SUFFIELD, CT, Nov 18, 2009 (MARKETWIRE via COMTEX) —-Evans Cooling Systems, patent holder and manufacturer of the only commercial waterless engine coolants, has produced a podcast focused on the benefits of waterless cooling technology for Rotax engines, which are popular in small aircraft and in UAVs.

A recent FAA revised Special Airworthiness Bulletin (SAIB) recommended that waterless coolants be used in certain Bombardier-Rotax engines. The podcast addresses the potential issues of conventional ethylene-glycol/water coolant use in Rotax 912 and 914 series engines if the engine coolant exit temperatures exceed 120 degreesC. Dangers include possible coolant losses, engine overheating, knocking, engine damage or in-flight shutdown.

The podcast details the advantages of using waterless coolant in these engines, including the higher boiling point of Evans waterless coolants — above 180 degreesC at atmospheric pressure. This provides a wide separation between its boiling point and the operating temperature of the system, avoiding the danger of overheating and possible engine shutdown.

Evans Cooling Technology Podcast Series focuses on the latest trends and developments in engine cooling. This podcast can be downloaded at http://www.evanscooling.com/media-gallery/. For more information on Evans waterless coolants, visit the Evans website at www.evanscooling.com, or call +1.860.668.1114.

About Evans Cooling Systems, Inc.

Evans Cooling Systems, Inc., with headquarters and R&D facilities in Sharon, Conn., has focused on engine cooling and related areas for over 35 years. The company has a distribution center, as well as a team of high performance engine cooling experts based in Pottstown, Penn., a heavy duty diesel sales and marketing office in Suffield, Conn., as well as facilities in China. Evans is committed to maintaining a cleaner, safer environment, and continually seeks to improve product and process choices for many heavy duty diesel, high performance and mainstream engine applications. Evans waterless engine cooling technology is used today by numerous fleets, with trials in process at major carriers worldwide. www.evanscooling.com, +1.860.668.1114.

Cuts Fan-On Time by Over 50 Percent, Reducing Fuel Consumption

SUFFIELD, Conn. – September 9, 2009 – Evans Cooling Systems (www.evanscooling.com), developer of the only waterless engine coolant, will showcase the benefits of its revolutionary waterless cooling technology for waste management vehicles at WASTECON 2009, Booth #1843, on September 22 -24, 2009 in Long Beach, Calif.

Earlier this year, Evans introduced its Heavy Duty Thermal Coolant (HDTC), and initial tests results show fuel savings and lower maintenance costs among a broad range of engine types and applications, including waste management vehicles.

A year-long test for USA Hauling showed fuel savings of 7.2 percent after using Evans’ HDTC, resulting from a greater than 50 percent reduction in fan-on time. Fan-on time totaled just over 300 hours, compared to the estimated fan-on time of more 700 hours required without Evans coolant.

Evans HDTC has a higher boiling point — 150 degrees warmer than the operating temperature of most engines — allowing the engine to safely operate at slightly higher temperatures. The huge separation of the boiling point from the operating temperature enables raising the fan-on temperature to 230°. Raising the fan-on temperature is critical, since the fan on a heavy duty diesel engine draws a considerable amount of horsepower, using significant amounts of fuel.

“Evans has learned that fan-on time on waste management vehicles can contribute significantly to fuel consumption, and with our waterless cooling systems we are able to deliver measureable fuel cost savings,” said Mike Tourville, Director of Marketing, Evans Cooling Systems. “Another major benefit of Evans waterless coolant for the waste management industry is lower maintenance costs, as our technology eliminates the corrosion and cavitation caused by water-based coolants — and our coolant never needs to be replaced.”

Independent testing has also proven that Evans’ cooling technology results in maintenance savings, all while providing a more environmentally friendly solution. In a recently completed John Deere Cavitation test, researchers found cylinder liner cavitation was significantly reduced when Evans HDTC was used for cooling. The absence of water and the resulting lower cooling system pressure maintains a virtual hermetically sealed system and reduces stress on cooling system plumbing and hoses. By preventing corrosion and pump and cylinder liner cavitation, Evans HDTC can deliver major maintenance savings.

Evans waterless engine cooling technology is in use in numerous fleets and by individual truck owners who have gone hundreds of thousands of miles without changing coolant.

1. Which engine coolants are water-based? All commercially available engine coolants, except Evans coolants, are water-based.

 

2. What is good about water in a coolant? Water is cheap. Water in the liquid state has excellent thermal conductivity characteristics.

 

3. What is bad about water in a coolant? The boiling point of water is too low. There is very little separation between the operating temperature of the coolant and the boiling point of water for the pressure of the system. The boiling point of water is the failure temperature of the cooling system. Water vapor has almost no thermal conductivity. Water is aggressive toward cooling system metals and promotes electrolysis between dissimilar metals within the cooling system.

 

4. Water-based coolant is mostly 50% glycol and 50% water. Why isn’t the failure temperature the boiling point of the mixture, rather than the boiling point of water? Some locations within the cylinder head generate so much heat that some of the nearby coolant boils. When local coolant boils, the resulting vapor is nearly 100% water vapor. If the coolant that is surrounding the water vapor is above the boiling point of water, the water vapor cannot condense. Under this condition, the water vapor makes an insulating barrier between hot metal and liquid coolant, causing the temperature of the metal to spike to high levels.

 

5. Why is the vapor from boiling a 50/50 glycol/water mixture (EGW) nearly 100% water vapor? When the mixture is boiled the water part is fractionally distilled, as it is far more volatile than the glycol portion. Water vapor is liberated while the glycol remains in the solution.

