Study on Wheat Straw/Sodium Sulfate/Water Glass Shaped Phase Change Plate for Walling Material

Novel shaped phase change plate was made of wheat straw impregnated with Na2SO4 solution and water glass as cementing agent. The plate was subsequently inserted into the concrete bricks with rectangular holes, assembled as phase change bricks. The latent heat of phase change of the plate was measured by DSC, the microstructure of the plate was observed by SEM, and the performance of the plate was also measured. In addition, the heat insulating property of the brick was investigated. The results are as follows. The wheat straws can encapsulate 1.86 times Na2SO4 center dot 10H(2)O in mass,and the phase change heat of the plate is 113 J/g. The microstructure shows that the straws and hardened water glass play an encapsulating action for Na2SO4 center dot 10H(2)O. The weight loss of the plate was 1.8% after 30 times of phase change cycles. For the concrete bricks (size: 240x240x 115 mm) inserted with phase change plates, when the heated surface temperature was 80 degrees C for 5 h or 8 h, the cold surface temperature increased by only 1.8 degrees C and 4.4 degrees C respetively,that is, the temperature difference between the cold with hot surface was 63.7 degrees C and 61.1 degrees C. This study reflects that if the brick is used as walling material, interior temperature does not fluctuate, even in extreme heat summer. It has dramatically saving energy and the effect of improving inhabited environment.