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INDUSTRIAL AND L ARGE ENGINES

Future-proof Crankcase
Ventilation Systems

INDUSTRIAL

Emis sions© UT99Future-proof Crankcase
Ventilation Systems
Alternative fuels offer high decarbonization potential, while increasing power densities and higher
oil temperatures improve engine efficiency. However, these trends have massive implications forcrankcase ventilation systems, which are exposed to higher aerosol concentrations as well as toxic
and potentially explosive gases. UT99 is therefore upgrading its crankcase ventilation systems interms of performance and flexibility.

2W R I T T E N BY

Crankcase ventilation systems
separate oil from the aerosol flow andreturn it to the oil pan. Thus, they makea crucial contribution in reducing oil
consumption and particulate matter(PM) emissions. Besides, such systems
also regulate the pressure in the crank­case to avoid leakage and reduce wearof seals. FIGURE 1 shows a schematic ofa closed crankcase ventilation (CCV)system consisting of two main compo­
nents, namely an oil mist filter and apressure control unit.
In recent years, improvements in aero­sol filtration efficiency have made CCV
systems the preferable option over open
systems [1]. This is especially true forengines running on gaseous fuels, as it
not only allows further reducing harm­
ful emissions but also increasing energy
efficiency by recirculating unburned fuelinto the combustion chamber. Such sys­
tems require very high separation effi­
ciencies > 99.5 wt% to avoid fouling of
the intake air and ensure r­ eliable turbo­
charger operation.
It is known from the literature [2] thatgeneral trends in engine development
include increasing oil temperature, in­­creasing Brake Mean Effective Pressure(BMEP), and increasing power density.
These trends have a major influence on
crankcase aerosol properties. Ultimately,
aerosol concentration increases and theshape of the particle size distributionchanges toward sizes near the most pen­etrating particle size (MPPS) [3, 4]. The
MPPS is typically around 0.2 to 0.5 µm
and represents the size that is least effec­
tively separated by an aerosol filter. To
counteract this development, crankcase
ventilation systems are constantly being
optimized. In addition, such systems areplaying an increasingly important role inachieving com­pliance with EU, EPA and
IMO limits for PM emissions.
gDipl.-Ing. Niclas Nowak
is Head of Research &Technology at UT99 AG
in Andelfingen (Switzerland).

Dipl.-Ing. Nicolai Roller
is Head of Development &­E ngineering at UT99 AG
in Andelfingen (Switzerland).

Dipl.-Ing. Christian Stieler
is Member of Customer Engineering
Crankcase Ventilation at UT99 AG
in Andelfingen (Switzerland).

FIGURE 1 Closed crankcase ventilation schematics (© UT99)

ALTERNATIVE FUELS

The type of fuel has a direct influenceon the composition of the aerosol in thecrankcase. While it is not possible todraw a general picture of particle con­centration and size for different fuels,as these are highly dependent on engine
design and oil properties, changes in gas
phase composition are predictable. The
main sources of crankcase gases are thegases that flow past the piston rings andthe turbocharger bearing. These gases,

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INDUSTRIAL

Emis sions

FIGURE 2 Engine running on 100 % hydrogen, equipped with aninsulated oil mist separator from UT99 (© 2G Energy)

also known as blow-by, contain por­tions of the actual fuel, fresh air, oilvapor, and combustion products.
Engines running on methanol andammonia generate crankcase aerosols
with high toxicity. This makes CCV­systems essential to prevent these gas­­es from being released into the envi­
ronment without catalytic treatment.
They should ensure reliable and pre­cise control of crankcase pressure by
maintaining the pressure typically at-1 to -5 mbar below the atmosphericlevel. In some cases, this may require
an auxiliary blower, especially if thecrankcase gases are to be returned tothe exhaust rather than the intake air,where exhaust backpressure must beovercome. This ventilation setup avoids
corrosion in the intake air, which canbe particularly relevant with ammonia.
Engines running on hydrogen gener­
ate crankcase gases that may containhydrogen concentrations exceeding
the lower explosion limit of 4 vol%.
Therefore, a ventilation system witha blow­­er may be required to purge
the crankcase with filtered air. Addi­
tionally, ATEX (­Atmosphères Explosi­­bles)-compliant ventilation systems
further reduce the risk of explosion.
Another challenge arises from thecombustion of hydrogen, which forms
large quantities of water that must be
kept in the gas phase by controlling
the temperature in the ven­tilation sys­tem, for example, through insulation.
Otherwise, the oil quality would dete­riorate, and emulsions could form

4

that eventually clog the ­filter. F­ IGURE 2
shows an engine running on 100 %hydrogen that is equipped with aninsulated UT99 filter.
CRANKCASE
VENTILATION SYSTEMS

