EXPERIMENTAL STUDY ON ORGANIC RANKINE CYCLE SYSTEM WITH SINGLE-SCREW EXPANDER FOR WASTE HEAT RECOVERY FROM DIESEL ENGINE EXHAUST

asme-orc2015 Tracking Number 47

Two single-screw expander prototypes with 155 mm and 117mm diameter screw were developed. An ORC (organic Rankine cycle) experimental systems for waste heat recovery from diesel engine exhaust were built. Experiments with two single screw expander prototypes were conducted for different expander torque and diesel engine loads. The experimental results indicated: (1) Single-screw expander is suitable for small/medium scale ORC system, it can obtain good performance at low-medium rotational speed. The maximums of power output 10.38 kW and shaft efficiency 57.88% are gotten at 1538 rpm. (2) The maximums of volume efficiency, adiabatic efficiency and expansion ratio of single-screw expander are 90.73%, 73.25% and 4.6, respectively. (3) The performance of ORC system is affected not only by the working case of diesel, but also by the torque of single-screw expander. The biggest ORC efficiency is 6.48%, which is gotten at 250 kW diesel power output and 64.43 N.m of single-screw expander. (4) With ORC system, the specific oil consumption of diesel is effectively decreased. When the power output of diesel is 250 kW, the specific oil consumption is decreased by 3.5%, and the overall system efficiency is 43.8%, which is increased by 1.53%. (5) With the reducing of flow mass rate pumped into evaporator, the dryness of vapor is accelerated, and heat exchange quantity almost linearly decreases. Flow rate of vapor into single-screw expander increases with increase of vapor dryness but volume efficiency decreases with that. The rising of expansion rate is due to increase of inlet pressure and decease of outlet pressure with the increase of vapor dryness and the biggest expansion ratio is 4.7. With the increase of vapor dryness, torque and power output of single-screw expander are rising.