solution

During January, at a location in Alaska winds at 23 F can be observed. Several meters below ground the temperature remains at 55 F, however. An inventor claims to have devised a power cycle exploiting this situation that has a thermal efficiency of 10%. Discuss this claim.

Figure P6.25 shows a system for collecting solar radiation and utilizing it for the production of electricity by a power cycle. The solar collector receives solar radiation at the rate of 0.315 kW per m2 of area and provides energy to a storage unit whose temperature remains constant at 220 C. The power cycle receives energy by heat transfer from the storage unit, generates electricity at the rate 0.5 MW, and discharges energy by heat transfer to the surroundings at 20 C. For operation at steady state, determine the minimum theoretical collector area required, in m2 .