Polyoxymethylene　dimethyl　ethers　(PODEn)　are　promising　diesel　additives　that　have　been　widely　evaluated　and　display　many　advantages　for　improving　the　combustion　and　emissions　of　diesel　engines.　There　have　been　few　investigations,　however,　that　have　performed　an　energy　balance　analysis　of　diesel/PODEn　blends.　Such　an　analysis　would　provide　new　insights　into　understanding　the　energy　flow　distribution　and　help　further　improve　the　energy　conversion　efficiency　of　diesel　engines　fueled　with　diesel/PODEn　blends.　For　this　reason,　an　energy　balance　analysis　was　conducted　on　a　heavy-duty　China　VI　diesel　engine　fueled　with　various　diesel/PODEn　blends　(mass　fractions　of　10%,　20%,　and　30%).　In　addition,　combustion　characteristics,　as　well　as　the　particulate　number　concentration　(PNC)-NOx　trade-off　relationship,　were　also　examined.　The　results　revealed　that　as　the　PODEn　blending　ratio　increased,　the　effective　work　ratio　(i.e.,　the　brake　thermal　efficiency)　gradually　increased,　while　the　exhaust　loss　ratio,　cooling　loss　ratio,　and　incomplete　combustion　loss　ratio　decreased　under　each　given　operating　condition.　Therefore,　fueling　with　diesel/PODEn　blends　caused　the　energy　distribution　to　be　superior　and　optimized　compared　to　fueling　with　diesel　fuel.　Moreover,　the　PODEn　addition　reduced　the　peak　in-cylinder　pressure,　mean　in-cylinder　temperature,　and　maximum　heat　release　rate.　Also,　both　the　ignition　delay　and　combustion　duration　were　shortened,　and　the　heat　release　process　became　both　more　concentrated　and　closer　to　the　top　dead　center.　This　significantly　improved　the　brake　thermal　efficiency,　with　the　maximum　increment　reaching　3.29%.　The　trade-off　between　the　NOx　and　PM　emissions　was　significantly　improved　by　blending　PODEn　during　all　operating　conditions.　In　conclusion,　diesel　blending　with　PODEn　effectively　improved　the　energy　conversion　efficiency　and　combustion　process　of　a　test　engine,　resulting　in　a　reduction　of　energy　losses,　especially　under　high　load　conditions.　©　2020　Elsevier　Ltd