopted to correct the boundary heat loss effect. The remedial strategy provided moisture content close to the gravimetric values. Abstract: 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.