$($b$)$ friction, and $($c$)$ indicated mean effective pressures; the $($d$)$ indicated and $($e$)$

fuel equivalent power; $($f$)$ the brake thermal efficiency, $($g$)$ the new rate of fuel

consumption, and $($h$)$ the new BSFC$.($i$)$ eomparing results from Problems $2\mathrm{.}4$

and $2\mathrm{.}5,$ does the engine run more efficiently at the lower on higher speed? Why? Table $2\mathrm{.}1.$ Comparison of properties of several fuels.

$[$a$]$ Minimum cetane rating for diesel fuel

$[$b$]$ Cetane rating$2\mathrm{.}6$ A $6-$cylinder, turbocharged diesel engine has a displacement of $8\mathrm{.}268$ liters and a

compression ratio of $17\mathrm{.}3$:$1.$ While running at $2200re\frac{v}{m}in$ engine speed, it

produces $634N*m$ of torque while consuming No$.2$ diesel fuel at the rate of

$30\mathrm{.}6k\frac{g}{h}.$ Through a study of the friction characteristics of the engine, it is

determined that the constants in Equation $2\mathrm{.}19$ for this engine are:

$C_o=77\mathrm{.}0$kPa

$C_1=-0\mathrm{.}0143kP\frac{a}{re\frac{v}{m}in}$

$C_2=1\mathrm{.}271E-5kP\frac{a}{(re\frac{v}{m}in{)}^2}$

Making use of data given in this problem and in Table $2\mathrm{.}1,$ calculate the $($a$)$

brake, $($b$)$ friction, and $($c$)$ indicated mean effective pressures. Also calculate the

$($d$)$ fuel equivalent, $($e$)$ indicated, $($f$)$ brake, and $($g$)$ friction power. Finally,

calculate the $($h$)$ indicated thermal, $($i$)$ mechanical, and $($j$)$ brake thermal effi$-$

ciencies, and $($k$)$ the BSFC $($brake specific fuel consumption$).$

$2\mathrm{.}7$ Continue Problem $2\mathrm{.}6$ by assuming that the torque is increased sufficiently to

maintain constant brake power while the engine speed is reduced to $1800$

$re\frac{v}{m}in.$ You may also assume that the indicated thermal efficiency remains

constant during the change in speed $($this is a reasonably accurate assumption$).$

For the engine running at $1800re\frac{v}{m}in$ as described, calculate the $($a$)$ brake,