Energy, efficiency, economic impact, and heat transfer aspects of solar flat plate collector with Al₂O₃ nanofluids and wire coil with core rod inserts

The energy and cost saving of flat plate collector using Al₂O₃/water nanofluids and with wire coil with core rod inserts were studied experimentally. The experiments were conducted for various particle loadings of nanofluid (0.1%, 0.2% and 0.3%) and nanofluid with various p/d values of wire coil with core-rod inserts (p/d = 1.79, 2.54 and 3.24). The potential increase of collector efficiency is converted into useful size reduction, weight reduction, cost, and energy saving of the collector. With the use of nanofluids in the collector its efficiency is enhanced. The maximum collector efficiency is 37.73% for particle loading of 0.3% in the collector at a flow rate of 300 lit/hr in validation with water collector. By providing wire coil with core-rod inserts, p/d value of 1.79 with 0.3% particle loading of nanofluid, the collector efficiency is further incremented to 64.15% at a flow rate of 300 lit/hr. Meanwhile, at the same experimental conditions, using 0.3% nanofluid, a maximum reduction in the collector area is 27.66%, and it is reduced to 39.33% for nanofluid of 0.3% with p/d of 1.79 insert. The original cost of the water collector is 223.88$, which is reduced to 161.94$ for 0.3% nanofluid and further reduced to 135.82$ for 0.3% nanofluid with p/d of 1.79 insert. Simultaneously, the embodied energy of materials used in the collector is reduced by using nanofluids and inserts in the collector. Besides, the heat transfer and friction factor are also evaluated, and the data is fitted.