Compound Parabolic Concentrators for Solar Water Heat Pasteurization: Numerical Simulation

Many people in less developed countries drink water with microbial contamination, which leads to the annual death of 5 million children. Although some people currently boil water, all microbes that cause disease in humans do not survive at temperatures >65oC, which solar water pasteurizers can easily produce. These pasteurizers are similar to box solar cookers, and typically have a small rectangular reflector. The objective of this work is to calculate the increase in output due to compound parabolic concentrators (CPCs) using numerical simulation. A CPC concentrates the maximum amount of radiation on a planar receiver consistent with the laws of thermodynamics. Since the average water temperature is nearly independent of the solar radiation, the heat losses are nearly constant. Therefore, higher concentration factors yield significantly higher efficiencies. Depending on climate, CPCs increase output by 1,000%-4,000%, while the additional reflector would only ~double the cost and necessitate weekly tilting.