Question

A single acting $N{H}_3$ compressor follows the compression law $(P{V}^{1.1}=C)$. The operating pressure for the vapour compression refrigeration are: 2.3637 bar $(-{15}^{\circ }C$) and 11.671 bar $(+{30}^{\circ }C$). The enthalpy at the exit of compression is 1560 kJ/kg. If refrigerant enters dry saturated to the compressor, then what is the heat loss from the compressor? The refrigeration capacity of the refrigerator is 10 tons..

• A. $2.9kW$
• B. $29KW$
• C. $65KW$
• D. $6.5KW$

Answer 1

The correct option is A $2.9kW$



Refrigeration capacity,
$RC=m(h_1-h_4)$

$10\times 35=m(1444.19-342.08)$

$m=0.03175kg/s$

Work done per kg for compressor,

$w_c=\frac{n}{(n-1)}\times p_1\times v_1\times [\left({\frac{p_2}{p_1}}^{\frac{n-1}{n}}\right)-1]$

$=\frac{1.1}{(1.1-1)}\times 2.3637\times {10}^2\times 0.50905\times [\left({\frac{11.671}{2.3637}}^{\frac{1.1-1}{1.1}}\right)-1]$

$=206.7899kJ/kg$

Apply SFEE to compressor,

So,
$m_2{h}_1-Q=m_2{h}_2-w_c$

$-Q=(m{h}_2-m{h}_1)-206.7899\times m$

$Q=2.888kW$