Experimental investigation of a transcritical Organic Rankine Cycle with scroll expander for low temperature waste heat recovery
Arnaud Landelle, Nicolas Tauveron, Remi Revellin, Philippe Haberschill, Stephane Colasson
Session: Session 2B: Small Scale Systems (1)
Session starts: Wednesday 13 September, 14:20
Presentation starts: 14:20
Room: Building 27 - Lecture room 02
Arnaud Landelle (CEA-LITEN)
Nicolas Tauveron (CEA-LITEN)
Remi Revellin (INSA Lyon)
Philippe Haberschill (INSA Lyon)
Stephane Colasson (CEA-LITEN)
During the last decades, organic Rankine cycle (ORC) became a popular way to recover low-grade waste heat. Ways of improvement for ORC have been investigated trough thermodynamics analysis. The use of transcritical cycle could theoretically improve the cycle efficiency and recover more heat from waste sources but there have been few experimental test benches to confirm the interest of transcritical cycles and investigate operational behaviours.
In this study, an experimental investigation of a transcritical organic Rankine cycle is presented. The test bench is composed of a diaphragm pump, two plate heat exchangers (PHE) for heating, a 10kWe scale hermetic scroll compressor modified to run as an expander, a PHE condenser and a PHE regenerator. The regenerator can be isolated to compare standard and regenerative configurations. The working fluid used is R134a refrigerant with a critical pressure and temperature of 40.5bar and 101.2°C. The heat source has a maximum power of 200kWth at 150°C and uses pressurized water as heat transfer fluid.
The prototype is tested at different conditions, both steady state and heat/cold sources dynamics are investigated. In order to evaluate the performance of the system, temperatures, pressures, mass flows are measured as well as expander and pump shaft speeds and electric powers. Heat source temperature ranges from 90°C to 120°C with a maximum power of 145kWth. The scroll expander runs with an inlet pressure up to 43bars and a pressure ratio around 2, producing a maximum power of 6kWe with a 68% expander efficiency at 1600rpm. An energetic and exergetic analysis of the cycle and the components is performed. Due to high pump consumption, the maximum net power is 2kWe resulting in a maximum energetic and exergetic efficiency of 2% and 8% respectively. Subcritical and transcritical operations are compared, expander has higher output power and efficiency at transcritical condition but the ORC performs equally just below and above the critical pressure mainly because of pump consumption increases.