7257

6763

كارشناسي ارشد

تبديل انرژي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مكانيك

1391

ده، 70ص: مصور، جدول، نمودار

ص.ع. به فارسي و انگليسي

علي اكبر عالم رجبي

احمد صابونچي

21/8/91

محمود اشرفي زاده، محمد رضا سليم پور

1396/09/21

كتابنامه

مكانيك

مهندسي مكانيك

ID6763

به فارسي و انگليسي: قابل رويت در نسخه ديجيتال

Effect of adding a secondary reflector on the distribution of input flux to the receiver tube of Fresnel concentrators Ali Minaeian a minaeian@me iut ac ir Date of Submission 2012 09 18 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Ali Akbar Alem Rajabi rajabi@cc iut ac irAbstract There are a number of problems associated with fossil fuels most of which stem from the by productscreated when they are burned to create energy Chief among those byproducts are carbon dioxide andnitrous oxide greenhouse gases that are major contributors to global warming Renewable energy is farcleaner than fossil fuels Many of the safety concerns surrounding fossil fuels such as explosions on oilplatforms and collapsing coal mines do not exist with renewable energy Most renewable energy comeseither directly or indirectly from the sun Sunlight or solar energy can be used directly for heating andlighting homes and other buildings for generating electricity and for hot water heating solar cooling and avariety of commercial and industrial uses One way to produce electricity from the sun is by using theconcentrating solar thermal system This is done by focusing the heat from the sun to produce steam Thesteam will drove a generator to produce electricity Many different types of concentrators are being used insolar industries including parabolic linear concentrators parabolic dishes central receivers Fresnelconcentrators etc Fresnel concentrators are simpler and easier to manufacture compared with parabolic concentratorcollectors though their efficiency might be slightly lower In these systems the parabolic reflectors whichare expensive are replaces by flat reflectors Sun rays which are reflected by flat reflectors are partly lostbecause they do not coincide on the absorber tube instead they pass near the absorber tube To increase theefficiency of Fresnel concentrators a second reflector is devised above the absorber tube This secondreflector diverts the otherwise lost rays towards the absorber tube The other advantage of the secondreflector is that it distributes the incident rays more uniformly on the absorber tube This is especiallyimportant in the systems which use a molten salt as the thermal transport medium In the present study sixdifferent designs for the second reflector are proposed and their performances are evaluated Each designhas been simulated in the MATLAB software and the effective parameters on its performance have beeninvestigated To analyze and compare the performance of different proposed designs first the systemperformance is evaluated without considering the secondary reflector Prior to this the tilt angle of each ofthe primary reflectors are adjusted to the optimum value in such a way that most of the reflected rays arediverted towards the absorber tube Then by adding the secondary reflector to the system its performance isevaluated The results show that for the secondary reflector a flat mirror reflector combined with flat wingson both sides is the best choice The results show that by devising this secondary flat reflector about 87 of the sun rays incident on the primary reflector are received by the absorber tube It collects more rays anddistributes them more evenly on the absorber tube Keywords Solar energy Fresnel reflectors secondary reflector solar power

علي اكبر عالم رجبي

احمد صابونچي

محمود اشرفي زاده، محمد رضا سليم پور