Scientists of the Samara National Research University in Samara, Russia, are developing a cryogenic engine that will use liquid nitrogen or liquefied natural gas as fuel. The team hopes that the engine will be able to power environmentally friendly vehicles in specially protected natural areas. The team also hopes to improve special purpose unmanned aerial vehicles (UAVs) which can remain invisible to infrared tracking devices as they will leave no thermal traces in the sky, according to their developers. The work is being carried out within the scope of the laboratory for cryogenic technology at Samara University.

“The main task of this laboratory is to study the prospects of using cold energy, that is, the energy stored in cryogenic substances and products,” said Dmitry Uglanov, deputy director of the Institute of Engines and Power Plants of Samara University, associate professor and chair of thermal engineering and thermal engines and scientific director of the Laboratory for Cryogenic Technology. “The laboratory has started developing a cryogenic engine, and currently a series of tests is underway on one of its main elements—a cryogenic fuel storage system.”

The storage system developed by the Samara scientists is based on a specially designed cryogenic tank equipped with various sensors and valves. In the course of laboratory tests, processes to store cryofuel and use low potential energy of cryoproducts are explored.

Scientists fill a cylinder with liquid nitrogen, which heats up thanks to the heat of its surrounding environment and, having turned into a high pressure gas, performs useful work in an expansion machine. Additionally, a cascade of thermoelectric generators used in the storage system generates additional energy due to temperature contrast between the cryogenic working fluid and the environment. “This storage system has an original design protected by invention patents. This cylinder is unique in that usually such containers are designed to store either high pressure gases or cryogenic working bodies in liquid state. Our development enables storing working substances in either liquid or gaseous state, depending on the task for this system and makes it possible to control its regasification time and achieve the needed parameters of the working body,” Uglanov explained.

Developing such a cryogenic engine will take three to four years. Among the main advantages of such an engine are its environmental friendliness, as well as various special purpose applications including the aforementioned UAVs. A cryogenically fueled drone will leave no thermal trail in the sky and remain untraceable by infrared sensors at night, unlike aircraft that use combustion engines or electric motors to create thrust. “Due to its exceptional environmental friendliness, the cryogenic engine can be used on board vehicles intended for operation in nature reserves, as just one example. It can also be used on special purpose unmanned aerial vehicles—unlike other vehicles, these will leave no thermal trail making it more difficult to detect,” Uglanov concluded.