 

6. What are various boiling points of interest? Water at sea level (1 atm. absolute) boils at 212° F.
   Water at sea level with a 1 atm. pressure cap (2 atm total) boils at 250° F.
   EGW at sea level (1 atm. absolute) boils at 224° F.
   EGW at sea level with a 1 atm. pressure cap (2 atm. total) boils at 263° F.
   Evans Waterless HDTC at sea level (1 atm. absolute) boils at 375° F.

 

7. What happens to the boiling points at higher elevations? The boiling points decline as the altitude increases.
   Water at 5000 ft. (0.83 atm. absolute) boils at 207° F.
   EGW at 5000 ft. (0.83 atm. absolute) boils at 218° F.
   Evans Waterless HDTC at 5000 ft. ( 0.83 atm. absolute) boils at 368° F. 

 

8. What is pump cavitation and how can it occur? Action of the coolant pump creates a low pressure area at the pump inlet. Pump cavitation occurs when coolant near its boiling point encounters the low pressure area and flash vaporizes within the pump. The gas pocket in the pump causes the pump to stop functioning and coolant circulation to stop. Coolant pump cavitation leads directly to catastrophic cooling system failure with the coolant being expelled from the system as steam pressure exceeds the pressure relief setting of the cap.

 

9. What is Afterboil? After-boil occurs after shut-down of a stressed engine when the coolant is near its boiling point and residual heat remains in the cylinder head or in an auxiliary circuit such as an EGR cooler. Upon shut-down the coolant pump ceases to circulate coolant through the cooling system. Residual heat boils the stagnant coolant, making steam pressure that exceeds the pressure relief setting of the cap. Coolant is pushed out of the system.

 

10. What is the primary purpose of an engine cooling system? To keep engine metal temperatures under control.

 

11. What burden must be uniquely borne by a functioning cooling system using any water-based coolant? The cooling system must keep the coolant below the boiling point of water for the pressure of the system under all operating conditions and after shut-down. This task is difficult because the coolant frequently operates close to the boiling point of water.

 

12. What is the most important operational feature of Evans Waterless HDTC? The huge separation between the operating temperature and the boiling point of the coolant, on the order of at least 100° .

 

13. What is the Reserve Capacity made available by changing to waterless Evans Waterless HDTC? The huge separation between the operating temperature and the boiling point of Evans Waterless HDTC unlocks a Reserve Capacity that already exists in systems designed for water-based coolants. Any cooling system designed to keep coolant below the boiling point of water for the pressure of the system under all operating conditions and after shut-down is liberated from those requirements with Evans Waterless HDTC. When temperatures happen to be higher, there are no failures due to the lower boiling point of water. In a 100° F environment a radiator that is 250° F will dissipate 25% more heat than one at 220° F.

 

14. Is Evans advocating operating engines at substantially higher temperatures? Not really. Operating temperatures are normally only slightly warmer than those of water-based coolant. When the engine is stressed and temperatures rise, the cooling system can accommodate that increase in temperature without cooling system failures.

 

15. How does Evans Waterless HDTC prevent engine hot spots? The huge separation between the operating temperature and the boiling point of Evans Waterless HDTC provides an environment where any locally generated coolant vapor immediately condenses into adjacent liquid coolant. Vapor cannot build into an insulating barrier, and contact between hot metal and liquid coolant is maintained at all times. Metal temperatures are under control at all times.

 

16. How does Evans Waterless HDTC prevent after-boil? After shut-down, the huge separation between the operating temperature and the boiling point
    of Evans Waterless HDTC has the capacity to absorb heat from hot metal parts of the cylinder head Boiling is avoided and there is no build-up of pressure to force coolant out of the system. Stresses on cylinder heads and EGR heat exchangers are avoided as metal temperatures are kept under control.

 

17. How does Evans Waterless HDTC prevent pump cavitation? The low pressure area of the coolant pump is never at a low enough pressure to flash vaporize. The pump never gets vapor bound and has the capability to pump coolant over a broad range of temperatures.

 

18. How does Evans Waterless HDTC prevent cylinder liner cavitation erosion? Cylinder liner cavitation erosion is a problem in water-based coolant systems. As the piston moves inside the cylinder there is vibration of the liner. The vibration of the liner against the coolant alternately makes low and high pressures. During the low pressure instant, vapor is created by flash vaporization. During the adjacent high pressure instant, the vapor collapses against the cylinder liner. This repeated action causes an attack against the metal liner, resulting in cavitation erosion.

 

19. How does Evans Waterless HDTC save fuel? In spark ignition engines Evans Waterless HDTC coolant saves fuel by better control of metal temperatures and the avoidance of hot spots. The consequent reduction of knock permits more efficient spark settings on engines having electronic controls with knock sensing inputs. In heavy duty engines having on-off fan clutches, the “on” temperature can be increased to 230° F, keeping the fan off a large percentage of the time and reducing a significant source of parasitic drag.

 

20. How long will Evans HDTC and its additives last? Evans Waterless HDTC coolant will last the life of the engine as long as it is not contaminated with water.

 

21. How do the additives in Evans Waterless HDTC remain in solution without the presence of water? Evans Waterless HDTC contains no additive that requires water to dissolve or to enable the additive to function.

 

22. How much water is acceptable after a conversion to Evans Waterless HDTC coolant? In heavy duty diesel applications the water content must not exceed 3.0%. Dry engine installation of HDTC is preferred.

