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Forced Convection Heat Transfer: An Experimental Study of Flat and Pinned Plates, Study Guides, Projects, Research of Heat and Mass Transfer

Jordan University of Science and Technology Heat and Mass Transfer

An experimental study of forced convection heat transfer, focusing on the relationship between air velocity and heat transfer efficiency. The study involved analyzing heat transfer over both flat and pinned plates under varying air velocities. The results demonstrate the dependence of the convection heat transfer coefficient on air velocity and the superior thermal performance of extended surfaces (pinned plates) compared to flat plates. The document also includes a detailed discussion of error analysis and recommendations for future research.

Typology: Study Guides, Projects, Research

2023/2024

Uploaded on 12/30/2024

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Table of Contents

1. Abstract ........................................................................................................................ 3

2. Results .......................................................................................................................... 4

Part (A): Flat plate .................................................................................................. 4

Part (B): Pinned plate ............................................................................................ 6

3. Discussion ................................................................................................................... 8

3.1 Definition ................................................................................................................ 8

3.2 Results Discussion ................................................................................................ 9

3.3 Error Analysis ...................................................................................................... 10

4. Conclusion ................................................................................................................. 11

5. Recommendations .................................................................................................... 12

6. References ................................................................................................................. 13

7. Appendices ................................................................................................................ 14

7.1 Appendix A: Raw Data ......................................................................................... 14

Part (A): Flat Plate ............................................................................................... 14

Part (B): Pinned Plate .......................................................................................... 15

7.2 Appendix B: Conversion Factors ......................................................................... 16

7.3 Appendix C: Sample of Calculations ................................................................... 17

2

Discover Study Guides, Projects, Research of Heat and Mass Transfer Jordan University of Science and Technology

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Download Forced Convection Heat Transfer: An Experimental Study of Flat and Pinned Plates and more Study Guides, Projects, Research Heat and Mass Transfer in PDF only on Docsity!

1.Abstract

This experiment aims to determine temperature distribution over flat and pinned

plates using the P.A. Hilton H111P convection heat transfer apparatus. Forced

convection heat transfer was studied to understand the relationship between air

velocity and heat transfer efficiency, crucial in thermal management applications.

Temperature values were digitally recorded over the flat plate, and the forced

convection heat transfer coefficient "h"for flat plate was calculated to be 22.67 (

𝑊/𝑚 °C)and 32.84 °C) at 5 m/s and 10.5 m/s respectively.The study found

2

that the heat transfer coefficient is proportional to air velocity.

The second stage involved computing the convection heat transfer coefficient along

pinned plate, which resulted in 250.4 ( 𝑊/𝑚 °C) at 10 m/s ,which is a larger value

2

compared to flat plate .The experiment confirms that the convection heat transfer

coefficient (h) over extended surfaces (finned surfaces) will typically be larger than

the convection heat transfer coefficient over a flat plate due to the increased surface

area for heat transfer..

Figure (2): Steady state temperature difference vs. velocity for flat plate

Part (B): Pinned plate

Table (2): Steady state results for Pinned plate

V

(m/s)

I

(A)

Voltage (V)

Q

(W)

T

(°C)

T

(°C)

T1- T

(°C)

( 𝑊/𝑚 °C)

2 . 10 116 0.7 81.2 43.3 36.4 7 250.

Figure (3): Unsteady state temp vs. time for each thermocouple for pinned plate

3.Discussion

3.1 Definition

Convection is the mechanism of heat transfer through a fluid in the presence of bulk

fluid motion. Convection is classified as natural (or free) and forced convection

depending on how the fluid motion is initiated. In natural convection, any fluid

motion is caused by natural means such as the buoyancy effect, i.e. the rise of

warmer fluid and fall of the cooler fluid. Whereas in forced convection, the fluid is

forced to flow over a surface or in a tube by external means such as a pump or fan.

Convection heat transfer is complicated since it involves fluid motion as well as heat

conduction. The fluid motion enhances heat transfer (the higher the velocity the

higher the heat transfer rate). The rate of convection heat transfer is expressed by

Newton’s law of cooling:

The convective heat transfer coefficient h strongly depends on the fluid properties

and roughness of the solid surface, and the type of the fluid flow (laminar or

turbulent). [1]

Figure (5): Forced convection

3.2 Results Discussion

The forced convection experiment analyzed heat transfer over both flat and pinned

plates under varying air velocities. Key findings and interpretations from the data

and graphs are detailed below.

