چكيده به لاتين
Solar energy has known as the largest renewable energy source, due this particular mount of energy, extraction and using solar energy became important in last decades. One of the most common ways of converting solar energy into thermal energy is solar collectors. Conventional solar collectors are not efficient enough. In order to increase the efficiency of solar collectors, new methods such as changing the conventional working fluid into the nanofluid, removing adsorbent plates and receptacles in solar collectors so solar energy is gained directly and volumetric by nanofluid.
In this dissertation, two nanofluids of graphene oxide-water and graphene-heat transfer oil are used in various mass concentrations as the working fluid in the direct absorption solar collector. Numerical simulation and one dimensional (1D) modeling have been used and thermal and optical behavior of nanofluid in direct absorption solar collector has been explored. By modeling with MATLAB software optimum concentration and height have been acquired in direct absorption solar collector. Using nanofluids as a working fluid in the direct absorption solar collectors lead the optical properties of nanofluids to an important role. For mass concentrations of 0.02%, 0.05%, 0.1% and 0.25% GO-water and pure water solar collector efficiency were obtained in end of 45 minutes of simulation 45%, 49%, 62%, 76% and 15%, respectively. The results of the simulation are compared with the results of the experimental experiments and the optimum mass concentration and optimum heights of direct absorption solar collector have been introduced. The efficiency of the collector with the graphene oxide-water nanofluid is higher than the efficiency of collector using the graphene-heat transfer oil. Direct absorption collector with a height of 48 mm and graphene-water nanofluid with a mass concentration of 0.1% has the best performance and collector efficiency became 75%, as well as the best performance of direct absorption solar collector with graphene-heat transfer oil nanoparticles at a mass concentration of 0.001% and collector efficiency returns 32% at the end of the test period.
Keywords:
Direct absorption solar collector, graphene oxide-water nanofluid, graphene-heat transfer oil, numerical one-dimensional simulation, thermal and optical properties
