Preparation Of Composite Phase Change Materials For Waste Heat Recovery In Ship And Investigation On The Device Heat Transfer Performance

The shortage of energy and serious environmental pollution have always been important issues of national concern,and energy storage technology can improve energy utilization and environmental protection.As a phase change energy storage material in the medium and low temperature phase change materials,inorganic hydrated salt has the characteristics of high phase change latent heat value and low price,and can be better used in the field of the ship waste heat recovery.However,there are serious supercooling and phase separation phenomena,which affect the stability and heat transfer performance of phase change materials.These shortcomings make the practical application of hydrated salts limited.In this paper,latent heat storage technology is mainly used,barium hydroxide octahydrate is used as the base material for the development of composite phase change materials,the Edisonian approach,was used to study the effect of different nucleating agents on the supercooling performance of barium hydroxide octahydrate.Graphite was selected as the thermal conductivity agent.The thermal conductivity of composite phase change materials was studied by DSC(differential scanning calorimetry)and Hotdisk(Transient plane heat source method).The phase separation phenomenon that occurs during the cycle of composite phase change materials can be improved to a certain extent by adding thickeners.At the same time,taking advantage of the simple structure and high-efficiency heat transfer characteristics of the pulsating heat pipe,the barium hydroxide octahydrate is coupled with the pulsating heat pipe,and to build a pulsating heat pipe phase-change heat storage and release experimental platform.In order to study the waste heat recovery device of ships,how to improve the heat transfer efficiency and heat recovery rate of the recovery device provides a reference.The main research is as follows:(1)By preparing composite phase change materials and conducting multiple experiments,the optimal ratio is obtained.Barium hydroxide octahydrate was selected as the base material,and five nucleating agents were selected for testing with different addition amounts.The results show that when the addition amounts of barium carbonate(Ba CO₃)is 1.2%,it can not only reduce to a certain extent degree of supercooling and latent heat performance are effectively improved.By adding different proportions of graphite powder and comparing the experimental results of phase change temperature,latent heat value and thermal conductivity of the obtained composite phase change material,the results show that optimal addition amount of graphite powder is 0.2%.By adding different proportions of sodium carboxymethyl cellulose(CMC)as a thickener,it is found that the addition of CMC at 1.0%has better effect on improving the phase separation phenomenon of the composite phase change material,and it can also reduce the degree of supercooling.(2)In order to strengthen the heat transfer performance of the phase change heat accumulator,improve the heat transfer efficiency and heat recovery rate of the device.In this paper,barium hydroxide octahydrate is used as the phase change material,the pulsating heat pipe is used as the heat transfer element,and methanol is used as the heat exchange working fluid,and the experimental platform of pulsating heat pipe phase change regenerator was built.In the heat storage experiment,by changing the heating temperature of the high-temperature silicone oil heat source,the heating fluid flow rate,and the filling rate of the working fluid,the temperature change of the phase change regenerator with time under different working conditions is studied,and the optimal setting parameters for enhancing heat transfer are found.When methanol is used as the working fluid,the heating temperature is 120?,the heating flow is 0.58m~3/h,and the filling rate is 0.3,the heat transfer effect is the best.In the heat release experiment,calculate the heat recovery rate of the phase change heat accumulator by changing the initial temperature of the cooling water.