The exhausted gas recirculation improved brake thermal efficiency and combustion characteristics under different intake throttling conditions of a diesel/natural gas dual fuel engine at low loads

•The performance of dual fuel engine was studied on EGR without or with intake throttling.•EGR without intake throttling can increase brake thermal efficiency and reduce emissions.•EGR coupled with proper intake throttling can obtain higher brake thermal efficiency and good combustion performance.•The brake thermal efficiency can be further improved by advanced diesel injection timing with EGR and intake throttling.