 

23. How does one test for the percent water content? The water content is readily determined by the use of a refractometer (Evans Part. No. E2190).The following are refractometer readings of Evans Waterless HDTC with corresponding water content percent:Brix Reading: Water Percent55.70: 0
    55.00: 1
    54.70: 2
    54.40: 3
    54.00: 4
    53.50: 5       

     

 

24. How do you calibrate the refractometer? Using a drop of new Evans Waterless HDTC, adjust the Brix reading to 55.70.

 

25. Evans Waterless HDTC contains a blend of glycols, including ethylene glycol, which is toxic. How toxic is Evans Waterless HDTC? Evans Waterless HDTC contains a substance that inhibits the metabolism of ethylene glycol, preventing its toxic metabolites from forming. In tests on rats according to EPA regulations, no rats died eating Evans Waterless HDTC, even in quantities that completely filled the stomachs of the rats, indicating a very low oral toxicity.

 

26. If Evans Waterless HDTC is so low in oral toxicity, why is there an ethylene glycol warning on the bottle? The U.S. Consumer Products Safety Commission requires the ethylene glycol warning on all products that contain over 10 percent ethylene glycol. Permission to waive the labeling requirement requires tests on human tissue that have not yet been performed.

 

27. How much power does the radiator fan for a typical heavy duty engine use? According to the Cummins MPG Guide (February 2007), the fan for an ISX engine draws 17, 26, 37, and 52 HP at 1300, 1500, 1700 and 1900 RPM, respectively. (Fan horsepower relates to RPM by Fan Law #3.)

 

28. At what temperatures do the fans for heavy-duty engines turn on and turn off? Typically, the fans turn on around 200° F-210° F and off between 180°F and 190°F.

 

29. Why are fan temperatures set so low? Fan temperatures are typically set low enough so that water based coolant can act as a heat sink to absorb residual heat, preventing an afterboil situation, at idle or shut-down following a stressful run.

 

30. Do low fan temperatures cause the fan to run more of the time? Yes, low fan temperature settings cause extended “fan-on” intervals as compared to higher fan temperature settings. Heat transfers more efficiently from a hotter radiator to the ambient air than from a cooler radiator. The fan does not have to run as long to transfer the same amount of heat.

 

31. Obviously, running the fan less will save fuel. How can Evans Waterless HDTC be used to reduce “fan-on” time? There is ample capacity for the coolant to absorb residual heat from both the cylinder head and the EGR cooler without causing boiling and other after-boil problems. With Evans Waterless HDTC the fan-on temperature can be safely increased to, say, 230° F, reducing the “fan-on” time. Keeping the radiator fan “off” more of the time reduces fuel consumption significantly.

 

32. How is the “fan-on” temperature raised? There are no internal hardware or software changes to the engine control module (ECM). A coolant temperature sensor (thermistor) that is similar to the one in use is tested to determine its resistance v. temperature profile. The additional resistance that would be required for the fan to turn on at 230° F is computed. A ResistorPac of that value is placed in series with the coolant temperature sensor. Evans Cooling Systems, Inc. is happy to provide further information or guidance on request. The fan will then turn on at 230° F.

 

33. The fan is needed for functions other than for controlling coolant temperature. What happens to the charge air temperature and the head pressure for the a/c system when the input signal to the ECM is altered for the coolant temperature? The fan will still respond to the conventional settings for charge air temperature and for the a/c head pressure. Typically, these functions do not require nearly as much fan as required for maintaining coolant temperatures.

 

34. Can higher temperature coolant thermostats be used with Evans Waterless HDTC for additional gains in fuel economy? Yes. SAE Type II testing was performed by the PAVE Research Institute at Auburn University that proved a 3 percent improvement in fuel economy with Evans waterless coolant and 215°F thermostats.

 

35. Are there additional requirements for using 215°F thermostats? The fan-off temperature must be increased so that the coolant does not have to be cooler than 215°F for fan-off. Contact Evans Cooling Systems, Inc. for further information.

In all engines hot metal in contact with coolant causes localized boiling called nucleate boiling at critical metal temperature locations in the engine. Nucleate boiling is a very efficient way to remove heat as the heat of vaporization is so high. This boiling forms vapor which is later recondensed back into liquid when the vapor reaches the appropriate temperature. For ethylene glycol and water (EGW) systems, the recondensation of vapor takes place generally in the radiator. Since vapor by volume from a 50/50 solution of EGW is more than 98% water vapor under one atmosphere of gauge pressure (14.0 PSIG), the water will not recondense until the temperature of the coolant is below the boiling point of water at the system pressure. During moderate loads and ambient temperature conditions, that temperature is normally seen inside the radiator. As the temperature of the coolant rises under stressed conditions, that vapor does not recondense even inside the radiator. Most engine designers and test engineers are unaware that vapor is in fact being generated and recondensed continuously inside the engine cooling system.

As a result of localized boiling, there is a layer of vapor which can build up on the surface of the hot metal within the coolant jackets. That layer keeps the coolant from coming in contact with the hot metal surface. The temperature of the metal covered by the vapor pocket increases, causing a “hot spot”. The hotter the spot, the more vapor produced, the larger the vapor pocket becomes, and the higher this critical metal temperature rises. These “hot spots” become so hot that they become secondary “spark plugs” or ignition points and are the cause of engine performance limitations (ignition instability) and emission problems. Thus it has been an important goal of the Evans Cooling System to reduce the vapor build-up on the hot metal surface and reduce or eliminate “hot spots”.

Vapor, which is created from localized boiling, actually affects the cooling efficiency of the engine. Large amounts of vapor in the cooling system decrease the amount of liquid to metal contact throughout the cooling system, reducing the ability of the cooling system to remove heat.

