a2 e9 d8 E4298 The Efficiency of an Engine OTTO CYCLE EFFICI

a=2
e=9
d=8
E=42.98

The Efficiency of an Engine OTTO CYCLE EFFICIENCY 0.7 An approximate equation for the efficiency E (in percent) of an engine is: E 100. 1 0.3 0.2 where R is the compression ratio. Find R if E-4[a].[e][d] Round the answer to two decimal places U10 12 140 COMPRESSION RATIO

Solution

E = 100 [1 - 1/(R)^2/5]

E = 4[a].[e][d] = 42.98

==> 42.98 = 100 [1 - 1/(R)^2/5]

==> [1 - 1/(R)^2/5] = 42.98/100

==> 1 - 1/(R)^2/5 = 0.4298

==> 1/(R)^2/5 = 1 - 0.4298

==> 1/(R)^2/5 = 0.5702

==> (R)^2/5 = 1/0.5702 = 1.753771

==> R = (1.753771)^5/2

==> R = 4.0732

==> R = 4.07