Two-Dimensional Transient Thermal Analysis of a Phase-Change-Material Canister of a Heat-Pipe Receiver under Gravity

High-temperature Phase Change Material (PCM) is used as a thermal storage medium of a heat-pipe receiver in an advanced solar dynamic system.With both void cavity and natural convection considered,thermal performance of the heat-pipe receiver is numerically analyzed under gravity.The results indicate that the PCM contained in the integrated heat pipe performs an averaging function of heat loadings.The thermal performance of the heat-pipe receiver is stable and reliable.When a heating cycle is stable,the temperature fluctuations both on heat-pipe wall and in PCM canister remain less than 13 K throughout a sunlight and eclipse cycle.The utility of PCM is essentially improved.The maximum melting ratio of PCM is 92%.Under gravity,PCM melts more quickly with the effect of natural convection.Natural convection accelerates the process of phase changes.Numerical results are compared with the experimental results concerned.The accuracy of numerical model under gravity is verified.The experiment for the PCM canister on the ground can be well prepared with our numerical simulation.

A model of crust-mantle differentiation for the early Earth

The Archean continents,primarily composed of the felsic tonalite-trondhjemite-granodiorite(TTG)suite,were formed or conserved since~3.8 Ga,with significant growth of the continental crust since~2.7 Ga.The difficulty in direct differentiation of the felsic crustal components from Earth’s mantle peridotite leads to a requirement for the presence of a large amount of hydrated mafic precursor of TTG in Earth’s proto-crust,the origin of which,however,remains elusive.The mafic proto-crust may have formed as early as~4.4 Ga ago as reflected by the Hf and Nd isotopic signals from Earth’s oldest geological records.Such a significant time lag between the formation of the mafic proto-crust and the occurrence of felsic continental crust is not reconciled with a single-stage scenario of Earth’s early differentiation.Here,inspired by the volcanism-dominated heat-pipe tectonics witnessed on Jupiter’s moon Io and the resemblances of the intensive internal heating and active magmatism between the early Earth and the present-day Io,we present a conceptual model of Earth’s early crust-mantle differentiation,which involves an Io-like scenario of efficient extraction of a mafic proto-crust from the early mantle,followed by an intrusion-dominating regime that could account for the subsequent formation of the felsic continents as Earth cools.The model thus allows an early formation of the preTTG proto-crust and the generation of TTG in the continent by providing the favorable conditions for its subsequent melting.This model is consistent with the observed early fractionation of the Earth and the late but rapid formation and/or accumulation of the felsic components in the Archean continents,thus sheds new light on the early Earth’s differentiation and tectonic evolution.