QUESTION $1$

$1\mathrm{.}1$ Explain the term, reciprocating, with regard to compressors.

$1\mathrm{.}2$ A four$-$stage reciprocating compressor compresses air from $0,1$MPa to

$11,2$MPa from a temperature of $305$ kelvin according to the law $p{v}^{1\mathrm{.}28}=c.$

Intercooling is complete for maximum efficiency and the clearance volume is

negligible. The compressed air has the characteristic constant of $0,287k\frac{J}{k}g.K.$

The air flow is one kilogram per second while atmospheric conditions are

$101,3$kPa and $15C.$

From this information, determine the following:

$1\mathrm{.}2\mathrm{.}1$ The delivery temperature of each stage, in degrees Celsius and

correct to three decimal places

$1\mathrm{.}2\mathrm{.}2$ The free$-$air delivery in $\frac{m^3}{k}W-$h

$1\mathrm{.}2\mathrm{.}3$ The isothermal power in kW

QUESTION $2$

$2\mathrm{.}1$ State TWO functions of a nozzle.

$2\mathrm{.}2$ A convergent$-$divergent nozzle has an efficiency of $89\%.$ The gas with

negligible inlet velocity has the adiabatic index and gas constant of $1,4$ and

$0,2875k\frac{J}{k}g.$ K$.$ At the throat, the pressure is $1,58$MPa. At the exit, the actual

temperature is $494$ kelvin. Across the nozzle, the isentropic temperature drop

is $300$ kelvin.

From this information, determine each of the following:

$2\mathrm{.}2\mathrm{.}1$ The absolute temperature in kelvin and pressure in kPa at the nozzle

inlet

$2\mathrm{.}2\mathrm{.}2$ The gas constant$-$pressure specific heat capacity

$2\mathrm{.}2\mathrm{.}3$ At the throat: the temperature in kelvin, velocity in $\frac{m}{s},$ and volume

in $\frac{m^3}{k}g$

$2\mathrm{.}2\mathrm{.}3$ At the throat: the temperature in kelvin, velocity in $\frac{m}{s},$ and volume

in $\frac{m^3}{k}g$

$2,2\mathrm{.}4$ The isentropic temperature in kelvin at the nozzle exit