Performance Simulation Of Diesel Engine’s TEG-ORC Waste Heat Recovery System In Different Engine Conditions

Energy conservation and environment protection are two big subjects in automobile industry development. The related research indicated, an internal combustion engine converts only approximately one-third of the fuel energy into mechanical power.We canincrease ICE’s heat efficiency through recover the waste heat of ICE.Thermoelectricgenerator(TEG) technology is a new energy conversion way that directly converts thermal energy into electric energy by using thermoelectric materials. This technology can work under high temperature,non-pollutionand no moving part in high temperature waste heat recovery of internal combustion engine. The Organic Rankine Cycle(ORC) is a kind of Rankine Cycle that using organic working fluid.But the fluid may resolve under the high temperature.The ORC is suited torecover the low-middletemperature waste heat.We can use TEG to recover the exhaustfirst,so it can reduce the temperature of the exhaust and make the ORC cycle working safty.So use TEG-ORC cycle to recover waste energy of engine is the main purpose of this research.This thesisestablishes the mathematical model of TEG-ORC cycle using MATLAB to recover the diesel engine’s waste heat.Based on the characteristics of vehicle diesel engine gas exhaustion under various operating conditions,the material of TEG is TAGS and Pb Te.The ORC cycle use R123, its decomposition temperatureis 600 K,the ORC’s evaporating pressure is 2MPa,the condensing temperature is 308 K.In order to make the system safty,the ORC pressure should not be high.The performance of combined TEG-ORC system under various operating conditions was analyzed by simulation. The results indicate that combined TEG-ORC system achieved the graded use of waste energy. This system can operate in almost all the engine’s operating conditions.The output power of combined system can reach as high as 30.36 k W, with TEG’s output power being 2.24 k W and ORC’s output power 28.12 k W. The indicated thermal efficiency of diesel engine increases by as much as 5.52%, and the maximum indicated thermal efficiency of the diesel engine with combined system is 47.1%.The TEG-ORC system work well in therange of 1700-1900r/min,70%-90% load of the engine’s operating conditions.In this range, the output power is high and the indicated thermal efficiency can rise about 5%.If the engine often works in this conditions, the TEG-ORC system could get more operation value.In the experimental aspect, designed and built a thermoelectric power generation system test bench. Using this test bench, the performance of thermoelectric modules aretested. When the cool side temperature is 293 K,hot side temperature is 473 K,the system has the maximum output power 39.648 W.Using the experiment results correctthe TEG system which is the part of TEG-ORC combined system.Make TEG more truly to reflect the multi modules thermoelectric generation system which recover the waste heat. This experiment bedding the future optimization study of TEG-ORC combined cycle,and it could contribute to the future experimental work.