In view of the new challenges posed byalternative fuels, the UT99 filter systems
are based on compatible materials suchas glass fiber, stainless steel, aluminumand PA66-GF50. Reliable operation isensured by a high-performance filter
media characterized by a steady-statepressure drop < 20 mbar and a separa­tion efficiency > 99.5 %, correspond­

FIGURE 3 UPF-SauKuL configuration
examples (© UT99)

ing to a residual aerosol concentration
typically < 5 mg/m3. These character­istics can be adjusted according to therequirements of the specific applica­tion by changing the media composi­tion to allow pressure drops < 10 mbar
and/or residual aerosol concentrations< 1 mg/m3.
The development of the filter series
UPF-SauKuL (Under Pressure Filter-­
Saubere Kurbelgehäuse Lösung)focused on modularity to ensure ma­­­­ximum flexibility in system design,
FIGURE 3. This means that the filters
can be arrayed in multiple layouts toensure a compact footprint, optimum
performance, and low cost on engine
series with different cylinder/power­configurations. Besides, the system
can be further customized with an­auxiliary blower or an Electronic
Pressure Regulator (EPR) to control
crankcase pressure and enable a purge
air ­system.
Additionally, pressure sensors
and a UT99 blow-by flow meter canbe installed. These options generatevaluable data that enable smart func­
tions such as monitoring, diagnostics,and predictive maintenance. Informa­tion is obtained not only on the statusof the crankcase ­ventilation system,
but also on engine wear, which canbe determined by blow-by flowrate analysis.
In summary, the advantages of theUT99 crankcase ventilation systems
are as follows:

www.ut99.com– ready for alternative fuels ina wide range of applicationsbetween 250 to 46.000 kW– high filtration performance with­separation efficiency > 99.5 %,– pressure drop < 20 mbar, andup to 32.000 h of maintenancefree operation– accurate crankcase pressure regula­tion within ±1 mbar of setpoint byblower system or EPR– new benefits through digital status
reports of the crankcase ventilation
system and blow-by flow rate data.

EPR-CCVELECTRONICPRESSURE REGULATORFOR CLOSEDCRANKCASE VENTILATIONWORLDPREMIEREAEROSOL FILTRATION

Detailed knowledge about the pro­
perties of the crankcase aerosol isthe foundation of filter development.
It is known that the blow-by flow
contains a very broad oil droplet size
dis­tribution ranging from tens of nano­meters to hundreds of microns [5].
Ty­­pical total crankcase aerosol con­centration is around 1000 mg/m3. How­ever, in practice, concentrations rang­
ing from 300 to more than 2000 mg/m3
have been observed. This underlines
the need to obtain aerosol data fromthe actual application to ad­­just filter
properties for the best fit.
UT99 filters are developed on custom
test rigs that mimic these conditions toobtain results that are relevant to theac­­tual application. FIGURE 4 gives an ideaof the performance of one standard UT99
UPF-SauKuL filter operating at 80 °C,500 l/min, and a raw aerosol concentra­tion of 900 mg/m3. The results show thatthe aerosol concentration down­­streamof the filter is always < 1 mg/m3 andthe pressure drop < 14 mbar, even whenreaching steady-state after about 50 h ofaerosol exposure. This state is reachedwhen no additional oil accumulates in
the filter. In practice, the steady-stateis a pseudo-stable-state because ash,soot and viscous organic components
reduce the permeability of the filter.
These processes must be considered todetermine the time frame between fil­­ter changes.

Advantages throughoptimal pressure conditionsin the engine's crankcase• No leakage of oil mist into the environment.
• No contamination of the lubricating oil
by dust sucked in as well as reduced wearof bearings and shaft seals.
• Increased service life of the oil mist filter.

Intelligent functions• Fail-safe, even in the event of a power failure.
• CANopen® bus interface for motormonitoring, maintenance and diagnosis.

PRESSURE REGULATION AND
BLOW-BY FLOW MONITORING• Prepared for IoT andCloud analytics platforms.

UT99 has a long history of providing
Open Crankcase Ventilation (OCV) blow­­ersystems designed to regulate crankcase• FlowSpin (optional) enables
extended engine and oil
oil mist filter diagnostics.

