0
RESEARCH PAPERS

Modeling Shadows on Evacuated Tubular Collectors With Cylindrical Absorbers

[+] Author and Article Information
Louise Jivan Shah

Department of Civil Engineering,  Technical University of Denmark, Building 118, DK-2800 Kgs. Lyngby, Denmarkljs@byg.dtu.dk

Simon Furbo

Department of Civil Engineering,  Technical University of Denmark, Building 118, DK-2800 Kgs. Lyngby, Denmark

J. Sol. Energy Eng 127(3), 333-342 (Nov 08, 2004) (10 pages) doi:10.1115/1.1878872 History: Received July 08, 2004; Revised November 08, 2004

A new TRNSYS collector model for evacuated tubular collectors with tubular absorbers is developed. Traditional flat plate collector performance equations have been integrated over the whole absorber circumference. On each tube the model determines the size and position of the shadows caused by the neighbor tube. An all glass tubular collector with tubular absorbers with 14 tubes connected in parallel is investigated theoretically with the model and experimentally in an outdoor collector test facility. Performance calculations with the new model are compared with measured results and a good degree of similarity between the measured and calculated results is found. Further, it is illustrated how the model can be used for geometrical parameter studies both for constant collector mean fluid temperatures and for varying temperature conditions in a solar heating plant. These investigations are performed for two climates: Copenhagen (Denmark) and Uummannaq (Greenland).

Copyright © 2005 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Design of the evacuated tubes (top) and the tubes connected to a solar panel (bottom)

Grahic Jump Location
Figure 2

The solar vector S, and the tube vector, N.

Grahic Jump Location
Figure 3

Illustration of the shaded area and the area exposed to beam radiation

Grahic Jump Location
Figure 4

Illustration of the beam radiation passing one tube and hitting the next tube

Grahic Jump Location
Figure 5

Photo of the tested collector

Grahic Jump Location
Figure 6

Measured and calculated outlet temperature for the test periods

Grahic Jump Location
Figure 7

Measured and calculated collector performance for the test periods

Grahic Jump Location
Figure 8

The angle on the tube exposed to beam radiation as a function of the solar azimuth and zenith, when the center tube distance is 0.067m

Grahic Jump Location
Figure 9

The angle of the tube exposed to beam radiation as a function of the solar azimuth and zenith, when the center tube distance is 0.047m

Grahic Jump Location
Figure 10

The thermal performance per tube, at a fuild mean temperature of 50°C, as a function of the collector tilt and orientation for Copenhagen (left) and Uummannaq (right)

Grahic Jump Location
Figure 11

The thermal performance per tube as a function of the inner tube radius for a collector fluid mean temperature of 50°C

Grahic Jump Location
Figure 12

The thermal performance per tube as a function of the tube center distance for different collector fluid mean temperatures

Grahic Jump Location
Figure 13

Schematic illustration of the TRNSYS mode

Grahic Jump Location
Figure 14

Assumed flow rate and temperatures in the district heating net

Grahic Jump Location
Figure 15

The thermal performance per tube [kWh/Tube/Year] as a function of the tube center distance, collector tilt and orientation (Copenhagen)

Grahic Jump Location
Figure 16

The thermal performance per tube (kW h/tube/year) as a function of the tube center distance, collector tilt, and orientation (Uummannaq)

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In