Comparisons of Man Fields’ Behavior

Summary

The new MAN field installed at the SSPS site during 1984 is compared to the original MAN field using data collected during April — June 1984.

The main differences between the fields are a layout that minimizes the field pipe lengths, especially on the hot side, improved insulation, and elimination of the long field pipe support (fins) of the old field. The field control was also improved and the new field shows a more stable operation characteristic than the old field.

The total energy of the direct irradiation during the day and total energy gained by the fields was selected as a basis for the evaluation. Efficiency here means the quotient thermal energy gained by the fields/direct irradiated energy .

The analysis shows that the new field features considerably lower losses, a marginally higher conversion efficiency and, as a result of this, is capable of a considerably higher thermal energy production. The improvement is in the region of 10% on clear days and is higher on days with energy at low irradiance levels. Nevertheless, the new field consumes twice as much electrical energy as the old field in producing 1 kWh of thermal energy.