TechnicalTechnical Reference Reference Technical Paper — Spiracle™ Crankcase Filtration Technical Article Spiracle™ Crankcase Filtration Technology Author: For more than 30 years, a focus on environmental air Veli Kalayci improvement has led original equipment manufacturers Spiracle™ Systems Team Leader (OEMs) to require their manufacturing business partners to design filtration systems that reduce the amount of crankcase blow-by aerosols vented into the atmosphere from diesel engines. This push to reduce diesel emissions and other particulate matter (PM) contaminants from the atmosphere began in the 1970s with the passing of the 100% 100% U.S. Environmental Protection Agency (EPA) Clean Air Act, 90% 90% which regulated on-road diesel emissions and was later 80% s 80% s amended, in 1990, to include regulations for off-road diesel n n o o i i s 70% s 70% s s i i vehicles. These standards set maximum allowable levels of m m E E 60% 60% AIR FILTRATION TECHNICAL REFERENCE AIR FILTRATION M emissions for new diesel engines and diesel fuel that have M P P l 50% l 50% a a t t been incrementally reducing emissions levels since 1988. o o T T 40% 40% f f o o t t n 30% n 30% e e c c r r With the significant technology advancements achieved in e 20% e 20% P P FIGURE 1 10% 10% curbing the exhaust emissions from the engine tailpipe, the EMISSIONS CONTRIBUTIONS 0% TAILPIPE & CRANKCA0%SE relative contribution of the emissions from the crankcase 1988-1990 1991-1993 1994-2006 2007 1988-1990 1991-1993 1994-2006 2007 blow-by aerosols started to become an increasing % Crankcase Contribution % Tailpipe Contribution % Crankcase Contribution % Tailpipe Contribution 100% contributor in total engine emissions. Figure 1 shows the 90% increasing relative contribution of crankcase emissions for 80% s on-road engines through 2007. n o i s 70% s i m E 60% As these regulations evolved in the U.S. and around the M P l 50% a world, Donaldson Company, a leading manufacturer t o T 40% f o of air and liquid filtration systems and replacement t n 30% e c parts, led the industry in the development of crankcase r e 20% P filtration technologies with the Spiracle™ Crankcase 10% Filtration Systems (CFS). The engineering advancements 0% 1988-1990 1991-1993 1994-2006 2007 of Spiracle™ CFS have continually been used to help Crankcase% emissionsCrankcase Contribution levels in diesel engines% Tailpip e Contribution meet the EPA’s stringent regulatory have remained relatively low compared to tailpipe emissions until 2006. On newer engines, requirements by providing high as emissions from tailpipes reduce, crankcase efficiency filtration solutions to OEMs emissions become a greater share of total allowable particulate matter (PM) emissions. and fleet operators around the world. www.buydonaldson.com Engine Air Filtration • 241 Technical Reference Technical Paper — Spiracle™ Crankcase Filtration Crankcase Ventilation Filtration distribution. Just as important, the crankcase emissions can vary Systems depending on the engine design especially the tolerances, materials, turbocharger, wear factors and operating conditions can impact the Crankcase ventilation filtration systems amount of blow-by escaping past the piston rings. are designed to be either "open" or "closed" systems. Donaldson has developed engine blow-by characterization methods and tools as part of its standard range of capabilities for crankcase Open crankcase ventilation filtration filtration technology and product development. One such piece systems (OCV) filter engine aerosols, of equipment is a mobile blow-by characterization system that including oil and soot, along with any Donaldson uses to measure the blow-by output of diesel engines. The bulk oil coming out of the valve cover or test bench can quantify the gravimetric and fractional content of the crankcase vent and discharges filtered blow-by mass output, volumetric flow rate, pressure and temperature air into the atmosphere. at different engine operating conditions. In closed crankcase ventilation filtration systems (CCV), crankcase blow-by aerosols, including oil and soot, are FIGURE 2 CRANKCASE BLOW-BY CHARACTERIZATION AT THREE filtered and the filtered crankcase flow ENGINE OPERATING MODES is directed back to the intake manifold 2.0E+07 or to the turbo compressor. Using high efficiency closed crankcase filtration 1.8E+07 systems, the performance of intake 1.6E+07 OEM No. 1 filters, turbochargers, aftercoolers Idle and exhaust system components can 1.4E+07 Rated Speed Road be maintained over extended engine 1.2E+07 usage. 