The amount of fluid flowing through one collector is referenced as "one basic flow unit," and the flow through every pipe section will be some multiple of a basic flow unit. Each pipe network is composed of pipe lengths with different diameters. The pipe internal diameter selection technique used here establishes the optimum distribution consistent with minimum installed pipe cost for a certain system pump work. Generally, the distribution varies from system to system, especially if the hot loop of a system is constructed from a different price pipe than the cooler loop. The lengths of pipe required for different internal diameters for the three considered system sizes are indicated in Table 5. These lengths are multiplied by a factor of\/2 to account for thermal expansion using the sawtooth approach. For example, in Table 5 the smallest internal diameter (I.D. - 1) indicated a basic oneway pipe length of 6196 feet for the 512 collector network. The actual pipe lengths are 8762 (6196 x"\/2) feet for the hot loop and 6196 (6196 x 1.0) feet for a cool loop at ambient temperature. Somewhat different efficiencies, fluid flowrates, pressures and temperatures are appropriate for each of the five transport systems. The parameters associated with each system are presented in Table 6. All entries in this table are inputs to the analysis except the fluid flowrate through a single collector and the Rankine efficiency which are determined by the cold side temperature chosen. The pump efficiency is for the transport fluid in converting from electric power input to hydraulic output. Besides consideration of the magnitude of the pumping power, the allowable pressure drop is another limiting criterion in determining the pipe diameter. The pressure drop must be realistic regardless of the magnitude of the pump work. The collector efficiency decreases with increasing fluid temperature as shown in Figure 7 in Section 3.1.1. The only apparent exception is the collector efficiency for the chemical transport system which is lower than would be expected compared to the other systems characterized in Table 5. This is due to the collector cavity temperature being at 700°C, despite the fact that
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