Naturally aspirated engines and turbocharged engines from MAN Engines

Focussed on generating power or heat: best possible efficiency using application optimised gas engines

Within its gas engine portfolio, MAN Engines offers a wide range of turbocharged engines with lean-burn combustion as well as naturally aspirated engines with stoichiometric combustion. Each type of engine technology offers particular advantages, depending on the application. Irrespective of whether the principal focus is on generating power or heat, MAN Engines has the right solution for more efficiency and greater effectiveness.

Advantages of MAN naturally aspirated engines

MAN naturally aspirated engines are the perfect choice when the primary purpose is to generate heat. With a combustion air ratio of λ=1, naturally aspirated engines generate an output of thermal energy around three to six percent higher than that of turbocharged engines. Since naturally aspirated engines do not have costly components such as turbo chargers and mixture coolers, their cost price is significantly lower than that of turbocharged engines. The reduced use of maintenance-intensive components, combined with lower mechanical and thermal stress, also mean longer maintenance intervals and minimized maintenance costs. A particular advantage of MAN naturally aspirated engines is their use of an inexpensive three-way catalytic converter. This reduces nitrogen oxides (NOx) and carbon monoxide (CO) to very low levels < 100 mg/Nm3.

Naturally aspirated engines from MAN Engines are always the first choice where the primary focus is on generating large amounts of heat or where emissions have to be reduced to a low level by cost-effective and reliable means.

MAN Engines offers naturally aspirated engines for operation with natural gas in the power range from 34 kW to 300 kW for markets with grid frequencies of 50 Hz and 60 Hz. Its unrivalled position in the market is a clear sign of the advantages of the 300 kW range MAN Engines!

Advantages of MAN turbocharged engines

MAN turbocharged engines are turbocharged gas engines with lean-burn combustion. The turbocharging of these lean-burn engines delivers a gain in electrical power, which also enables higher mechanical efficiency. But also under adverse conditions and at high altitudes, cogeneration plants and generating sets with turbocharged engines from MAN Engines prove their performance and reliability in many ways. If solutions for exhaust gas aftertreatment are required, MAN can offer its proven SCR system for turbocharged engines. This has been proven time and again in a wide range of mobile applications.

Turbocharged engines from MAN Engines focus on generating power and the additional generation of heat. Furthermore, they are used rather than naturally aspirated engines in applications where high power outputs are required.

Turbocharged engines from MAN Engines are available at 1500 rpm and 1800 rpm in the power range 68 kW to 580 kW. They can be operated with natural gas or with CO2-neutral special gases, such as biogas from agricultural biogas plants or sewage gas from municipal sewage works.

Combustion air-fuel ratio (Lambda):
Stoichiometric combustion air-fuel ratio: The fuel-air mixture ratio in a combustion chamber of a gas engine is stoichiometric when all fuel molecules can react completely with the oxygen in the combustion air so that no residual oxygen or unburnt fuel remains. Such complete combustion is denoted by a combustion ratio λ (Lambda) = 1.
Rich combustion air-fuel ratio: If the air ratio is λ < 1 (e.g. 0.9), there is more fuel in the combustion chamber of the engine than the available air necessary for combustion (fuel-rich gas mixture).
Lean-burn combustion air-fuel ratio: Lean-burn engines work at a combustion air-fuel ratio/Lambda > 1. At for instance λ > 1.5, 50% more air molecules are supplied to the combustion process than are necessary for a stoichiometric reaction (fuel-lean gas mixture).

Comparison between a MAN naturally aspirated engine and a MAN turbocharged engine

Lambda 1-naturally aspirated engine   Turbocharged lean-burn engine
+++ Cost price per kW installed power +++
+++ Service interval ++
+++ Maintenance costs +
+++ Efficiency, thermal ++
+ Efficiency, electrical/mechanical +++
+ Power, electrical/mechanical +++
+++ Cost-effective lowest NOx emission standards achievable +
+++ Load response behaviour ++
Three-way catalytic converter Exhaust gas aftertreatment options SCR system + oxidation catalytic converter
Natural gas Service products Natural gas, special gases (e.g. biogas, sewage gas)

Reasons for choosing a gas engine from MAN Engines:

For decades, MAN Engines has been successfully engaged in the development and production of gas engines for power generation and for combined heat and power. This is reflected in its market penetration. Read about the advantages that MAN gas engines offer to their operators here.


Application example for a naturally aspirated engine focussed primarily on heat generation

A naturally aspirated engine is used for heating an assembly shop with a paint shop at the MAN factory site in Nuremberg, Germany.

The MAN E3262 E302 delivers 275 kWmech at 1500 rpm (50 Hz) and generates about 1.25 million kWh of electricity in the course of a year.

The V12-naturally aspirated engine from MAN Engines delivers 275 kWmech - a unique selling point in respect of mechanical power.

With its small physical size, the engine is predestined for use in a natural gas compact module.

Application example for a turbocharged engine focussed primarily on power generation

Biogas systems are a classic application for turbocharged engines from MAN Engines.

The turbocharged MAN E3262 LE202 engine was specially developed for biogas and special gas applications.

In continuous operation, the MAN engine runs more than 8,600 hours a year.

View into the upper container with an SCR catalytic converter for each of the two cylinder banks of the V engine. Generous room around the unit makes servicing easier.