Abstract:
A solar collector with external reflector. A solar collector includes a glass housing having a heat pipe disposed within the housing and a light reflector disposed external to the housing.

Description:
The invention is directed to a collector having an externally disposed nonimaging reflector and more particularly is directed to a solar collector with a heat pipe positioned within an evacuated glass tube with an externally disposed nonimaging reflector. 
     BACKGROUND OF THE INVENTION 
     It was recognized more than 20 years ago, that combining selective absorbers, vacuum insulation and nonimaging concentration (using Compound Parabolic Concentrator, or “CPC”, type optics as shown in  FIG. 9A-9C ) enabled stationary mid-temperature collectors to have a useful operating range approaching 300 degrees Celsius”. Following the early proof-of-concept experiments, a commercial collector was developed in the last 5-years with good performance up to 250 degrees Celsius. These configurations integrated all the optics within the vacuum envelope. For this reason we refer to them as ICPC&#39;s (integrated CPC&#39;s). Their cost of manufacture is presently too high for widespread applications. On the other hand, the advent of very low-cost evacuated tubes allows us now to consider these as candidates for low-cost mid-temperature applications. One can combine various of these features to use such low-cost tubes (intended as stand-alone low-temperature collectors for providing domestic hot water) as receivers and now combined with external nonimaging reflectors. Since these glass tubes were originally intended for low-temperature (domestic hot water) use, their use at higher temperatures raised issues such as providing for efficient heat transfer to a working fluid, and assuring against thermal-induced tube breakage. 
     A solar collector which is efficient at temperatures in the 125 to 150 degree Celsius above ambient range would therefore be of great utility for many high-value applications. For example, operating temperatures for solar cooling in conjunction with double-effect chillers are in this range. At the same time the collector component would need to be low-cost, have minimal operation and maintenance cost and long life. The external reflector form of a CPC has the potential for satisfying these criteria. The vacuum receiver has intrinsically long-life, being protected from the environment. The impressive commercial development of vacuum solar collectors in China over the last decade and more demonstrates that these can be manufactured and sold at low-cost. To give an example; in the year 2000 the all-glass dewar type solar tube made in China was available at an OEM cost of $3 US. Since the volume of manufacturing has been rising, prices are not increasing. It is significant to observe that a wide-angle CPC reflector will “unwrap” the cylindrical solar tube to an aperture of approximately 0.2 square meters. Therefore the vacuum component contributes $15 per square meter to the cost. The heat extraction device which may be a manifold likely adds a similar amount. The nonimaging reflector can be estimated at $20 per square meter, which is dominated by the material cost for a high quality aluminum mirror. An installed cost of approximately $100 per square meter would be a reasonable goal. The availability of an efficient mid-temperature solar collector for $100 per square meter would have a broad vista of applications. 
     SUMMARY OF THE INVENTION 
     A solar collector system is directed to a combination of a heat pipe disposed within a housing which is at least partially transparent to light with the housing preferably evacuated. The heat pipe includes a copper pipe and coupled aluminum heat transfer fins disposed about the heat pipe. The fins are molded to optimize thermal contact with the heat pipe and interior surface of the housing. The solar collector further includes a reflector assembly externally disposed to the housing to simplify construction and costs of manufacture. Preferably the reflector is a nonimaging design. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows XCPC thermal model performance and measured performance of a test panel with dewar tubes; 
         FIG. 2  shows instantaneous solar to thermal conversion efficiency for a heat pipe embodiment for mid temperature performance ranges; 
         FIG. 3  shows performance limits of a commercial VAC 2000 solar collector; 
         FIG. 4A  shows a disassembled embodiment of a portion of a solar receiver and  FIG. 4B  shows a cross section of an assembled unit; 
         FIG. 5  shows a partially assembled collector system with the manifold and heat pipe in position; 
         FIG. 6  shows a first collector configuration with external reflector; 
         FIG. 7  shows a second collector configuration with external reflector; 
