- May 31, 2017
- Posted by: Sudhi
- Category: Blog
I just got back from the 2017 VTMS13 (Vehicle Thermal Management Systems) conference in London from May 17th-18th. The conference attendance was lighter than 2 years ago (VTMS12 in Nottingham in 2015) and majority of the attendees for this year’s conference were from UK OEMs and academia. The topics discussed at this year’s conference were quite interesting and more relevant than ever. Below are few notes on the papers that stood out to me:
- On Active Charge Air Cooling: This paper discussed the application of a turbo-expander in addition to an air-to-air charge air cooler to provide sub-ambient charge air across a wide range of engine operating conditions. This would produce a fuel economy benefit and result in very practical packaging and cost structure. The technology combines two turbo-chargers, with the second stage acting as a turbo-expander. As quoted succinctly in the paper, “Air expansion through the turbo-expander turbine provides the power to drive its compressor. The overall loss of enthalpy through the second stage of compression and expansion is compensated for by the increased work in the first compressor. The net effect on the engine is increased exhaust pressure into the main turbine.” The paper highlights an 35% increase in torque and about 10% increase in power using this technology. It was indeed a clever way of achieving sub-ambient air charge temperature without active cooling using refrigerant. This technology is currently being tested on vehicles with potential fuel economy benefits.
- On Organic Rankine Cycle: A few interesting papers discussed the progress made on Organic Rankine Cycle (ORC) technology as it matures for both commercial and passenger vehicles. One paper by Professor Vincent Lemort et al. discussed the thermo-economic optimization of the ORC by considering six different architectures and four different expander types (scroll, screw, piston and vane). The paper proposes an interesting 3 step optimization methodology. The paper indicates ethanol and screw expander ahead in the race.
A second paper on ORC by Jaguar-Land Rover discussed ORC for a mild-hybrid vehicle. The paper showed significant energy recovery and fuel economy improvement in certain steady state operating conditions. The paper indicated that more work needs to be done in stability of the system behavior in transient conditions.
- Waste Heat Recovery Technologies: CSEG, in collaboration with Tenneco, also presented a paper discussing comparative assessment of four different waste heat recovery technologies – the EHRS, TEG, ORC and TAC (Thermo-acoustic converter). This study focused on the amount of waste heat recovered by each technology and the type of power generated and their corresponding fuel economy impact on the vehicle. The technical characteristics and pros/cons of these technologies were evaluated using a complete vehicle energy model for a light duty pick-up truck and a class 8 truck, as applicable. Interestingly, it was found that there is no correlation between the amount of waste heat captured and the fuel economy benefit. The fuel economy benefit is very dependent on the type of energy generated, its transient response, and how this energy is used in the vehicle.
- Thermal management: There were a couple of interesting papers from Professor Paul Shayler on engine oil warm-up and the impact of various oil sump designs on warm-up profile. Even though various sump designs indicated different temperatures at oil pick-up, it was very interesting to note a heavy influence of the oil pump in moderating any temperature variation downstream into the main gallery. The cool-down results, however, were more intuitive when it came to sump designs, with the smaller surface area leading to a lower loss in heat from the sump.
I’m happy to a more detailed chat about the conference and my takeaways if any particular topic is of more interest to you. If you are interested in our paper on comparative assessment of the waste heat recovery technologies, please send me a note. I can email it across.
See you next time!