In May of this year, an aerodynamic bus was exhibited at the Beijing Science and Technology Expo and received reports from CCTV's "News Network". Product exhibitors introduce this kind of passenger car that uses a steady stream of air as a source of power, which sounds like a perfect transportation solution: resources are inexhaustible and emissions are pollution-free air – which is very attractive. The search shows that the company has also raised funds for this purpose, but it has been criticized by anti-macbage networks and other institutions, referring to its fundraising scam for the original shares. What is the principle behind an aerodynamic car? Aerodynamics is not a new technology, dating back to 1820. At that time, the main idea was similar to the design of the tram. The high-pressure air pipe was laid along the track to provide high-pressure air to the engine to drive the vehicle on the track. There was also a name called “PneumaTIc Railwayâ€. However, due to the technical conditions of the year, the locomotives were not actually produced. Until 70 years later, compressed air-based engine vehicles began to be launched and put into use. The early pneumatic engines used the same structure as the steam engine. They were bulky and inefficient, and could not solve the urban traffic problems. Today, more than a hundred years later, the aerodynamic engine has made great progress. The engine is more compact and more efficient, and the efficiency is also significantly increased, which makes people use the brains of aerodynamic cars. Aerodynamic vehicles have been developed for more than 100 years, such as the United States, France, and South Korea have developed their own products. For example, the French company Citroen has announced that aero-powered cars may be put on the market in 2016. The car is a hybrid of aerodynamics and fuel, fuel costs will be reduced by 45%, if driving in town, the cost can be reduced to 80%. Due to the cost advantage of the aerodynamic system, the car will cost about $1,500 less than the existing hybrid car. This report was released in 2013, but by July 2015, it seems that I have not seen any news about the launch of this car. Domestic companies are more reliable than French joint ventures. At the 15th China Science and Technology Fair held in Beijing, there was such a product: an aerodynamic bus. According to the data of the official website of the vehicle, this model should be Xiangtian A4-0001, the power can reach 240KW, the speed is 140km/h, the cruising range is 200km, and the displacement is 6L. The vehicle is equipped with a 6-speed gearbox with 53 seats and a kerb quality of 16800kg. Many visitors were very concerned about this car, and the staff also introduced the working principle of this car. Xiangtian aerodynamic bus From the currently known parameters, the bus is equipped with a 2000L gas cylinder. The pressure of the cylinder is about 30MPa. By heating and expanding, the gas volume will increase by 1224 times. According to the laws of thermodynamics, the energy of gas expansion during adiabatic process is the least (adiabatic expansion), and the energy of work is the most (isothermal expansion) when the endothermic process is completely endothermic. Therefore, the energy contained in the compressed air of the container in the storage tank is related to the expansion mode when the gas is released, and the specific value thereof should be between the adiabatic expansion and the isothermal expansion. So how much energy does these compressed gases contain? Based on the above conclusions, we bring in relevant data and calculate the results. If the exhaust pressure is 0.15 MPa, the 2000L cylinder contains energy between approximately 117 MJ and 318 MJ. (Note: The adiabatic coefficient is calculated according to 1.4). The calculation result can be understood as the gas expansion work does not exceed 318MJ at most, this calculation result is not intuitive, but it is converted into electric energy but about 88 degrees of electricity. If this is calculated as gasoline, it is only 5-6 liters. The result of this calculation made me a little bit broken. For the 200-kilometer battery life requirement, the energy stored in the tank was not as high as I expected. Is there a problem with my basic data? Except for tank pressure and exhaust pressure, other parameters are official parameters, and the probability of a problem is not large. Moreover, according to the thermodynamics knowledge, the difference between the tank pressure and the exhaust pressure can be known, which determines the amount of energy. Therefore, I want to further "audit" the data. According to the data disclosed in the invention patent "CN201310292631-compressed aerodynamic vehicle" and the utility model patent "CN201320413749-compressed aerodynamic vehicle" (hereinafter collectively referred to as "patent"), the pressure of the automobile storage tank is between 20 and 45 MPa, preferably 30 MPa. Export pressure, according to the "News Network", the gas will expand 1224 times to calculate. See what happens to the calculations this time. The energy stored in the tank is positively related to the tank pressure. When the pressure reaches 45 MPa, the stored energy reaches about 640 MJ, and the converted electric energy is about 180 KWh. This figure calculated under extremely ideal conditions did not bring me too much surprise. As a compressed aerodynamic system, the actual energy actually obtained is much smaller than the stored energy. First of all, in theory, the calculation results of 640MJ are obtained under the ideal conditions of isothermal expansion. Under actual working conditions, isothermal expansion is actually difficult to achieve. So anyway, the energy stored in the actual tank is about a value between 117MJ and 640MJ. Second, the power of the air motor is positively related to the pressure difference between the engine inlet and outlet. If the pneumatic machine is working (when the power output is guaranteed), especially when the car is climbing or accelerating, due to the increase in power demand, there is a need for a sufficient pressure difference between the inlet and outlet of the pneumatic machine. That is to say, the gas pressure in the tank cannot be completely used. When the pressure is reduced to a certain level, the power output requirement of the air motor