Study On The Performance Of Heat Storage Unit Assembled Solar Heat Storage Device

Solar thermal utilization is a renewable energy in one of the most extensiveapplication prospect, but its development and utilization problem is affected by thechange of day and night, the seasons, climate change, energy supply is notstable.Therefore, designing a set of economic, practical, solar thermal storage devicemodule production,through standardization, the standardization of product assembly, toachieve energy superposition.In order to achieve docking with the users better, solve thecontradiction between energy supply and demand do not match in time and space.Toachieve the above facts, first of all,it need to understand the thermal storageperformance of each unit, so the research on the heat storage performance of thermalstorage unit, has a very important practical significance.The paper select medium temperature phase change material molten salt used mostwidely and design a solar thermal storage unit device structure assembly, theregenerative process was studyed by experiment and numerical simulation.First, according to the energy supply and demand, designing a unit assembly typesolar heat storage device, building a photothermal conversion system experimentplatform was studied through experiment, estimating the economic of themal storagedevice. The results show that: the natural convection accelerate the phase changematerial melting, delay solidification effect, and the rate of change of upper layertemperature thermal storage device is greater than that of the lower rate of temperaturechange, heat transfer temperature increases, thermal storage time is short.Second, through the establishment of physical model,using the Fluent softwaremelting/solidification in the regenerative process of phase change material by numericalanalysis, by comparing the numerical and experimental results, to verify the reliabilityof the mathematical model, obtained under different initial conditions, changes in therelationship between the melting process of phase change material with time, obtain theexpression between phase change time, heat storage temperature time and heat transfermedium velocity,temperature difference.Improve the references for designing thermalsystems and heat storage device.Finally, enhanced heat transfer-thread tube heat exchanger structure and doublecircular spiral tube heat exchanger structure, by strengthening the comparison of heat transfer and temperature field, the results show that:(1) using thread tube heat exchanger for heat transfer enhancement, the phasetransition material to a certain extent, accelerate the speed of phase change heat storagetime,phase change time is increased by about35%, storage time is increased by about20%, obtain the relationship the heat transfer medium flow rate, temperature and phasetransition time, storage time; but the heat storage device still has heat transfer deadzone.(2) Because of the distribution of double circular spiral tube heat exchangerstructure in the heat storage device, each plane has small temperature difference, heatfaster, the time of phase change thermal storage time is increased by about50%, storagetime is increased by40%, the double circular spiral tube heat exchanger structure hassolved the dead zone melting heat transfer the process of phase change material inquestion; it has certain practical significance to the research on the application ofenhanced heat transfer method and practice.