Investigation Of Waste Heat Recovery System And Expander For Internal Combustion Engines

China is a major manufacturer of internal combustion engine?ICE?and it is widely used in many areas.Petroleum consumption by ICE occupies a large fraction of the total.ICE waste heat recovery is a promising way to improve energy conversion efficiency and reduce the pollutants,which is an important issue on energy conservation and emission reduction.Compared with the mature technology abroad,research and application on ICE waste heat recovery is still at the early stage in China.In order to promote the development this technology,study on thermal system and expander is conducted in this research.A design approach of Organic Rankine Cycle?ORC?system for ICE waste heat recovery is presented,including the design of thermal system and radial-inflow turbine.This research focuses on the waste heat recovery of an ICE manufactured by Hudong Heavy Industry Company.Both heat load from the jacket cooling water and the engine exhaust gas are intended to be utilized.System with two separated ORC,preheating system and dual-loop system are designed and analyzed.As for the preheating system,performance comparison between pure working fluid and zeotropic working fluid is conducted.Based on the exergy analysis,the influence of the temperature glide during phase change process of zeotropic working fluid on the system performance is evaluated.The fraction of the compositions of the zeotropic working fluid is optimized to achieve the maximum net power output.The design method and performance predicition method of organic radial-inflow turbine are studied.As for the low temperature loop of the dual-loop system,the radial-inflow turbine is designed,including the nozzle and the rotor.Based on the CFD results,the design parameters are validated and the flow characteristics in addition to the off-design performance of the turbine are investigated.As for small scale ICE waste heat recovery system,the potential of using Tesla turbine is evaluated.The original 1-D model for Tesla turbine is improved by introducing in the nozzle limit expansion ratio,the flow loss in the nozzle and the radial pressure gradient in the gap spacing between the discs.In addition,the compressible governing equations are adopted and the friction factor in the boundary layer is determined by the flow condition.As for the ORC system for jacket cooling water heat recovery,the Tesla turbine efficiency is predicted by the improved 1-D model and the system performance is estimated.The Tesla turbine can generate a comparable power output thus it can be regarded as an attractive option in small scale systems also due to is simple structure and low manufacturing cost.Supercritical CO₂?S-CO₂?cycle has emerged as a novel power cycle with high thermal efficiency and compact system structure.The potential of using S-CO₂ cycle for ICE waste heat recovery is investigated.Comparative study of simple preheating system,system with two preheaters and system with a regeneration branch is conducted.Influence of the preheating temperature on the system performance are evaluated.This research on the S-CO₂ cycle system would provide suggestions for design and application of S-CO₂based ICE waste heat recovery system.