Possible semi-circumglobal teleconnection across Eurasia driven by deep convection over the Sahel

The Sahel region, located between the tropical rainforests of Africa and the Sahara Desert, has rainfall that varies widely from year to year, associated with extremely deep convection. This deep convection, strongly heated by water vapor condensation, suggests the possibility of exerting a remote influence on mid- and high-latitude climate similar to the well-known influences of tropical oceanic convection on global climate. Here we investigate the possibility that deep convection over the Sahel initiates a semi-circumglobal teleconnection extending to eastern Eurasia. Statistical analysis and numerical experiments support the possible existence of this teleconnection at an interannual time scale. We propose that the anomalous heat source due to deep convection over the Sahel in the late monsoon season influences meandering of the mid-latitude jet stream over Europe through the combination of a Matsuno-Gill response and advection of absolute vorticity. This subtropical jet meander may in turn drive an eastward propagation of a Rossby wave across Eurasia as far as East Asia. Because deep convection over other subtropical land areas may exert a similar remote influence upon extratropical extreme weather, further studies of the influence of overland convection may provide us with an expanded comprehension of teleconnections.

An Experimental Investigation of Water Vapor Condensation from Biofuel Flue Gas in a Model of Condenser, (1) Base Case: Local Heat Transfer without Water Injection

Waste heat recovery from flue gas based on water vapor condensation is an important issue as the waste heat recovery significantly increases the efficiency of the thermal power units. General principles for designing of this type of heat exchangers are known rather well; however, investigations of the local characteristics necessary for the optimization of those heat exchangers are very limited. Investigations of water vapor condensation from biofuel flue gas in the model of a vertical condensing heat exchanger were performed without and with water injection into a calorimetric tube. During the base-case investigations, no water was injected into the calorimetric tube. The results showed that the humidity and the temperature of inlet flue gas have a significant effect on the local and average heat transfer. For some regimes, the initial part of the condensing heat exchanger was not effective in terms of heat transfer because there the flue gas was cooled by convection until its temperature reached the dew point temperature. The results also showed that, at higher Reynolds numbers, there was an increase in the length of the convection prevailing region. After that region, a sudden increase was observed in heat transfer due to water vapor condensation.

A Comparative Study of Hemispherical Solar Stills With Various Modifications to Obtain Modified and Inexpensive Stills Models

This study is intended to comparative and analyze the operational performances of the conventional hemispherical solar still (CHSS), hemispherical solar still with glass cover cooling (HSS-C), and hemispherical solar still with CuO-water based nanofluid (HSS-N). To Obtain the best modifications that achieve the highest productivity with the lower inexpensive. The conventional hemispherical still (CHSS) was utilized as the reference case to investigate the best modification. In the first modification, CuO nanoparticles with three different concentrations (0.1, 0.2, and 0.3%) were added to the basin water, to increase the intensity of absorbed solar energy, improve the thermal properties of basin fluid, and then increase the rate of vapor generation inside the distillation basin. In the second modification, water film glass cooling technology with three different flow rates (1.5, 2, and 2.5 L/h) was utilized to increase the water vapor condensation rate. The experiments test of the three distillers (CHSS, HSS-N, and HSS-C) was conducted at the same weather conditions at 1 cm basin fluid depth. The average daily accumulative yield of CHSS is 3.85 L/m2/day, while the daily accumulative yield of HSS-N increases to 5.75, 6.40, and 6.80 L/m2/day with improvement 49.3, 66.2, and 76.6% at volume fraction 0.1, 0.2, and 0.3%, respectively. Also, the daily accumulative yield of HSS-C increases to 4.9, 5.35, and 5.7 L/m2/day with improvements of 27.3, 39, and 48% at water film flow rates of 1.5, 2, and 2.5 L/h, respectively. The cost of distilled water produced from CHSS is 0.0106 $/L, while the utilization of HSS-C (2.5 L/h) and HSS-N (0.3%) reduces the cost of distilled water to 0.0072 and 0.0066 $/L, respectively. Based on accumulative yield and economic analyzes, it is recommended that utilized the modified HSS-N (0.3% volume fraction) to achieving the highest accumulative yield and the lowest price of the produced distilled water.