1.0E+07 OEM No. 2 Idle 8.0E+06 Rated Speed Crankcase Emissions from Diesel Road Engines and Emission Control 6.0E+06 4.0E+06 Crankcase emissions are created Number Concentration dN/dLogDp (#/cc) during the combustion process of 2.0E+06 reciprocating engines. The primary source of crankcase emissions are 0.0E+00 0.02 0.03 0.04 0.070 .15 0.26 0.43 0.731 .17 1.86 2.94 combustion gases and particulate Particle Size (µm) matter (PM) that escape past the piston rings and enter the crankcase. Other FIGURE 3 sources of crankcase emissions include PEAK ENGINE TORQUE COMPARISON WITH AND WITHOUT turbocharger shaft seal leaks, valve SPIRACle™ FILTRATION SYSTEM AIR FILTRATION TECHNICAL REFERENCE AIR FILTRATION guides and general movement of parts. These "blow-by" gases must be vented through a tube into the atmosphere to avoid pressurizing and damaging components of the engine. After mixing with oil mists in the crankcase, the gases, PM, and oil aerosols either coalesce and drop out of the vent tube onto the ground, or enter into the atmosphere as pollutants. Crankcase emissions vary greatly depending on a number of factors. Engine rating, displacement, engine operating conditions such as load, speed and the age of the engine all influence the blow-by volumetric flow rate, mass output rate and particle size 2 242 • Engine Air Filtration www.buydonaldson.com TechnicalTechnical Reference Reference Technical Paper — Spiracle™ Crankcase Filtration The mobile blow-by characterization system allows Donaldson to The precise dimensions, shapes and quantitatively assess their customers’ crankcase emissions under innovative fiber bonding of the dynamic conditions (Fig. 2 and Fig. 3) from their diesel engines and Synteq XP media provide the ideal tailor filtration systems to address these needs. This cutting-edge solution for the challenge of balancing technology allows Donaldson a unique capability in the industry and high efficiency and low pressure drop, provides the benefit of custom designed products to fit customer and increased filter life. needs. Larger particles, typically from 1 to 10 It is imperative that crankcase filtration manufacturers develop microns are efficiently separated by products that can handle crankcase emissions that vary significantly interception and inertial impaction. Sub- over the operating range and life of the engine. In addition, these micron particles, often the most harmful systems must be designed to operate in the extreme conditions for for compressor blades, are efficiently temperature, shock, and vibration – typical of medium- and heavy- separated by diffusion. Donaldson’s duty applications. Synteq XP media is specifically designed to combine interception, inertial impaction and diffusion, thereby offering Spiracle™ Filtration Technology high efficiency for all particle sizes (see FIGURE 4 Donaldson has a long track record SPIRACLE SYSTEM ON A Fig. 5). SCHOOL BUS of success with its Spiracle CFS After the oil mist particles are captured, technology. In an effort to meet EPA’s they are coalesced into larger droplets continued mandates and realizing the and drained from the media. The (1) health benefits to passengers , school drainage within the media pack is also bus fleet owners have installed a optimized. Pressure drop across the Spiracle CFS combined with a second self-draining filter is kept low and stable emissions reduction technology; i.e., over time, and no engine downtime is Diesel Oxidation Catalysts (DOC), required to drain the oil out of the media TECHNICAL REFERENCE AIR FILTRATION Diesel Particulate Filters (DPF) or a pack. Diesel Multi-stage Filters (DMF). The combination creates a retrofit solution The large pore size of Synteq XP media that delivers maximum emission (Fig. 6) reduces the pressure drop across the filter. Multiple layers of the reduction both inside and outside the As part of California ARB and US EPA bus. emissions retrofit programs, over 16,000 media allows custom design flexibility units have been installed on school for a wide range of filtration efficiencies Crankcase filtration manufacturers buses and trucks across the U.S. and field life depending on the needs are challenged to tailor their products and requirements of OEMs. to meet a host of manufacturers’ applications with differing size, efficiency, pressure loss, and life requirements while delivering high efficiency filtration and reliability. FIGURE 6 SCANNING ELECTRON With the introduction of Donaldson Synteq XP™, a revolutionary, MICROGRAPHS OF SYNTEQ XP™ MEDIA @ 200X patented filter media, Donaldson engineered the Spiracle CFS creating new open and closed crankcase filtration systems solutions. FIGURE 5 PARTICLE SIZES AND FILTRATION PRINCIPALS Synteq XP ™ Close-up of Synteq XP media (clean) Close-up of Synteq XP media after 1200 hours of field use. The open areas that are free of contaminant offer additional filter service life. 3 www.buydonaldson.com Engine Air Filtration • 243 Technical Reference Technical Paper — Spiracle™ Crankcase Filtration One of the unique FIGURE 7 A Better Product and Technology features of Synteq XP FILTER OIL LINE COMPARISON to Control Diesel Engine filtration technology is AFTER 16 HOURS Crankcase Emissions its exceptional ability Steady State Oil Line Height Comparison Donaldson Spiracle CFS is a serviceable to coalesce oil and after 16 hours then drain. unit. Its benefits include lower cost, higher efficiency, and reliability over a Oil that is held in the Oil soaked area wide range of engine conditions and filter will increase is blocked or longer filter life creating less demand on pressure drop and plugged media the diesel engine.