Experiment Research Of The Expandedgraphite/Paraffin Composite Phase Change Thermal Storage Materials

With the development of social economy, human depends on conventional energywhich suffered serious challenges in our survival and development. The solar energy is akind of widespread and clean energy, which it has the most development and utilizationprospects in the new century. But the use of solar thermal energy was subject todiscontinuity, instability and the low thermal efficiency factors etc. In order to solve theproblem of this instability and discontinuity, energy storage technology is plays animportant role in solar heat energy utilization. Phase change heat storage technology hasthe widest application. It has higher heat storage density and is easy to control because ofthe constant temperature during phase change process, which makes it well received. Inorder to adapt to solar energy heat utilization temperature, this article use paraffin as phasechange heat storage materials of basic material. The composite phase change heat storagematerials used expanded graphite porous properties and higher adsorption performanceimproves the thermal performance of paraffin wax.This paper set up a cube experiment platform of the heat storage device. Study of thecomposite phase change material based the performance, by comparing experimentalmethods, research the storage device composite phase change material for the heat storageperformance as the object and prepared different proportions of expandable graphiteprepared/paraffin composite phase change material. Firstly it tested various proportions ofexpanded graphite/paraffin composite phase change thermal storage material thermalparameters by the differential scanning calorimetry (DSC); then experimentationresearched heat storage of the various proportions of composite phase change heat storagematerial by a given temperature (60℃,65℃,70℃,75℃,80℃) and given the fluidflow (160L/h); finally selected the best ratio(4%) of composite phase change material usedin solar hot water collector system. The experiment results showed that when thepreparation of composite phase change materials, the expanded graphite mass contentshould be less than5%; phase transition temperature of paraffin and enthalpy has small changes by adding expended graphite; In the process of thermal storage: it was divided intothree phases, respectively, solid phase sensible heat storage, latent heat storage and liquidphase sensible heat storage, at the heating process, the uplifted temperature of thecomposite phase change materials was completely out of sync in the heat accumulator, theupper location temperature was increased faster than the lower position; but in anexothermic process, the temperature of composite phase change materials was lowered bydecreasing in the heat accumulator. When the heat source temperature were60℃,65℃and70℃, the greatest influence of the composite phase change materials the process ofthermal storage, the expanded graphite mass content were3%,4%,5%; When the heatsource temperature were75℃and80℃, the process of thermal storage was smallchanges by adding expanded graphite. the heat accumulator with the4%expanded graphitewas used solar collector system, it was to improve the solar energy heat utilization rateabout10%by the test, which can provide40℃shower water for1-3extra individuals intheory.This article mainly studies the thermal energy storage experimental researches ofexpanded graphite/paraffin composite phase change heat storage technology and itspractical application combining with heat pipe type solar collector. The research resultsprovide reference for researchers who studies phase change heat storage technology, whichprovide the basis for future direction of solar heat storage system.