CN218160483U - Recovery efficiency improving system of fuel cell system - Google Patents

Abstract

The utility model relates to a system for improving recovery efficiency of a fuel cell system. The air supply of an air compressor is connected to an air-to-air heat exchanger, a thermal process inlet, and a thermal process outlet passes through an intercooler to send air to the electric stack cathode inlet, and the electric stack cathode outlet. The air outlet is connected to the air-to-air heat exchanger through the gas-liquid separator, and the other heat outlet is supplied to the turbine through the ice-breaking auxiliary heater. The turbine drives the compressor motor, and the compressor motor drives the air compressor. The turbine is connected to the tail row Tube. Its structure is simple and compact, and it can effectively integrate components, improve the safety and reliability of use, life expectancy, improve capacity recovery efficiency, reduce the heat burden of fuel cells or overall use, and reduce energy loss.

Description

Fuel cell system Improve recovery efficiency system

technical field

The invention relates to the field of fuel cells, in particular to a system for improving recovery efficiency of a fuel cell system and a control method thereof.

Background technique

A hydrogen fuel cell is an electrochemical device that directly converts chemical energy into electrical energy. It uses hydrogen and oxygen in the air as fuel, and the reaction produces only water and air that does not participate in the reaction. The power generation efficiency can reach 55% or more. With the advantages of no pollution, high efficiency, low noise, and wide application range, it will become the main source of power to replace traditional internal combustion engines in the future.

In order to provide clean compressed air for the fuel cell system, an air compressor is required to compress the air and send it to the cathode inlet of the fuel cell after being cooled by an intercooler. At present, there are two types of mature fuel cell compressors on the market: screw compressors and centrifugal compressors. Among them, the use of screw compressors has gradually decreased and tended to be due to the disadvantages of high noise, low power density, and inability to achieve 100% oil-free. to be eliminated. Centrifugal compressors with air bearings feature low noise and 100% oil-free, and are currently the preferred solution for air compressors. Fuel cell systems with medium and small power generation mostly use single-stage or two-stage compression. The centrifugal air compressor is driven by a high-voltage controller to drive a high-speed motor and drive the impeller to rotate to compress the air. It is the component with the highest parasitic power consumption among fuel cell accessories. The total power consumption can account for 15-30% of the output power of the stack.

Improving the overall efficiency of the air compressor and reducing the power consumption of the air compressor are critical to increasing the total output power of the fuel cell system and reducing hydrogen consumption. So, for medium to heavy duty fuel cell systems, turbine air compressors with energy recovery are the main solution. The turbine uses the fuel cell electrochemical reaction to generate heat and the temperature rises from the cathode to discharge waste heat and pressure to drive the turbine to rotate, and the expansion works to generate power to assist the electric drive of the air compressor, so as to achieve the purpose of reducing power consumption.

The disadvantages from the logical point of view of the prior art include:

1. The water content of the cathode outlet is high, and the relative humidity is generally above 85% R.H. The dew point temperature is close to the temperature of the exhaust gas at the cathode outlet. During the working process, a large amount of liquid water in the form of droplets is produced along the tube wall, and the liquid water enters with the exhaust gas The turbine impacts the high-speed rotating turbine impeller and blades, which can easily lead to mechanical damage to the impeller and blades, thereby affecting the working performance and life, and in severe cases, it will cause the air compressor to fail.

2. The cathode outlet uses a gas-liquid separator to separate part of the liquid water before connecting it to the turbine inlet. Disadvantages, due to the high water content of the cathode outlet and the long length of the pipe wall along the length of the work, a large amount of liquid water in the form of droplets is produced due to condensation, the separation efficiency of liquid water is low, and a large amount of liquid water still enters the turbine and causes impellers and blades damage or failure; in addition, gas-liquid separators mostly use the principle of centrifugation or baffles to leak a part of the exhaust gas flow during work, the pressure loss is large and a part of the heat is lost, and the waste heat and pressure of the exhaust gas entering the turbine decreases. The energy recovery efficiency is low, the volume of the gas-liquid separator is large, and additional costs are added.

