A new approach for air dehumidification at refrigerator temperatures: Electrolytic vapor dehumidifier with Proton Exchange Membrane (PEM)Nouvelle approche pour la déshumidification de l’air à la température des réfrigérateurs : le déshumidificateur à vapeur électrolytique avec membrane échangeuse de protons (PEM)

https://doi.org/10.1016/j.ijrefrig.2020.05.023Get rights and content

Highlights

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    Dehumidifier with PEM is suitable for the humidity control in refrigerators.

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    Performance of PEM dehumidifier under -10~10°C conditions was experimentally investigated.

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    The dehumidifier has a starting voltage, which is higher at lower air temperatures.

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    With the increase in applied voltage, the operating current first increases and then drops.

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    Performance changing rate with operating parameters is much lower under sub-zero temperatures, due to possible icing and swelling inside the membrane.

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    The low temperature performance is not as good as normal, but the efficiency is still competitive.

Abstract

Dehumidifier with Polymer electrolyte membrane (PEM) is suitable for high-accuracy, limited-space humidity control in refrigerators. This study experimentally investigated the performance of PEM-based dehumidifier under the temperature range of -10~10°C. Empirical equations of PEM water content at refrigerator temperatures were developed. Results showed that although the low-temperature performance of electrolytic dehumidifier is not as good as that of room temperature, the efficiency (~1.3 × 10−2 g·J−1·m−2) is still competitive to desiccant or electrochemical methods. The dehumidifier has a starting voltage, and the voltage is higher at lower air temperatures (i.e. 1.3V for 26.1°C and 2.3 V for -3.9°C). During dehumidification, the operating current first increases significantly and then drops as the applied voltage increases, leading to a first increase and then steady dehumidification rate. The peak of current occurs at a smaller voltage as the air temperature decreases, i.e. 1.8V for 0°C and 2.5V for 26°C. Furthermore, the dehumidification rate increases as the air temperature and flow rate increases, while the changing rate with operating conditions was lower at sub-zero temperatures. Dehumidification has little effect on the oxygen concentration or temperature increment of the supply air. Characterizations also indicated that there was no obvious physical change on the PEM surface after operating at low temperatures. However, there exists a starting temperature for the dehumidifier, i.e. -9.5°C for the 3V applied voltage, which is due to the possible icing and swelling problem within the membrane. This study provided a new method, and proved its feasibility for dehumidifying at refrigerator temperatures.

Section snippets

Inroduction

Refrigerators with a temperature range of -10~10 °C are widely used in many processes in the beverage, food, chemical and pharmaceutical industries. With the increase in storage demand and life quality in recent years, humidity control in refrigerators has attracted increasing attentions. For example, people prefer to store dry goods, such as tea, dried seafood and some precious herbs in areas where the air relative humidity is below 45%. In addition, food or pharmaceutical can be compromised

Test rig

A PEM-based electrolytic experimental rig was established, as shown in Fig. 2. The PEM assembly is composed of a PEM in the middle, a porous an IrO2 anode and Pt cathode catalytic layers composed of metal particles, and carbon fibre paper as a diffusion layer on both sides. The air channel, with the thickness of 2mm, is assembled on the outermost side. When a DC voltage is applied, the following reactions occur. In the experiments, Nafion 117 was used as an electrolyte membrane.Anode:2H2O→4H++4e

Results

In this section, the experimental results under various operating conditions were shown, for analyzing the effects of influencing factors such as air temperature, mass flow rate and external electric field on dehumidification performance.

Empirical-Equation Development

With the steady-state fast prediction model established in our previous studies (Qi et al., 2017, Qi et al., 2018, Li et al., 2019), the dehumidification performance at room temperatures could be easily calculated, as shown in Eq. (6).m˙removal=m˙aA(ωaA,out−ωaA,in)=12IeNA+ndIeNA−Dwm∂C∂x=MH2O2iAareaeNA+ndiAareaeNA−Dwm−ρdryMH2OAarea(λwA−λwC)Ewδmwhere ρdry means the dry density, and Ew stands for the equivalent weight of the electrolyte membrane. Aarea and δm is the area and thickness of PEM,

Conclusions

Dehumidifier (PEM) with polymer electrolyte membrane has the advantages of high accuracy, limited space and electric drive, which is suitable for dehumidification in refrigerators with a temperature range of -10~10 ° C. In this study, the experimental performance of the PEM-based dehumidifier under refrigerator temperatures was studied using a self-developed test rig. Empirical equations for the PEM water content were developed, for eliminating the issue where previous models severely

Disclosure Statement

We disclose there is no any actual or potential conflict of interest including any financial, personal or other relationships with other people or organizations within three (3) years of beginning the work submitted that could inappropriately influence (bias) our work. Examples of potential conflicts of interest which should be disclosed include employment, consultancies, stock ownership, honoraria, paid expert testimony, patent applications/registrations, and grants or other funding. Potential

Acknowledgments

The project is supported by the National Natural Science Foundation of China (51876067), Natural Science Fund for Distinguished Young Scholars of Guangdong Province (2018B030306014). It is also supported by the Natural Science Foundation of China (No. 51936005), the Fundamental Research Funds for the Central Universities and the Guangdong High-level Talent Project.

I, Qi Ronghui, on behalf of all authors, claim that, there is no such conflict of interests listed below.

Conflict of interest may

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