Question No: $04$

This is a subjective question, hence you have to write your answer in the Text$-$Field given below.

A$)$ A reciprocating air compressor has cylinder with $30cm$ bore and $40cm$ stroke. Compressor admits air at $1$ bar, $20C$ and compresses it up to $\frac{5}{b}ar.$ Compressor runs at $150rpm.$ Considering the compressor to be single acting, single stage and has polytropic index of $1\mathrm{.}2.$ Considering the compression process to be isothermal, polytropic and adiabatic, determine the following:

$[4]$

a$.$ Draw the $P-V$ diagram for these processes

b$.$ Find out the mean effective pressure and horsepower required to run the compressor

c$.$ Calculate the isothermal efficiencies when the compression is of polytropic and adiabatic type

B$)$ A commercial refrigerator with refrigerant$-134$a as the working fluid is used to keep the refrigerant space at $-30C$ by rejecting its waste heat to cooling water that enters the condenser at $20C$ at a rate of $0\mathrm{.}3k\frac{g}{s}$ and leaves at $30C$ The refrigerant enters the condenser at $1\mathrm{.}2$MPa and $60C.$ The inlet state of the compressor is $60$kPa. Determine the following:

$[4]$

a$.$ Quality of refrigerant at evaporator inlet

b$.$ Refrigeration load

c$.$ COP of the refrigerator