         FIG. 8  shows a third collector configuration with external reflector; 
         FIG. 9A  shows a CPC shape for various incidence angles,  FIG. 9B  shows 0° (normal) incidence and  FIG. 9C  SHOWS 30° incidence; 
         FIG. 10A  shows a plot of thermal performance of collector test number C444 with wind;  FIG. 10B  shows the performance without wind; 
         FIG. 11A  shows a plot of thermal performance of collector test number C500 with wind;  FIG. 11B  shows the performance without wind; and 
         FIG. 12A  shows a plot of thermal performance of collector test number C370 with wind;  FIG. 12B  shows the performance without wind. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     In accordance with the invention, two types of preferred combination of solar collectors  12  (concentrators or receivers) are described, including an all glass dewar-type tube  11  and a heat-pipe  10  in a conventional evacuated tube  13  (see  FIGS. 4A ,  4 B and  5 ). The dewar-type  11  is very low-cost since it is made in large quantities by a large number of manufacturers and uses a very low-cost borosilicate glass tubing. Good heat transfer poses technical challenges, and our experiments with a heat transfer compound to couple the tube  11  to a manifold  20  gave encouraging results. The preliminary mid-temperature performance obtained with a test panel with dewar tubes is compared with that predicted by a simple model shown in  FIG. 1 . The heat-pipe evacuated tube  13  (see  FIG. 4B ), uses the same very low-cost glass tubing. The heat transfer is accomplished in an elegant way by the incorporation of the heat pipe  10  within the evacuated tube  13  which in turn is disposed in a full panel array  15  (see  FIGS. 4A ,  4 B and  5 ). The heat pipe  10  of  FIGS. 4A and 4B  includes a copper heat pipe  16  and contoured aluminum heat transfer fins  18  with the heat pipe  10  inserted into the glass tube  14  sandwiched between two aluminum fins  18 . The fins  18  are molded to maximize contact with the heat pipe  10  and the inside surface of the evacuated glass tube  14 . The heat pipe  10  transfers heat to the manifold  20  shown in  FIG. 5  via heat transfer liquid inside the hollow heat pipe  10 . The hollow centre of the heat pipe  10  includes a vacuum, so that at even at temperatures of around 25-30° C. the well known heat transfer compound will vaporize. When heated the vapor rises to the tip (condenser) of the heat pipe  10  where the heat is transferred to the water flowing through the manifold  20 . The loss of heat causes the vapor to condense and flow back down the heat pipe  10  where the process is once again repeated. The preliminary mid-temperature performance obtained with the prototype heat-pipe version is shown in  FIG. 2 . The performance limit of known CPC-type vacuum solar collectors (not shown) can be gauged from  FIG. 3 . In this type of solar device both absorber and nonimaging concentrating optics are encased in an integral glass envelope, and this is called the integrated CPC or I CPC. Commercial collectors of this type have a higher cost than the all glass dewar type with external CPC reflectors  22  of  FIGS. 6-8 . However, it does indicate a practical and realizable performance upper limit for the stationary nonimaging solar collectors  12 . One can further combine the advantages of the low-cost all-glass evacuated receiver with the heat pipe. As shown in  FIGS. 4A ,  4 B and  5 , the heat pipe  10  and absorber fin assembly is inserted in the double-walled evacuated tube  14  and the heat pipes  10  are inserted into the simple flow-through heat exchanger manifold  20 . There is no fluid connection which is one of the chief advantages of a heat application, but appears sufficiently robust to withstand stagnation temperatures. Various examples of performance of a conventional evacuated tube but externally disposed reflector (without the heat pipe  10 ) are shown in Examples I-III wherein collector test results are shown in  FIGS. 6-8  for the collector configurations. These tests were made by Solartechnik Prüfung Forschung, located in Bern, Switzerland. 
     While preferred embodiments have been illustrated and described, it should be understood that changes and modifications can be made therein in accordance with one of ordinary skill in the art without departing from the invention in its broader aspects. 
     EXAMPLES 
     The following non-limiting examples describe various embodiments and associated performance test results. 
     Example I 
     Collector Test No. C444. The embodiment of  FIG. 6  is described in Table 1 and was subjected to various tests as set forth in Table 2. Note there was no stagnation temperature for standard values ISO 9806-2 and EN 12975-2 are 30° C./1000 W/m 2 . The thermal performance (flowrate at test: 204 l/h) is shown in  FIGS. 10A and 10B , with and without wind, respectively. 
     
