Concluding Remarks

Experiments have been conducted here to investigate the evaporation heat transfer of R-134a and R-407C in the small tubes with Di=0.83 & 2.0-mm. The effects of the refrigerant saturated temperature, mass flux, imposed heat flux, tube dimensions and vapor quality of R-134a and R-407C on the evaporation heat transfer coefficients have been examined in detail. The results show that the R-134a and R-407C evaporation heat transfer coefficient in the small tubes increases almost linearly with the vapor quality and the increases are significant except at low imposed

heat flux, refrigerant mass flux and saturated temperature. Moreover, the increases of the R-134a and R-407C evaporation heat transfer coefficient in both tubes with the imposed heat flux, refrigerant mass flux and saturated temperature are also substantial.

Besides, the evaporation heat transfer coefficients for R-134a are lower than that for R-407C at the same Tsat, G and q, but are within 25% and 28% in 2.0-mm and 0.83-mm tubes, respectively.

Furthermore, for R-134a in the smaller tubes (Di=0.83-mm) partial dryout may occur, resulting in the decline of hr at increasing inlet vapor quality at high xin. This is normally seen at high imposed heat flux and saturated temperature, lower mass flux.

Finally, an empirical correlation is proposed to correlate the present data for R-134a and R-407C evaporation heat transfer in the small tubes.

Table 4.1 List of conditions of the experimental parameters for R-134a and R-407C refrigerants

0 200 400 600 800 1000 G ( kg/m²s )

0 1000 2000 3000

hl ( W/m2 o C )

Single-Phase Heat Transfer in 2.0mm small tubes

$

^R-407C M ^R-134a

D.B. for R-407C

--- Gn. for R-407C D.B. for R-134a

--- Gn. for R-134a

Fig. 4.1 Comparison of the present data for the liquid phase of R-134a and R-407C heat transfer coefficient in 2.0-mm small tubes with the Dittu-Boelter and Gnielinski correlations

0 1000 2000 3000 4000 G ( kg/m²s )

0 2000 4000 6000 8000 10000

hl ( W/m2 o C )

Single-Phase Heat Transfer in 0.83mm Small tubes

$

^R-407C + ^R-134a

D.B. for R-407C

--- Gn. for R-407C D.B. for R-134a

--- Gn. for R-134a

Fig. 4.2 Comparison of the present data for the liquid phase of R-134a and R-407C heat transfer coefficient in 0.83-mm small tubes with the Dittu-Boelter and Gnielinski correlations

0 0.2 0.4 0.6 0.8 1 2000

3000 4000

2o h r( W/mC )

(a)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at G=200 kg/m²s, q=5kW/m²

’ ^Tsat=5^oC - ^Tsat=10^oC # ^Tsat=15^oC

0 0.2 0.4 0.6 0.8 1

2000 3000 4000 5000

2oh r( W/mC )

(b)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at G=300 kg/m²s, q=5kW/m²

’ ^Tsat=5^oC - ^Tsat=10^oC # ^Tsat=15^oC

0 0.2 0.4 0.6 0.8 1

x_in

2000 3000 4000 5000 6000

2o h r( W/mC )

(c)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at G=400 kg/m²s, q=5kW/m²

’ ^Tsat=5^oC - ^Tsat=10^oC # ^Tsat=15^oC

Fig. 4.3 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at q=5 kW/m² for various T for (a) G=200

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at G=200 kg/m²s, q=10kW/m²

(b)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at G=300 kg/m²s, q=10kW/m²

(c)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at G=400 kg/m²s, q=10kW/m²

’ ^Tsat=5^oC - ^Tsat=10^oC # ^Tsat=15^oC

Fig. 4.4 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at q=10 kW/m² for various Tsat for (a) G=200

0 0.2 0.4 0.6 0.8 1 3000

4000 5000

2o h r( W/mC )

(a)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at G=200 kg/m²s, q=15kW/m²

’ ^Tsat=5^oC - ^Tsat=10^oC # ^Tsat=15^oC

0 0.2 0.4 0.6 0.8 1

3000 4000 5000 6000

2o h r( W/mC )

(b)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at G=300 kg/m²s, q=15kW/m²

’ ^Tsat=5^oC - ^Tsat=10^oC # ^Tsat=15^oC

0 0.2 0.4 0.6 0.8 1

x_in

3000 4000 5000 6000 7000

2o h r( W/mC )

(c)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at G=400 kg/m²s, q=15kW/m²

