8240ZC Diesel Engine Supercharging System Improvemen

8240ZC diesel engine is a type of in-line8cylinder for240/275series of CNR(DALIAN) Diesel Engine Co., Ltd.,which has been applied to marine area as electric propulsion mainframe. Supercharger system has also adopted standard constant-pressure supercharging of240/275series diesel engine, the rated speed is1000r/min and the rated power is1840kW. To optimize and improve the inner performance under part of working condition, and to further adapt to the requirements of the traction of shunting locomotive, marine propulsion, etc., by comparing the advantages and disadvantages of all kinds of supercharge form, a program which adopts MPC supercharger system to replace the original constant pressure supercharging has been put forward.Under the existing structure of8240ZC diesel engine, an appropriate firing order has been selected to decrease the interference of each cylinder caused by MPC supercharger system, and one-dimensional dynamics BOOST software of AVL is adopted to build the working process model of8240ZC diesel engine. First, the test data of8240ZC diesel engine is used to adjust and demarcate the model, an emulating calculation has been done in different pipe diameters, angles of fire and shrinking percentages of throat of MPC exhaust pipe, so that we can get the change rule of parameters, such as supercharger pressure, explosion pressure, exhaust gas temperature and specific fuel consumption. Consequently, MPC exhaust pipes of two kinds of pipe diameters,160mm and145mm respectively, have been determined.Structural design has been carried out according to the above result, and two kinds of simple structured MPC exhaust pipes of8240ZC diesel engine have been manufactured. The monomer exhaust pile is casting structure, between which are connected in series with metal bellows and fixed with V-type clamp. The whole pile connects with exhaust gas turbocharger at one end, and another is sealed.Then, a series of verification tests of8240ZC have been carried out which are related to the load characteristic and propeller characteristics of160mm MPC exhaust pipe. Test result shows that under the same supercharge matching,8240ZC diesel engine supercharged with MPC performs better than constant-pressure supercharging. Under all operation working conditions, if specific fuel consumption decreases, the supercharger pressure will increase; the partial loading discharge temperature also has a large decline; governor control characteristic is also better; inhomogeneity of each cylinder has been acceptable with less difference under the two kinds of fire orders. All these performances are consistent with the previous calculation. Due to the reasons such as manufacture, it is a pity that the related test about the145mm MPC exhaust pipe has not been done. However, it is approved that the program that8240ZC diesel engine adopts MPC supercharging system as a substitution of the original constant pressure supercharging is correct and achieves the desired effect, according to the calculation and test of160mm MPC exhaust pipe.8240ZC diesel engine with160mm MPC exhaust pipe has been used in direct propulsion and electric propulsion and operates well.