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Based on the projections of three shared socioeconomic pathways (SSPs) scenarios of three climate models of CMIP6, this study analyzed the standardized precipitation evapotranspiration index (SPEI) to understand the future meteorological dryness/wetness changes in the Poyang Lake basin (PLB) from 2021 to 2100. The effect of temperature change on the dryness and wetness variation was explored by comparing the trends of SPEI and standardized precipitation index (SPI) at multiple-time scales and different SSPs scenarios. The results indicate that the frequency of drought events may increase by 1.1~3.8% than the historical period in the three scenarios, and they may be higher than that of wetness events in the future of this century. Cumulative months of drought events are higher in most decades than the wetness events, and especially in the 2090s. A total of 43 months may suffer drought events in the 2090s under the SSP585 scenario, which is more than twice the wetness events. With the enhanced concentration of greenhouse gas (GHG) emissions, both the frequency of droughts and the proportion of extreme droughts show a significant increasing trend at 99% confidence in PLB. The spatial distribution of net precipitation is generally in the southwest–northeast pattern, yet it is still in different values in most scenarios; thus, the uncertainty of dryness/wetness spatial conditions should be considered. The SPI detects more wetness events and a more intensive wetting trend, while the SPEI shows the opposite. The difference between SPI and SPEI gradually increases with GHG emission concentration, and may even lead to contrary conclusion in the last two decades at a 48-month scale under the SSP245 and 585 scenarios, indicating the unneglectable impact of increasing temperature and evapotranspiration on the dryness/wetness conditions in the future. The research results can help to predict the evolution pattern of dry and wet occurrence in the PLB in the future and promote flood/drought control and disaster mitigation.

To further improve the flat-type loop heat pipe (LHP) performance, this study evaluates the practical potential of use of highly enhanced boiling structures. It is found that in our proposed new heat pipe (NHP) system, the working fluid from the evaporator outlet to the condenser inlet is in a liquid–vapor two phase flow, which is different from the classical LHP theory. A new P-T diagram is developed to better understand the thermal and hydraulic process during the NHP steady operation. In this study, by using the laser ablation technique two different types of micro- and nanoscale hybrid structures are synthesized on the boiling pool substrate. It is indicated that the formed valleys with a larger opening width play an important role in more effectively improving the bubble nucleation and bubble growth at the micrometer sites, which can subsequently lead to an increased number of active nucleation sites. The best loop performance is obtained with the micro-cone structured substrate at a heat load of 140 W, at which the maximum boiling pool heat transfer coefficient of 42.17 kW/m2·K is achieved. Compared with the polishing Cu substrate, it is enhanced by 110%. When maintaining the boiling pool temperature lower than 85 °C, the proposed new heat pipe system can tolerate a maximum heat flux of 35.12 W/cm2, which is larger than that of the most conventional LHPs with methanol as the working fluid.

The flow boiling heat transfer characteristics of subcooled air-dissolved FC-72 on a smooth surface (chip S) were studied in microgravity by utilizing the drop tower facility in Beijing. The heater, with dimensions of 40 × 10 × 0.5 mm3 (length × width × thickness), was combined with two silicon chips with the dimensions of 20 × 10 × 0.5 mm3. High-speed visualization was used to supplement observation in the heat transfer and vapor-liquid two-phase flow characteristics. In the low and moderate heat fluxes region, the flow boiling of chip S at inlet velocity V = 0.5 m/s shows almost the same regulations as that in pool boiling. All the wall temperatures at different positions along the heater in microgravity are slightly lower than that in normal gravity, which indicates slight heat transfer enhancement. However, in the high heat flux region, the pool boiling of chip S shows much evident deterioration of heat transfer compared with that of flow boiling in microgravity. Moreover, the bubbles of flow boiling in microgravity become larger than that in normal gravity due to the lack of buoyancy Although the difference of the void fraction in x-y plain becomes larger with increasing heat flux under different gravity levels, it shows nearly no effect on heat transfer performance except for critical heat flux (CHF). Once the void fraction in y-z plain at the end of the heater equals 1, the vapor blanket will be formed quickly and transmit from downstream to upstream along the heater, and CHF occurs. Thus, the height of channel is an important parameter to determine CHF in microgravity at a fixed velocity. The flow boiling of chip S at inlet velocity V = 0.5 m/s shows higher CHF than that of pool boiling because of the inertia force, and the CHF under microgravity is about 78–92% of that in normal gravity.