Page 31 - Kỷ yếu hội thảo quốc tế: Ứng dụng công nghệ mới trong công trình xanh - lần thứ 9 (ATiGB 2024)

22 TRƯỜNG ĐẠI HỌC SƯ PHẠM KỸ THUẬT - ĐẠI HỌC ĐÀ NẴNG

2. METHODOLOGY between 60 and 130 vacuum pressure points. When
the engine runs at 7500rpm with this arrangement, the
HHO supply valve will open between 30ºCA and
180ºCA (Figure 3b). This variation has an impact on
the ratio of HHO pulled into the cylinder, which
makes it difficult to properly regulate the gas mixture.
Additionally, when HHO is not drawn into the engine
completely, it can backfire because it builds up on the
intake manifold.
At the end of the compressed phase, the desired
HHO/air ratio and equivalency ratio (ϕ=1) are not
achieved due to the vacuum valve not opening
Fig. 1. Supplemental HHO supply by suction method continuously under low vacuum pressure conditions
a) Supplemental HHO supply by injection method b) at the venturi throat. This also results in leftover HHO
in the intake manifold, which might ignite the
Intake manifold, combustion chamber, and remaining gas mixture, particularly when the cylinder
cylinder are all included in the computation space. temperature is high.
The cylindrical longitudinal section at 90°CA and the
computational space at 0°CA and 180°CA are shown
in Figure 2. Dynamic meshing was used in the
cylinder space because of the volume shift that occurs
during piston displacement. To compare the
assessment of backfire ability, simulations were run
using the Ansys Fluent 2021R1 program. Initially, an
additional HHO supply was simulated using the
suction approach, and subsequently, an additional
HHO supply was simulated using the spray method.
Regarding the quantity of H 2 left in the intake
manifold, this is the primary issue with supplying
more HHO.

Fig. 2. Fuel content, HHO, HHO/air ratio, and ϕ in Fig. 3. Changes in pressure at the venturi throat in
relation to crankshaft rotation angle response to the crankshaft rotation angle when the HHO
a), gasoline concentration, H 2 and ϕ on intake pipe is not being supplied (a) and when it is supplied b)
b), and HHO supply via suction method (n=7500rpm,
p=2000Pa)
3. RESULTS AND DISCUSSION
3.1. Supplement hho using a suction technique
The pressure differential at the venturi throat
determines how much more HHO is supplied to the
engine via the vacuum valve (Figure 1a). HHO can
enter the intake manifold when the valve opens due to
the throat vacuum pressure exceeding the valve spring
tension. Due to its reliance on engine speed and load,
this vacuum cannot be actively adjusted.
Figure 3a illustrates that the suction at the throat
only reaches 15000Pa at engine speed of 3000rpm,
but reaches a maximum of 35000Pa when engine
speed is 7500rpm. When the engine runs at 3000rpm,
the vacuum valve, if it is intended to open, will open
ISBN: 978-604-80-9779-0