Testing of Materials for Heat and Moisture Transport

Abstract:

The article deals with testing materials for using in enthalpy exchangers. The purpose of the enthalpy heat exchangers is to transport the heat and moisture together. Such heat exchangers are used in heat and ventilation air conditioning units. There are several methods how to test transport of moisture through material used in textile industry. However, these methods are not suitable for testing of materials, which are considered to be in heat exchangers. Methods for testing of moisture transport are usually based on free convection around membrane, which separates spaces with air of low humidity and air saturated with water. The free convection does not occur in heat exchangers and moisture varies in wide range. Therefore we developed and tested a devise to simulate moisture transport in enthalpy heat exchangers with plates, where co-current and countercurrent occur. With the help of this device, we could compare materials and evaluate the influence of the surface structure, which affect the boundary layers and heat and mass transport, when the flow is tangential to the material surface. We could also investigate the effect of flow velocity and humidity. The methods of evaluation are discussed and some results are presented.

• Periodical: Advanced Materials Research (Volume 896)
• Pages: 650-655
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.896.650
• Online since: February 2014
• Authors: Václav Dvořák*, Petr Novotny, Tomáš Vít
• Keywords: Efficiency of Moisture Transport, Measuring of Moisture Transport, Membrane, Moisture Transport

References

[1] J.L. Niu, L.Z. Zhang, Potential Energy Savings for Conditioning Fresh Air with a Membrane-Based Energy Recovery Ventilator, ASHRAE Trans. 108 (1) (2002) 54-63.

[2] L.Z. Zhang, J.L. Niu, Energy requirements for conditioning fresh air and the longterm savings with a membrane-based energy recovery ventilator in Hong Kong, Energy 26 (2001) 119–135.

DOI: 10.1016/s0360-5442(00)00064-5

[3] M. S. Nasif, G. L. Morrison and M. Behnia, Membrane Based Enthalpy Heat Exchanger Performance in HVAC System, J. Applied Membrane Science & Technology, 2 (2005) 31–46.

DOI: 10.11113/amst.v2i1.3

[4] J.L. Niu, L.Z. Zhang, Membrane-based Enthalpy Exchanger: material considerations and clarification of moisture resistance, Journal of Membrane Science 189 (2001) 179–191.

DOI: 10.1016/s0376-7388(00)00680-3

[5] E. Piera, M.A. Salomon, J. Coronas, M. Menendez, J. Santamaria, Synthesis, characterization and separation properties of a composite mordenite/ZSM-5/chabazite hydrophilic membrane, Journal of Membrane Science 149 (1998) 99-114.

DOI: 10.1016/s0376-7388(98)00184-7

[6] L.Z. Zhang, Fabrication of a lithium chloride solution based composite supported liquid membrane and its moisture permeation analysis, Journal of Membrane Science 276 (2006) 91–100.

DOI: 10.1016/j.memsci.2005.09.035

[7] L.Z. Zhang, Investigation of moisture transfer effectiveness through a hydrophilic polymer membrane with a field and laboratory emission cell, International Journal of Heat and Mass Transfer 49 (2006) 1176–1184.

DOI: 10.1016/j.ijheatmasstransfer.2005.08.029

[8] L.Z. Zhang, Evaluation of moisture diffusivity in hydrophilic polymer membranes: A new approach, Journal of Membrane Science 269 (2006) 75–83.

DOI: 10.1016/j.memsci.2005.06.020

[9] L.Z. Zhang, C.H. Liang, L.X. Pei, Heat and moisture transfer in application scale parallel-plates enthalpy exchangers with novel membrane materials, Journal of Membrane Science 325 (2008) 672–682.

DOI: 10.1016/j.memsci.2008.08.041

[10] ASTM: E96. 2000. American Standard Test Methods for Water Vapor Transmission of Materials, American Society for Testing and Materials, 842-849.

[11] P. Novotny, V. Nguyen, Measurement of Moisture Transport in the Membrane–Based Enthalpy Exchanger, In. Experimental Fluid Mechanics 2012, Hradec Kralove 20th-23rd November (2012) 532-535.

[12] M. Vestfalova, Evaluation of material properties determining the moisture transfer, In. Experimental Fluid Mechanics 2012, Hradec Kralove 20th-23rd November (2012) 762-765.