’ ^Tsat=5^oC - ^Tsat=10^oC # ^Tsat=15^oC

Fig. 4.5 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at q=15 kW/m² for various T for (a) G=200

0 0.2 0.4 0.6 0.8 1 2000

3000 4000 5000

2o h r( W/mC )

(a)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=5^oC, q=5kW/m²

’ G=200 kg/m²s - G=300 kg/m²s # G=400 kg/m²s

0 0.2 0.4 0.6 0.8 1

2000 3000 4000 5000

2o h r( W/mC )

(b)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=10^oC, q=5kW/m²

’ G=200 kg/m²s - G=300 kg/m²s # G=400 kg/m²s

0 0.2 0.4 0.6 0.8 1

x_in

2000 3000 4000 5000

2oh r( W/mC )

(c)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=15^oC, q=5kW/m²

’ G=200 kg/m²s - G=300 kg/m²s # G=400 kg/m²s

Fig. 4.6 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at q=5 kW/m² for various G for (a) Tsat=5℃, (b)

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=5^oC, q=10kW/m²

(b)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=10^oC, q=10kW/m²

(c)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=15^oC, q=10kW/m²

’ G=200 kg/m²s - G=300 kg/m²s # G=400 kg/m²s

Fig. 4.7 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at q=10 kW/m² for various G for (a) Tsat=5℃, (b)

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=5^oC, q=15kW/m²

(b)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=10^oC, q=15kW/m²

(c)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=15^oC, q=15kW/m²

’ G=200 kg/m²s - G=300 kg/m²s # G=400 kg/m²s

Fig. 4.8 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at q=15 kW/m² for various G for (a) Tsat=5℃, (b)

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=5^oC, G=200 kg/m²s

(b)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=5^oC, G=300 kg/m²s

(c)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=5^oC, G=400 kg/m²s

’ ^q=5kW/m2 - ^q=10kW/m2 # ^q=15kW/m2

Fig. 4.9 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at Tsat=5℃ for various q for (a) G=200 kg/m²s,

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=10^oC, G=200 kg/m²s

(b)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=10^oC, G=300 kg/m²s

(c)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=10^oC, G=400 kg/m²s

’ ^q=5kW/m2 - ^q=10kW/m2 # ^q=15kW/m2

Fig. 4.10 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at Tsat=10℃ for various q for (a) G=200 kg/m²s,

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=15^oC, G=200 kg/m²s

(b)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=15^oC, G=300 kg/m²s

(c)Evaporation Heat transfer Coefficient of R-134a (Di =2.0mm) at Tsat=15^oC, G=400 kg/m²s

’ ^q=5kW/m2 - ^q=10kW/m2 # ^q=15kW/m2

Fig. 4.11 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at Tsat=15℃ for various q for (a) G=200 kg/m²s,

0 0.2 0.4 0.6 0.8 1 1000

3000 5000 7000

2oh r( W/mC )

(a)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) G=200 kg/m²s, q=5kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

0 0.2 0.4 0.6 0.8 1

1000 3000 5000 7000

2oh r( W/mC )

(b)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) G=300 kg/m²s, q=5kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

0 0.2 0.4 0.6 0.8 1

x_in

2000 4000 6000

2o h r( W/mC )

(c)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) G=400 kg/m²s, q=5kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

Fig. 4.12 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at q=5 kW/m² for various Tsat for (a) G=200

0 0.2 0.4 0.6 0.8 1 2000

4000 6000

2o h r( W/mC )

(a)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at G=200 kg/m²s, q=10kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

0 0.2 0.4 0.6 0.8 1

2000 4000 6000 8000

2o h r( W/mC )

(b)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at G=300 kg/m²s, q=10kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

0 0.2 0.4 0.6 0.8 1

x_in

2000 4000 6000 8000 10000

2o h r( W/mC )

(c)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at G=400 kg/m²s, q=10kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

Fig. 4.13 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at q=10 kW/m² for various T for (a) G=200

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at G=200 kg/m²s, q=15kW/m²

(b)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at G=300 kg/m²s, q=15kW/m²

(c)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at G=400 kg/m²s, q=15kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

Fig. 4.14 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at q=15 kW/m² for various Tsat for (a) G=200

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=5^oC, q=5kW/m²

(b)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=10^oC, q=5kW/m²

(c)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=15^oC, q=5kW/m²

’ G=200 kg/m²s - G=300 kg/m²s # G=400 kg/m²s

Fig. 4.15 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at q=5 kW/m² for various G for (a) Tsat=5℃, (b)