In addition as the engine and cooling system is used under stressed conditions or in higher ambient temperature locations, coolant temperatures typically rise above 220° F. As EGW coolant temperatures increase above 220° F, the vapor which is generated cannot be recondensed efficiently inside the system and can be seen as cloudy coolant. Often at about 220° F the pump starts to cavitate and the flow rate of the coolant starts decreasing , increasing further the temperature of the coolant. This results in additional cavitation and the loss of coolant through overflow vents. Evans has developed computerized models of EGW cooling systems which generate vapor tables plotting this phenomenon. These theoretical vapor tables track empirical test data very accurately and are proof that vapor is constantly being generated and recondensed. The vapor tables also allow for accurate design predictions of system components size requirements identified during dynamometer testing.

In examining the vapor generation it became apparent that water is the reason for such a high amount of vapor production within the engine with resultant “hot spots”. Water is the cause of cavitation. Water is the reason for requiring pressurized cooling systems to elevate the acceptable operating coolant temperatures above the boiling point of water. Even so the coolant temperatures cannot exceed 224°F for pressurized water. Therefore the use of water as a coolant requires adding poisonous ethylene glycol to raise the pressurized boiling point to 250° and decrease the freezing point. Water has been found to be the reason that additives used for corrosion deplete and “fall out”, causing limited coolant life. Water is also the cause of corrosion of parts inside the cooling system and in some systems the resultant accumulation of high concentrations of lead and other heavy metals in the coolant after prolonged use. The solution was to remove the water from the coolant.

In choosing the proper replacement coolant Jack Evans, the inventor, attempted to solve a number of problems: the toxicity/waste stream environmental issue, the cavitation issue, the corrosive coolant issue, the heavy metal deposit issue, the depletion of additives issue, the liquid to metal contact or “hot spot” issue and the overheat issue.

Non-Aqueous Propylene Glycol (NPG) with additives to protect metal surfaces was chosen as the replacement liquid. Because of the specific heat and specific gravity differences between NPG and EGW coolants, it is theoretically necessary to increase NPG’s coolant flow approximately 27% over that for EGW to remove equal amounts of heat from the engine. In actual application however, where current cooling systems produce significant amounts of vapor, less flow increase can provide the same, and even increased, heat rejection. Since there is no water in the system to cause cavitation of pumps, the increased speed is easily achieved. The flow can be further increased to provide even better cooling of the engine. The physics of why NPG cooling allows for higher engine performance can be best understood by looking at how the vapor is managed.

Bubble Size: The size of the bubbles formed on the hot metal surface, which then break off into the liquid, directly affect the size of the vapor buildup on the metal surface. Nucleate boiling produces bubbles, the size of which depends on a liquid characteristic known as surface tension. Lower surface tension and directly proportional cohesive characteristics produce smaller surface layer bubble sizes. NPG has lower surface tension and lower cohesive tendencies than EGW.

Another fluid characteristic which works in favor of decreasing bubble size is the difference in vapor pressure. The vapor pressure of water is 100 times that of NPG (vapor by volume from a 50/50 solution of EGW is more than 98% water vapor under one atmosphere of gauge pressure).

The more turbulent flow of the NPG system produces shear forces which tend to shear bubbles into smaller bubbles at the metal surface.

Heat of Vaporization Cal/Mole: Another characteristic, which determines the amount of vapor generated in changing a liquid to a gas when a given weight of liquid changes to a vapor, is called the Heat of Vaporization. When the heat transferred from the hot metal surface vaporizes liquid it does so according to the heat of vaporization. NPG has a heat of vaporization of 12,500 Cal/Mole compared to 9,720 for EGW. Simply stated, each vapor bubble of NPG coolant carries 29% more calories (heat) than a vapor bubble of EGW coolant. Therefore NPG generates less vapor by volume and will displace less coolant from the surface than will EGW for the same amount of heat transferred.

Reduction of “hot spots”: Obviously if the vapor bubbles condense back into liquid rapidly there is less vapor traveling through the cooling system. Less vapor means higher metal to liquid contact. The fact that NPG generates less vapor for the same heat transfer helps here also (See Below; “h Molar Heat of Vaporization:”).

Compared to NPG, water vapor from the EGW condenses at a lower temperature and hence is not fully condensed until it is in the radiator. However the temperature of NPG in the cooling system is considerably below its saturation temperature (boiling point), readily condensing NPG vapor back into the liquid locally. Evans has been able to ensure that all NPG vapor generated inside the engine rapidly condenses back into liquid before the coolant leaves the engine.

Small bubble sizes assists here also as the smaller the bubble the lower the ratio of vapor volume to bubble surface area (the recondensation occurs at the liquid/gas interface, the surface of the bubble).

Reduction of “hot spots” & turbulent coolant flow: Turbulent flow of the coolant increases coolant scrubbing of the vapor from the surface of the metal, thereby improving the wetting of the metal surface by the coolant.

Other Technical Considerations:

• Boiling Point: 369° F for NPG versus 224° F for 50/50 “EGW” ethylene glycol and water (at atmospheric pressure – 0.0 psig) – benefits include elimination of afterboil and overheating, allowing temperature excursions above those for EGW, faster recondensation of vapor inside the engine, low (2.0 – 4.0 PSIG) or non-pressurized system, no coolant loss operating in high ambient temperatures, and the capability to increase thermostat temperature settings if desired.
• Molar Heat of Vaporization: 12,500 Cals/Mole for NPG versus 9,720 Cals/Mole for EGW – benefits include faster recondensation because less vapor is produced, and a reduction of hot spots because of improved liquid to metal contact. All of which eliminate the occurrence of “Film Boiling” and the accumulation of excessive surface vapor.
• Surface Tension: 35 Dynes/Cm for NPG versus 56 Dynes/Cm for EGW — benefits include small vapor bubble sizes, allowing for faster recondensation of vapor and increased liquid to metal interface, and decreased area of nucleate boiling centers, again increasing liquid to metal interface.
• Freezing Point: -70° F for NPG versus -38° F for EGW. NPG does not freeze, it crystallizes and supercools (contracts slightly and becomes a viscous slurry).
• Toxicity: EGW is considered a hazardous waste whereas NPG is not as PG is used as a food additive and pharmaceutical base fluid.
• Vapor Pressure: 590 mm of Hg for EGW at 212° F versus 18 mm of Hg for NPG. This is the major reason for the dramatic decrease in cylinder liner and pump cavitation. Although most vehicles overheat at EGW coolant temperatures of approximately 250° F (pressurized to 13.0 psig), the non-aqueous coolant can tolerate temperatures above 350° F. Although using higher coolant temperatures can introduce other problems, (i.e.: increased oil temperatures) the NPG will allow the possibility of increasing coolant temperatures with all the resultant performance improvements as those problems are addressed and resolved. EGW is temperature constrained only by the physics of the liquid.

