# Natural convection heat transfer characteristics of flat plate enclosures

## Abstract

Heat transfer by natural convection in rectangular enclosures has been experimentally studied using interferometric techniques. The effects of Grashof number, tilt angle, and aspect ratio on both the local and average heat transfer coefficients have been determined. The Grashof number range tested was 4 x 10/sup 3/ to 3.1 x 10/sup 5/, and the aspect ratio (ratio of enclosure length to plate spacing) varied between 9 and 36. The angles of tilt of the enclosure with respect to the horizontal were 45, 60, 75 and 90 deg. Correlations are developed for both local and average Nusselt number over the range of test variables. The effect of tilt angle is found to reduce the average heat transfer by about 18 percent from the value of 45 deg to that at 90 deg. No significant effect of aspect ratio over the range tested was found. A method for characterizing the flow regimes that is based on heat transfer mechanisms is proposed.

- Authors:

- Publication Date:

- Research Org.:
- Mechanical and Nuclear Engineering Departments, University of Wisconsin, Madison, Wisconsin.

- OSTI Identifier:
- 6149804

- Resource Type:
- Journal Article

- Journal Name:
- J. Heat Transfer; (United States)

- Additional Journal Information:
- Journal Volume: 101:1

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 14 SOLAR ENERGY; FLAT PLATE COLLECTORS; NATURAL CONVECTION; ASPECT RATIO; BOUNDARY LAYERS; CORRELATIONS; GRASHOF NUMBER; INTERFEROMETRY; NUSSELT NUMBER; CONVECTION; ENERGY TRANSFER; HEAT TRANSFER; LAYERS; SOLAR COLLECTORS; 141000* - Solar Collectors & Concentrators

### Citation Formats

```
Randall, K.R., Mitchell, J.W., and El-Wakil, M.M.
```*Natural convection heat transfer characteristics of flat plate enclosures*. United States: N. p., 1979.
Web. doi:10.1115/1.3450901.

```
Randall, K.R., Mitchell, J.W., & El-Wakil, M.M.
```*Natural convection heat transfer characteristics of flat plate enclosures*. United States. doi:10.1115/1.3450901.

```
Randall, K.R., Mitchell, J.W., and El-Wakil, M.M. Thu .
"Natural convection heat transfer characteristics of flat plate enclosures". United States. doi:10.1115/1.3450901.
```

```
@article{osti_6149804,
```

title = {Natural convection heat transfer characteristics of flat plate enclosures},

author = {Randall, K.R. and Mitchell, J.W. and El-Wakil, M.M.},

abstractNote = {Heat transfer by natural convection in rectangular enclosures has been experimentally studied using interferometric techniques. The effects of Grashof number, tilt angle, and aspect ratio on both the local and average heat transfer coefficients have been determined. The Grashof number range tested was 4 x 10/sup 3/ to 3.1 x 10/sup 5/, and the aspect ratio (ratio of enclosure length to plate spacing) varied between 9 and 36. The angles of tilt of the enclosure with respect to the horizontal were 45, 60, 75 and 90 deg. Correlations are developed for both local and average Nusselt number over the range of test variables. The effect of tilt angle is found to reduce the average heat transfer by about 18 percent from the value of 45 deg to that at 90 deg. No significant effect of aspect ratio over the range tested was found. A method for characterizing the flow regimes that is based on heat transfer mechanisms is proposed.},

doi = {10.1115/1.3450901},

journal = {J. Heat Transfer; (United States)},

number = ,

volume = 101:1,

place = {United States},

year = {1979},

month = {2}

}