According to the volume fraction of 0

10%

20% and 30%

methanol was blended into polyoxymethylene dimethyl ethers (PODE) to prepare the PODE-methanol blends and marked as M0

M10

M20 and M30

respectively. The in-cylinder combustion process and emission performance of the blends at different loads and maximum torque speed was studied on a high pressure common rail diesel engine. Results show that the in-cylinder pressure decreases and the ignition delay period is gradually prolonged by using PODE methanol blends. With the increase of methanol ratio at low and medium loads

the peak value of heat release rate increases first and then decreases

while the peak value of heat release rate increases gradually at high lows. When the volume fraction of methanol is low

the combustion duration is shortened under various loads. When the volume fraction of the methanol reaches 30%

the combustion duration is prolonged under low and medium loads

and the heat release center (CA50) is delayed under various loads. With the increase of the volume fraction of methanol

the emission of NOx decreases while the emission of HC and CO increases

and the smoke emission decreases first and then increases. Formaldehyde emission increases gradually due to the low temperature oxidation of methanol. At the same time

the NO2 emission and NO2/NOx ratio increase with the increase of the volume fraction of methanol. Compared with pure PODE

the NO2 emission and NO2/NOx ratio of M30 at low loads increase by 65% and 107%

respectively.