Dytech ENSA (formerly known as Dayco ENSA) designs, develops and manufactures EGR systems for automotive and commercial vehicle applications, both off and on road. Matthew Beecham talked with Stuart Kirby, commercial and business development director, Dytech ENSA SL about the company’s EGR innovations.
just-auto: Demands on engine cooling product performance, packaging and cost are continually increasing. In addition, automakers expect economical solutions that help reduce emissions from cars and trucks. With these demands in mind, how have you responded?
Stuart Kirby: In order to meet the new regulations EGR rates have increased, the amount of gas recirculated, and more complex EGR systems are required. Extra space under the bonnet, even on a large truck, has never been exactly easy to find and packaging more complex systems and more components into the space available becomes an exercise in putting the famous square peg into the round hole. Early EGR system, late 90’s, comprised usually of a fairly small EGR cooler and EGR valve and tubing to connect it all together, a Euro VI system may well be dual loop systems with a high pressure and a low pressure EGR system, a much larger EGR cooler and perhaps a diesel oxidation catalyst (DOC) too and of course tubing to connect it all together including the EGR valve.
Dytech ENSA’s response to this has been from three fronts. Firstly, improved EGR cooler performance. Second, component integration and third, modular systems. Let us look at these three items in a little more detail.
- Cooler Performance — EGR rates have more than doubled between Euro III and Euro V and cooler outlet temperatures have had to drop significantly too. All of this, of course, in the same real space and with the added burden that increased EGR induces more fouling (deposits of un-burnt hydro carbons, soot, etc.) within the EGR system which reduces the cooler efficiency. In order to meet Euro IV type standards Dytech ENSA introduced corrugated tube to the tube bundles of our tube and shell coolers. The corrugated tube increases EGR gas turbulence within the tube and improves the heat transfer allowing more cooling in the same space. Euro V too, in most cases, can be dealt with corrugated tube and shell coolers, however some applications require more compact solutions. Dytech ENSA has developed over the past three years a technology we call Hybrid Tube. Hybrid Tube takes the best of tube and shell coolers and combines this with concepts found in plate and insert heat exchangers. The result is a more compact cooler offering superior heat rejection and excellent fouling resistance. Further, as the production concepts for Hybrid Tube coolers owe more to tube and shell rather than plate style coolers, irregular cooler geometries and sections are possible. Cooler bodies need not be round or rectangular, indeed it is possible to have any cross sectional shape as the packaging requires. This greatly helps the square peg to fit in the round hole.
- Component Integration — As a system supplier Dytech ENSA is able to offer all components of the EGR system. As a principal EGR Tube supplier we are able then to produce coolers with integrated tubes. This eliminates flanges, screws and gaskets and produces a more compact, more cost effective solution. By-Pass valves too are Dytech ENSA products. An EGR By-Pass Valve is used to by-pass the cooler during engine warm-up which permits the engine to reach temperature in a shorter time thus reducing catalyst light-off times. Integrating By-Pass Valves into cooler bodies reduces overall volume and space once again is saved. Component integration too reduces engine assembly line complexity and therefore cost of installation. The OEM installs one not two components taken from one, not two boxes.
- Modules — Further integration can produce a single one piece module containing the EGR valve, By-Pass valve and cooler. Indeed we currently produce various a modules with this level of integration. Our highest level of integration also has the vacuum tank, vacuum switch and thermostat as part of a one piece EGR module. A complete EGR module fixed to an engine with just four screws and a gasket is a reality today, although of course not every application can benefit from such a high level of integration Dytech ENSA can study and advise customers on the best solution to the problem posed.
just-auto: As we understand it, the key trends in the engine cooling sector are turbocharging and EGR. In what ways have you addressed the trend for supercharged diesel engines?
Stuart Kirby: Technically, the term “supercharging” refers to any pump that forces air into an engine. However, in common usage it refers to pumps that are driven directly by the engine as opposed to turbochargers that are driven by the pressure of the exhaust gases. The end result is the same; more air is forced into the engine. For the EGR system too the result is the same; increased EGR rates. We are not currently working on any engines with superchargers rather than turbos, however watch this space. High EGR rates on high pressure systems remove available exhaust from the turbine, while low pressure EGR systems take the exhaust gas from further down the line with no effect on the gas available for the turbine. Low pressure EGR systems are certainly being examined much more closely than before.
just-auto: In what ways does the EGR impact on the engine cooling system? i.e. for instance, is there a need for additional engine cooling due to the load the EGR puts back into the engine coolant.
Stuart Kirby: Yes, clearly. Higher EGR cooling increases the load on the engine cooling system as a whole. Many new engine developments are considering dual cooling loops for the EGR cooler/s. One high temperature cooling circuit to one cooler and one low temperature coolant circuit to another, especially on larger commercial vehicle engines. This increased cooling load has to be dealt with and the engine cooling system will need to cope with these complexities and increased load.