3. Turbine impellers and blades are reinforced with matrix materials or/and coated with coating technology, and used in conjunction with gas-liquid separators. Disadvantages, due to the low separation efficiency of the gas-liquid separator, a large amount of liquid water still enters the turbine; the turbines that use matrix materials to strengthen or/and coating process impellers and blades can reduce the possibility of failure in a short period of time, but for Vehicle fuel cell systems that require long life still have relatively high risks.

4. The high-temperature air compressed by the air compressor is cooled by the intercooler and then sent to the cathode inlet of the fuel cell. Disadvantages: Since the air compressed by the air compressor can reach a maximum temperature of 180°C and has a large flow rate, the intercooler uses cooling water to cool the air, which increases the burden on the fuel cell system or the water heating system of the vehicle. At the same time, the compressed air Hot air energy is not utilized.

5. A certain amount of liquid water remains in the turbine casing and at the turbine impeller and blades after work. In a low temperature environment, the freezing of liquid water may lead to the risk of cold start failure and reduce the service life of the air compressor.

6. Air compressors, gas-liquid separators, and intercoolers are physically far away on the fuel cell system, with scattered layout and long pipelines along the way, which is not conducive to the reduction of the size of the fuel cell system, the increase of power density, and the heat generated along the way. Large dissipation and pressure loss.

Contents of the invention

The present invention provides a fuel cell system with a simple and compact structure, which can effectively integrate components, improve safety and reliability, improve service life, improve capacity recovery efficiency, reduce fuel cell or overall use heat burden, and reduce energy consumption loss. its control method.

The technical solution adopted in the present invention is: a fuel cell system improving recovery efficiency system, including a stack, an air compressor, a turbine, and a compressor motor, characterized in that: the air compressor is connected to an air-to-air heat exchanger for air supply The inlet of one heat path, the outlet of one heat path passes through the intercooler and then sends air to the cathode inlet of the stack, the outlet of the cathode of the stack passes through the gas-liquid separator and connects to the air-to-air heat exchanger The other heat path inlet, the outlet of the other heat path is heated by ice breaking The gas supply of the air compressor is connected to the turbine, the turbine drives the compressor motor, the compressor motor drives the air compressor, and the turbine is externally connected to the exhaust pipe.

The gas from the cathode outlet of the stack is connected to the gas-liquid separator through the humidifier, and the gas-liquid separator is connected to the inlet of another heat path of the air-to-air heat exchanger.

The gas-liquid separator is a large droplet gas-liquid separator.

After the intercooler, the gas is supplied by the humidifier and then connected to the cathode inlet of the stack.

The intercooler is a water-cooled intercooler.

The air compressor intake pipe is provided with an air filter.

The air-to-air heat exchanger, intercooler, gas-liquid separator, and ice-breaking auxiliary heater are integrated into a packaged integrated cooler.

The upper opening of the integrated cooler is directly connected to the air outlet of the air compressor and the air inlet of the turbine.

Corresponding to the opening position of the integrated cooler of the turbine air inlet, an ice-breaking auxiliary heater is set.

A method for improving the recovery efficiency of a fuel cell system, characterized in that: the high-humidity residual heat and residual pressure exhaust gas at the cathode outlet of the stack first passes through the large droplet gas-liquid separator to separate the large droplets, and then passes through another heat exchanger of the air-to-air heat exchanger. The high-temperature and high-pressure fresh air compressed by the air compressor performs heat exchange between the high-temperature and high-pressure fresh air. The principle of enthalpy and humidity change, the relative humidity and condensation temperature in the exhaust gas decrease so that the particle size of liquid water becomes smaller or until it is invisible; the compressed fresh air is temperature-regulated by a water-cooled intercooler to meet the precise temperature of the cathode inlet of the stack Requirements: The exhaust gas passing through the air-to-air heat exchanger passes through the ice-breaking auxiliary heater. In the low-temperature environment, the auxiliary heating function is turned on or off according to the system’s ice-breaking strategy to solve the problem of cold start and damage to the turbine impeller or blade. The ice-breaking auxiliary heater is directly heated or Using PTC for heating, reducing until removing the liquid water entering the turbine, the turbine is driven by the compressor motor driven by the exhaust gas to compress the air compressor.

