Estimation of Characteristics of Hydrophobic Membrane Applied to a Low-Temperature Heat Storage System Based on Differential Aqueous Solution Concentration

• Published in: KAGAKU KOGAKU RONBUNSHU Vol. 17; no. 6; pp. 1080 - 1087
• Main Authors: Yamada, Akira, Ebara, Katsuya, Takahashi, Sankichi
• Format: Journal Article
• Language: English; Japanese
• Published: The Society of Chemical Engineers, Japan 1991
• Subjects: Absorption; Cooling System; Heat Storage; Hydrophobic Membrane; Refrigerator
• ISSN: 0386-216X; 1349-9203
• DOI: 10.1252/kakoronbunshu.17.1080

A low-temperature heat storage system based on differential aqueous solution concentration using a hydrophobic membrane is proposed. The hydrophobic membrane is used to concentrate and dilute a heat-storage medium. The optimum structure of the multilayered membrane module is obtained through experimental studies examining permeation characteristics of vapor. PTFE (polytetrafluoroethylene) is selected as the membrane material due to its hydrophobic character and relationship between opening ratio and pore size and thickness. Features of the pressure drop through the membrane module are studied under static process conditions wherein alternating operation of heat storage and heat release modes is performed, using experimental equipment, and variously shaped membrane modules are installed in a concentration and dilution vessel. The results are summarized as follows : (1) The pressure drop with low pressure vapor is exponentially reduced when the pore size is increased from 0.2μm to 3.0μm. (2) In the case of 3.0μm pore size, the pressure drop depends decisively on concentration and temperature polarization in solution passages, and on vapor flow in vapor passages. (3) The characteristics of permeation are correlated with vapor flux and pressure drop.