Over the years engineers have solved many of the problems of using EGW at the limits of its physical properties. The same can be expected to happen with NPG, allowing full use of NPG’s high boiling point. Currently, however, most all NPG conversions are operated at traditional thermostat settings (180° – 200°F) with the high temperature capabilities of NPG utilized as a “safety measure”.

Important Benefits of NPG Coolant:

For Gasoline Engines:

• Higher Gasoline Efficiency
• Reduces Emissions
• Higher Compression & Power
• Knock Reduction
• Improved Octane Tolerance (lower octane fuel usable).
• Reduction of Hot Spots (Critical Metal Temperatures)

For Diesel Engines:

• Higher Fuel Efficiency
• Lower Particulate Emissions
• Higher Power
• Reduction of Hot Spots (Critical Metal Temperatures)
• Elimanation of overheating and after-boil
• Elimination of Cylinder wall and pump cavitation
• Elimination of corrosion on cooling system parts
• Significant Reduction of Coolant Leaks; NPG operates at a low (i.e.; 4.0 – 7.0 PSIG ) or atmospheric pressure.
• Not a Hazardous or Dangerous Waste.
• Long Life, Stable Coolant. Increased from 40,000 (with EGW) to more than 400,000 miles. The system has been tested to 400,000 miles in a Class 8 Detroit Diesel engine running at North American Van Lines. After 400,000 miles additives have decreased by only 11%, still within initial manufacturing tolerances for the coolant.
• Fleet applications: decreased maintenance requirements and costs.

 

Secondary Benefits of NPG Coolant:

For Gasoline Engines:

• Non-pressurized: (or low pressure, i.e. 4.0 psig) decreased leaks, lower pressure parts, decrease of thermal flexing or cycling (component life extended), elimination of accidents resulting from accidental removal of radiator caps from hot engines.
• Allows for a totally closed system (Hermetically Sealed) requiring no service checks and is not subject to contamination.
• Improved stability of engine operating temperatures.
• Improved aerodynamic styling. The radiator no longer needs to be higher than the engine and can be placed anywhere.
• Weight reduction possible if higher coolant temperatures are used. Smaller radiators, less coolant, light-weight metals (such as magnesium for engines), small cooling jackets in the engine, smaller fans.
• Decreased duty cycle of coolant fan for the same coolant temperature by allowing for higher temperature excursions for short intervals with no adverse effects on the engine.
• Faster combustion chamber metal surface warm-up, CO reduced in start-up (liners get hot faster) mostly because of lower specific heat of cold NPG.
• Elimination of premature spark plug failure and head cracking by better cooling of head.
• Reduction or elimination of pre-ignition and detonation:
  • Reduce head distortion and cracking at high compression and supercharged / turbocharged boost levels.
  • Reduce head gasket fire ring failure.
  • Reduce piston dome and ring failure.
  • Reduce valve face sinking (“tuliping”).
  • Reduce rod bearing failure (caused by cylinder pressure, detonation related, spikes).

For Gasoline Engines:

• Non-pressurized (or low pressure, i.e. 4.0 psig) system provides fewer leaks, lower pressure parts, decrease of thermal flexing or cycling (extended component life) and elimination of accidents resulting from accidental removal of radiator caps from hot engines.
• Elimination of Cylinder Liner Cavitation allowing for reduction of thickness of cylinder liners with the following benefits:
  • Weight and critical engine dimension reduction.
  • Better cooling of piston cylinder wall surfaces.
• Totally closed system requiring no service checks and no contamination.
• Weight reduction if higher coolant temperatures are used with smaller radiators, less coolant, smaller cooling jackets in the engine, and smaller fans.
• Decreased duty cycle of coolant fan for the same coolant temperature by allowing for higher temperature excursions for short intervals with no adverse affects on the engine.
• Faster combustion chamber metal surface warm up of cylinder liners & combustion domes provides lower emissions, improved gas mileage.
• Eliminates frequent maintenance checks of coolant additives and subsequent adjusting of additive levels.
• Reduction of coolant disposal costs as no coolant needs to be replaced (limits of coolant life have not yet been found. Some vehicles have been tested up to 500,000 miles).

There are two significant fuel saving techniques for Heavy Duty Engines:

1. Use Evans Waterless HD Thermal Coolant to reduce fan-on time.
2. Use Evans Waterless HD Thermal Coolant to increase the thermostat temperature.

The following points provide case studies and reports to explain how Evans increases fuel efficiency.

A.  The engine fan is a significant consumer of fuel.

 

It is well-known that the fans for heavy duty diesel engines draw considerable horsepower.  Cummins, for example, in its MPG Guide (February 2007), discloses that the fan for an ISX engine draws 17, 26, 37, 52 and 70  HP at 1300, 1500, 1700, 1900 and 2100 RPM, respectively.  These horsepower numbers may be converted to fuel rates by the following methodology:

1 horsepower equals 2545 BTU/hour

1 gallon of diesel fuel contains about 139,000 BTU.

