汽油机曲轴240转/min,活塞S=120cm2,冲程长0.3m,做功冲程压强500000Pa,.求汽油机功率、效率给出分析、过程,特别是第2问.汽油热植4600J/kg,四冲程汽油机.每分钟燃烧20g汽油

(1)S=120cm2=0.012m2 F=p*s=500000pa*0.012m2=6000N S=0.3m W总=F*S*4*4=6000N*0.3m*4*4=28800j p=W/t=28800j/60s=480w (2)M=20g=0.02kg W有＝Q*M=4600000j/kg*0.02kg=92000j 效率＝W有／W总＝28800j/92000j=31.3%...