Part A: Forced Convection over a Flat Plate

The temperature versus time graph (as shown in figure (1)) for the flat plate at air

velocities of 5 m/s and 10.5 m/s illustrates the unsteady-state behavior of the system.

At lower velocities, the plate surface temperature took longer to reach steady state,

indicating slower heat dissipation due to reduced convective heat transfer. At higher

velocities, the steady state was achieved faster, showcasing the enhanced heat

transfer resulting from increased air movement.

The steady-state temperature difference (ΔT = Ts – T∞) plotted against velocity (as

shown in figure (2)) revealed an inverse relationship. As air velocity increased, the

temperature difference decreased. For instance, at 5 m/s, ΔT was 18°C, while at 10.

m/s, it dropped to 14.2°C. This behavior aligns with the theoretical expectations that

increased velocity reduces the thermal boundary layer thickness, enhancing heat

transfer.

The calculated convective heat transfer coefficients (ℎexp) showed a direct

relationship with velocity. At 5 m/s, ℎexp was 57.74 W/m²·K, whereas at 10.5 m/s, it

increased to 73.63 W/m²·K. These values highlight the dependence of ℎexp on air

velocity, as faster-moving air removes heat more effectively. Compared to the

published values (ℎpub), errors of 60.7% and 55.4% were observed at 5 m/s and 10.

m/s, respectively, indicating potential discrepancies due to experimental limitations,

including sensor calibration or heat loss to the surroundings.

Part B: Forced Convection over a Pinned Plate

The unsteady-state temperature profiles (as shown in figure (3)) for the pinned plate

revealed gradual temperature increases over time for all thermocouples. T3 (10 mm

from the surface) consistently exhibited the highest temperatures, followed by T

and T5, as expected due to their relative proximities to the heat source.

The steady-state temperature profile along the pin (as shown in Figure (4)) indicated

a clear temperature gradient, with the highest temperature at the base (T3 = 43.3°C)

and the lowest at the tip (T5 = 36.4°C). This trend reflects the conductive heat

transfer along the pin's length and the effect of convective cooling by the

surrounding air.

4.Conclusion

● The forced convection heat transfer coefficient "h" for a flat plate was e was equal

to 22.67 ( 𝑊/𝑚 °C)and 32.84 °C) at 5 m/s and 10.5 m/s.

2

● the convection heat transfer coefficient along a pinned plate, which was equal to

250.4 ( 𝑊/𝑚 °C) at 10 m/s demonstrating the superior thermal performance of

2

extended surfaces.

● Temperature difference is inversely proportional to air velocity.

● Heat transfer coefficient is directly proportional to air velocity.

● Temperature is inversely proportional to distance away from the prime surface in

the pinned plate.

5.Recommendations

● Enhance insulation around the experimental setup to minimize heat loss to the

surroundings, ensuring more accurate heat transfer measurements.

● Regularly calibrate temperature sensors to reduce systematic errors.

● Use automated systems for consistent air velocity, reducing variability in results.

● Conduct experiments over a broader range of air velocities and surfaces to

explore more diverse heat transfer behaviors.

● Investigate the effect of varying pin shapes and sizes on the heat transfer

coefficient for future studies.

● Shield the setup from environmental factors such as drafts or temperature

fluctuations that could affect the results.

