Study On Low Temperature Solid-Liquid Phase Change Material Of Ocean Buoy

The ocean,as an energy carrier,hides enormous energy.Ocean thermal energy is a performance of ocean energy.With the development of ocean thermal power generation and related technologies,the research on the acquisition of ocean thermal energy materials has been promoted.Solid-liquid phase change material that shrink the volume when heat release makes the material change from liquid into solid,and expansion volume when the material change from solid into liquid during endothermic process.The power generation device drives the motor to work by utilizing the volume change of the phase change material to achieve power generation.As power working medium,it should have appropriate phase change temperature,larger volumetric contraction rate and good thermal performance.In recent years,with the energy demand and energy utilization requirements increasing,solid-liquid phase change material is becoming a research hotspot on energy utilization and new materials in China and abroad.In this paper,two kinds of phase change materials were elected:n-hexadecane,1# matrix material.A method for determination of the phase transition temperature,the volumetric contraction rate,the melting time of the phase change material was established.Effects of modifiers n-octane,n-nonane,n-heptane and para-xylene on phase transition temperature and volumetric contraction rate,the melting time of n-hexadecane with 5% of n-Octane were investigated.Effects of different modifiers DR,J6,B on phase transition temperature and volumetric contraction rate of 1# matrix material were studied.Effects of different modifiers addition and the phase transformation times on the volumetric contraction rate of n-hexadecane and 1# matrix material were studied.Finally achieved the purpose of adjust the phase transition temperature to 10-15℃,the volumetric contraction rate is higher than 9% and reduce the melting time of phase change material.At the same time,1# parent material is cheaper than n-hexadecane.There is no report on the study of 1# matrix material in related literature.The results are follows as:(1)A method is proposed to reduce the error on measuring the volumetric contraction rate in order to solve the problem which bubble will separate out during the melting process of phase change material.It means that the method of extracting the bubbles in the test tube after the melting process is completed,which can effectively solve the bubbles generated during the process of phase transformation,thereby reducing the experimental measurement error.(2)Modifiers of n-octane,n-nonane,n-heptane,p-xylene can adjust the phase transition temperature of n-hexadecane and had a good solubility with n-hexadecane.The modifiers of n-octane,n-nonane can reduce the complete melting time of n-hexadecane.However,the volumetric contraction rate of n-hexadecane would decrease sharply with the addition of n-nonane,n-heptane or para-xylene respectively,while the effect of n-octane on the volumetric contraction rate of n-hexadecane is quite small.The order of modifiers advantages and disadvantageswas:n-octane>n-non ane>n-heptane>p-xylene.The optimum modifier was n-octane,and the optimum addition amount was 5%.By using multiple phase transformations,the volumetric contraction rate was 9.6% and the phase transition temperature would reach to 13.3℃ with 5% of n-octane,With the increase of octane,the melting time of n-hexadecane reduced 15%-59% under different temperature.It can meet the requirement that the volumetric contraction rate is higher than 9% and the phase transition temperature is 10-15℃.(3)Modifiers of DR,J6,B can adjust the phase transition temperature,and mutually dissolvable with 1# matrix material.The optimum modifier was J6,and the optimum addition amount was 2%.By using multiple phase transformations,the volumetric contraction rate would reach to 9.6% and the phase transition temperature was 13.3℃ with 2% of J6.It can meet the requirement that the volumetric contraction rate is higher than 9% and the phase transition temperature is 10-15℃.(4)1# matrix material has a significant cost advantage compared with n-hexadecane.According to 20 L solid liquid phase change material loaded in the ocean buoy,considering the cost of heat transfer material,each ocean buoy can save 2882 yuan directly,which can bring considerable economic benefit.