| Compared to other solar thermal power technology, trough concentrating solarthermal power technology is the first commercialized operation. Absorber in troughsolar collector is hosted solar thermal conversion process, the efficiency of thecollector directly affect the level of the system. Currently line focus solar collectorsystem uses straight-tube as the absorber. It exist advantages such as small heat lossand high efficiency, with the disadvantages of high cost and long-running vacuumleakage. Cavity is another absorber besides vacuum tube, can be used in the line focussolar collector. Although the thermal efficiency is low, it has the advantages of lowcost and high reliability. Cavity’s absorber wall has a high absorption rate coating willhave good reflection of light absorbed by the secondary effects, greatly improving thethermal efficiency of the cavity. The main work of this paper includes research thedifferent existing coatings effect on the absorption and transfer properties of thecavity, development of stable performance of the solar selective absorbing coating,the details are as follows.(1) Using2m2parabolic trough reflector and triangular cavity absorber systemtests the existing absorbing coating effect on the cavity. In the same weatherconditions, the efficiency curves of the cavity absorber with different coatings(lacquer coating, anodizing) and uncoated coating were obtained. Based on thecharacteristics of the solar radiation absorbing coating, the transmission mathematicalmodel of the line-focus solar heat absorbed cavity was build. And the heat absorptionand transmission characteristics were theoretically researched.The results showed that the absorber surface temperature of the cavity has a linearrelationship with of the concentrating energy. The maximum temperature can reach450K. Solar absorbing coating has great effect on the heat-absorbing cavity, and hassignificantly higher heat absorbing efficiency with low coefficient of infrared emission. The absorption rate of the cavity that has an absorption coating is about8%higher than the blank cavity. When the flux density is medium, the rate of infraredradiation energy loss was minimum value. Forced convection inside the tube cansignificantly improve the performance of heat-absorbing pipe. The heat absorptionefficiency increased with the increasing flow rate, i.e., when the flow rate adds10g/s,the heat efficiency increase about2%, while the wall temperature is decreasedsignificantly.(2) This paper used the pulsed magnetron sputtering apparatus sputtered SS-AlNsolar selective absorbing film. A spectral reflectance curve measured with aspectrophotometer was obtained, and the reflection curve of the sample by thesimulation was obtained. The results showed that the theoretical simulation curves,though not fully consistent with the actual measurements, but the absorption rate isbasically the same. Single theory experimentally measured by pulsed magnetronsputtering apparatus with the maximum absorption absorber rate=90.81%, themaximum value of was92.65%. Optical efficiency can be ensure their effectivelyapplied in high-temperature solar energy field.(3) In this paper, obtained by chemical oxidation selective absorbing layer, andstudy the optimal reaction conditions, high temperature, acid and abrasion resistance.Experimental results show that the best condition for sputtering PbS on coppersubstrates, whilec(Pb(Ac)2)=c(Thiourea)=0.4mol/L, c(NaOH)=1.2c(Pb(Ac)2),the reaction temperature was40℃, reaction time was30min. The temperaturecorresponding to the absorption rate α was0.888, the reflectivity was0.112. PbScoating has good thermal stability in the high temperature region, When the ignitiontemperature of400℃, still up0.86. After plating corrosion-resistant andanti-reflective layer, the absorbing coating can be effectively used in the solar energymedium-high temperature field.
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