| Promoting development of the country’s industry, the energy has been consumed increasingly. Energy conservation and emission reduction is still the basic strategy we adhere over a long term. Not only did vigorous development of auto industry bring convenient to our life, but also accelerated energy consumption. On the other hand, the energy for power output of internal combustion engine(ICE) only accounts for about 1/3 of total fuel energy. Same with this quite a part of the energy lost via exhausting. Fuel underused turned out to be huge losses. Recovery waste heat from diesel engine exhaust using power turbine or heat exchanger is going to be an innovative research direction to improve fuel efficiency. And it’s grabbing some serious attention as advantages for less modification to original engine, simple and flexible layout.Based on a certain type turbocharged diesel engine, the study represented researches on feasibility and effects of exhaust waste heat recovery using power turbine or heat exchanger. According to simulate result of established model in GT-POWER, calculated energy amount contained in exhausting by MATLAB. Result revealed that exhaust waste heat is worthy to be recycled for it occupies 33.27% of fuel energy when diesel worked under rated speed.The author established simulation model of turbo-compound diesel with a tandem or parallel turbine separately in GT-POWER. Analyzed influences on turbocharger, diesel and whole system for addition of power turbine through simulation. It turned out that both method would damage performance of diesel and turbocharger. For the tandem-compound way, under high engine speed condition, it would improve power output of system and decrease brake specific fuel consumption(BSFC), but it would lead to performance deterioration when engine worked under low speed condition. For the parallel-compound way, it would led to deterioration of whole system’s performance, as well lost meaning of waste heat recovery.After analyzing effects of tandem-compound turbine for reclaiming exhaust heat, the research calculated flow rate of waste kinetic energy, waste heat energy and waste pressure energy in exhaust designed to examine series turbo-compound system’s effects on waste heat utilization. As a result, tandem turbine could recovery three formal of energy in varying degree under rated diesel speed. And waste pressure energy got remarkable, waste heat energy took second place. Eventually could reclaim 5% of total exhaust energy.The research simulated the process of warming engine oil or cooling liquid with waste heat via heat exchanger series with turbocharge. Results indicated that engine oil would reach at normal point(85°C) within 120 s heated by exhaust, that led to reduce warm-up time by two-third. As for oil liquid, temperature could increase 44 K within 150 s. Engine warm-up time got decreased effectively in these ways, so that would improve performance of engine under cold startup condition. |
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