As a traditional processing method, the Nine-Steam-Nine-Bask method has been widely used in the special processing of Chinese medicinal materials. With the highly integrated design and innovation of infiltrating equipment, steaming equipment, drying equipment, and other equipment, a new type of integrated equipment for the Nine-Steam-Nine-Bask method was finally developed and successfully applied in Polygonatum cyrtonema processing. Moreover, seven new processes were explored. The longer the steaming time was, the more steaming and drying cycles, the lower the product recovery rate and the higher the energy consumption. The higher the steaming pressure was, the lower the product recovery rate, the higher the energy consumption and the shorter the drying time. The longer the drying time was, the lower the product recovery rate and polysaccharide content, and the higher the energy consumption. The best new process was XGY1, which had the highest overall score. The steaming process was the most time-consuming and energy-intensive production process, followed by the drying process. The obtained results can provide knowledgeable guidance for the further optimization of the integrated equipment of the Nine-Steam-Nine-Bask method and the development and application of technology for processing characteristic Chinese medicinal materials.
As zero-emission technologies, a daytime radiative cooling (RC) strategy developed recently, and photovoltaic (PV) and thermoelectric (TE) technologies have aroused great interest to reduce fossil fuel consumption and carbon emissions. How to integrate these state-of-the-art technologies to maximise clean electricity from the sun and space remains a huge challenge, and the limit efficiency is still unclear. In this study, a spectral-splitting PV-TE hybrid system integrated with RC is proposed to maximise clean electricity from the sun and space without any emissions. For the sun acting as a typical constant heat-flux heat source, the current thermoelectric theory overestimates the thermoelectric efficiency highly since the theory is based on constant temperature-difference conditions. A new theory based on heat-flux conditions is employed to achieve maximum thermoelectric efficiency. The PV-TE hybrid system with RC is superior to the conventional hybrid system, not only in terms of higher efficiency but also in its 24-h operation capacity. In a system with a single-junction cell, the total efficiency with 30 suns (39.4%) is higher than the theoretical PV efficiency at 500 suns (38.2%). In a hybrid system with four-junction cells, total efficiency is over 65% which is superior to most current photoelectric and thermal power systems.
Molecular dynamics simulation is carried out for the bubble nucleation of water and liquid nitrogen in explosive boiling. The heat is transferred into the simulation system by rescaling the velocity of the molecules. When heat is added into the molecular cluster, liquid initial equilibrium temperature and molecular cluster size can affect the energy conversion in the process of bubble nucleation. The potential energy of the system violently varies at the beginning of the bubble nucleation, and then varies around a fixed value. At the end of the bubble nucleation, the potential energy of the system slowly increases. In the process of bubble nucleation of explosive boiling, the lower initial equilibrium temperature leads to the bigger size of the molecular cluster. With more heat added into the system of the simulation cell, the potential energy varies in a larger range. The primary potential of water molecules includes Lennard-Jones potential energy and Columbic force caused by static charges of oxygen and hydrogen atoms. This is the reason why the bubble nucleation of water is different from that of liquid nitrogen. Pressure controlling is applied in the simulation of water, which makes the bubble more fully extended than that of liquid nitrogen.
Microscale jet array impingement cooling has been proved to be an efficient cooling technique for high-heat-flux electronics. In order to meet the current development trend of electronic components, jet impingement cooling performance needs to be continuously improved. In this work, a target surface enhancement approach for direct-on-chip microscale jet array with alternating feeding and draining jets was proposed. Trapezoid diversion columns were set regularly around inlet jets on the target surface to guide spent fluid and enhance overall performance. Besides, the inlet Reynolds number ranged from 20 to 2000 and deionized water was used as the coolant. Firstly, the impact of trapezoid diversion columns on flow and heat transfer characteristics was studied by numerical method. The results showed that the Nusselt number of current jet array was enhanced remarkably than that of convectional jet array at the almost same cost of pressure loss. Then the optimization of columns height, shape and location were carried out to improve overall performance. As a result, an optimal jet array structure with best overall performance was proposed. In the end, the maximum thermal removal capacity of optimal jet array and basic jet array was compared. It was found that the proposed optimal jet array can remove heat flux of 1950 W/cm2 when the temperature rise of heated surface was below 85 °C, which was 28.3% higher than that of basic jet array.
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