       
         
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
             
             
               
                 Contact 
                 Ritter Solar GmbH, D-72135 Dettenhausen 
               
               
                   
                 Tel. +49 (07157) 5359-0, 
               
               
                   
                 Fax +49 (07157) 5359-20 
               
               
                 Distributed in* 
                 DE 
               
               
                 Type 
                 ETC, cylindrical absorbers, CPC, 
               
               
                   
                 direct heat transfer 
               
               
                 Assembly 
               
               
                 Installation* 
                 Installation on sloping roof, 
               
               
                   
                 Flat roof with support 
               
               
                 Rated flowrate* 
                 180 l/h 
               
               
                 Absorber coating* 
                 Al/Al N 
               
               
                 Dimensions 
                 2.010 m 2 , 1.988 m 2 , 2286 m 2   
               
               
                 (absorber, aperture, gross) 
               
               
                 Gross dimensions: 
                 1.640 × 1.394 × 0.105 
               
               
                 l, w, h (in m) 
               
               
                 Weight including glazing* 
                 35 kg 
               
               
                   
               
               
                 *= manufacturer information 
               
             
          
         
       
     
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                 Carried 
                   
                   
               
               
                 Test 
                 out 
                 Section 
                 Report* 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Durability test according to ISO 
                 No 
                 3 
                 LTS C444 
               
               
                 Durability test according to EN 
                 No 
                 3 
                 C444LPEN 
               
               
                 Measurement of stagnation temperature 
                 No 
                 3.1 
               
               
                 Efficiency measurement acc. SPF 
                 Yes 
                 4.1 
               
               
                 Efficiency measurement acc 
                 Yes 
                 4.1 
               
               
                 ISO, DIN, EN 
               
               
                 Incidence angle modifier (IAM) 
                 Yes 
                 4.4 
               
               
                 Measurement of pressure drop 
                 No 
                 4.5 
               
               
                 Measurement of thermal capacity 
                 Yes 
                 4.6 
               
               
                 Measurement of time constant 
                 Yes 
                 4.6 
               
               
                   
               
               
                 *= contact manufacturer for details! 
               
             
          
         
       
     
     Tables 3A and 3B illustrate characteristic efficiency values (normal incidence, G=800 W/m 2 ) for efficiency with and without wind, respectively. Tables 4A and 4B show power output (power in watts per collector, normal incidence, beam irradiation) with and without wind, respectively. 
     
       
         
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                 TABLES 3A and 3B 
               
             
          
           
               
                 Reference area 
                 Absorber 
                 Aperture 
                 Gross 
                 Reference area 
                 Absorber 
                 Aperture 
                 Gross 
               
               
                   
               
               
                 η (T* m  = 0.00) 
                 0.62 
                 0.62 
                 0.54 
                 η (x = 0.00) 
                 0.62 
                 0.62 
                 0.54 
               
               
                 η (T* m  = 0.05) 
                 0.56 
                 0.57 
                 0.49 
                 η (x = 0.05) 
                 0.56 
                 0.57 
                 0.50 
               
               
                 η (T* m  = 0.10) 
                 0.50 
                 0.51 
                 0.44 
                 η (x = 0.10) 
                 0.50 
                 0.51 
                 0.44 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                 TABLES 4A and 4B 
               
             
          
           
               
                 Irradiation 
                 400 W/m 2   
                 700 W/m 2   
                 1000 W/m 2   
                 Irradiation 
                 400 W/m 2   
                 700 W/m 2   
                 1000 W/m 2   
               
               
                   
               
               
                 t m  − t e  = 10K 
                 474 
                 846 
                 1′218 
                 t m  − t e  = 10K 
                 475 
                 847 
                 1′219 
               
               
                 t m  − t e  = 30K 
                 429 
                 801 
                 1′173 
                 t m  − t e  = 30K 
                 431 
                 803 
                 1′175 
               
               
                 t m  − t e  = 50K 
                 382 
                 754 
                 1′126 
                 t m  − t e  = 50K 
                 385 
                 757 
                 1′129 
               
               
                   
               
             
          
         
       
     
     Table 5 shows incidence angle modifier (IAM), Table 6 shows pressure drop in Pascals (test fluid 33.3% Ethylenglykol) and Table 7 shows thermal capacity and time constant. 
     
