Discussion About One Vehicle Pneumatic Exhaust Energy Recovery Technology

Only25-45percent of whole heat energy, which is produced by fuel in the engine isconverted into effective work, and most of the remaining heat energy is released to theenvironment by water coolant and high temperature exhaust gas. High temperature exhaustgas of exhaust pipe upstream has high enthalpy in the vehicle engine. It can apparentlyenhance indicated power of the engine and thermal efficiency if the energy in the exhaustpipe is effectively taken advantage of.The thesis introduces and analyzes the distribution energy of fuel combustion from engineheat balance point of view. Taking the CA6DL2-35E3high pressure common rail andturbocharged inter-cooled diesel engine for example, the size and applicability of every partof waste heat energy is calculated, making sure high temperature exhaust gas of engine asthe most valuable waste heat.One kind of vehicle pneumatic exhaust energy recovery system is introduced, and its targetis to recover the heat energy of high temperature exhaust gas. The system is composed by“secondary turbine-compressed air-expander-generator”. The recovery system is able toproduce high pressure air, and the compressed air could make the expander rotate. At last,the generator connected to the expander by driving belt or gears can produce electricity withthe help of the drive of the expander.Whether the recovery system could be applied or not is determined by the ability of theexpander to some extent. In the thesis, vane air motor is picked as the expander in therecovery system, and the recovery ability of the air motor is examined, using the compressedair generated by air pump to simulate the high pressure air produced by recovery system.The experiment results indicate that the air motor can work normally, and8bar compressedair can produce0.518kW effective output power.In order to know the degree of the compressed air produced by the pneumatic exhaust energyrecovery system and to study the influence of the recovery system to the original machine,the recovery system is tested on the engine bench. On the test bench of CA6DL2-35E3dieselengine, the recovery system is able to work normally and can produce compressed air whosepressure reaches up to4.6bar. However, all of the vane air motors require the pressure ofentrance compressed air be more than6bar, thence the structure of the original recoverysystem needs to be changed with the purpose of getting compressed air with more highpressure.The model of CA6DL2-35E3high pressure common rail and turbocharged inter-cooleddiesel engine is conducted by GT-POWER, which is similar to true condition of the engine,and it could be used to next simulation and calculation. By simulation and calculation to theimproved recovery system, it is found that the system can enhance the output power undersome working condition and the system can recover a part of energy of the high temperature exhaust gas.The simulation is operated at engine revolving speed1650rpm and1965rpm, and everyspeed corresponds to six working condition whose throttle opening is from10%to100%.The simulation results indicate that specific fuel consumption, pump loss and exhaust gastemperature decrease and the engine torque raise a little comparing to original machine atmany working conditions after installing the recovery system. The simulation resultsdemonstrate that the improved recovery system can not only recover the heat energy of hightemperature exhaust gas but also enhance the performance of original engine.