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=5^oC, q=10kW/m²

(b)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=10^oC, q=10kW/m²

(c)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=15^oC, q=10kW/m²

’ G=200 kg/m²s - G=300 kg/m²s # G=400 kg/m²s

Fig. 4.16 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at q=10 kW/m² for various G for (a) Tsat=5℃, (b)

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=5^oC, q=15kW/m²

(b)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=10^oC, q=15kW/m²

(c)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=15^oC, q=15kW/m²

’ G=200 kg/m²s - G=300 kg/m²s # G=400 kg/m²s

Fig. 4.17 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at q=15 kW/m² for various G for (a) Tsat=5℃, (b)

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=5^oC, G=200 kg/m²s

(b)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=5^oC, G=300 kg/m²s

(c)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=5^oC, G=400 kg/m²s

’ ^q=5kW/m2 - ^q=10kW/m2 # ^q=15kW/m2

Fig. 4.18 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at Tsat=5℃ for various q for (a) G=200 kg/m²s,

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=10^oC, G=200 kg/m²s

(b)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=10^oC, G=300 kg/m²s

(c)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=10^oC, G=400 kg/m²s

’ ^q=5kW/m2 - ^q=10kW/m2 # ^q=15kW/m2

Fig. 4.19 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at Tsat=10℃ for various q for (a) G=200 kg/m²s,

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=15^oC, G=200 kg/m²s

(b)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=15^oC, G=300 kg/m²s

(c)Evaporation Heat transfer Coefficient of R-407C (Di =2.0mm) at Tsat=15^oC, G=400 kg/m²s

’ ^q=5kW/m2 - ^q=10kW/m2 # ^q=15kW/m2

Fig. 4.20 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 2.0-mm small tubes at Tsat=15℃ for various q for (a) G=200 kg/m²s,

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at G=800 kg/m²s, q=5kW/m²

(b)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at G=1150 kg/m²s, q=5kW/m²

(c)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at G=1500 kg/m²s, q=5kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

Fig. 4.21 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at q=5 kW/m² for various T for (a) G=800

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at G=800 kg/m²s, q=10kW/m²

(b)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at G=1150 kg/m²s, q=10kW/m²

(c)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at G=1500 kg/m²s, q=10kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

Fig. 4.22 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at q=10 kW/m² for various Tsat for (a) G=800

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at G=800 kg/m²s, q=15kW/m²

(b)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at G=1150 kg/m²s, q=15kW/m²

(c)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at G=1500 kg/m²s, q=15kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

Fig. 4.23 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at q=15 kW/m² for various T for (a) G=800

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=5^oC, q=5kW/m²

(b)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=10^oC, q=5kW/m²

(c)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=15^oC, q=5kW/m²

’ G=800 kg/m²s - G=1150 kg/m²s # G=1500 kg/m²s

Fig. 4.24 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at q=5 kW/m² for various G for (a) Tsat=5℃, (b)

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=5^oC, q=10kW/m²

(b)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=10^oC, q=10kW/m²

(c)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=15^oC, q=10kW/m²

’ G=800 kg/m²s - G=1150 kg/m²s # G=1500 kg/m²s

Fig. 4.25 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at q=10 kW/m² for various G for (a) Tsat=5℃,

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=5^oC, q=15kW/m²

(b)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=10^oC, q=15kW/m²

(c)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=15^oC, q=15kW/m²

’ G=800 kg/m²s - G=1150 kg/m²s # G=1500 kg/m²s

Fig. 4.26 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at q=15 kW/m² for various G for (a) Tsat=5℃,

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=5^oC, G=800 kg/m²s

(b)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=5^oC, G=1150 kg/m²s

(c)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=5^oC, G=1500 kg/m²s

’ ^q=5kW/m2 - ^q=10kW/m2 # ^q=15kW/m2

Fig. 4.27 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at Tsat=5℃ for various q for (a) G=800 kg/m²s,

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=10^oC, G=800 kg/m²s

(b)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=10^oC, G=1150 kg/m²s

(c)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=10^oC, G=1500 kg/m²s

’ ^q=5kW/m2 - ^q=10kW/m2 # ^q=15kW/m2

Fig. 4.28 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at Tsat=10℃ for various q for (a) G=800 kg/m²s,