In a diesel engine, about 1/3 of the energy in diesel fuel is converted to horsepower.  Each horsepower produced therefore requires a delivery of 7635 (three times 2545) BTU per hour from the fuel.

Each fan horsepower therefore requires a fuel rate of 7635/139000 = .055 gallon per hour.

The per hour fuel rates required by the Cummins ISX engine radiator fan for various engine speeds are shown below.

 

It is clear that minimizing fan operation leads directly to significant fuel savings.  In the typical stock configuration, a fan clutch engages the fan in the coolant temperature range of 200^o to 210^o F.  This report describes how Evans waterless HD thermal coolant (“HDTC”) enables the fan temperature to be safely raised, reducing fan-on time and resulting in reduced fuel consumption.  When the fan-on temperature is raised, there is always a fuel savings.

A case study – The fan-on temperature was raised to 230^o F.  Fuel consumption dropped 5.5% during the spring 2008 test period and 8.5% during the summer 2008 test period.

The tests were conducted in Connecticut on two 2006 Mack Model MR688 trucks, both equipped similarly and having Mack E7 350 horsepower engines.  One truck was retrofitted and the other kept in the stock configuration (water-based coolant and stock fan settings) for comparison.  Both trucks were operated under similar conditions.  (More information is available upon request.)

From Fuel Economy Report dated April 29, 2008 (Spring Period)
The following data was collected during April 2008

Baseline data from Control truck:



Eninge Hours:
27.6 hrs
A


Fan-on Hours:
8.0 hrs
B


Fuel Consumed during Period:
131 gal
C


Baseline Fuel Rate (C/A):
4.75 gal/hr
D


(1) Avg engine baseline HP (D * 18.2):
86.38 hp
E


Avg horsepower as percent of rated HP (E / 350):
24.7%
F


Percent of time fan is on (B/A):
29%
G




Data from Test Truck



Engine Hours:
25.2 hrs
H


Fan-on Hours:
2.5 hrs
J


Percent of time fan is on (J/H):
9.9%
K




Percent reduction in fan-on time using 230F vs 205F turn-on (1-(K/G)): 65.8%



Estimated engine RPM when fan is on:
1550 RPM
L


(2) Fan HP at est avg engine RPM when fan on:
25.1 hp
M


Fan HP as a percent of avg engine HP (M/E):
29.1%
N


Percent of baseline fuel used by fan during baseline (G*N):
8.43%
P


Percent of baseline fuel used by fan after retrofit (K*N):
2.88%
Q




Percentage of fuel saved by reduced fan-on time (P-Q): 5.54%

(1) 1 gal diesel fuel has 139,000 btu.  1/3 of the BTU's become horsepower.
    1 BTU/hour = 0.000393 HP
    Each gal/hour makes an average of (0.000393 *(139,000/3)) = 18.2 horsepower.

(2) According to Borg Warner the fan draws 50HP @ 1950 engine RPM, assuming a
    pulley ratio of 1.77 (the crank pulley is approx. 9.5" dia; the fan pulley
    is approx 5.5" dia).
    By Fan Law #3, the fan HP at L RPM = 50 times (L/1950)^3

 

From Fuel Economy Report dated July 11, 2008 (Summer Period)
The following data was collected late June-early July 2008

Baseline data from Control truck:



Eninge Hours:
151.2 hrs
A


Fan-on Hours:
77.2 hrs
B


Fuel Consumed during Period:
781 gal
C


Baseline Fuel Rate (C/A):
5.17 gal/hr
D


(1) Avg engine baseline HP (D * 18.2):
94.01 hp
E


Avg horsepower as percent of rated HP (E / 350):
26.9%
F


Percent of time fan is on (B/A):
51.1%
G




Data from Test Truck



Engine Hours:
133.8 hrs
H


Fan-on Hours:
25.5 hrs
J


Percent of time fan is on (J/H):
19.1%
K




Percent reduction in fan-on time using 230F vs 205F turn-on (1-(K/G)): 62.7%



Estimated engine RPM when fan is on:
1550 RPM
L


(2) Fan HP at est avg engine RPM when fan on:
25.1 hp
M


Fan HP as a percent of avg engine HP (M/E):
26.7%
N


Percent of baseline fuel used by fan during baseline (G*N):
13.64%
P


Percent of baseline fuel used by fan after retrofit (K*N):
5.09%
Q




Percentage of fuel saved by reduced fan-on time (SUMMER)  (P-Q): 8.55%

(1) 1 gal diesel fuel has 139,000 btu.  1/3 of the BTU's become horsepower.
    1 BTU/hour = 0.000393 HP
    Each gal/hour makes an average of (0.000393 *(139,000/3)) = 18.2 horsepower.

(2) According to Borg Warner the fan draws 50HP @ 1950 engine RPM, assuming a
    pulley ratio of 1.77 (the crank pulley is approx. 9.5" dia; the fan pulley
    is approx 5.5" dia).
    By Fan Law #3, the fan HP at L RPM = 50 times (L/1950)^3

The fuel economy figures shown above are for a trash-hauling truck.  Refuse trucks repeatedly start and stop and frequently perform service in circumstances that lack ram air.  A truck’s use and its working environment determine the amount of baseline fan-on time.  The greater the baseline fan-on time, the greater are the opportunities for reductions in fan-on time.

