The influence of magnetic field on heat transfer of magnetic nanofluid in a double pipe heat exchanger proposed in a small-scale CAES system

Globally, the integration of renewable energy (which has an intermittent nature) into the power system requires the system operators to improve the system performance to be able to effectively handle the variations of the power production in order to balance the supply and demand. This problem is seen as a major obstacle to the expansion of renewable energy if it is not handled in a suitable way. Efficient electricity storage technology is one of the feasible solutions. The current study proposes Fe3O4/water nanofluid under magnetic field as the secondary fluid in the proposed double pipe heat exchanger before the cavern. The heat of compressed air is absorbed by the secondary fluid and it is stored in an isolation tank. This stored fluid is used to warm up the air that leaves the cavern for expanding in the turbine. The results demonstrated that increasing the mass flow rate of secondary fluid decreases the cavern temperature. Also, the value of convective heat transfer of ferrofluid increases when the volume fraction of nanoparticle as well as magnetic field increases. Furthermore, increasing the volume fraction and magnetic field increases the pressure drop and friction factor of ferrofluid.