Page 322 - Defrosting for Air Source Heat Pump

Technoeconomic performances 317

In Eqs. (10.28)–(10.30), the system operating duration in the cooling season, T ODC ,
was assumed at 12 h in this study. Using the three equations, the total running cost
could be expressed as,

C r,C ¼ C e,unit P C + P id, fan + P od, fan T Y T CD T ODC (10.31)

The total running cost in the cooling season was obtained by,

Q id,air,C
C r,C ¼ (10.32)
COP C
In the four typical cases, the energy supplied to the indoor air during operation, Q id, air, C ,
was replaced by the rated cooling capacity of the ASHP unit, at 5.2 kW. At the same
time, the COP in the cooling season, COP C , was also used at the rated value, at
3.25. The two values are both listed in Table 10.1.
(3) Economic analysis model
The total running costs in the four typical cases were:

C r,i ¼ C r,FDH,i + C r,NFDH,i + C r,C,i i ¼ D3and D4ð Þ (10.33)

Considering the Eqs. (10.19), (10.25), (10.31), and (10.33), it could be evaluated by,

C r ¼ C e,unit T Y T FDH T OT ½ P F + P id, fan + P ave,od, fan T DF

+ P DF + P id, fan T DD Š + P H + P id, fan + P od, fan T NFDH T ODH

Q id,air,DF
+ P C + P id, fan + P od, fan T CD T ODC + (10.34)
COP F
C r was also calculated by Eqs. (10.20), (10.26), (10.32), and (10.33), as,

Q id,air,F + Q id,air,DF Q id,air,NFDH Q C
C r ¼ + + + C r,comp,DF + C r,id, fan,DF
COP F COP NFDH COP C
(10.35)

And thus, the total costs in the four typical cases were:

C t,i ¼ C f ,i + C r,i i ¼ D3and D4ð Þ (10.36)
It could be expressed separately as:

Q id,air,F + Q id,air,DF Q id,air,NFDH Q C
C r,D3 ¼ + + (10.37)
COP F COP NFDH COP C
+ C r,comp,DF + C r,id, fan,DF + C ASHP