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=15^oC, G=800 kg/m²s

(b)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=15^oC, G=1150 kg/m²s

(c)Evaporation Heat transfer Coefficient of R-134a (Di =0.83mm) at Tsat=15^oC, G=1500 kg/m²s

’ ^q=5kW/m2 - ^q=10kW/m2 # ^q=15kW/m2

Fig. 4.29 Variations of R-134a evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at Tsat=15℃ for various q for (a) G=800 kg/m²s,

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at G=800 kg/m²s, q=5kW/m²

(b)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at G=1150 kg/m²s, q=5kW/m²

(c)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at G=1500 kg/m²s, q=5kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

Fig. 4.30 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at q=5 kW/m² for various Tsat for (a) G=800

0 0.2 0.4 0.6 0.8 1 2000

4000 6000 8000

2o h r ( W/mC )

(a)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at G=800 kg/m²s, q=10kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

0 0.2 0.4 0.6 0.8 1

3000 5000 7000 9000

2o h r( W/mC )

(b)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at G=1150 kg/m²s, q=10kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

0 0.2 0.4 0.6 0.8 1

x_in

4000 6000 8000 10000

2o h r( W/mC )

(c)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at G=1500 kg/m²s, q=10kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

Fig. 4.31 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at q=10 kW/m² for various T for (a) G=800

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at G=800 kg/m²s, q=15kW/m²

(b)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at G=1150 kg/m²s, q=15kW/m²

(c)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at G=1500 kg/m²s, q=15kW/m²

’ Tsat=5^oC - Tsat=10^oC # Tsat=15^oC

Fig. 4.32 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at q=15 kW/m² for various Tsat for (a) G=800

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=5^oC, q=5kW/m²

(b)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=10^oC, q=5kW/m²

(c)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=15^oC, q=5kW/m²

’ G=800 kg/m²s - G=1150 kg/m²s # G=1500 kg/m²s

Fig. 4.33 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at q=5 kW/m² for various G for (a) Tsat=5℃, (b)

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=5^oC, q=10kW/m²

(b)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=10^oC, q=10kW/m²

(c)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=15^oC, q=10kW/m²

’ G=800 kg/m²s - G=1150 kg/m²s # G=1500 kg/m²s

Fig. 4.34 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at q=10 kW/m² for various G for (a) Tsat=5℃,

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=5^oC, q=15kW/m²

(b)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=10^oC, q=15kW/m²

(c)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=15^oC, q=15kW/m²

’ G=800 kg/m²s - G=1150 kg/m²s # G=1500 kg/m²s

Fig. 4.35 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at q=15 kW/m² for various G for (a) Tsat=5℃,

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=5^oC, G=800 kg/m²s

(b)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=5^oC, G=1150 kg/m²s

(c)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=5^oC, G=1500 kg/m²s

’ ^q=5kW/m2 - ^q=10kW/m2 # ^q=15kW/m2

Fig. 4.36 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at Tsat=5℃ for various q for (a) G=800 kg/m²s,

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=10^oC, G=800 kg/m²s

(b)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=10^oC, G=1150 kg/m²s

(c)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=10^oC, G=1500 kg/m²s

’ ^q=5kW/m2 - ^q=10kW/m2 # ^q=15kW/m2

Fig. 4.37 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at Tsat=10℃ for various q for (a) G=800 kg/m²s,

0 0.2 0.4 0.6 0.8 1

(a)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=15^oC, G=800 kg/m²s

(b)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=15^oC, G=1150 kg/m²s

(c)Evaporation Heat transfer Coefficient of R-407C (Di =0.83mm) at Tsat=15^oC, G=1500 kg/m²s

’ ^q=5kW/m2 - ^q=10kW/m2 # ^q=15kW/m2

Fig. 4.38 Variations of R-407C evaporation heat transfer coefficient with inlet vapor quality in 0.83-mm small tubes at Tsat=15℃ for various q for (a) G=800 kg/m²s,

0 3000 6000 9000 12000 15000

h_r,evp ( Present data )

0 3000 6000 9000 12000 15000

hr,evp ( Correlation data )

+35%

-35%

Evaporation Heat Transfer present data

%

Present data

Proposed Correlation

Fig. 4.39 Comparison of the measured data for heat transfer coefficient in the evaporation of R-134a and R-407 in 0.83-mm and 2.0-mm small tubes with the proposed correlation.

CHAPTER 5

在文檔中 R-134a和R-407C冷媒在水平多排小圓管內蒸發熱傳及壓降特性之實驗研究 (頁 64-106)