7.Appendices

7.1 Appendix A: Raw Data Part (A): Flat Plate

Part (B): Pinned Plate

1. Abstract........................................................................................................................
1. Results..........................................................................................................................
  - Part (A): Flat plate..................................................................................................
  - Part (B): Pinned plate............................................................................................
1. Discussion...................................................................................................................
- 3.1 Definition................................................................................................................
- 3.2 Results Discussion................................................................................................
- 3.3 Error Analysis......................................................................................................
1. Conclusion.................................................................................................................
1. Recommendations....................................................................................................
1. References.................................................................................................................
1. Appendices................................................................................................................
- 7.1 Appendix A: Raw Data.........................................................................................
  - Part (A): Flat Plate...............................................................................................
  - Part (B): Pinned Plate..........................................................................................
- 7.2 Appendix B: Conversion Factors.........................................................................
- 7.3 Appendix C: Sample of Calculations...................................................................
- 0 13:20:58 35.43 32.46 111.1631 0. Sample Time T1 ℃ T2 ℃ Voltage (V) Current (A)
- 1 13:21:29 36.9 32.47 114.5359 0.
- 2 13:21:59 38.37 32.48 114.7268 0.
- 3 13:22:29 39.84 32.49 115.0449 0.
- 4 13:22:59 40.83 32.99 115.1086 0.
- 5 13:23:30 41.81 33 115.4268 0.
- 6 13:24:00 42.81 33.03 115.4268 0.
10 13:26:01 46.28 33.58 115.6177 0.
11 13:26:31 46.77 33.59 115.4268 0.
12 13:27:01 47.29 33.61 115.4268 0.
13 13:27:32 47.78 33.63 115.4904 0.
14 13:28:02 48.28 33.64 115.9995 0.
15 13:28:32 48.79 34.15 116.1904 0.
16 13:29:02 49.29 34.16 116.1904 0.
20 13:31:03 50.31 34.21 111.9268 0.
21 13:31:34 50.81 34.22 114.7268 0.
22 13:32:04 50.84 34.73 114.154 0.
32 52.42 35.34 114.6631 0.606037 52.
33 52.45 35.37 117.2086 0.641198 52.
34 52.94 35.38 117.2086 0.641198 52.
35 52.96 35.39 117.4631 0.645636 52.
40 13:41:08 53.52 35.47 114.6631 0.
41 13:41:39 53.52 35.47 114.9177 0.
- 0 14:32:08 37.84 35.35 35.35 35.35 36.81 113.7086 0. Sample Time T1 ℃ T3 ℃ T4 ℃ T.5 ℃ T9 ℃ Voltage (V) Current (A)
- 1 14:32:38 38.81 36.33 35.84 35.84 36.81 114.154 0.
- 2 14:33:09 39.3 37.3 36.81 36.81 36.81 114.5359 0.
- 3 14:33:39 40.27 37.79 37.3 37.3 36.81 114.854 0.
- 4 14:34:09 40.76 38.27 37.79 37.79 36.81 114.854 0.
- 5 14:34:39 41.24 38.76 38.27 38.27 36.33 115.2995 0.
- 6 14:35:10 41.24 39.24 38.76 38.27 36.33 115.0449 0.
- 7 14:35:40 41.73 39.24 38.76 38.76 36.33 115.4268 0.
- 8 14:36:10 42.22 39.73 39.24 39.24 36.33 115.1722 0.
- 9 14:36:40 42.22 39.73 39.24 39.24 36.33 115.6177 0.
10 14:37:11 42.22 40.22 39.24 39.24 36.33 115.9995 0.
11 14:37:41 42.72 40.23 39.74 39.74 36.34 115.9995 0.
12 14:38:11 42.72 40.23 39.74 39.74 36.34 116.1267 0.
13 14:38:41 42.73 40.24 39.76 39.76 36.35 116.5722 0.
14 14:39:12 42.73 40.73 39.76 39.76 36.35 116.5086 0.
15 14:39:42 42.73 40.73 40.24 39.76 36.35 116.7631 0.
16 14:40:12 43.21 40.73 40.24 39.76 36.35 116.8904 0.
17 14:40:42 43.23 40.74 40.25 40.25 36.36 117.2086 0.
18 14:41:13 43.23 40.74 40.25 40.25 36.36 117.0813 0.
19 14:41:43 43.24 40.75 40.27 40.27 36.38 117.0813 0.
20 14:42:13 43.25 40.77 40.28 40.28 36.39 117.3358 0.
21 14:42:43 43.25 40.77 40.28 40.28 36.39 117.3995 0.
22 14:43:14 43.26 41.26 40.29 40.29 36.4 117.654 0.

Forced Convection Heat Transfer: An Experimental Study of Flat and Pinned Plates, Study Guides, Projects, Research of Heat and Mass Transfer

Related documents

Partial preview of the text

Download Forced Convection Heat Transfer: An Experimental Study of Flat and Pinned Plates and more Study Guides, Projects, Research Heat and Mass Transfer in PDF only on Docsity!

