Figure 1.
Schematics of the solar air heater with a transverse triangular block at the bottom of air duct.
Figure 1.
Schematics of the solar air heater with a transverse triangular block at the bottom of air duct.
Figure 2.
Schematics of the two-dimensional computational domain.
Figure 2.
Schematics of the two-dimensional computational domain.
Figure 3.
Comparison of Nusselt number predicted by different turbulence models with Dittus-Boelter empirical correlation for smooth duct.
Figure 3.
Comparison of Nusselt number predicted by different turbulence models with Dittus-Boelter empirical correlation for smooth duct.
Figure 4.
Grid system after successive gradient adaptations for a fixed value of pitch (P = 150 mm) and length (l = 65 mm), and different value of height (e) at Reynolds number of 12,000.
Figure 4.
Grid system after successive gradient adaptations for a fixed value of pitch (P = 150 mm) and length (l = 65 mm), and different value of height (e) at Reynolds number of 12,000.
Figure 5.
Nusselt number for different value of pitch (P), length (l), and for a fixed value of height (e) with Reynolds number.
Figure 5.
Nusselt number for different value of pitch (P), length (l), and for a fixed value of height (e) with Reynolds number.
Figure 6.
Velocity contours at Reynolds number of 12,000 for a fixed value of pitch (P = 150 mm) and length (l = 65 mm), and different value of height (e).
Figure 6.
Velocity contours at Reynolds number of 12,000 for a fixed value of pitch (P = 150 mm) and length (l = 65 mm), and different value of height (e).
Figure 7.
Variation of temperature in the test section at Reynolds number of 12,000, for a fixed value of height (e = 40 mm) and length (l = 65 mm), and for different value of pitch (P).
Figure 7.
Variation of temperature in the test section at Reynolds number of 12,000, for a fixed value of height (e = 40 mm) and length (l = 65 mm), and for different value of pitch (P).
Figure 8.
Velocity contours at Reynolds number of 12,000 for a fixed value of pitch (P = 150 mm) and length (l = 65 mm), and different value of height (e).
Figure 8.
Velocity contours at Reynolds number of 12,000 for a fixed value of pitch (P = 150 mm) and length (l = 65 mm), and different value of height (e).
Figure 9.
Enhancement in Nusselt number for different value of pitch (P), length (l), and for a fixed value of height (e) with Reynolds number.
Figure 9.
Enhancement in Nusselt number for different value of pitch (P), length (l), and for a fixed value of height (e) with Reynolds number.
Figure 10.
Friction factor for different value of pitch (P), length (l), and for a fixed value of height (e) with Reynolds number.
Figure 10.
Friction factor for different value of pitch (P), length (l), and for a fixed value of height (e) with Reynolds number.
Figure 11.
Contours of pressure at Reynolds number of 12,000 for a fixed value of pitch (P = 150 mm) and length (l = 65 mm), and different value of height (e).
Figure 11.
Contours of pressure at Reynolds number of 12,000 for a fixed value of pitch (P = 150 mm) and length (l = 65 mm), and different value of height (e).
Figure 12.
Contours of eddy viscosity at Reynolds number of 12,000, for a fixed value of height (e = 40 mm) and length (l = 65 mm), and different value of pitch (P).
Figure 12.
Contours of eddy viscosity at Reynolds number of 12,000, for a fixed value of height (e = 40 mm) and length (l = 65 mm), and different value of pitch (P).
Figure 13.
Enhancement in friction factor for different value of pitch (P), length (l), and for a fixed value of height (e) with Reynolds number.
Figure 13.
Enhancement in friction factor for different value of pitch (P), length (l), and for a fixed value of height (e) with Reynolds number.
Figure 14.
Variation of THPP for different value of pitch (P), length (l), and for a fixed value of height (e) with Reynolds number.
Figure 14.
Variation of THPP for different value of pitch (P), length (l), and for a fixed value of height (e) with Reynolds number.
Figure 15.
Plot of ln (Nu) as a function of ln (Re).
Figure 15.
Plot of ln (Nu) as a function of ln (Re).
Figure 16.
Plot of ln () as function of ln (e/h).
Figure 16.
Plot of ln () as function of ln (e/h).
Figure 17.
Plot of ln () as function of ln (l/e).
Figure 17.
Plot of ln () as function of ln (l/e).
Figure 18.
Plot of ln () as function of ln (P/e).
Figure 18.
Plot of ln () as function of ln (P/e).
Figure 19.
Comparison of simulation and predicted values of Nusselt number.
Figure 19.
Comparison of simulation and predicted values of Nusselt number.
Figure 20.
Comparison of simulation and predicted values of friction factor.
Figure 20.
Comparison of simulation and predicted values of friction factor.
Table 1.
Geometric parameters for solar air heater with a transverse triangular block at the bottom of air duct.
Table 1.
Geometric parameters for solar air heater with a transverse triangular block at the bottom of air duct.
Parameters | Value | Parameters | Value | Parameters | Value |
---|
Duct length (mm) | Entrance | 400 | Duct height (mm) | 80 | e (mm) | 20, 40, 60 |
Test section | 1800 | Duct width (mm) | 500 | P (mm) | 120, 150, 180 |
Exit | 700 | Hydraulic diameter, (-) | 0.138 | l (mm) | 10, 65, 120 |
Table 2.
Range of operating parameters for computational investigation.
Table 2.
Range of operating parameters for computational investigation.
Parameters | Range | Parameters | Range |
---|
Uniform heat flux, ‘q’ (W/m2) | 800 | e/h (-) | 0.25–0.75 (3 values) |
Reynolds number (-) | 8000, 12,000, 16,000, 20,000 | p/e (-) | 2–9 (8 values) |
Prandtl number of air (-) | 0.7442 | l/e (-) | 0.16667–6 (9 values) |
Table 3.
Number of cells and Nusselt number after each gradient adaptation for a solar air heater with a transverse triangular block at the bottom of the air duct for fixed value of height (e = 40 mm), pitch (P = 150 mm), length (l = 65 mm), and Reynolds number (Re = 12,000).
Table 3.
Number of cells and Nusselt number after each gradient adaptation for a solar air heater with a transverse triangular block at the bottom of the air duct for fixed value of height (e = 40 mm), pitch (P = 150 mm), length (l = 65 mm), and Reynolds number (Re = 12,000).
Gradient Adaptation | Number of Cell | Nusselt Number | Percent Change in Number of Cell (%) | Percent Change in Nusselt Number (%) |
---|
No adaptation | 211,920 | 83.117 | - | - |
I Adaptation—temperature | 239,385 | 80.306 | 12.960 | 3.382 |
II Adaptation—velocity | 320,886 | 79.898 | 34.046 | 0.508 |
III Adaptation—pressure | 489,672 | 77.730 | 52.600 | 2.713 |
IV Adaptation—wall shear stress | 496,149 | 77.706 | 1.323 | 0.031 |
V Adaptation—turbulence intensity | 647,814 | 77.647 | 30.568 | 0.076 |