PROJECT DESCRIPTION

For companies in the transport sector, reducing vehicle fuel consumption and CO2 emissions is a major challenge.

Our client for this project wanted to implement a Rankine cycle to recover thermal energy produced by a vehicle. The energy recovery concept was to exploit the thermal expansion of a heat transfer fluid to drive a turbine or piston.

TECHNICAL CHALLENGES

Tests should be performed continuously over hundreds of hours on a mixture of lubricants and coolants under conditions which precisely represent the operating conditions of the thermal cycle (temperatures over 250°C and pressures of 30 bar).

OUR METHODOLOGY

Our teams of experts conducted tests on the mixture in order to:

• Select a suitable oil which maintains steady operating conditions over time
• Simulate the product behaviour over many hundreds of hours. Small-scale tests were conducted in sapphire reactors to allow visual monitoring of the mixture over time. Lab equipment had been adapted to operate continuously, safety equipment had been upgraded accordingly.
• The mixture was sampled over time and analyzed to validate the composition and/or degradation
• In parallel, corrosion of metallic components of turbine and piston had been conducted.

The tests were performed on different oils in a system which exactly emulated the operating conditions of the intended cycle.

RESULTS

The tests allowed:

• Effective screening of commercially-available lubricants and those under development
• Shortlisting of several lubricants on which further characterization was performed (including compatibility tests with particular materials) on engine bench to define the best performing lubricant for this application.