Table of Contents

1.Abstract

This experiment aims to determine temperature distribution over flat and pinned

plates using the P.A. Hilton H111P convection heat transfer apparatus. Forced

convection heat transfer was studied to understand the relationship between air

velocity and heat transfer efficiency, crucial in thermal management applications.

Temperature values were digitally recorded over the flat plate, and the forced

convection heat transfer coefficient "h"for flat plate was calculated to be 22.67 (

𝑊/𝑚 °C)and 32.84 °C) at 5 m/s and 10.5 m/s respectively.The study found

that the heat transfer coefficient is proportional to air velocity.

The second stage involved computing the convection heat transfer coefficient along

pinned plate, which resulted in 250.4 ( 𝑊/𝑚 °C) at 10 m/s ,which is a larger value

compared to flat plate .The experiment confirms that the convection heat transfer

coefficient (h) over extended surfaces (finned surfaces) will typically be larger than

the convection heat transfer coefficient over a flat plate due to the increased surface

area for heat transfer..

Figure (2): Steady state temperature difference vs. velocity for flat plate

Table (2): Steady state results for Pinned plate

V

I

(A)

Q

(W)

T

(°C)

T

(°C)

T1- T

(°C)

( 𝑊/𝑚 °C)

Figure (3): Unsteady state temp vs. time for each thermocouple for pinned plate

3.Discussion

3.1 Definition

Convection is the mechanism of heat transfer through a fluid in the presence of bulk

fluid motion. Convection is classified as natural (or free) and forced convection

depending on how the fluid motion is initiated. In natural convection, any fluid

motion is caused by natural means such as the buoyancy effect, i.e. the rise of

warmer fluid and fall of the cooler fluid. Whereas in forced convection, the fluid is

forced to flow over a surface or in a tube by external means such as a pump or fan.

Convection heat transfer is complicated since it involves fluid motion as well as heat

conduction. The fluid motion enhances heat transfer (the higher the velocity the

higher the heat transfer rate). The rate of convection heat transfer is expressed by

Newton’s law of cooling:

The convective heat transfer coefficient h strongly depends on the fluid properties

and roughness of the solid surface, and the type of the fluid flow (laminar or

turbulent). [1]

The forced convection experiment analyzed heat transfer over both flat and pinned

plates under varying air velocities. Key findings and interpretations from the data

and graphs are detailed below.

Part A: Forced Convection over a Flat Plate

The temperature versus time graph (as shown in figure (1)) for the flat plate at air

velocities of 5 m/s and 10.5 m/s illustrates the unsteady-state behavior of the system.

At lower velocities, the plate surface temperature took longer to reach steady state,

indicating slower heat dissipation due to reduced convective heat transfer. At higher

velocities, the steady state was achieved faster, showcasing the enhanced heat

transfer resulting from increased air movement.

The steady-state temperature difference (ΔT = Ts – T∞) plotted against velocity (as

shown in figure (2)) revealed an inverse relationship. As air velocity increased, the

temperature difference decreased. For instance, at 5 m/s, ΔT was 18°C, while at 10.

m/s, it dropped to 14.2°C. This behavior aligns with the theoretical expectations that

increased velocity reduces the thermal boundary layer thickness, enhancing heat

transfer.

The calculated convective heat transfer coefficients (ℎexp) showed a direct

relationship with velocity. At 5 m/s, ℎexp was 57.74 W/m²·K, whereas at 10.5 m/s, it

increased to 73.63 W/m²·K. These values highlight the dependence of ℎexp on air

velocity, as faster-moving air removes heat more effectively. Compared to the

published values (ℎpub), errors of 60.7% and 55.4% were observed at 5 m/s and 10.

m/s, respectively, indicating potential discrepancies due to experimental limitations,

including sensor calibration or heat loss to the surroundings.

Part B: Forced Convection over a Pinned Plate

The unsteady-state temperature profiles (as shown in figure (3)) for the pinned plate

revealed gradual temperature increases over time for all thermocouples. T3 (10 mm

from the surface) consistently exhibited the highest temperatures, followed by T

and T5, as expected due to their relative proximities to the heat source.

The steady-state temperature profile along the pin (as shown in Figure (4)) indicated

a clear temperature gradient, with the highest temperature at the base (T3 = 43.3°C)