The beneficial effects of the present invention are:

1. First, the exhaust gas at the cathode outlet of the stack first passes through the large droplet gas-liquid separator to separate the large droplets. The air-to-air heat exchanger lowers the temperature of the compressed air and also heats the exhaust gas. According to the principle of enthalpy and humidity changes in humid air, the exhaust gas The relative humidity and condensing temperature are lowered so that the particle size of liquid water becomes smaller or becomes invisible, and then the ice-breaking auxiliary heater is directly heated or heated by PTC, and the ice-breaking auxiliary heater may not be used during non-cold start to further reduce energy consumption. . At this time, the exhaust gas entering the turbine does not contain liquid water, which solves the problem of high liquid water content at the inlet of the turbine, poor reliability and low life in the prior art solution;

2. The hot air energy compressed by the air compressor firstly heats and utilizes the exhaust gas, and after cooling down, it is further cooled by a water-cooled intercooler and then entered into a humidifier for humidification, and finally sent to the cathode inlet of the stack for electrochemical power generation , the heat energy is fully utilized, which is conducive to reducing the burden on the fuel cell system or the water heating system of the vehicle;

④The ice-breaking auxiliary heater turns on or off the auxiliary heating function in the low-temperature environment according to the system ice-breaking strategy to solve the problem of cold start and damage to the turbine impeller or blade, and solve the problem of remaining liquid water freezing in the low-temperature environment. There is a risk of failure during cold start and reduces The service life of the air compressor;

4. The air compressor, gas-liquid separator, and intercooler are physically integrated, which is more efficient in reducing heat dissipation and pressure loss along the process, and has a high degree of integration.

The invention uses the high-temperature air compressed by the air compressor to heat the high-humidity waste heat and pressure waste gas at the cathode outlet of the stack through the air-to-air heat exchanger to greatly reduce the relative humidity and condensation temperature, thereby reducing the particle size of liquid water. In addition, the integrated design The integrated cooler reduces heat dissipation and pressure loss along the pipeline, and the smaller size is more conducive to the volume reduction and power density improvement of the fuel cell system.

Description of drawings

Fig. 1 is a schematic diagram of the system of the present invention.

In the figure: air filter 1, air compressor 2, compressor air outlet 201, turbine 202, air compressor high-speed motor 203, air-to-air heat exchanger 3, integrated cooler 4, large droplet gas-liquid separator 5, booster Wet device 6, electric stack 7, water-cooled intercooler 8, ice-breaking auxiliary heater 9, exhaust pipe 10.

detailed description

The present invention will be further described below in conjunction with drawings and embodiments.

As shown in Figure 1: a fuel cell system improving recovery efficiency system, including air filter 1, air compressor 2, compressor air outlet 201, turbine 202, air compressor high-speed motor 203, air-to-air heat exchanger 3, integrated cooling Device 4, large droplet gas-liquid separator 5, humidifier 6, electric stack 7, water-cooled intercooler 8, ice-breaking auxiliary heater 9, exhaust pipe 10.

An air filter 1 is arranged on the air intake pipe of the air compressor 2 for air intake, and the air supply port 201 of the compressor is connected to the air-to-air heat exchanger 3, a heat path inlet, and a heat path outlet passes through a water-cooled intercooler 8 and a humidifier 6 The post-supply gas is connected to the cathode inlet of the stack 7, and the cathode outlet of the stack 7 passes through the humidifier 6, the large droplet gas-liquid separator 5, and connects to the air-to-air heat exchanger 3 and another heat path inlet, and the other heat path exits through ice breaking The auxiliary heater 9 is supplied with air and connected to the turbine 202 , the turbine drives the air compressor high-speed motor 203 to drive the air compressor 2 , and the turbine 202 is externally connected to the exhaust pipe 10 .

In the product structure of this embodiment, the large droplet gas-liquid separator 5, the air-to-air heat exchanger 3, the water-cooled intercooler 8, and the ice-breaking auxiliary heater 9 adopt an integrated design to form a whole integrated cooler 4, and the air compressor 2 The air outlet 201 of the compressor and the inlet of the turbine 202 are directly installed on the integrated cooler 4 . The ice-breaking auxiliary heater 9 is installed on the turbine inlet or the integrated cooler or between the two.

