For unmanned aerial vehicle (uav), we really passively to intervene, a military project at the university of Taiwan in 2010, 

with 2012 of mechanics in tongji university developed a leap, fixed wing uavs, made in 2015 with comac fixed-wing unmanned 

aerial vehicle (uav). More than 2016 people ask whether we can do rotor unmanned aerial vehicle (uav) system. Although there 

are a few of the aircraft development, but passively, and for the industry we are not particularly understand, today I really 

is with a mentality of communication to communicate with you, after all, I have been familiar with fuel cell, may have no idea 

about unmanned aerial vehicle (uav), later have the opportunity to communicate with you 

      

  
Tongji university "number one" leap unmanned aerial vehicle (uav), is the pure fuel cell, use lithium battery, take off the 

glide time longer.
A brief introduction of fuel cell.
  
  Fuel cell with now, the biggest difference between lithium battery is lithium battery energy storage device, and the fuel 

cell itself is a generator, the traditional internal combustion engine combustion chemistry into internal energy, then into 

mechanical energy into electrical energy, we are the chemical energy one pace reachs the designated position is converted into 

electrical energy, so the efficiency is higher. But in this, can see the fuel cell as a generator, a small chemical factory, we 

often do the fuel cell in order to make it work, just do one thing, to ensure that water and heat balance value of the fuel 

cell. The temperature is high, the performance is better, might break the balance of water, may put fuel cells become more dry, 

from the external characterization of performance attenuation, this is the process of water and heat balance

  The principle of simple
Middle is equivalent to + electrolyte of lithium battery diaphragm material, is a kind of solid electrolyte, electronic cannot 

pass. Hydrogen into a hydrogen atom and broken down into protons and electrons, protons through the membrane, the membrane 

formation potential difference on both sides, electronic current formation, it is the basic principle of batteries work. All 

ran to the cathode, oxygen reacts with air side water, so that's one pace reachs the designated position, directional current 

form directly.
     Structurally, as shown in figure among the black part is the core part, the equivalent of the inside of the lithium battery 

anode, cathode + diaphragm and electrolyte. For the weight, the weight of this part, from the fuel cell, may be less than 10% 

of the weight. Weight the most part is the double plate, is mainly used to ensure uniform distribution of hydrogen fuel cells 

inside, now there are two main types of material, one kind is with graphite products, additionally one kind is metal, stainless 

steel, titanium alloy. Golden yellow part is the end plate, hydrogen is the most difficult to seal gas in the world, we used to 

do the pressure seal.
      Proton exchange membrane fuel cells, each unit of PEMFC only 0.6 0.7 V voltage, monomer series of batteries into the 

battery pile are needed to improve the voltage.
From 2010 began to contact unmanned aerial vehicle (uav) now, found that all the requirements of unmanned aerial vehicle (uav) 

industry partners gave us a, weight loss weight loss and weight loss. We are also thinking about a lot of weight loss, how 

reduce? Mainly in three aspects: 1, the structural weight, that is to say by optimizing the structure, the board do more thin, 

in a kind of materials; 2, functional, weight loss, by improving the environmental adaptability, reduce some structural things, 

such as by improving the performance of MEA, reduce the power of the fan, fan selection can reduce the weight, by improving the 

low temperature performance, reduce the demand for heat preservation and heat insulation; 3, improve performance, the same area 

of the battery, is 300 ma and 400 ma/cm2 at ordinary times, increased to 500 or 550 ma/cm2, virtually reduced the weight.

     Standard fuel cell, with stainless steel shell, with graphite plate; Lightweight, shell with bakelite, did some hollow out 

processing on structure, graphite plate using low density graphite plate, slightly do thinning processing; Ultra-low weight, we 

are developing, made the double plate, stainless steel and titanium alloy than power, its overall weight is the weight will be 

lighter.
Standard of fuel cell, with 1000 w, for example, the standard version will probably be 6 kg, equivalent to 160 w/kg, now with a 

lightweight graphite plate can be almost 350 w/kg, with a metal plate can be more than 500 w/kg. If it is more rotor take-off 

weight 20 kg, 10, according to the fuel cell to about 2000 w, with lightweight batteries, fuel cells, weight about 5.5 kg - 5.6 

kg, if with ultra-low weight batteries may be less than 4 kg. Here just to compare the fuel cell, if the more intuitive 

comparison, to compare with the lithium battery, here involves the main system.

     To improve environmental adaptability
Improve the working temperature. From 52 to 62 degrees, the fuel cell can be relatively stable work. Said in front of the fuel 

cell structure, characteristics, the fuel cell lining resistance must be at work, must be hot, hot to take away, heat exchange 

is nothing more than three: convection, radiation, heat transfer, by improving the performance of fuel cell operation, usually 

the temperature at the levels of 52, 53 degrees, 55 degrees is a slightly higher, if for more than 35 degrees Celsius 

temperature thermal capacity may not, means must fall power, have to drop the power of words, the consequences may be the 

airline. We specifically for this raise the working temperature of fuel cells, enables the fuel cell to at the time of 40 

degrees can work normally. In the environment at 40 degrees Celsius temperature performance and the performance of the 

environment at 50 degrees Celsius temperature difference 3.9%, basically the equivalent of impact is negligible.

