Table 3 Correlations of Re, Pr, and Nu in different tubes

THT, ΔT = 25 °C

1. Nu = 1.69Re^0.335Pr^1/3, R² = 0.973

2. Nu = 1.76Re^0.346Pr^1/3, R² = 0.999

THT, ΔT = 50 °C

3. Nu = 0.798Re^0.387Pr^1/3, R² = 0.993

4. Nu = 1.54Re^0.265Pr^1/3, R² = 0.943

TET

5. Nu = 0.422Re^0.523Pr^1/3, R² = 0.984

6. Nu = 1.36Re^0.325Pr^1/3, R² = 0.996

CT

7. Nu = 0.617Re^0.337Pr^1/3, R² = 0.995

8. Nu = 0.902Re^0.295Pr^1/3, R² = 0.993