cannot be guaranteed, which gives the aerodynamic vehicle a discount. Third, according to the thermodynamic principle, the gas decompression expansion process is generally an endothermic process. Therefore, this step is bound to cause a temperature drop. In a positive sense, we can get some extra cold, which can be used to cool the car system and make the system more efficient. However, in practical applications, these cooling quantities are not so convenient in application. Regardless of the refrigerant used as the transmission medium, it is not necessarily necessary to dissipate heat when the amount of cooling occurs in time. Conversely, when heat is required, there is not necessarily enough cold to use. Therefore, when using this part of the gas to expand the amount of work generated by the work, for the stability of the system, at least an additional cooling system is needed to prepare for the unexpected. Or you can store the cold amount and use it when you need it. But no matter which method you choose, it will make the system more complicated. Complex systems can bring additional functionality, but they also incur additional costs and additional failures. The benefits are limited, and the trouble is quite a lot. If the pressure is reduced to 0.1 MPa at 1 MPa, it may bring about a temperature drop of several tens of degrees, which means that the temperature may drop directly to zero, which may cause the tube. The road is frosted or frozen, causing a drop in heat transfer efficiency or even damage. Therefore, at this time, a heating device is necessary, and in the patent, it is also equipped with a heating device. This heating device can raise the problem of gas and increase the output of work during expansion, but it will also bring new energy loss, which will once again reduce the life of the aerodynamic car. Fourth, depending on the thermodynamic properties of the gas, the pressure of the gas is positively correlated with temperature under isovolumetric conditions. This means that the storage capacity of the tank is closely related to the ambient temperature. At 25 degrees Celsius, assuming that the cylinder pressure is 30 MPa, then at a temperature of minus 10 degrees, the cylinder pressure is only 26.5 MPa (calculated according to the ideal gas), which means that at least 10% of the energy is lost. . Of course, you can do insulation to solve this problem. Fifth, as a device such as an engine, its efficiency is very limited. There is a very large energy loss between the energy contained in the compressed air in the cylinder and the energy released by the pneumatic engine. This may be the largest energy loss term in the entire aerodynamic system. It is limited by the laws of thermodynamics and is basically an insurmountable barrier. Although the patent states that the efficiency of the system is improved by exhaust gas pressure recovery, it is worth exploring whether the energy consumed by the recovery and the energy recovered are more valuable. In addition to the above, there are two important issues to be aware of in aerodynamic batteries. First, where does the compressed air come from. The process of compressing air is a very energy intensive process. According to the law of conservation of energy, the energy consumed by air compression must be greater than the energy of the compressed air itself. In general, the isentropic efficiency of an air compressor is only 70 to 80%. Moreover, there is also a certain loss of heat loss during the compression process. From an environmental point of view, it may just be a transfer of pollution and it does not solve the pollution problem. Especially due to the problem of conversion efficiency, when the same energy is obtained, more energy may be wasted, resulting in more emissions. Second, it is still a common issue of security. In the "patent", the tank pressure describing the aerodynamic vehicle is between 20 and 45 MPa, which is a fairly high value. When applied to a car in motion, once it is broken due to external forces or other factors, the consequences are unimaginable. In addition, such a high pressure system is still in a bumpy, vibrating environment, and the requirements for sealing are also high. As a genre of future technology, the aerodynamic system and the compressed air on the energy storage are on the same door. Air-powered cars have many advantages over hundreds of years of research in different countries. For example, the cost of an aerodynamic vehicle will be more advantageous than that of a new energy vehicle based on electric energy; under normal use, the life of an aerodynamic system is higher than that of an electrochemical power system. In terms of form, by adding compressed air, it is also more convenient than charging. All of this shows that there is still market space for aerodynamic vehicles. But I think we must find a reasonable application, such as a hybrid system, or do some special applications, such as cleaning the forklift in the warehouse, or low-speed vehicles for short-distance. From the application point of view, I prefer to use it as a power-compensated application, rather than solving the endurance problem based on the energy storage form. This is because the density of the compressed air system itself is not too high (especially volumetric energy). There are some cases in energy storage, which are applied to the peaking unit with compressed air. As an aerodynamic vehicle product, I think it should be tested for several years, both to verify the technology and to verify whether it can meet the market requirements. Taihang Power begin to produce rechargeable battery since 1956, our Nickel Cadmium Battery capacity range is from 10ah to 1200ah. NICD battery has the properties of rigid construction, long service life,wide work temperature, resistance to overcharge and overdischarge, low self-discharge, high reliability and easy maintenance. Nickel Cadmium Alkaline Battery Nickel Cadmium Rechargeable Battery,Nickel Cadmium Alkaline Battery,Alkaline Nicd Batteries,Nicd Battery For Ups Henan Xintaihang Power Source Co.,Ltd , https://www.taihangbattery.com
They are widely used as DC power source for railway vehicle, rolling stocks, petrochemical, oil and gas, electricity industries,electrical appliance,telecommunications, UPS, military, AGV,electric power system,wind and solar energy storage system,etc.