Mass Transfer Equations of Electrolytic Water Removal Device Using Solid Polymer Electrolyte Membrane

Yamauchi, Shiro; Sakuma, Syuuichii; Nakatani, Hajime; Mitsuda, Kenro

doi:10.1541/ieejfms1990.120.5_607

Cited by 7 publications

(5 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…12 is valid, the two-layer model expressed by the set of equations (1)(2)(3)(4) can be reduced to the simplified form as Eq. 13 or 13a.…”

Section: Resultsmentioning

confidence: 99%

“…This device consists of a proton-conductive solid polymer electrolyte and porous electrodes with a catalytic layer composed of noble metal particles. This device can dehumidify the space facing the anode and humidify the space facing the cathode when a DC voltage is applied to the electrodes [4]. The dynamic characteristics of the SPE dehumidifier were numerically analyzed and found to be well explained by a two-layer model for the SPE dehumidifier [5].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Sakuma¹,

Yamauchi²,

Takai

2010

J Appl Electrochem

Self Cite

View full text Add to dashboard Cite

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 Dehumidifier Á Physical model Á Steady-state current characteristics Á Solid polymer electrolytic membrane List of symbols DDiffusion coefficient of water in the dehumidifying element (cm 2 s -1 ) eElectron charge = 1.602 9 10 -19 (C) I Current of the dehumidifying element (A) j g Coefficient relevant to the diffusion velocity of water from the air to the SPE membrane (cm s -1 ) j s 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) N A Avogadro's number = 6.02 9 10 23 (mol -1 ) RHRelative humidity (%) R s Electrical resistance of the dehumidifying element (X) S Area of the dehumidifying element (cm 2 ) S' Equivalent leakage area with the rate constant kg of water transfer (cm 2 ) t time (s) T g Temperature of the gas space surrounding the dehumidifying element (K) U s Voltage applied to the dehumidifying element (=3 V) V g,p , V g,n Volumes of the spaces facing the anode and the cathode (cm 3 ), respectively aThe average number of water molecules carried by a proton moving to the cathode q g , q sWater density in the air surrounding the dehumidifying element and water content of the element (g cm -3 ), respectively

show abstract

“…12 is valid, the two-layer model expressed by the set of equations (1)(2)(3)(4) can be reduced to the simplified form as Eq. 13 or 13a.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Sakuma¹,

Yamauchi²,

Takai

2010

J Appl Electrochem

Self Cite

View full text Add to dashboard Cite

show abstract

“…The following reactions occur at the anode and the cathode when a DC voltage is applied to the dehumidifying device [1].…”

Section: Basic Equations For the Modelmentioning

confidence: 99%

“…The device consists of a proton-conductive solid polymer electrolyte and porous electrodes with a catalytic layer composed of noble metal particles. When a DC voltage is applied to the electrodes, the device can dehumidify the space facing the anode and humidify the space facing the cathode [1]. This type of electrolytic dehumidifying device has several advantages of no-drain, space saving and small input power compared to conventional dehumidifying techniques such as those using a Peltier element or space heater.…”

Section: Introductionmentioning

confidence: 99%

Water transfer simulation of an electrolytic dehumidifier

Sakuma¹,

Yamauchi

Takai

2008

J Appl Electrochem

Self Cite

View full text Add to dashboard Cite

A model for a dehumidifying device using a solid polymer electrolyte membrane (Nafion 117, Dupont) is proposed. The dehumidifier in the model is represented by a physical model composed of a two-layer membrane and electrodes on the membrane surfaces. Measurement of the membrane weight shows that the ratio of the water content of the membrane to humidity in the surrounding air is a function of temperature under equilibrium conditions. The results for the water ratio are used for determining the parameters required for the modeling. The electrical resistance of the dehumidifier was measured and is given as a function of temperature and the membrane water content. Simulation of the characteristics of the dehumidifying device is presented and the results are found to agree with the measured characteristics of the device. We also report an attempt to determine the parameters describing the dehumidifying processes.Keywords Dehumidifier Á Physical model Á Solid polymer electrolytic membrane Á Water transfer List of symbols Variables D Diffusion coefficient of water in the dehumidifying element e Electron charge = 1.602 9 10 -19 (C) I Current of the dehumidifying element (A) I st Current at steady state condition (A) J Current density of the dehumidifying element k g Coefficients relevant to the diffusion velocity of water from the air to the membrane k s Coefficient relevant to the diffusion velocity of water from the membrane to the air. This is defined by k s = k so exp(-W s /RT) L Thickness of the dehumidifying element (= 0.017 cm) M o Molecular weight of water m g,pWater mass in the space facing the anode (g) N A Avogadro number = 6.02 9 10 23 (mol -1 ) R Gas constant = 8.31 (Pa m 3 k -1 mol -1 ) RH t x Relative humidity at time t x R m Electrical resistance of the membrane of the device (X) p g,p , p g,n Water vapor pressure in the air facing the anode and the cathode, respectively R s Electrical resistance of the dehumidifying element (X) S Area of the dehumidifying element of the device t Time (s) T g Temperature of the gas space surrounding the dehumidifying element (K) U s Applied voltage to the dehumidifying element (V) V g,p , V g,n Volumes of the spaces facing the anode and the cathode, respectively

show abstract

“…However, because the CFC substitutes cannot even prevent completely the destruction of the ozone layer and further they are greenhouse gases, we need to develop and spread air conditioners that do not use CFCs. One such candidate technology is the application to air conditioners of dehumidifying cells 1,2 that use proton exchange membranes ͑PEMs͒ to electrolyze indoor moisture at a water vapor electrolysis cell, simultaneously transporting indoor moisture by electro-osmosis to the outdoors. This dehumidifying cell was developed and advertised for use in desiccation containers.…”

mentioning

confidence: 99%

Polymer Electrolyte Dehumidifying Cell and Its Application to Air Conditioners

Onda

Kyakuno

Hattori

et al. 2005

J. Electrochem. Soc.

View full text Add to dashboard Cite

Large amounts of chlorofluorocarbons (CFCs) have been released into the atmosphere, resulting in the destruction of the ozone layer in the stratosphere. There is thus a need to develop air conditioners that do not use CFCs. As one such air conditioner, we propose a combined system of dehumidifying cells that use proton exchange membranes (PEMs) with a water evaporation air cooler. PEMs are the solid electrolytes for polymer electrolyte fuel cells and can transfer water molecules with protons. The performance of existing dehumidifying cells using PEMs is not well understood. As important factors to determine the dehumidifying performance, in this study we first measured the transmissibility and the electro-osmotic coefficient nd of water molecules through the membrane and electrode assembly (MEA), water vapor diffusivity through the gas diffusion layer (GDL), and the mass-transfer coefficient between the channel flow and the GDL. These measured factors were then adopted in a performance analysis of our dehumidifying cell. Our simulation code solves simultaneously the conservation equations of mass and energy with an equivalent electric circuit of the cell. The calculated results describe well the experimental dehumidifying performance. By extending this simulation code we predicted the coefficient of performance (COP) of our novel air-conditioning system. The calculated COP for our test cells is small at 0.10 or 0.21, but can be made as large as 4 if nd of PEM can be increased to 5.

show abstract

Mass Transfer Equations of Electrolytic Water Removal Device Using Solid Polymer Electrolyte Membrane

Cited by 7 publications

References 0 publications

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

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

Water transfer simulation of an electrolytic dehumidifier

Polymer Electrolyte Dehumidifying Cell and Its Application to Air Conditioners

Contact Info

Product

Resources

About