Low temperature heat recovery in engine coolant for stationary and road transport applications

Abstract

Small scale, low-temperature ORC (heat source at around 358 K – 85°C) is a specialty of ENOGIA which has sold to date more than 40 stationary ORC systems, with electrical power outputs ranging from 5 to 40 kW. These ORC cover a large variety of applications: agricultural biogas combined heat and power engines, landfill biogas plants, biomass boilers, concentrated solar thermal systems and small geothermal plants. With IFPEN, new developments have been made to deliver a 100 kW stationary ORC model.Regarding the transport industry, most of projects related to ORC systems propose performance optimized solutions with heat recovery in engine exhaust gas, where the exergy content of the heat loss is high. However recovery potential is important, real life is much more difficult, with severe thermal constraints on the system and complicated control strategy in transient behavior. This generates important development and manufacturing costs and risks in terms of system durability.IFPEN and ENOGIA have joined forces to investigate another way for heat recovery for transportation means, aiming at reducing the cost of the system and facilitating its integration on-board a truck or a passenger car. The development is focused on the design of ORC turbine-based components. As heat source, engine coolant is selected for its low and stable temperature conditions. At the end, ORC operating pressure and temperature are low, allowing a lightweight, compact and low-cost solution.