A method for improving the recovery efficiency of a fuel cell system: fresh air is filtered by an air filter 1 and then enters an air compressor 2 for compression, and the compressed high-temperature compressed air flows into the air-to-air heat exchanger 3 from the cathode outlet of the stack The high-humidity waste heat and waste pressure waste gas is used for heat exchange and cooling. Before that, the waste gas from the cathode outlet of the stack first passes through the large liquid droplet gas-liquid separator 5 to separate the large liquid droplets. The air-to-air heat exchanger 3 reduces the temperature of the compressed air and at the same time The exhaust gas is heated. According to the principle of enthalpy and humidity change of humid air, the relative humidity and condensation temperature in the exhaust gas decrease, so that the particle size of liquid water becomes smaller or becomes invisible, and then the compressed air at the outlet of the air-to-air heat exchanger 3 passes through a small-sized water-cooled After temperature adjustment, the intercooler 8 enters the humidifier 6 to humidify and finally sends it to the cathode inlet of the electric stack 7 for electrochemical power generation. The exhaust gas at the outlet of the air-to-air heat exchanger 3 passes through an ice-breaking auxiliary heater 9. In a low-temperature environment, the auxiliary heating function is turned on or off according to the system’s ice-breaking strategy to solve the problem of cold start and damage to the turbine impeller or blade. The ice-breaking auxiliary heater 9 can be used Direct electrical heating or use PTC for heating, and the auxiliary ice-breaking heater 9 may not be used during non-cold start to further reduce energy consumption. At this time, the exhaust gas entering the turbine 202 does not contain liquid water, which solves the problem of excessively high liquid water content at the inlet of the turbine, poor reliability, and low life in the prior art solution; The recovered energy is greatly improved, which reduces the power consumption of the high-speed motor 203 of the air compressor. 8 can meet the temperature adjustment requirements of the cathode entering the stack, reducing the burden on the fuel cell system or the water heating system of the vehicle, and the energy of the compressed hot air is also utilized, and the efficiency of the fuel cell system can be further improved.

In this embodiment, the turbine recovers energy and has higher efficiency, and the energy-saving effect is more obvious; the air compressor and cooler are more integrated, reducing the size and energy loss along the pipeline. The control method adopted can reduce or even eliminate the liquid water entering the turbine, which solves the biggest disadvantage of the fuel cell system using the turbine to recover energy.

Claims (9)

1. The utility model provides a fuel cell system promotes recovery efficiency system, includes galvanic pile, air compressor, turbine, compressor motor, its characterized in that: the air compressor supplies air and connects a hot stroke import of an air-air heat exchanger, and a hot stroke export is sent gas and is connected with galvanic pile cathode entry after the intercooler, and galvanic pile cathode export is given vent to anger and is connected another hot stroke import of air-air heat exchanger through vapour and liquid separator, and another hot stroke export is supplied air and is connected with the turbine through the auxiliary heater that opens ice, and turbine drive compressor motor, compressor motor drive air compressor, and the external tail calandria of turbine.

2. The system for improving recovery efficiency of a fuel cell system according to claim 1, wherein: and the outlet gas of the cathode outlet of the electric pile is connected with a gas-liquid separator through a humidifier, and the gas-liquid separator is connected with the other hot stroke inlet of the air-air heat exchanger.

3. The system for improving recovery efficiency of a fuel cell system according to claim 1 or 2, wherein: the gas-liquid separator is a large-droplet gas-liquid separator.

4. The system for improving recovery efficiency of a fuel cell system according to claim 1, wherein: and the air is sent to the cathode inlet of the electric pile through the humidifier after the intercooler.

5. The fuel cell system recovery efficiency improving system according to claim 1 or 4, wherein: the intercooler is a water-cooling intercooler.

6. The system for improving recovery efficiency of a fuel cell system according to claim 1, wherein: and an air filter is arranged at the air inlet pipe of the air compressor.

7. The system for improving recovery efficiency of a fuel cell system according to claim 1, wherein: the air-air heat exchanger, the intercooler, the gas-liquid separator and the ice breaking auxiliary heater are integrated into a whole integrated cooler.

8. The system for improving recovery efficiency of a fuel cell system according to claim 7, wherein: the upper opening of the integrated cooler is directly connected with an air outlet of the air compressor and an air inlet of the turbine.

9. The system for improving recovery efficiency of a fuel cell system according to claim 8, wherein: and an ice breaking auxiliary heater is arranged at the opening position of the integrated cold area device corresponding to the air inlet of the turbine.

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