Strip angle and strip width
Calculations are carried out with different strip angles for the curved absorbers and different strip widths for the flat absorbers. The interval for the strip angle investigated is from 150° to 179°. The investigated strip width for Seido 1-8 is in the interval from 0.075 m to 0.095 m. For Seido 10-20 with
flat absorber the investigated interval is from 0.045 m to 0.065 m. The optimum strip angle and width of the absorbers are the values resulting in the largest absorber area. The optimum angles and widths for the solar collectors can be seen in Table 5.
A change of the strip angle and strip width from the values in Table 1 to 179° and 0.095m / 0.065 m will result in a change in the optimum tilt of the collectors. The largest change in the optimum tilt is again seen in Nuussuaq where the tilt is increased with 6° for Seido 5-8 and 1-8. For Seido 10-20 the increase in the tilt is
slightly less, around 2°. In Sisimiut and Copenhagen only a slight change is seen as a result of a change in the absorber area. The optimum orientation is also found for the optimum strip angle and width. Here the optimum orientation changes for Nuussuaq so that the solar collectors should be turned even more towards east so that they are turned between 55° and 60° from south towards east. For Sisimiut Seido 5-8 and 1-8 should be turned back towards south so that the solar collectors are only turned 6° and 4° degrees from south to west where they in the original optimum orientation were turned 12° and 10°. In Copenhagen the collectors should all be turned slightly more towards west, about 1°. The improvement of the thermal performance as a function of the mean collector fluid temperature is shown for Nuussuaq in Fig 4. The improvement is largest for Seido 10-20 with flat absorber where the improvement is about 17 % as an average for mean collector fluid temperatures from 20 °C to 100 °C. For Seido 5-8 Seido 1-8 the thermal performance decreases for high mean collector fluid temperatures.
This is caused by an increasing heat loss from the increase in absorber area. The same tendency is seen for Sisimiut and Copenhagen. The improvement in thermal performance for the four collectors at a mean collector fluid temperature of 60 °C is for Seido 5-8 about 1.5 %, for Seido 1-8 about 2 %, for Seido 10-20 with curved absorber about 12 % and for Seido 1020 with flat absorber about 16%.
