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Experimental and Numerical Investigations of the Double-Barrel Distributor for Air Conditioner
CHI ZHANG,Dandong Wang,JIANGPING CHEN,Xihui Sun 대한설비공학회 2015 International Journal of Air-Conditioning and Refr Vol.23 No.3
Flow mal-distribution of refrigerant in small diameter tube heat exchangers is a great concern, which may lead to a 25% efficiency loss. Two-phase refrigerant distributors are set before evaporators to separate refrigerant into parallel paths uniformly. In this paper, a new type of distributor with two barrels is proposed. Experimental test and numerical simulation were both carried out to evaluate the performance and to understand internal hydrodynamic flow behavior. Compared with the previous distributor, it is found that the double-barrel distributor with proper parameters performs better. The relative error between experimental and simulation results is less than 15%, which proves the reliability of the established simulation model. Computation fluid dynamics (CFD) calculation indicates that the distribution performance is improved with properly larger bottom and top barrel diameters. With the increase of the bottom barrel diameter, bene¯cial reflux of refrigerant occurs in bottom barrel and when top barrel diameter is larger, little refrigerant flows directly into outlet capillary tubes without mixture or reflux. In addition, parameters such as top barrel diameter, top barrel height, bottom barrel diameter, bottom barrel height, mass flow rate and quality are studied by Taguchi Method to analyze the parameter sensitivity. The effect of the parameters listed below ranges from biggest to smallest: mass flow rate, bottom barrel height, quality, top barrel height, bottom barrel diameter and independent top barrel diameter. An optimized two-barrel distributor is achieved with proper top and bottom barrel diameters and larger bottom and top barrel heights.
You‑dan Dong,Liang Gao,Feng‑juan Wu,Ren Lin,Yuan Meng,Li‑hong Jia,Xiao‑fei Wang 대한독성 유전단백체 학회 2020 Molecular & cellular toxicology Vol.16 No.2
Background Bisphenol A (BPA) is an environmental estrogen widely exposed to human beings, and there are more studies on its reproductive toxicity, endocrine disruption and neurobehavioral disorders. Recent few studies have found that BPA has immunotoxicity, and its mechanism is not clear. Therefore, the effects of BPA on immune system have attracted extensive attention. The aim of this study was to investigate the effect and mechanism of perinatal exposure to BPA on regulatory T cells (Treg) and Th17 cells in female offspring mice. Methods Twenty-one pregnant C57BL/6 mice were randomly divided into three groups: a control group, low-dose BPA (0.2 μg/mL) and high-dose BPA (2.0 μg/mL) exposure group. All received BPA exposure via drinking water from gestational day 6 to the end of lactation. Female offspring were fed a normal diet and drinking water for 1 month. The percentages of Treg and Th17 cells, the levels of Foxp3 and RORγt protein and IL-17 and TGF-β from spleen tissue or blood were measured in female offspring. Results The percentage of Treg cells and levels of Foxp3 protein decreased, while the percentage of Th17 cells and levels of RORγt protein increased, which showed a dose–effect relationship. The levels of serum TGF-β were significantly lower and the levels of serum IL-17 were statistically higher in BPA-exposed female offspring compared with controls (P < 0.05 or P < 0.01). But there were no statistical difference in the levels of serum TGF-β and IL-17 between 0.2 μg/mL and 2.0 μg/ mL BPA groups (P > 0.05). Conclusion BPA exposure during pregnancy and lactation could cause abnormal differentiation and function of Treg and Th17 cells in female offspring mice, which was associated with down-regulated Foxp3 and up-regulated RORγt protein, respectively. Our findings indicated that BPA exposure during early development may play an important role in the development of autoimmune diseases later.