Preliminarydesignandsimulationofafreepistonenginesuitableforsmall-scaleenergyproductionindistributedenergysystemsispresentedinthispaper.Theproperties,particularlythepropertiesofgassealsoftheenginearesimulatedusingasimulationprogramdevelopedforthiscase,andtheresultsareutilizedinpreliminarymaindesignparameterselection.TheenginesimulationprogramwasdevelopedbycombiningandmodifyingthesourcecodesofthesimulationandcalculationprogramsobtainedfromHelsinkiUniversityofTechnology,TampereUniversityofTechnology,andLappeenrantaUniversityofTechnology.Becauseofthecontact-freelabyrinthsealusedinthepiston,theefficiencyofthemotorislowerthantheefficiencyofaconventionalmotorwithoillubricatedpistonrings.Ontheotherhand,thelackofbearinglosses,andthelackoflossesassociatedwithacrankshaftsystemandagearbox,aswellasthelackoflubricationoilexpenses,compensatesthiseffect.Asanetresult,thisnewmotorwouldperformslightlybetterthantheconventionalone.Beingcompletelyoil-free,itisveryenvironmentallyfriendly,anditsexhaustgasesarecompletelyfreeofoilresidualswhicharecausingproblemsinnormalgasmotors.
