Preparing Of The Concrete Heat Storage Materials For Solar Thermal Power Plants And Simulating Of The Heat Store Unit

The most frequent reason for solar transients is clouds. The solar power can be affected suddenly by the clouds, the radiation on the receiver will decrease rapidly. The steam generator can not cope with such uncontrolled transients. The heat storage system can charge heat when sunshine is rich and discharge the heat to support steam generator working normally when sunshine was not enough. It works as a buffer. In addition heat store system can store the solar power with heat form, and discharge the heat at night to support power plant. It works to shave peak and fill valley. Heat store system is an important part of solar power plants.Ranges of heat store concrete are made by CA-80, copper slag, iron slag, graphite powder and others. The result showed that the concrete was affected by the content of the aluminates cement, when the cement contend was 10% and the graphite contend was 5%, the compression strength reached to 42MPa, flexural strength reached to 6.3MPa after baked, and when cement contend is 6%, the compression strength reduced to 31.4MPa, and flexural strength reduced to 5.3MPa.The strength decreased, the thermal conductive increased with the graphite content increasing. Carbon fiber belonging to flexible fiber had little influence on compression strength, but increase flexural strength by 33%. Steel fiber is helpful to increase the compression strength and flexural strength. Since the copper slag and iron slag with higher density, increase the slag content can increase the density of the concrete.Based on the material parameter get by experiments, the simulation was made by ansys which simulated the heat charge and discharge circulation of the heat store material. The cubic module was constructed according to the real concrete heat store system. The circulation was divided into four periods, heat charging, heat preservation, heat discharging and second heat preservation, Since the corner of the module was far from the center pipe, it appeared a hysteresis phenomenon when loaded different heat load. And the thermal conductivity was lower, the phenomenon was more notable. When the thermal conductivity was higher, the speed of the thermal charging and discharging were faster. The temperature of the material can balance immediately. Simulate the distance of the pipe affect the performance of the heat store material. The result show that shortens the distance of the pipes can improve the performance of the material with lower thermal conductive. But at the same time, it increases the quantity of the pipes and the cost of the heat store system.Two new structure modules are designed, the first one, pipes arrange in triangle, so the small unit changed from square to hexagon, honeycomb, it had better symmetry, keep the area unchanged, the distance shortened by 15%, the heat transfer performance improved a little.The other module, graphite pieces were put at the corner of the hexagon, the mass content was 5%, The effective thermal conductivity increased one time, surpassed 5W/m℃,compared to the concrete that content 5% graphite powder. In the processing of heat charging and discharging the heat grads in the graphite pieces was small but the flue was very large. It is possible that the performance can be improved by designing the structure of the heat store unit.