       
         
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 5 
               
               
                   
                   
               
               
                   
                 0° 
                 10° 
                 20° 
                 30° 
                 40° 
                 50° 
                 60° 
                 70° 
                 80° 
                 90° 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 K(Θ), long   
                 1.0 
                   
                   
                   
                   
                 0.90 
                   
                   
                   
                 0.0 
               
               
                 K(Θ), trans   
                 1.0 
                   
                 1.01 
                 1.0 
                 1.01 
                 1.01 
                 1.05 
                 1.16 
                   
                 0.0 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
             
               
               
             
           
               
                   
                 TABLE 6 
               
               
                   
                   
               
               
                   
                 100 l/h 
                 150 l/h 
                 250 l/h 
                 350 l/h 
                 500 l/h 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 20° C. 
               
               
                   
                 60° C. 
               
               
                   
                 80° C. 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
               
               
             
           
               
                   
                 TABLE 7 
               
               
                   
                   
               
               
                   
                 Thermal capacity (kJ/K) 
                 Time constant (s) 
               
               
                   
                   
               
             
             
               
                   
                 16.2 
                 202 
               
               
                   
                   
               
             
          
         
       
     
     These tests were performed by SPF, Hochschule Rapperswil (HSR) at Oberseestr. 10, CH-8640 Rapperswil. 
     Example II 
     Collector Test No. C500. (Consolar GmbH, TUBO 11 CPC) The embodiment of  FIG. 7  is described in Table 8 and the tests of Table 9 were performed. There was no stagnation temperature for standard values ISO 9806-2 and EN-12975-2 were 30° C./1000 W/m 2 . The thermal performance (flowrate at test: 100 l/h) is illustrated in  FIGS. 11A and 11B , with and without wind, respectively. 
     
       
         
               
               
             
           
               
                 TABLE 8 
               
               
                   
               
             
             
               
                 Contact 
                 Consolar GmbH, D-60489 Frankfurt/M. 
               
               
                   
                 Tel. +49 (069) 61 99 11 30, 
               
               
                   
                 Fax +49 (069) 61 99 11 28 
               
               
                 Distributed in* 
                 DE, AT, *EU* 
               
               
                 Type 
                 ETC, cylindrical absorbers, CPC, 
               
               
                   
                 direct heat transfer 
               
               
                 Assembly 
               
               
                 Installation* 
                 Installation on sloping roof, 
               
               
                   
                 Flat roof with support 
               
               
                 Rated flowrate* 
                 100 l/h 
               
               
                 Absorber coating* 
                 Metal carbide 
               
               
                 Dimensions 
                 0.873 m 2 , 0.967 m 2 , 1.163 m 2   
               
               
                 (absorber, aperture, gross) 
               
               
                 Gross dimensions: 
                 1.860 × 0.625 × 0.045 
               
               
                 l, w, h (in m) 
               
               
                 Weight including glazing* 
                 13 kg 
               
               
                   
               
               
                 *= manufacturer information 
               
             
          
         
       
     
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 9 
               
               
                   
               
               
                   
                 Carried 
                   
                   
               
               
                 Test 
                 out 
                 Section 
                 Report* 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Durability test according to ISO 
                 No 
                 3 
                 LTS C500 
               
               
                 Durability test according to EN 
                 No 
                 3 
                 C500LPEN 
               
               
                 Measurement of stagnation temperature 
                 No 
                 3.1 
               
               
                 Efficiency measurement acc. SPF 
                 Yes 
                 4.1 
               
               
                 Efficiency measurement acc 
                 Yes 
                 4.1 
               
               
                 ISO, DIN, EN 
               
               
                 Incidence angle modifier (IAM) 
                 Yes 
                 4.4 
               
               
                 Measurement of pressure drop 
                 Yes 
                 4.5 
               
               
                 Measurement of thermal capacity 
                 No 
                 4.6 
               
               
                 Measurement of time constant 
                 No 
                 4.6 
               
               
                   
               
               
                 *= contact manufacturer for details! 
               
             
          
         
       
     
     Tables 10A and 10B illustrate characteristic efficiency values (normal incidence, G=800 W/m 2 ) for efficiency with and without wind, respectively. Tables 11A and 11B show power output (power in watts per collector, normal incidence, beam irradiation) with and without wind, respectively. 
     