B.  Additional Fuel Economy is Available by Increasing the Actuation Temperature of the Coolant Thermostats to 230° F.

In January 2009 Auburn University’s PAVE Research Institute at Opelika, Alabama performed a fuel consumption test according to SAE J1321 (TMC RP-1102) Type II procedures under the direction of technical consultant Bob Rosenthal.  Use of Evans waterless coolant and 230° F thermostats showed a fuel economy improvement of 3.04 percent!

The test was conducted with the coolant fans of both the test truck and the control truck locked 100% “on” in order to eliminate the fan from being a variable.  In other words, the 3.04 percent improvement in fuel economy from using the 215° F thermostats is in addition to whatever savings are obtained by increasing the fan temperature to 230° F.

The full SAE Type II test report is available from PAVE’s website here.

 

C.  A discussion of what Evans Waterless HDTC is and how it works as compared to water-based coolants:

All commercially available automotive antifreezes and coolants (more than 250 brands), except Evans coolants, are water-based.  Water is good because it is cheap and because it has excellent thermal conductivity in its liquid state.  On the other hand, water is a poor choice because the boiling point of water is too low.  There is very little separation between the operating temperature of the coolant and the boiling point of water (for the pressure of the system).  The boiling point of water is the failure temperature for a cooling system using a water-based coolant because water vapor has almost no thermal conductivity.  Water is aggressive toward cooling system metals.  Water acts as an electrolyte, promoting electrolysis between dissimilar metals within the cooling system.

Although water-based coolants are mostly 50% glycol and 50% water, the failure temperature is the boiling point of water, not the boiling point of the mixture.  Some locations within the cylinder head generate so much heat that some of the nearby coolant boils, even though the bulk coolant is below the boiling point of the mixture of glycol and water.  When local coolant boils, the resulting vapor is nearly 100% water vapor because of fractional distillation.  The water portion is far more volatile and is liberated as water vapor.  The glycol portion remains in the solution.

If the coolant that is surrounding the water vapor is above the boiling point of water, the water vapor cannot condense.  Under this condition, the water vapor makes an insulating barrier between hot metal and liquid coolant, causing the temperature of the metal to spike to high levels.  Graph 2 compares the thermal conductivity of Evans Waterless HDTC to the liquid and vapor phases of 50%/50% EGW.

Water-based coolant must be kept cold enough to avoid pump cavitation.  Action of the coolant pump creates a low pressure area at the pump inlet.  Pump cavitation occurs when coolant near its boiling point encounters the low pressure area and flash vaporizes within the pump.  The gas pocket in the pump causes the pump to stop functioning and coolant circulation to stop.  Coolant pump cavitation leads directly to catastrophic cooling system failure with the coolant being expelled from the system as steam pressure exceeds the pressure relief setting of the cap.

Water-based coolant must be kept cold enough to avoid afterboil.  Afterboil occurs after shut-down of a stressed engine when the coolant is near its boiling point and residual heat remains in the cylinder head or in an auxiliary circuit such as an EGR cooler.  Upon shut-down the coolant pump ceases to circulate coolant through the cooling system.  Residual heat boils the stagnant coolant, making steam pressure that exceeds the pressure relief setting of the cap.  Coolant is pushed out of the system.

 

A cooling system using water-based coolants is burdened by the requirement to keep the coolant below the boiling point of water for the pressure of the system under all operating conditions and after shut-down.  This task is difficult because the coolant frequently operates close to the boiling point of water.

The primary purpose of any engine cooling system is to keep engine metal temperatures under control.  In order to accomplish that with water-based coolant, significant energy must be expended to keep the coolant cold enough so that it remains functional.  The most important operational feature of Evans Waterless HDTC is its huge separation between the operating temperature and the boiling point of the coolant, on the order of at least 100^o F.  [HDTC boils at 375^o F (at atmospheric pressure) and freezes below -70^o F.]

Graph 3 compares the boiling points of HDTC, 50/50 EGW and water:

 

The huge separation between the operating temperature and the boiling point of Evans HDTC unlocks a Reserve Capacity that already exists in systems designed for water-based coolants.  Any cooling system designed to keep coolant below the boiling point of water for the pressure of the system under all operating conditions and after shut-down is liberated from those requirements when the coolant is changed to Evans HDTC.  The same sized cooling system can accommodate a broader range of temperatures safely.  When ambient temperatures happen to be higher, there are no failures due to the boiling point of water.  In a 100^o F environment a radiator that is 230^o F can dissipate 22% more heat than the same one at 205^o F.

Evans HDTC prevents hot spots in the engine.  The huge separation between the operating temperature and the boiling point of Evans HDTC, on the order of at least 100^o F, provides an environment where any locally generated coolant vapor immediately condenses into adjacent liquid coolant.  Vapor cannot build into an insulating barrier and contact between hot metal and liquid coolant is maintained at all times.  Metal temperatures are under control at all times.

Evans HDTC prevents afterboil because of the huge separation between the operating temperature and the boiling point of Evans HDTC.  After shut-down, the coolant acts as a heat sink into which heat from hot metal parts of the cooling system can dissipate.  Boiling is avoided and there is no build-up of pressure to force coolant out of the system.  Stresses on cylinder heads and EGR heat exchangers are avoided as metal temperatures are kept under control.

Evans HDTC prevents pump cavitation, again because of the huge separation between the operating temperature and the boiling point of Evans HDTC.  The low pressure area of the coolant pump is never at a low enough pressure to flash vaporize Evans HDTC.  The pump never gets vapor bound and has the capability to pump coolant over a broader range of temperatures.

