Multiple reflector solar concentrators and systems

Abstract

The present invention relates to multiple reflector light or solar energy concentrators and systems using such concentrators. More particularly, the invention is concerned with an arrangement of optical elements for the efficient collection of light while minimizing complexities of optics needed to achieve light collection and concentration. At least three reflectors are involved. A concave primary reflector receives the solar energy and sends it to a secondary convex reflector positioned in the focal zone of the first reflector. In turn, the secondary reflector sends the solar energy, at least in part, to a third non-imaging reflector positioned in the focal zone of the secondary reflector. In a system, a receiver is placed in the focal zone of the third reflector. The present arrangement allows for the receiver to be in a fixed position, enhancing the ability of certain variants of the system to generate steam directly in the receiver. Preferred embodiments of the concentrator can be either in a trough or a dish configuration.

We claim:  
     
         1 . A light energy trough concentrator comprising: 
 a) a primary reflector having a linear concave configuration defining a first focal zone, and having a first longitudinal axis;    b) a secondary reflector having a linear convex configuration defining a second focal zone and having a second longitudinal axis in parallel alignment with the first longitudinal axis, the secondary reflector being disposed within the first focal zone;    and    c) a tertiary reflector having a linear non-imaging configuration defining a third focal zone and having a third longitudinal axis in parallel alignment with the first and second longitudinal axes, the tertiary reflector being disposed within the second focal zone;    wherein light energy reflecting from the primary reflector can be directed first to the secondary reflector, next to the tertiary reflector, and finally into the third focal zone.    
     
     
         2 . The light energy concentrator of  claim 1  wherein the primary reflector has a parabolic configuration and the secondary reflector has a hyperbolic configuration.  
     
     
         3 . The light energy concentrator of  claim 1  wherein the secondary reflector and tertiary reflectors are shaped and disposed so as to reflect into the third focal zone at least  75 % of the light energy being reflected from the primary reflector.  
     
     
         4 . The light energy concentrator of  claim 1  wherein the primary reflector has a circular arcuate configuration.  
     
     
         5 . The light energy concentrator of  claim 1  also comprising a non-imaging quaternary reflector defining a fourth focal zone and having a fourth longitudinal axis in parallel alignment with the second longitudinal axis, the quaternary reflector being disposed on the non-convex face of the secondary reflector.  
     
     
         6 . The light energy concentrator of  claim 1  wherein the secondary reflector is selective, allowing a portion of light energy from the primary reflector to pass through and a photovoltaic device is disposed so as to receive such pass through light energy.  
     
     
         7 . The light energy concentrator of  claim 6  wherein the light energy passed through is in a spectral range of substantial efficiency for the photovoltaic device.  
     
     
         8 . The light energy concentrator of  claim 6  wherein the light energy passed through is in the near infrared range.  
     
     
         9 . A light energy concentrating system comprising the light energy concentrator of  claim 1  and a first linear receiver disposed within the third focal zone, along the third longitudinal axis.  
     
     
         10 . The light energy concentrating system of  claim 9  wherein water is passed through the first receiver to create steam.  
     
     
         11 . The light energy concentrating system of  claim 9  also comprising a means for rotating the light energy concentrator to track diurnal solar movement.  
     
     
         12 . The light energy concentrating system of  claim 11  wherein the linear receiver does not move.  
     
     
         13 . The light energy concentrating system of  claim 9  also comprising the light energy concentrator of  claim 5  and a second linear receiver disposed within the fourth focal zone, along the fourth longitudinal axis.  
     
     
         14 . The light energy concentrating system of  claim 9  also comprising a second linear receiver disposed in a conductive relationship with the non-hyperbolic face of the secondary reflector.  
     
     
         15 . The light energy concentrating system of  claim 14  wherein the second receiver preheats a fluid passing through the first receiver.  
     
     
         16 . A light energy concentrating system comprising the solar energy concentrator of claim  65  and a first linear receiver disposed within the third focal zone, along the third longitudinal axis.  
     
     
         17 . A light energy dish concentrator comprising: 
 a) a primary reflector having a circular concave configuration defining a first focal zone and having a first longitudinal axis;    b) a secondary reflector having a circular convex configuration defining a second focal zone, the secondary reflector being disposed within the first focal zone; and    c) a tertiary reflector having a circular non-imaging configuration defining a third focal zone, the tertiary reflector being disposed within the second focal zone;    wherein light energy reflecting from the primary reflector can be directed first to the secondary reflector, next to the tertiary reflector, and finally into the third focal zone.    
     
     
         18 . The light energy concentrator of  claim 17  wherein the primary reflector has a parabolic configuration and the secondary reflector has a hyperbolic configuration.  
     
     
         19 . The light energy concentrator of  claim 17  wherein the secondary reflector and tertiary reflectors are shaped and disposed so as to reflect into the third focal zone at least 75% of the light energy being reflected from the primary reflector.  
     
     
         20 . The light energy concentrator of  claim 17  wherein the primary reflector has a circular arcuate configuration.  
     
     
         21 . A light energy concentrating system comprising the light energy dish concentrator of  claim 17  and a means for tracking the diurnal movement of the sun attached to the dish concentrator.  
     
     
         22 . The light energy concentrating system of  claim 21  also comprising a means for transducing light energy collected in the focal zone.  
     
     
         23 . The light energy concentrating system of  claim 21  wherein the energy transducer means is a heat engine.  
     
     
         24 . The light energy concentrating system of  claim 21  also comprising a receiver disposed within the third focal zone and a means for transferring thermal energy from the receiver.  
     
     
         25 . The light energy concentrating system of  claim 24  comprising a plurality of dish concentrators and a means for connecting the thermal energy transfer means.