       
         
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                 TABLES 10A and 10B 
               
             
          
           
               
                 Reference area 
                 Absorber 
                 Aperture 
                 Gross 
                 Reference area 
                 Absorber 
                 Aperture 
                 Gross 
               
               
                   
               
               
                 η (T* m  = 0.00) 
                 0.73 
                 0.66 
                 0.55 
                 η (x = 0.00) 
                 0.73 
                 0.66 
                 0.55 
               
               
                 η (T* m  = 0.05) 
                 0.66 
                 0.59 
                 0.49 
                 η (x = 0.05) 
                 0.67 
                 0.60 
                 0.50 
               
               
                 η (T* m  = 0.10) 
                 0.59 
                 0.53 
                 0.44 
                 η (x = 0.10) 
                 0.61 
                 0.55 
                 0.46 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                 TABLES 11A and 11B 
               
             
          
           
               
                   
                 400 
                 700 
                 1000 
                   
                 400 
                 700 
                 1000 
               
               
                 Irradiation 
                 W/m 2   
                 W/m 2   
                 W/m 2   
                 Irradiation 
                 W/m 2   
                 W/m 2   
                 W/m 2   
               
               
                   
               
               
                 t m  − t e  = 10K 
                 241 
                 431 
                 622 
                 t m  − t e  = 10K 
                 244 
                 434 
                 624 
               
               
                 t m  − t e  = 30K 
                 217 
                 407 
                 597 
                 t m  − t e  = 30K 
                 224 
                 414 
                 604 
               
               
                 t m  − t e  = 50K 
                 192 
                 383 
                 573 
                 t m  − t e  = 50K 
                 204 
                 394 
                 584 
               
               
                   
               
             
          
         
       
     
     Table 12 shows incidence angle modifier (IAM), and Table 13 shows pressure drop in Pascals (test fluid 33.3% Ethylenglykol). 
     
       
         
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 12 
               
               
                   
                   
               
               
                   
                 0° 
                 10° 
                 20° 
                 30° 
                 40° 
                 50° 
                 60° 
                 70° 
                 80° 
                 90° 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 K(Θ), long   
                 1.0 
                   
                   
                   
                   
                 0.93 
                   
                   
                   
                 0.0 
               
               
                 K(Θ), trans   
                 1.0 
                 1.0 
                 1.0 
                 0.95 
                 0.82 
                 0.84 
                 0.90 
                 1.02 
                 1.03 
                 0.0 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 13 
               
               
                   
                   
               
               
                   
                 50 l/h 
                 100 l/h 
                 150 l/h 
                 175 l/h 
                 200 l/h 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 20° C. 
                 6400 
                 13300 
                 21400 
                 26000 
                 30700 
               
               
                   
                 60° C. 
               
               
                   
                 80° C. 
               
               
                   
                   
               
             
          
         
       
     
     Example III 
     Collector Test No. C370. (Paradigma-Schweiz, CPC 14 Star) The embodiment of  FIG. 8  is described in Table 14, and the tests of Table 15 were performed. The stagnation temperature for standard values ISO 9806-2 and EN 12975-2 were for 30° C./1000 W/m 2 , 269° C. The collector also passed a durability test. The thermal performance (flowrate at test: 179 l/h) is shown in  FIGS. 12A and 12B , with and without wind, respectively. 
     
       
         
               
               
             
           
               
                 TABLE 14 
               
               
                   
               
             
             
               
                 Contact 
                 Paradigma-Schweiz, CH-6201 Sursee 
               
               
                   
                 Tel. +41 (041) 925 11 22, 
               
               
                   
                 Fax +41 (041) 925 11 21 
               
               
                 Distributed in* 
                 CH, DE, AT, *EU*, PL, HR 
               
               
                 Type 
                 Evacuated tube collector, 
               
               
                   
                 cylindrical absorbers, CPC, 
               
               
                   
                 direct heat transfer 
               
               
                 Installation* 
                 Installation on sloping roof, 
               
               
                   
                 Flat roof with support, 
               
               
                   