Evans HDTC prevents cylinder liner cavitation erosion in heavy duty engines.  As the piston moves inside the cylinder there is vibration of the liner.  The vibration of the liner against the coolant alternately makes low and high pressures.  In systems using water-based coolant, vapor is created by flash vaporization during the low pressure instant.  During the adjacent high pressure instant, the vapor collapses against the cylinder liner.  This action is repeated at the frequency of the vibration, causing an attack against the metal liner.  Cavitation erosion of the liner is a consequence of this action.

With Evans HDTC there is a huge separation between the operating temperature and the boiling point, on the order of at least 100^o F.  The operating temperature of the coolant is so much lower than the boiling point of the coolant that the flash vaporization does not occur during the low pressure instant and so there is no collapse of vapor during the high pressure instant.  In this manner, cavitation erosion is avoided.  In a recognized test (the “John Deere Engine Cavitation Test”) performed in April 2009 by a third-party laboratory, the results using Evans HDTC were so good that no water-based coolant formulations, even ELC formulations, regardless of additives or SCAs, come close.

Evans HDTC waterless coolant is an engineered fluid formulated from a proprietary blend of glycols and compatible additives.  It will last the life of the engine as long as it does not become contaminated with water.  The coolant does not require supplementary coolant additives (SCA’s) or filters that release additives.  It contains no additive that requires water to dissolve the additive or to enable the additive to function.

In heavy duty diesel applications the water content is required to be no more than 3 percent.  The most preferred installation of the coolant is into a dry engine and radiator.  The water content can readily be determined by use of a refractometer.  Any “Brix scale” refractometer may be used if it includes the range 50-60 degrees Brix.  The following are refractometer readings of Evans HDTC with corresponding percentages of water content:

Brix Reading
Percent Water


55.70
0


55.00
1


54.70
2


54.40
3


54.00
4


53.50
5

Evans HDTC is low in oral toxicity.  Although HDTC contains ethylene glycol, it also contains a substance that inhibits the metabolism of ethylene glycol, preventing its toxic metabolites from forming.  In tests on rats according to EPA regulations, no rats died eating the ethylene glycol/inhibitor combination, even in quantities that completely filled the stomachs of the rats, indicating a very low toxicity.  Evans HDTC carries ethylene glycol warnings on its packaging because of the U.S. Consumer Products Safety Commission requirement that all products containing over 10 percent ethylene glycol carry such warnings.  Permission to waive the labeling requirement requires proof of safety by in-vitro testing on human tissue.  The in-vitro testing is underway and is expected to be completed during 2009.

 

D.  Maximizing the Fuel Economy Potential Means 215° F Thermostats, 230° F Fan-On Temperature, and Reprogramming of the ECM

Raising the thermostat temperature to 215^o F requires the use of prototype thermostats that Evans Cooling Systems can arrange to provide.  At 215^o F there is huge separation between the boiling point of the coolant and the operating temperature of the coolant.  The engine will not overheat and there will be no loss of control of metal temperatures.

Low fan temperature settings cause extended “fan-on” intervals as compared to higher fan temperature settings because heat transfers more efficiently from a hotter radiator to the ambient air than from a cooler radiator.  The fan does not have to run as long to transfer the same amount of heat.  With Evans HDTC there is ample capacity for the coolant to absorb residual heat from both the cylinder head and the EGR cooler without causing boiling or afterboil problems.  With HDTC the fan temperature can be safely increased to 230^o F, reducing the “fan-on” time. 

The engine’s ECM requires re-programming of several items in order for the system to function without interference.  In addition to the fan-on temperature, the fan-off temperature must be adjusted upward.  De-rating and automatic shut-down temperatures must also be increased.  The following temperature settings would be reasonable:

Fan-on
230o F


Fan-off
220o F


Derating
235o F


Shut-down
240o F

 

E.  Why Aren’t the Engine OEMs Already Using Waterless Coolants?

In the foregoing it is explained how the features of Evans HDTC are superior to water-based coolants and how HDTC enables innovative techniques that save fuel.  This section addresses the question, “If HDTC is so great, why is its use not widespread throughout the heavy duty engine industry?”  In simple terms, the engine OEMs have been comfortable with existing cooling system arrangements.  If no OEM moves, then no OEM has to.  Everybody uses giant radiators and amazingly powerful radiator fans.  OEMs have their own private-label products and at least one OEM has a major subsidiary producing its recommended consumables.

OEMs have requirements for coolant that fit only water-based blends.  The ASTM testing methods for coolants are usable only for water-based products.  Evans HDTC can pass ASTM standards but the test methods require modifications appropriate for waterless coolants.  The factor keeping the OEMs in control of coolants for their engines has been the engine warranty.  The threat of engine warranty invalidation has been the club by which the OEMs control their customers.  But something has changed.

The change is the economic value of fuel economy.  Five-dollar diesel was a wake-up call; the price has come down but the memory persists.  Fleet owners are deciding that it is not worth thousands of dollars per truck per year to keep water-based coolant cold enough to maintain functionality.  They are weighing the value of their engine warranties and deciding if that value is more important than thousands per truck annually in fuel savings. On a dollars and cents basis, the fuel savings trump warranty risk (particularly since Evans HDTC, higher temperature or not, won’t harm the engine).

The OEMs will eventually come around, but Evans Cooling Systems is working with fleet owners who want these savings now, not in 5 or 10 years.  In the future large fleets will be specifying equipment to be delivered with Evans HDTC in the cooling system and to be equipped with 215^o F thermostats and programmed for fan-on at 230^o F. 

As it becomes known that engines protected with HDTC waterless coolant aren’t rusty inside, aren’t caked with baked-on coolant additives, and don’t have cylinder liners  damaged by cavitation erosion, vehicle resale value will increase.   Fleet owners using Evans HDTC will get premium prices when it is time to sell.