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INDUSTRIAL

Emis sions

pressure. This is accomplished througha robust control unit that uses the crank­case pressure signal to adjust the blowerspeed. Blower systems used in CCV em­­ploy a similar design that takes into ac­­count the intake air vacuum provided by
the turbocharger.
For applications that do not requirea blower, UT99 recently introduced theEPR. The EPR is a maintenance-freemechatronic throttle that was specifi­
cally developed to adjust crankcase
pressure within ±1 mbar of the set­point. The device is placed in thecrankcase ventilation path between
the oil mist separator and the intake
air. While the external dimensions
always remain the same, the geome­try of the throttle body can be custom­ized by selecting one of five versions
between DN14 and DN50. This ensures
optimum pressure control accuracy
for a wide range of flow and pressure
conditions [5]. The throttle angle iscontrolled by the integrated data pro­cessing unit. This unit uses the actual
crankcase p­ ressure signal obtained
directly from a sensor or from the en­­gine control unit. Advanced featuresare supported, including EPR status
reporting via CAN bus communica­tion and blow-by flow monitoring
through an optional flow meter con­nected directly to the EPR, F­ IGURE 5.
The UT99 blow-by flow meter isalso available in a stand-alone ver­sion with two impeller geometries
and a measuring range of 150 to2500 l/min. Current­­ly, this device isbeing tested in field trials. FIGURE 6shows results of these tests, which
focus on the correlation of flow meter
speed with actual blow-by flow rate
determined with a ­reference device.
Apparently, the measurement accu­racy is stable, even after several thou­sands of hours of operation.

FIGURE 4 Filter pressure drop and clean gas aerosol concentration (© UT99)

FIGURE 5 EPR equippedwith the optional blow-bymeter (© UT99)

CONCLUSIONS

Crankcase ventilation systems are in­­creasingly coming into focus due to thechallenges associated with alternativefuels, high separation targets, and re­­gu­
latory requirements. UT99 addresses
these challenges with crankcase ven­­tilation solutions that are compatible,
highly efficient (> 99.5 %), and cus­tom­
izable. There is a wide product portfolio,including crankcase pressure control by

6FIGURE 6 Actual blow-by flow rate plotted against the flow meter frequency (© UT99)

www.ut99.com

a blower system or an EPR that also pro­vides digital data on the s­ tatus of theventilation system. Valuable data is also
provided by the UT99 blow-by flow me­­ter, which can be used not only for pre­dictive replacement of fi­ lter elements
but also for analysis of engine wear.
With this customizable ventilation­system and further developments inclose cooperation with OEMs, solu­
tions are found that meet the require­ments of the respective application.
REFERENCES[1] Oppliger, R.; Stieler, C.: Advantages of Closed
Crankcase Ventilation for Large Engines
In: MTZworldwide 11/2020, pp. 66-71[2] Figer, G.; Schmidleitner, K.; Schönbacher, M;
et al.: 300 bar Peak Firing pressure for a New Generation of Diesel and Gas engines. In: MTZworldwide 6/2019, pp. 70-75[3] Scheiber, K.; Nowak, N.; Lorenz, M.; et al.:Comparison of four diesel engines with regard toblow-by aerosol properties as a basis for reduction
strategies based on engine design and operation.
In: Automotive and Engine Technology 6/2021,pp. 79-90[4] Nowak, N.; Sinn, T.; Scheiber, K.; et al.: Onaerosol formation by condensation of oil vapor in
the crankcase of combustion engines, In: Aerosol
Science and Technology 2/2022, pp. 101-116[5] Nowak, N.; Sirtl, C.; Rymann, O.; et al.:­A erosol Separation and Pressure Control of a
Smart Crankcase Ventilation System. In: Proceedings of the ASME 2022 ICE Forward Conference,
Indianapolis, 2022

HIGH PERFORMANCE
BLOW-BY-FILTERPLATFORM

FOR COMBUSTION ENGINESUP TO 4000 KW

Advantages• scalable platform• mountable on the engine• robust and service-friendly• configurable interfaces• integrated oil drain• compact unit
• low pressure drop

RESIDUAL OIL CONTENTAFTER FILTRATION< 1mg/m3

Characteristics• engines up to 4000 kW
IMPRINT:Special Edition 2023 in cooperation with UT99 AG,
Schaubenstrasse 5, 8450 Andelfingen;Springer Fachmedien Wiesbaden GmbH,
Postfach 1546, 65173 Wiesbaden,
Amtsgericht Wiesbaden, HRB 9754, USt-ldNr. DE81148419
MANAGING DIRECTORS:
Stefanie Burgmaier | Andreas Funk | Joachim Krieger
PROJECT MANAGEMENT: Anja Trabusch
COVER PHOTO: © Bertold Werkmann | Stock.adobe.com• for open (OCV) and closed crankcase

ventilation (CCV) systems• for genset, marine and off

highway application at gas,dual fuel and diesel engines• for applications with ammonia,

methanol and hydrogen as fuelSwitch to CCV and benefit from the 7advantages of a clean crankcase ventilation

MARKET LEADER
WITH A PASSION FORPERFECTION ANDENVIRONMENTAL
PROTECTION

UT99 AG
Schaubenstrasse 58450 Andelfingen
Switzerland

www.ut99.com