Research On Preparation And Properties Of Latent Heat Storage Mortar

PCMs(Phase change materials) play an important role in improving energy utilization for building energy conservation. The phase temperature of phase change materials applied to the interior of building is ranging from 20 ℃ to 28 ℃, which are decided by the regional climate and comfortable temperature of body conditions. In this paper, we take liquid paraffin and commonly used 46# solid paraffin as the organic PCMs, then mixing them with certain proportion and creating the composite paraffin of different phase temperature. Besides, we select the composite paraffin as the organic PCMs whose phase temperature are suit and are of larger phase change latent heat. New adsorption substrate γ-Al2O3 is adopted to adsorb composite paraffin and produce organic/inorganic shape-stabilized PCMs in the case of 60 ℃ and negative pressure. The problem of leakaging when solid becomes liquid is solved because this process is happened within certain constraint conditions. Afterwards, The PCMs mixed into cement mortar to study the transform of mechanics performance、thermal performance、durable performance and thermal control performance. Based on the numerical simulation method, the process of two wall unsteady heat transfer is analyzed and solved to discuss the influence of phase change mortar walls on the transmission of temperature wave.The results indicate:(1) when 46# Solid paraffin mixed with liquid paraffin, Phase changes temperature and latent heat decreases as the proportion of liquid paraffin increases. When the mass ratio of the liquid paraffin and 46# solid paraffin are 4:6、5:5, their phase temperature are ranging from 20 ℃ to 28 ℃.(2) The composite paraffin(The mass ratio of the liquid paraffin and 46# solid paraffin is 4:6) is adsorbed at 60 ℃ and under negative pressure by γ-Al2O3, when the mass ratio of compostite paraffin and γ- Al2O3 is 2:1.8, they can be almost completely absorption stabilized. Phase change temperature of shape-stabilized phase change materials will rise. it’s phase temperature is 26.7 ℃ and phase change latent heat is 73.8 W/g and thermal stability is well.(3) After 100 and 200 cycles from heating to cooling, composite paraffin/γ- Al2O3 shape-stabilized PCMs are added to cement mortar by 10 %, 20 % and 30 %, the mass loss of cement mortar is less than 1 % but the mass loss is nearly 1 % and it has minor surface cracks with 30 %.(4) With the different ratio of composite paraffin/γ-Al2O3 shape-stabilized PCMs are added to cement mortar, The specific heat capacity, heat storage coefficient, index of thermal inertia and decay rates and time lags of heat are increasing with the adulterating of shape-stabilized PCMs increase; Heat transfer coefficient are decreasing and thermal effect is more obvious with the adulterating of shape-stabilized PCMs increase. Under the circumstances of experiment, compressive and flexural strength of mortar are decreasing with the adulterating of shape-stabilized PCMs increase.(5) Simulating calculation of the thermal performance of ordinary mortar walls and mortar walls whose bilateral phase-stablized PCMs are accounted 20 %, The results show that the delay time of bilateral phase change mortar walls is 7.27 h, which is delayed approximately an hour compared with ordinary mortar walls.