Hydrogen-Air PEM Fuel Cell

Integration, Modeling, and Control

Shiwen Tong, Dianwei Qian, Chunlei Huo

• Publisher: De Gruyter
• Year: 2018
• ISBN:
  9783110600360
• Edition: 1
• Topic: Technologie et ingénierie
• Subtopic: Science des matériaux

The book presents the modeling and control of hydrogen-air PEM fuel cells, including simultaneous estimation of the parameters and states, fuzzy cluster modeling, SPM-based predictive control and advanced fuzzy control. MATLAB/Simulink-based modeling and control programs are discussed in detail. With simulations and experiments, it is an essential reference for both scientists and industrial engineers.

1 Introduction

With the continuous development of mankind, people have become more dependent on energy. However, traditional fossil energy has been constantly decreasing. Furthermore, fossil fuel releases a lot of carbon monoxide, carbon dioxide, sulfur dioxide, and other harmful gases in the combustion process, which poses a threat to the human living environment. For the sustainable development of mankind, almost all countries in the world are committed to finding and developing new energy sources instead of relying on traditional energy sources. These energy sources include solar, wind, bio-, hydrogen, tidal, geothermal, and nuclear energy. After years of exploration and efforts, people have finally found a new energy structure, that is, generating hydrogen and oxygen by electrolysis of water with the solar, and then producing electric energy by the chemical reactions of hydrogen and oxygen. In the future energy systems, the solar energy will serve as a major primary energy alternative to the current coal, oil, and natural gas, the three major energy sources. Hydrogen is the clean energy for the twenty-first century, as an alternative energy source to the gasoline, diesel, city gas, and other. One of the forms of utilization for the hydrogen energy is the conversion of it into electrical energy through various types of fuel cell devices.

1.1 Overview of fuel cell

In 1839, Grove made the first hydrogen fuel cell in the United Kingdom. He developed a single cell with platinum plating electrode, using hydrogen as fuel, oxygen as oxidant, and diluted sulfuric acid as a liquid electrolyte, and produced electricity successfully. The power generation principle for the hydrogen-oxygen fuel cell has been achieved.

The 1950s was a turning point in the development of fuel cells. Bacon in the University of Cambridge, United Kingdom, conducted a long-term and fruitful research for the hydrogen-oxygen alkaline fuel cells. The main contributions are as follows: first, he proposed a new nickel electrode, using double-hole structure to improve the gas transmission characteristics; second, he proposed new preparation process, using lithium-ion embedded nickel plate pre-oxidation roasting to solve the problem of electrode oxidation corrosion; third, he proposed a new drainage program to ensure the quality of electrolyte work. Thus, a 5 kW alkaline fuel cell was successfully developed, whose life can be 1,000 h. This is the first practical fuel cell. Bacon’s achievements have laid the technical idea of modern fuel cells, and encouraged people to try to achieve practical commercialization of fuel cells [1].

The 1960s is an important stage of development for the application of fuel cells in the aerospace industry. The United States launched the manned spacecraft plan in 1962. It used the polymer fuel cell made by GE. In 1968, alkaline fuel cell, which is utilized the Bacon’s technology, was selected by NASA in the Apollo moon landing program [2].

Since the 1990s, the fuel cell has been undergoing rapid development. The research hotspot is the proton exchange membrane fuel cell [3]. Canadian Ballard company, an international fuel cell industry giant, built the world’s first fuel cell plant, and formally put it into production in February 2001 [4].

A fuel cell is a power generation device that directly converts chemical energy stored in fuel and oxidant into electrical energy by an electrode reaction. The greatest advantage of it is that the reaction process does not involve combustion, thus, not subject to the restriction of the Carnot cycle. The energy conversion rate can be up to 60% ~ 80%. The practical efficiency is two to three times more than the ordinary gas turbine. In addition, it has the advantages of fuel diversification, minimum environmental pollution, low noise, good reliability, and good maintenance, and is recognized as the preferred clean and efficient power generation technology in the twenty-first century [5].

1.2 Classification of fuel cell

Fuel cells can be classified by the operating temperature, the source of the fuel, and the use of different electrolytes. [6].

With respect to different working temperatures, fuel cells can be classified into low-temperature fuel cell, medium-temperature fuel cell, and high-temperature fuel cell.

With respect to different fuel sources, fuel cells can be classified into direct fuel cell, indirect fuel cell, and renewable fuel cell.

With respect to the use of different electrolytes, fuel cells can be classified into five categories: alkaline fuel cell, phosphoric acid fuel cell, molten carbonate fuel cell, solid oxide fuel cell, and proton exchange membrane fuel cell. The basic characteristics of these five fuel cells are shown in Table 1.1, and the electrochemical reactions at the anode and cathode are shown in Table 1.2.

1.3 Characteristics of fuel cell

Compared with other energy sources, fuel cells have certain advantages, which are discussed in this section.

First, the energy conversion efficiency is very high in a fuel cell. In theory, the fuel cell can convert 90% of the fuel energy into electricity and heat. Phosphorus fuel cell power generation efficiency is currently close to 37% ~ 42%. Molten carbonate fuel cell power generation efficiency can be more than 60%. Solid oxide fuel cell efficiency is still higher. Moreover, the efficiency of the fuel cell is independent of its size. Thus, the fuel cell can run at its half rated power while maintaining high fuel efficiency [7].

Table 1.1: Basic characteristics of different types of fuel cells.

Table 1.2: Basic electrochemical reactions of various fuel cells.

Second, fuel cells have a high degree of reliability. The fuel cell power generation device is made up of a battery pack connected by a series of cells. The battery pack is connected in parallel to determine the size of the entire power generation unit. These battery combinations are of module structure, constituting the basic operation and maintenance unit of the power generation system. Thus, maintenance becomes very convenient. In addition, even if it is overloaded above the rated power, or below the rated power, it can withstand without lowering the efficiency dramatically [8].

Third, fuel cells have good environmental benefits. The by-product of electrochemical reaction in a fuel cell is water. Since the rotating parts of the fuel cell are rare, the working noise is very low. The environmental friendliness of the fuel cell is the main reason, which makes it a strong vitality and long-term development potential.
But fuel cell still has many shortcomings, which can be summarized as follows:

• first, it is costly and expensive;
• second, the life and stability are not ideal in a high-temperature environment;
• third, the fuel cell technology is not popular enough; and
• fourth, there is no perfect fuel cell supply system.

1.4 PEM fuel cell working principle

The proton exchange membrane (PEM) fuel cell is a new type of fuel cell in the developing process. The electrolyte is a solid organic film, which can conduct protons in case of humidification. Platinum is generally used as a catalyst and the working temperature is generally 60°C ~ 80°C.

Each cell in the PEM fuel cell is mainly composed of a membrane electrode, a sealing ring, and a flow field plate with a gas passage. Membrane electrode is the core of the PEM fuel cell. In the middle of the membrane electrode is a layer of thin film – PEM – which does not conduct electrons but is an excellent conductor of hydrogen ions, both as an electrolyte providing hydrogen ion channels and as a diaphragm isolating bipolar reaction gas. At both sides of the membrane are gas electrodes, made of carbon paper and catalyst. The anode is the hydrogen electrode, and the cathode is the oxygen electrode. The flow field plate is usually made of graphite. PEM fuel cell uses hydrogen as fuel and air or pure oxygen as oxidant. Multiple cells are connected in series or in ...