Numerical study on combustion process of methanol-diesel spray using stratified injection

抄録

With the increasingly stringent requirements for carbon emissions, methanol fuel has attracted much attention due to its low carbon dioxide emissions. However, because methanol itself has the physical characteristics of low cetane number and large latent heat of vaporization, relatively large ignition energy is required. Therefore, it is difficult to achieve independent combustion of methanol in internal combustion engines. In this study, we propose a diesel methanol stratified injection technology based on the stratified water injection technology. The stratified injection technology is to inject two kinds of fuel into the injector in a stratified manner to make the spray out of the stratified state of the two sprays. In this study, we used CONVERGE software to model a marine medium-speed single-cylinder diesel engine in three dimensions. And through the test data to calibrate the model of the machine. Then the injector is modeled in the model, and the method of coincident point injector is used to simulate the stratified injection. By verifying the ignition delay, a combustion model that is suitable for both diesel combustion and methanol combustion is fitted. Then simulate the stratified injection of methanol and diesel to observe the combustion characteristics under the stratified injection mode to verify the feasibility of the scheme. After the verification is successful, we tried to formulate different diesel and methanol injection schemes with the number of layers unchanged. Observe the difference in cylinder pressure and heat release rate under different diesel and methanol ratios and finally choose one. The most suitable injection scheme for methanol and diesel stratified injection, which provides a theoretical basis for methanol stratified injection in the future.