A simple saturation cycle using R-12 is designed for taking a load of 10 tons. The refrigerant and ambient temperatures are 00C and 300C respectively. A minimum temperature difference of 50C is required in evaporator and condenser for heat transfer. Find the
(i) mass flow rate through the system
(ii) power required in kW
(iii) Cylinder dimensions assuming L/D ratio of 1.2 for a single cylinder single acting compressor if it runs at 300 rpm with a volumetric h of 0.9. The following properties are taken for R12. Sp. Heat of R12 vap = 0.95 kJ/kg K.
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Sat temp
°C
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Sat Pressure bar
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Specific volume
(m3/kg)
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Enthalpy (kJ/kg)
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Entropy (kJ/kgK)
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|
|
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Sat liquid (10-3)
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Sat Vapour
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Sat Liquid
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Sat Vapour
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Sat Liquid
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Sat
Vapour
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-5°C
|
2.61
|
0.71
|
0.0650
|
31.4
|
185.4
|
0.1251
|
0.6991
|
|
0°C
|
3.08
|
0.72
|
0.0554
|
36.1
|
187.5
|
0.1420
|
0.6966
|
|
30°C
|
7.45
|
0.77
|
0.0235
|
64.4
|
199.6
|
0.2399
|
0.6854
|
|
35°C
|
8.47
|
0.79
|
0.0206
|
69.5
|
201.5
|
0.2599
|
0.6839
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