kWe machine. The pressure ratio varies with turbine inlet temperature, but is approximately equal to 2. These results are partially based on Reference 7 and partially on AiResearch results (Ref. 4) and represent a design that is on the higher side of the cost range of Figure 14. It does indicate the temperature sensitivity of the Brayton engine to hot side temperature. In Figure 14, the cavity heat exchanger costs are included with those of the Brayton engine. The cavity gas heat exchanger is assumed to cost $33/kWt, 2 Based on 74.4 kWt intercepting the 1000 ft aperture of a 36 foot diameter dish, the 70% collector transfers 52 kWt into the fluid. The cavity receiver costs $1720. Considering the overall system efficiency to be 22.5%, the collector- Brayton engine combination would be rated at 16.7 kWe. Thus, the cavity receiver would cost about 100$/kWe. 3.3.2 Rankine Heat Engine The currently available Rankine energy conversion power plant was described briefly in Section 2.2.3. The thermal performance and costs of this commercially mature technology are presented in this section. 3.3.2.1 Rankine Plant Performance. The Black and Veatch calculation procedure detailed in Reference 1 is a suitable guide for calculating the performance of steam Rankine power plants. Appendix B of that reference develops expressions for net heat rates for typical Rankine power plants without reheat. The methodology considers wet bulb temperature, load, feedwater heating and turbine inlet conditions. For power plants greater than about 100 MWe, the resulting overall correction factor is about 1.06 in order to arrive at the actual net heat rate compared to the theoretical. Thus, the net efficiency is about 94.3% of theoretical. There appears to be a linear relationship between 10 MWe and 100 MWe,with the heat rate correction factor being 1.12 at 10 MWe. To take advantage of this characteristic of actual equipment,the nominal rating of the power plant is taken as
RkJQdWJsaXNoZXIy MTU5NjU0Mg==