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196 SAM Help Optical Calculations The optical calculations are values that SAM calculates using the equations described below. You cannot directly edit these values. Variable Name Length of single module Equation = Length of Collector Assembly ÷ Number of Modules per Assembly Note used in End Loss at Design described below. Incidence angle Not used in actual modifier at summer efficiency calculation. solstice Provided as reference only. Theta is in radians. End loss at Optical end loss at summer solstice noon on the summer solstice due to where: reflected radiation spilling off of the end of the collector assembly. This value is provided as a reference and is not used in determining the design of the solar field. Optical efficiency = Track ing Error × Geometry Effects × Mirror Reflectance × Dirt The collector's optical at design on Mirror efficiency under × General Optical Error design conditions. 7.1.4 Receivers (HCEs) To view the Receivers page, click Receivers (HCEs) on the main window's navigation menu. Note that for the physical trough input pages to be available, the technology option in the Technology and Market window must be Concentrating Solar Power - Physical Trough System. A receiver (HCE, heat collection element) is a metal pipe contained in a vacuum within glass tube that runs through the focal line of the trough-shaped parabolic collector. Seals and bellows ensure that a vacuum is maintained in each tube. Anti-reflective coatings on the glass tube maximize the amount of solar radiation that enters the tube. Solar-selective radiation absorbing coatings on the metal tube maximize the transfer of energy from the solar radiation to the pipe. Note. See the Troughnet website at http://www.nrel.gov/csp/troughnet/solar_field.html for more information about receivers. On the Receivers page, you define the characteristics of up to four receiver types. On the Solar Field page, January 2014
