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buletinul institutului politehnic din iaşi - Universitatea Tehnică ...

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78 Ion Zabet and Graţiela-Maria Ţârlea<br />

COP c [-]<br />

2,50<br />

2,00<br />

1,50<br />

1,00<br />

0,50<br />

Without Injection<br />

With Injection<br />

0,00<br />

5,00 5,50 6,00 6,50 7,00 7,50<br />

π [-]<br />

Fig. 8 – Cooling COP versus pressure ratio.<br />

W cp [kW], COP [-], Φ 0 [kW]<br />

35<br />

28<br />

21<br />

14<br />

7<br />

0<br />

Wcp COP<br />

0,08 0,084 0,088 0,092 0,096<br />

INJR=M inj;cp / Msu;cp [-]<br />

Fig. 9 – Compressor power, cooling capacity and COP versus vapour injection ratio.<br />

This trend is due to two counteracting phenomenon: first the increase of<br />

the pressure inside the scrolls due to vapour injection and second the decrease<br />

of the enthalpy at injection point as the injection ratio increases.<br />

t ex;cp [°C]<br />

128<br />

112<br />

96<br />

80<br />

64<br />

48<br />

Φ0<br />

t ex;cp<br />

0,08 0,084 0,088 0,092 0,096<br />

INJR=M inj;cp / Msu;cp [-]<br />

Fig. 10 – Compressor discharge temperature versus vapour injection ratio.<br />

4. Conclusions<br />

1. The experimental analysis shown in this paper allows us to compare<br />

the compressor behaviour with two different configurations: the first one<br />

without injection and the second one with vapour injection.

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