ENGINE - 3 Modes
Mono Energy - Mode 1
(available on all MDI vehicles)
The pre compressed air in the tanks is
transferred to a chamber (called "active") which provides
“work” before being expanded in the cylinders to perform the
stroke phase. There are no polluting emissions generated and
the use of renewable energy in the air filling stations
allows the production of a completely clean energy loop
(compression - expansion).
Dual Energy Engine - Mode 2
The engine is the same as the Mode 1
engine, however a burner is added between the compressed air
storage tank and the engine. The burner provides a
continuous low temperature combustion increasing the volume
of the intake air and therefore increases the freedom and
independence of the system. The performance of the engine in
terms of torque and power remain identical to Mode 1.
This external continuous combustion at a controlled
temperature at around 600°C does not produce nitrogen oxides
or sulphur dioxides and eliminates any discharge of unburnt
hydrocarbons. Although using a fossil fuel, it is never the
less a clean engine. Unlike the internal combustion engine,
it is totally insensitive to the load (throttle position)
and provides unparalleled consumption efficiency.
For example, on an AirPod, only 0.3l/100km (or 6.8g of CO2
per km) are needed to heat up the air coming from the tanks
and double the range of the vehicle, and 0.5 l/100 km (or
11.4g of CO2 per km) are used to triple the range, up to
The operation in Mode 1 is always possible on the products
equipped with dual energy Mode 2 engines. Mode 2 is used on
all MDI vehicles.
Dual Energy Engine - Mode 3
Compared to previous modes, the dual-energy engine - Mode 3
has an augmented cylinder for the same purposes. In fact,
when the energy source is the fuel for the external
combustor, part of the power is used for motor output (as in
Modes 1 and 2), and the rest is used to compress the air
necessary for operation. Being a real external combustion
engine with active chambers, it augments the dual-energy
engine Mode 2 in terms of emissions, i.e. no oxides of
nitrogen and no unburnt hydrocarbons. It offers extremely
low consumption with a range of fuel options .
Fitted on an AirCity, only 2.5 litres of fuel are required
to travel 100 kms at 100kms/h (with only 57g of CO2 per Km).
The range is no longer linked to the volume of compressed
air stored and can reach close to 2,000 kms with a petrol
tank equivalent to those of the current cars. Insensitive to
the load (throttle position), the consumption obtained,
thanks to the dual-energy Mode 3, are less than 1l/100km in
urban cycle (for only 22.8g of CO2 per km).
The operations in Mode 1 and Mode 2 are always possible on
the products equipped with the dual energy Mode 3. This
clean engine will be offered on most of AVL’s vehicles
(except the AirPod).
The MDI engineers and technicians have created an efficient
an efficient thermodynamic cycle. They are constantly working
to improve the performance of their engines by working on
cycles which are as close as possible to the isothermal
expansion ideal. This is done at a constant temperature.
It’s also the one that produces the most work for a given
quantity of air and therefore corresponds to the best
In the active chamber engines developed by MDI, the filling
of a volume with air to expand already creates work
potential. This is one of the ways to move closer to the
isothermal expansion and therefore to increase the yield.
The lack of expansion valve and multi staged expansions
(allowing a recovery of thermal ambient energy), are other
elements which, associated with the active chamber, allow
MDI to obtain exceptional yields between 68 and 75%.
Dual energy mode efficiency When using the dual energy mode, one
must not only consider the phases of compression and
expansion of the compressed air, but also the efficiency of
the combustion (being continuous and external to the
engine). The increase in the temperature difference between
the cold source (air tank at ambient temperature) and the
hot source of the system (combustion) leads to an increase
in the overall efficiency which in "Mode 2" is between 50
and 67% for a combustion not exceeding 600°C.
Bigger Engine 72 kW
MDI has two production
engines that cover its multiple applications:
- Small Engine
- 7 kW @ 1,500 rpm, 45 Nm, 430 c.c.
- Bigger engine
72 kW @ 3,000 rpm, 230 Nm, 1,000 c.c.
Engine 7 kW
The engines can be grouped together (‘banked’)
so, by way of example for electricity production, if 8 engines were
banked with each engine providing 7 kW of electricity the total
electricity provided would be 56 kW. Similarly 8 of the larger
engines banked together would provide over 500 kW of electricity.
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