Water management is critical to the smooth operation of PEM (proton-exchange membrane, or polymer-electrolyte membrane) fuel cells. To achieve strong ionic conductivity, a high water content in the membrane is a must when using a PEM fuel cell, especially at high conductivity.
Membrane electrode adhesion can be exacerbated by low water content, which reduces the membrane’s durability and increases the risk of water buildup in the cathode GDL. Overwatering the cathode can condense and seal part of the GDL porosities, making it difficult for oxygen to reach the cathode catalyst. Flooding reduces the chemical reaction rate in the cell, resulting in a voltage decrease. This phenomenon.
When the current density is high, especially at low flow rates and low temperatures, flooding might occur. As a result, the adequate and optimum water content is critical for the long-term endurance and efficiency of PEM fuel cells. This can be achieved by humidifying reactant gases prior to their entry into the cell and by controlling humidity, particularly on the anode side of the cell; however, air humidification is required to prevent the membrane from drying out at the anode entrance as well.
A PEM fuel cell operates at a 20-40% lower efficiency when running in a humidified condition without humidifying the reactant gases.To date, a wide range of techniques for humidifying reactant gases have been developed, principally divided into external and internal humidification.
Stack-integrated membrane humidifiers, steam or liquid water injection, membrane additives and porous absorbent sponges are all used in the internal humidification to ensure adequate water distribution.
WHAT IS MEMBRANE HUMIDIFICATION?
There are a variety of methods for adding moisture to the air without using a humidifier.
The membrane humidification is the easiest and most used approach with the least energy usage. It decreases sophistication of fuel cell stack and parasitic power. This approach employs a semi-permeable membrane. In summary, in architectural terms, the membrane humidifiers might fall into two categories: planar and tubular
In the membrane humidifier, moist gas (or liquid water) and fuel (or air) passes through the channels on each side of the membrane. Owing to the variation in water pressure and temperature seen between two sides, water and heat are transported from wet side to the dry side through membrane by diffusion technique which humidifies and warms the dry air in the channel/membrane junction through vaporization.
In humidifiers like heat exchangers there are three major flow configurations, counter-flow, parallel-flow, and cross-flow.
WHAT IS THE USE OF MEMBRANE HUMIDIFIER?
- FUEL CELL
Membrane humidifiers are frequently employed in the indirect humidification of the polymer membrane of a PEM fuel cell in order to improve the overall performance of the cell. When opposed to plate technology, our wounded design allows for a greater performance from the humidifier overall.
- AIR DISINFECTANTS IN ROOMS
A push is being made right now to conduct studies on the disinfection of room air using a newly manufactured humidifier. Viruses (including influenza and coronaviruses) in the room air can be safely eliminated at a low cost by introducing modest volumes of our disinfectant HPH MED to the water side of the system.
- REFRIGERATION AND AIR-CONDITIONING
The membrane humidifier may be utilised in a variety of applications, including refrigeration and air conditioning technologies, as a legionella-proof wet cooling tower, and for integrated temperature and humidity management, particularly in warm spaces. Humidification and dehumidification applications benefit from membranes with excellent water vapour permeability and selectivity. Flue gas, natural gas, or compressed air dehydration are all examples of sectors in which this technology may be used.
Another application is in building air conditioning, where a heat transfer is frequently required in addition to water vapour movement. Enthalpy exchangers and energy recovery ventilators are two terms used to describe these membrane systems. External humidifiers, which are a part of polymer electrolyte membrane fuel cells, benefit greatly from humidification membranes (PEMFC).
- Fuel cells, ambient air/gas humidification, reactant gas humidification, environmental chambers, and respiratory gas humidification in the laboratory are just a few of the applications for which humidifiers may be utilised successfully. A huge portion of your gas stream may be passively enriched with water vapour thanks to the high permeability of water vapour in silicone and the wide membrane surface area exposed to the gas stream. This eliminates the necessity for boiling water or bubbling your gas through water.
WHY SHOULD YOU CHOOSE MEMBRANE HUMIDIFIER?
The PEMFC’s monomeric membrane must be properly hydrated for optimal operation. Loss of proton conductivity affects performance and durability if the ionomeric membrane isn’t properly hydrated.
Carbon dioxide (CO2) fuel cells and polymer electrolyte membrane fuel cells (PEM) have the potential to replace fossil fuels in both automobile and auxiliary stationary power production applications. Increasing the usage of fuel cells would help to lessen our reliance on foreign oil while also lowering greenhouse gas emissions.
The expense of fuel cells, on the other hand, is a significant barrier to their broad deployment. The platinum catalyst loading and the fuel cell power density are the two factors that have the greatest impact on fuel cell expenses.
Whatever catalyst is used, the overall method for boosting power density while lowering expensive catalyst loading stays unchanged; that is, to operate the fuel cell at greater temperatures and pressures is the same regardless of the catalyst utilised. In today’s automotive applications, fuel cells generally operate in a temperature range of 50-90°C and at pressures of up to 3 atmospheres. Increasing the temperature and pressure of the fuel cell allows for a reduction in catalyst loading as well as an increase in voltage output from the fuel cell.
New membrane materials for thermal and water management are required to cope with the harder working conditions. It is the goal of this review to provide an overview of a variety of humidification membrane materials that are currently available and in development in order to identify a humidification membrane material that can operate at higher temperatures and pressures in order to increase fuel cell efficiency while simultaneously decreasing humidification.