                 Facade installation 
               
               
                 Rated flowrate* 
                 180 l/h 
               
               
                 Absorber coating* 
                 Al/Al N 
               
               
                 Dimensions 
                 2.332 m 2 , 2.325 m 2 , 2.618 m 2   
               
               
                 (absorber, aperture, gross) 
               
               
                 Gross dimensions: l, w, h (in m) 
                 1.613 × 1.623 × 0.120 
               
               
                 Weight including glazing* 
                 42 kg 
               
               
                   
               
               
                 *= manufacturer information 
               
             
          
         
       
     
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 15 
               
               
                   
               
               
                   
                 Carried 
                   
                   
               
               
                 Test 
                 out 
                 Section 
                 Report* 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Durability test according to ISO 
                 Yes 
                 3 
                 C370QPISO 
               
               
                 Durability test according to EN 
                 Yes 
                 3 
                 C370QPEN 
               
               
                 Measurement of stagnation temperature 
                 Yes 
                 3.1 
                 C370QPEN 
               
               
                 Efficiency measurement acc. SPF 
                 Yes 
                 4.1 
                 LTS C370 
               
               
                 Efficiency measurement acc 
                 Yes 
                 4.1 
                 C370LPEN 
               
               
                 ISO, DIN, EN 
               
               
                 Incidence angle modifier (IAM) 
                 Yes 
                 4.4 
               
               
                 Measurement of pressure drop 
                 No 
                 4.5 
               
               
                 Measurement of thermal capacity 
                 Yes 
                 4.6 
               
               
                 Measurement of time constant 
                 No 
                 4.6 
               
               
                   
               
               
                 *= contact manufacturer for details! 
               
             
          
         
       
     
     Tables 16A and 16B illustrate characteristic efficiency (normal incidence, G=800 W/m 2 ) for efficiency with and without wind, respectively. Table 17A and 17B show power output (power in watts per collector, normal incidence, beam irradiation) with and without wind, respectively. 
     
       
         
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                 TABLES 16A and 16B 
               
             
          
           
               
                 Reference area 
                 Absorber 
                 Aperture 
                 Gross 
                 Reference area 
                 Absorber 
                 Aperture 
                 Gross 
               
               
                   
               
               
                 η (T* m  = 0.00) 
                 0.68 
                 0.68 
                 0.60 
                 η (x = 0.00) 
                 0.68 
                 0.68 
                 0.60 
               
               
                 η (T* m  = 0.05) 
                 0.59 
                 0.60 
                 0.53 
                 η (x = 0.05) 
                 0.60 
                 0.60 
                 0.54 
               
               
                 η (T* m  = 0.10) 
                 0.50 
                 0.51 
                 0.45 
                 η (x = 0.10) 
                 0.52 
                 0.52 
                 0.46 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                 TABLES 17A and 17B 
               
             
          
           
               
                 Irradiation 
                 400 W/m 2   
                 700 W/m 2   
                 1000 W/m 2   
                 Irradiation 
                 400 W/m 2   
                 700 W/m 2   
                 1000 W/m 2   
               
               
                   
               
             
          
           
               
                 t m  − t e  = 10K 
                 593 
                 1′065 
                 1′537 
                 t m  − t e  = 10K 
                 597 
                 1′069 
                 1′541 
               
               
                 t m  − t e  = 30K 
                 517 
                 989 
                 1′461 
                 t m  − t e  = 30K 
                 528 
                 1′000 
                 1′472 
               
               
                 t m  − t e  = 50K 
                 437 
                 909 
                 1′381 
                 t m  − t e  = 50K 
                 455 
                 928 
                 1′400 
               
               
                   
               
             
          
         
       
     
     Table 18 shows incidence angle modifier (IAM). 
     
       
         
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 18 
               
               
                   
                   
               
               
                   
                 0° 
                 10° 
                 20° 
                 30° 
                 40° 
                 50° 
                 60° 
                 70° 
                 80° 
                 90° 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 K(Θ), long   
                 1.0 
                   
                   
                   
                   
                 0.90 
                   
                   
                   
                 0.0 
               
               
                 K(Θ), trans   
                 1.0 
                   
                 1.01 
                 1.00 
                 1.01 
                 1.01 
                 1.05 
                 1.16 
                   
                 0.0