    Fuel cell is essentially a chemical plant, the chemical reaction is normal, must ensure that water and heat balance. 

Thermal equilibrium by fan, water balance by controlling the temperature. Water is the fuel cell reaction, gathered in the air 

side produced water, the water to self humidifying of membrane, the rise of temperature, water evaporation speed faster and 

faster, make sure that the evaporation rate at high temperature in a certain range, in addition to ensure that the fuel cell 

electrode has a higher tolerance for humidity

   The environment temperature 40 degrees, the air is dry humidity, moderately from 20% to 20%. The desert are extremely dry 

conditions in western Sahara or humidity is around 10%, meaning that 20% is very low humidity, the better the performance 

contrast. The low humidity of 20% and 20%, compared to high humidity performance attenuation is 3.5%, to reform the electrode 

process, to ensure that the fuel cell under the high temperature 40 degrees to 20 degrees 15 degrees or room temperature 

performance change is less than 5%. This than just telling light fuel cells have much more meaningful, because of the unmanned 

aerial vehicle (uav) work environment is certainly not pure environment, adaptability to the environment requirement is very 

high.
 
 Low-temperature startup performance
Asked the fuel cell can work at minus 20 degrees, 30 degrees below zero? I can only say that conditional work. Tell me the 

problem of the 5 degrees below zero start first. We put the fuel cell environment room 5 degrees below zero frozen for 24 

hours, to ensure that the fuel cell stack temperature 5 degrees below zero, by hydrogen gas, the fuel cell stack temperature 

rise to 0.2 degrees, fuel cell has broke through the freezing point. After 2 minutes, reactor temperature to 16.6 degrees, 

after 4 minutes to 27 degrees, fuel cells can normal work. 3-4 minutes, basically stable voltage, fuel cells in 27 degrees when 

almost normal work, and this system structure can be launched five degrees below zero, but lower. 10 degrees below zero, fuel 

cells, water just produce frozen, blocks the ion migration channels and subsequent reaction can't proceed. 30 degrees to 20 

degrees below zero, if start thirty degrees below zero, to ensure that the fuel cell is likely to be above zero start, as long 

as the guarantee to produce heat to keep the whole heap temperature around 20 degrees, fuel cells can work normally. To do some 

adjustment in system structure or heat above, we had the lowest 38 degrees below zero in Harbin's up and running, here comes to 

the specific system structure design, including overall system deployment, interested friends can communicate after the 

meeting.
     The influence of altitude on performance
Not only have an effect on unmanned aerial vehicle (uav) above sea level, is have effect on fuel cell, fuel cells work mostly 

hydrogen and oxygen, hydrogen gas can be a pure hydrogen, but the higher the altitude, the lower the oxygen content. We do high 

altitude test, from plain to nearly 2000 meters, the performance dropped by 5.4%. If we do a powered by fuel cells more uav 

rotorcraft, at design time, more consideration to power redundancy.

   Switch machine test
If we use lithium battery, the attention is not much more special, fuel cells, due to some of their own characteristics, 

frequent switch machine, if you don't pass or fail in the MEA catalyst, frequent switch to relatively large impact on the 

performance of it. We specially made 1017 tests, some fuel cell companies said can do the test, but test is conditional, fuel 

cell power rating normal running for half an hour, and then shut down, do not allow the inside of the hydrogen gas discharge, 

according to the normal shutdown, to ensure that the fuel cell inside still have part of hydrogen, cooling, 2 hour to boot. Why 

can't emphasize the inside of the fuel cell hydrogen forced row? 2 hours, the key problems of cooling, hydrogen side hydrogen 

will gradually consumed, form a negative pressure air, the formation of hydrogen and oxygen mix, form tiny battery, 

distribution for the base material is relatively large, and this is why we must according to the kind of core processes to do 

1017 times. If we start up, shutdown, 0.1 seconds a cycle, tens of thousands of times.

    Hydrogen partial
Fuel cells can be done, about 500 / kg, when, or even higher, but must match the corresponding hydrogen tanks. Basically, there 

are several solutions: chemical hydrogen to boron sodium cyanide and magnesium hydride, domestic only reached 35 mpa, now we 

use 35 mp9 high-pressure cylinders, weight ratio can reach 7%. This equipment if it is heavy 100 g, you can leave about 7 g of 

hydrogen. Change a perspective, the hydrogen fuel cell + tanks now, than can come when, can be 350 to 450, when/kg, this is 

lithium battery 2 times now, the future can be almost 600 / kg, when, is about three times now.