HHO cell
A cell that is used for water electrolysis in motor vehicles is called an HHO cell . When the electrolysis gas is burned in the engine, fuel should be saved.
Layout and function
HHO cells can be set up as wet cells and dry cells. In a wet cell, the electrodes are located in a vessel and are completely surrounded by water. The vessel is built gas-tight so that the gas can flow into the gas hose. The structure of the dry cell is completely different. No vessel is used there, but the electrodes themselves form a vessel so that the cell remains dry on the outside. While a wet cell, like a tub, holds the water for electrolysis, a dry cell needs to be supplied with water, because the dry cell would "dry out" and overheat very quickly without a constant water supply. The water inlet is provided by a water tank that must be installed above the dry cell so that the water can flow into the cell through gravity. With every type of cell, the anode and cathode are always close to each other (usually 1.5 mm - 3 mm). In the case of a dry cell, the electrodes are provided with holes or slits at the top and bottom so that the water can run through the entire cell below and the gas can escape above. The electrodes are kept at a distance from one another with a rubber seal in the form of a ring. Electrodes and rubber rings thus form the vessel of the dry cell in which the water is electrolyzed. Each dry cell has a water inlet (below) and a gas outlet (above). The cell and water tank thus form a cycle. Water constantly flows from the tank into the cell and gas, mixed with water, runs back into the tank. This circuit serves not only to supply water, but also to cool.
A cell consists of a stack of plates of electrodes that are connected to the vehicle's electrical system (12 or 24 volts). A feeder supplies water while the electrolysis gas ( oxyhydrogen , consisting of hydrogen and oxygen ) is collected together.
Effects when applied
The cell is often advertised as a means of saving fuel. The electricity supplied by the alternator breaks down the water in the cell and the resulting oxyhydrogen is mixed into the engine's intake system for combustion. In this way, however, there is initially no energy saving in terms of fuel, but increased consumption.
Savings would only be conceivable if small admixtures lead to a significant increase in the efficiency of the internal combustion engine. Although the efficiency of a gasoline engine improves with hydrogen as the fuel gas (including higher flame speed, wider ignition range), a fundamental increase in efficiency is not possible.
A numerical example illustrates this even with highly idealized values: With a gasoline engine with an efficiency of 30% in pure gasoline operation, 30 kW of mechanical power can be achieved with 100 kW of thermal gasoline combustion heat output. Now 10% fuel savings are to be achieved through electrolysis by adding the oxyhydrogen. Assume that you use 1 kW of the mechanical power (which is to be increased for this purpose) (realistic value for a large alternator). With a generator efficiency of 90% and an electrolysis efficiency of 70% (both unrealistically high ideal values), a chemical power of the oxyhydrogen material flow of 630 watts is obtained. The admixture would have to improve the efficiency of the gasoline engine by 4% to 34% in order to reduce fuel consumption to 90 kW. If, on the other hand, the system was completely omitted, the same savings would be achieved by increasing the efficiency to 33.3%.
Only about 19% of one unit of gasoline comes from the HHO cell in the form of the combustible gas. The total loss of this chain of producers is about 81%.
From a physical point of view, this principle is not functional, the fuel savings cannot be scientifically justified to the extent advertised. In the reports cited, including those from NASA or the Jet Propulsion Laboratory , there are indeed effects of improved combustion efficiency in the engine after the addition of oxyhydrogen, but the energy used to generate the oxyhydrogen is not taken into account.
In this respect, the plants discussed are a form of " snake oil ".
Further risks are the handling of the explosive oxyhydrogen gas and the increased engine load due to higher combustion temperatures, the changed ignition behavior and the higher combustion speed. Modern engines with map control cannot correctly take the changed fuel mixture into account.
Individual evidence
- ↑ https://epub.wupperinst.org/frontdoor/deliver/index/docId/6647/file/6647_Wasserstoff-Studie.pdf Jörg Adolf et al .: Shell hydrogen study Energy of the future? Sustainable mobility through fuel cells and H 2 , torn down on April 6, 2019
- ↑ hhogas.at: Emissions and Total Energy Consumption of a Multicyliner Piston Engine Running on Gasoline and a Hydrogen-gasoline Mixture. (PDF; 2.3 MB).