Numerical Simulation Research of Natural Convection Heat Exchanger
In this paper, computer software is employed to simulate the temperature-field and flow-field of AP1000 PRHR HX, and investigate its heat-transferring and flow characteristic. Through comparative analysis of the distribution of temperature-field and flow-field in different locations at the same time, and the change of temperature-field and flow-field in the same location at different times, heat-transferring process and natural convection situation of PRHR HX are deeply understand. It contributes to analyze the natural circulation capacity of PRHR HX, and provides some references for the effective operation of passive residual heat removal system.
Parametric analysis of heat transfer rate of passive residual heat removal heat exchanger submerged in water tank
Abstract The heat transfer performance of a miniaturized passive residual heat removal heat exchanger (PRHR HX) is experimentally investigated. It comprises 42 C-shaped tubes, submerged in a water tank that has a height of 6 m. The average heat flux is measured for various values of the working pressure and mass flow rate of the water inside the tubes. The pressure varies from 5 MPa to 15 MPa, the mass flux varies from 95 kg/(m2 s) to 320 kg/(m2 s), and the inlet temperature varies up to 300 °C. Moreover, the distribution of the heat flux along the tube is analyzed using empirical correlations available in the literature. The predicted heat removal rate of the tubes is in a good agreement with the measured value; the discrepancy is smaller than 4%. These results could be employed for designing PRHR HXs for nuclear reactors.
Synergistic and antagonistic combinations of drugs in human prostate cancer cell lines in vitro
Microtubulin binding agents such as docetaxel have significant preclinical and clinical activity in the treatment of hormone-refractory prostate cancer. We have previously used median-effect analysis in vitro to define both synergistic and antagonistic drug combinations which may be of value in management of human disease. These studies extend our findings in defined prostate cancer cell lines. A semi-automated microtiter culture system was used. Docetaxel was combined with 18 other agents, incubated with DU 145, LnCaP or PC 3 prostate cancer cell lines for 72 h and the cells then incubated with MTT to determine cytotoxic effect. Both doublet and triplet combinations were examined. Synergy and antagonism as measured by the combination index were determined for each combination. The non-mutually exclusive criterion was applied. Docetaxel demonstrated cytotoxic additive effects or synergy with cis-retinoic acid, cyclosporin A and vinorelbine in all three cell lines. Docetaxel combined with either epirubicin or doxorubicin displayed cytotoxic synergistic effects in hormone-refractory DU 145 and PC 3 cell lines. In contrast, drugs which have been combined clinically to treat hormone-refractory prostate cancer, i.e. cisplatin, carboplatin or etoposide, were antagonistic when combined with docetaxel. We conclude that combinations of docetaxel with either cis-retinoic acid or vinorelbine may offer an enhanced cytotoxic effect in the management of hormone-refractory prostate cancer and need to be evaluated for therapeutic effect. The combination of docetaxel with an anthracycline was also synergistic in the two hormone-refractory cell lines, DU 145 and PC3, thus suggesting a potential role in advanced disease after endocrine failure. Combinations of docetaxel with platinum or etoposide may lead to subadditive effects in treatment.