| Energy is an indispensable element for human survival and social development,however,the environmental problems caused by a large amount of energy consumption are increasingly prominent.Therefore,the replacement of coal-based fossil energy with the new energy and renewable energy is the direction of energy structure transformation.There are time and space mismatches between the supply and demand of renewable energy,such as,solar energy and wind energy.Meanwhile,both fossil energy and renewable energy are basically used in the form of electric energy,and the power system has a serious load peak-valley difference.Energy storage technology can well solve the problem of energy imbalance between supply and demand,which can also play a role in the electric power field.It has been demonstrated that phase change materials as energy storage materials are widely used in the energy storage field,hence,it is crucial to evaluate the heat transfer performance of latent heat thermal energy storage system(LHTESS).In this work,based on the traditional herringbone corrugated plate heat exchanger and the phase change materials(PCMs),we innovatively propose a new corrugated plate LHTESS.First,the system model and mesh are conducted and divided by using the modeling software.Moreover,the melting process of PCMs in the new corrugated plate LHTESS is numerically investigated by employing the Solidification/Melting model of the fluid dynamics software FLUENT.It should be note that the paraffin,water/air,and tri-layer phase change material with a thickness of 15 mm are selected as the phase change material,thermal fluid,and heat transfer unit,respectively.The effects of the structural parameters and the inlet parameters of the thermal fluid on the heat transfer process are studied.It can be observed that when the amount of PCMs is constant,the smaller thickness of phase change material layer leads to the better heat transfer performance of phase change accumulator and shorter total melting time of phase change material with the constant volume of PCMs.When the thickness of PCM is reduced from 15 mm to 5 mm,the total melting time is decreased from 72°s to 90 s.When the three corrugated plate structures with wave inclination angles of 30°,45° and 60° are studied,the difference of heat transfer performance can be neglected.Furthermore,the higher inlet fluid temperature and the faster flow rate give rise to the better thermal storage capacity of the LHTESS.As the temperature and the flow rate increase,the effect of performance enhancement becomes weaker.When the inlet flow rate enhances,the pressure drop of the overall flow process elevates.Afterwards,the fins are used to enhance the heat transfer of the new LHTESS,The effects of the arrangement,number and height of the fins on the heat transfer process in the phase change material side are investigated.We can observe that the heat transfer performance of the fin with herringbone layout is better than that of the transverse and longitudinal fins with the same fin spacing.It is obvious that the structures with fins have a better heat transfer performance.The total melting time of PCM in a herringbone finned system is only 81%of that in a no finned system.Finally,we propose a wave like composite corrugated plate structure on the basic of the herringbone corrugated plate structure,in which the area of PCM is composed of two orthogonal directions of sinusoidal composite superposition.The effect on the heat transfer process in the herringbone corrugated plate LHTESS is studied.It is obtained that the total melting time of PCM in the composite corrugated plate heat transfer unit can be reduced by about 36.7%in comparison with the smooth plate structure,and the time required for the complete melting of the central point is about 46%less than that of the smooth plate structure.Similarly,the heat transfer performance of the heat exchange unit increases when the inlet fluid velocity and temperature increases,and the increasement trend also declines when the velocity and temperature increases. |
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