An engineer claims to have made an engine delivering 10 kW power with fuel consumption of 1g/sec. The calorific value of the fuel is 2 kcal/g. The claim of the engineer

Options

A. is valid
B. is invalid
C. depends on engine design
D. depends on the load

Answer

B

Explanation

Input energy `= (1g)/("sec") xx ("2 kcal")/(g) = "2 kcal/sec"`
Output energy `= 10 kW = 10 kJ//s = (10)/(4.2) "kcal/sec"`
`:. eta = ("Output energy")/("Input energy") = (10)/(4.2 xx 2) gt 1`