![]() ![]() A significant feature experienced by the IIT Delhi team during laboratory tests shows that it is difficult for the injector to survive in the severe thermal environment of the combustion chamber. An effective HPDI system prevents backfire in the intake manifold and auto-ignition during combustion and thus makes it possible to achieve controlled combustion. In an HPDI system, the pressure is so high that hydrogen fuel can be directly injected into the combustion chamber even during the compression stroke. A properly designed LPDI system facilitates hydrogen injection early in the compression stroke and hence there exists a higher degree of possibility for better mixing of hydrogen and air. Direct cylinder injection in a hydrogen engine can be accomplished by two routes: high-pressure direct cylinder injection (HPDI) and low-pressure direct cylinder injection (LPDI). Direct cylinder injection, by definition, is a sound mixture formation concept because it intrinsically precludes the possibility of backfire as the air–fuel mixture is formed in the cylinder after the intake valve closure. Timed manifold injection (TMI) and direct cylinder injections have proven effective in getting rid of backfire ( Das, 2002b Mathur and Das, 1991). Hence the carburetion technique is not acceptable for long-term application.Ĭontinuous carburetion and continuous manifold injection techniques were also observed to be highly susceptible to flashback and thus cannot be recommended for long-term application. Sometimes, in the higher ranges of equivalence ratio the intensity and frequency of backfire are very high. But, it is highly susceptible to backfire and preignition problems. The carbureted version is perhaps the simplest configuration to operate a hydrogen engine. Hydrogen flow commences after intake valve closure and is completed before significant compression pressure riseĮxtensive tests in the IIT Delhi’s lab were carried out to assess the comparative benefits and shortcomings of each mode of fuel induction. Low-pressure direct cylinder injection (LPDI) Hydrogen flow commences after opening of the intake valve but completed prior to intake valve closure ![]()
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