Journal of Applied Electrochemistry

, Volume 40, Issue 12, pp 2153–2160

Estimation of dehumidifying performance of solid polymer electrolytic dehumidifier for practical application

Original Paper

DOI: 10.1007/s10800-010-0197-4

Cite this article as:
Sakuma, S., Yamauchi, S. & Takai, O. J Appl Electrochem (2010) 40: 2153. doi:10.1007/s10800-010-0197-4

Abstract

A two-layer model for a solid polymer electrolytic (SPE) dehumidifier is applied to a system in which the chamber to be dehumidified has some leakage area. By introducing this area, the attainable humidity in the chamber, which is the steady-state humidity to be attained after a long-time dehumidification, can be defined. Experimental results of dehumidification by an SPE dehumidifier are compared to the calculations based on the two-layer model for the SPE dehumidifier, which was presented in our previous paper. Equations for the two-layer model are simplified by making use of assumptions for the current characteristics and a constant environmental condition, and it is reduced to equations including a differential equation on the time variation of the humidity in the chamber. The differential equation to describe the attainable humidity in the chamber and time constant for the dehumidification is obtained. The current flowing in the dehumidifier under steady state conditions is also given as a function of the humidities in the spaces facing the anode and the cathode. A diagram to estimate the attainable humidity and the time required for dehumidification from the dehumidifying area and leakage area is also given.

Keywords

DehumidifierPhysical modelSteady-state current characteristicsSolid polymer electrolytic membrane

List of symbols

D

Diffusion coefficient of water in the dehumidifying element (cm2 s−1)

e

Electron charge = 1.602 × 10−19 (C)

I

Current of the dehumidifying element (A)

κg

Coefficient relevant to the diffusion velocity of water from the air to the SPE membrane (cm s−1)

κs

Coefficient relevant to the diffusion velocity of water from the membrane to the air (cm s−1)

L

Thickness of the dehumidifying element (= 0.017 cm)

NA

Avogadro’s number = 6.02 × 1023 (mol−1)

RH

Relative humidity (%)

Rs

Electrical resistance of the dehumidifying element (Ω)

S

Area of the dehumidifying element (cm2)

Sℓ

Equivalent leakage area with the rate constant kg of water transfer (cm2)

t

time (s)

Tg

Temperature of the gas space surrounding the dehumidifying element (K)

Us

Voltage applied to the dehumidifying element (=3 V)

Vg,p, Vg,n

Volumes of the spaces facing the anode and the cathode (cm3), respectively

α

The average number of water molecules carried by a proton moving to the cathode

ρg, ρs

Water density in the air surrounding the dehumidifying element and water content of the element (g cm−3), respectively

ρg,p, ρg,n

Water density in the air facing the anode (positive electrode) and cathode (negative electrode) (g cm−3), respectively

ρs,p, ρs,n

Water contents in the anode half and the cathode half of the dehumidifying element defined by two-layer model of the dehumidifier (g cm−3)

Subscripts

g

Gas space

n

Negative electrode or cathode

p

Positive electrode or anode

s

Solid polymer electrolytic dehumidifying element

Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  1. 1.Ryosai Technica Company Ltd.AmagasakiJapan
  2. 2.Tada Electric Co.SetouchiJapan
  3. 3.Nagoya UniversityNagoyaJapan