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

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 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

A Full-Solid-State Humidity Pump for Localized Humidity Control

“…Our device showed better humidity transfer performance when compared to TE cooling and solid polymer electrolyte membrane dehumidifiers, [19][20][21][22] reported in the literature (Figure 3F). Note that, we recalculated the experimental results reported in these references according to the same assessment criteria.…”

V–I characteristics of solid polymer electrolytic (SPE) dehumidifier

“…Therefore, the current under a steadystate condition should be proportional to the supply rate of water to the anode area. The authors showed the relation between the steady-state current of the dehumidifying element and the water content in the vicinity of the electrodes in a previous article [2], as follows.…”

“…On the other hand, the current of the SPE dehumidifying element was found to be proportional to the water content in the vicinity of the anode, and the following formula was presented in our previous article [1,2], when the applied voltage is constant.…”

“…The dehumidifying processes of the dehumidifying device can be well simulated by a two-layer model for the dehumidifying device that was proposed in our previous article [1,2], and it was also shown [2] that the current flowing in the device was proportional to the water content in the vicinity of the anode when the applied voltage was constant.…”

Combined Ionic Membrane and Silica Desiccant Configuration for Maintenance-Free Humidity Control in Equipment

“…An alternative technology that has attracted increasing interest in the past few years is ionic membranes [20][21][22][23][24][25][26][27]. These devices work based on electrolysis, and they typically comprise a proton-conductive electrolytic layer sandwiched between two porous electrodes with catalytic layers composed of noble metal particles.…”