Thermal Performance of Low Flux Solar Collector Using CuO – H2O based Nanofluid

Abstract

In this developing world, energy demand is growing day by day. But due to the scarcity and continuous depletion of conventional fuels, Renewable energy is an alternative source. Among all renewable energies, we have solar energy in abundance and solar collectors are commonly used to harvest the energy. The conventional fluids which are used as the heat transfer medium in solar collectors, suffer from poor thermal and heat absorption properties. It has been found that these conventional fluids have a limited capacity to carry heat up, which in turn limits the collector performance. It has been observed that for conventional fluids, suspending the nanoparticles in a liquid (Nanofluid) can be a good substitute because of the improved thermal properties. A new type solar collector named ‘Direct Solar Absorption System’ (DASC) is used as the experimental set-up. DASC is more efficient collector then the conventional type solar collector, as in DASC the fluid absorbs solar thermal energy volumetrically and thus captures more heat energy. Being a new technology, a very few research has been done in the past years and it has seen that Solar collector efficiency enhanced by 4 – 5 % than the conventional fluids. Reported experimental work pertains to the application of nanofluids and performance check of the solar collectors and it is found that by using CuO – H2O nanofluid, collector performance increases up to 6 %, for mass flow rate of 60 to 100ml/hr. The collector efficiency is also affected by the volume fraction of nanoparticles. In thesis work it is reported that at higher volume concentration the problem of settle down of nanoparticles increases, which results in lowering the collector efficiency. As volume fraction goes down from 0.05% to 0.005%, efficiency is increased by a value of 2% – 2.5% on an average. This collector efficiency enhancement can be achieved up to 10 – 15 %, by overcome the problem e.g. settling down of nanoparticles, make this suitable for higher mass flow rate.