3.2 ENERGY TRANSPORT Two basic types of energy transport have been evaluated: the use of a fluid medium and the use of electric transport. The fluid media considered are liquids (water, NaK) and gases (steam, helium and CO + H2). Electric energy transport is associated with distributed generation at each dish collector, and is presented in Section 3.2.2. The use of various fluids is discussed in the next section which presents the analytical approach used as well as the results as a function of fluid temperature rise and the magnitude of heat transported. Collector efficiency and ground cover ratio are also considered. 3.2.1 Fluid Transport The analytical approach for the five fluid systems considered is presented as well as the results and discussion of this analysis. 3.2.1.1 Analytical Approach. A pipe network transports the fluid from the power conversion plant to the collectors for energy input and then returns the energized fluid to the central power plant. The five fluids considered are water, steam, NaK, He and CO + H2. For each of the five considered flow systems, the same geometrical network is applied to enable a valid cost comparison. One of the major parameters is the magnitude of the heat transported. To evaluate this factor three different collector field sizes are considered; the three sizes are 512 collectors, 4608 collectors and 41,472 collectors. A factor of nine exists between each successive size of system. These numbers of collectors roughly correspond to 10 MWe, 90 MWe and 800 MWe based on a 36 ft dish operating near an overall system efficiency of 26%. The pipe network for the 512 collector system is shown in Figure 10. The power plant is located in the square at the center of the array, and the numbers associated with each pipe length in Figure 10 indicate the number of basic flow units flowing through each section for the 512 collector case. For the 4608
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