3D FEM MODEL TO IMPROVE THE HEAT TRANSFER IN CONCRETE FOR THERMAL ENERGY STORAGE IN SOLAR POWER GENERATION

Solar thermal energy has been shown to be a viable alternative resource At this time, the concentrating solar power systems costs are 13-17 cents/kWh. The goal of DOE is to reduce the cost to 5 cents/kWh by 2015 using energy storage techniques Several storage schemes and materials have been developed over the past two decades. Concrete is an inexpensive storage medium for sensible heat. Research has been done lately using concrete blocks which arc heated up by circulating synthetic oil at a maximum temperature of 390 degrees C through a series of pipes embedded in the concrete However. the efficiency of the storage unit can be improved by increasing the operating temperature, which is in turn limited by the materials used. A 3-D finite element computer model was written in order to perform parametric studies during the thermal charging and discharging of concrete. The program allows modifying the physical properties of the heat transfer fluid and storage material. A feature to add fins attached to the flow line was developed to evaluate improvements in heat transfer Several fin configurations were studied. The increase in energy stored in the system, and the corresponding cost increase are reported.