# Analysis of a solar water-heater design by Remigio Lazo Franco
# Last edited on 2005-08-29 21:25:19 by stolfi

REMIGIO'S HEATER

  The heater consists of a roughly hemisherical reflector and a
  collector that absorbs the reflected sunlight. The heater is
  designed to be mounted in a fixed orientation, possibly buried into
  the roof of a house.
  
  In Remigio's design, the collector is a cylinder, coaxial with 
  the reflector.  The collector is divided into two segments:
  a "warmer" that produces warm water, and a "boiler" that 
  (hopefully) produces steam.
  
THE PROBLEM

  The analysis problem is to compute how much solar energy the heater
  can capture, as a function of the direction of incident sunlight.
  The synthesis problem is to adjust the shape of reflector and
  collector so as to maximize that quantity (or achieve some other
  performance goal).

ANALYSIS TECHNIQUE

  The analysis problem can be conveniently solved with POV-Ray. The
  idea is to paint the collector in red (or some other distinctive
  color), then render the heater as seen from the sun. In the
  resulting image, a pixel P will be colored red iff the rays from the
  sun that cross P will eventually hit the collector. Therefore, the
  number of red pixels in the image is proportional to the solar power
  captured by the heater, in that situation.
  
  For best results, the collector must be painted with self-lighted
  color (i.e. with finish "ambient 1 diffuse 0"). The mirror
  must be painted with a neutral reflecting color with the 
  correct efficiency {R} (i.e. with pigment color "<1,1,1>",
  finish  "ambient 0 diffuse 0 reflection {R}").  Then the 
  relative intensity of a red pixel P is the fraction of the energy 
  of the corresponding rays that actually reaches the collector.