Phase separation, which decreases the synergistic effect, are observed during amount of surfactant/polymer (SP) or alkali/surfactant/polymer (ASP) flooding field applications and laboratory experiments. The idea of adding hydrophobic groups to a water-soluble polymer is to make polymeric surfactant that could be applied in Enhanced Oil Recovery (EOR). However, pole-scale displacement mechanisms and field performances of polymeric surfactant have not been investigated throughtly. In this work, we synthesized two types of polymeric surfactants and evaluated their physi-chemical properties, including chemical structure, rheological characteristic, emulsification and salt tolerance. Beside these physi-chemical property tests, a micro-visual model and core-flooding tests were performed to investigate the efficiency of polymeric surfactant flooding to recover the bypassed or trapped residual oil after water flooding. Finally, field performances of polymeric surfactant were estimated by monitoring the production dynamics and development index from a pilot test in Daqing oilfield. Results show that the polymeric surfactant has characteristics of strong viscosity, salt-resistance and emulsification. The high viscosity of the polymeric surfactant gurantantees a better mobility control than the ordinary polymer. What's more, the enhanced swept volume, emulsifiability and high elasticity makes the polymeric surfactant flooding has higher recovery factor than traditional polymer during chemical flooding. The heterogeneous core flooding experiments show that extra 10% overall recovery can be obtained with polymeric surfactant flooding after traditional polymer flooding. The application of the two types of polymeric surfactants in the pilot area shows that polymeric surfactants make the middle and low permeability zones absorb more water than traditional polymer flooding. If the surfactants were injected after water flooding, oil recovery can be improved by more than 20%, and significant reduction in water cut. With these unique properties and good performances for trials in the pilot test, polymeric surfactants can be considered as a replacement to the traditional polymer in highly heterogeneous reservoirs after water flooding or polymer flooding.

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In the present work, three dimensional numerical study is conducted to investigate the heat transfer and flow characteristics of twisted tubes of different cross section shapes with the Reynolds number ranging from 50 to 2000. The constant wall temperature condition is used in the simulation analysis. The numerical results of twisted square tube are compared with the available previous experimental data. The results indicate that the heat transfer performance of twisted tube is enhanced compared with the smooth tube, while the pressure drop increases as well. One of the key findings is that the transition point of twisted square tube from laminar flow to turbulent flow is identified and located at Re = 500. It is also found that the cross section shape has little effect on the heat transfer of twisted tubes, while it has great influence on the flow pattern. The results also reveal that the twist pitch has remarkable effects on the heat transfer performance of twisted tubes. In addition, the maximum value of PEC of 2.69 is obtained in twisted pentagon tube with twist pitch ratio of 0.17, and the Reynolds number of 350. These results are significant because it will contribute to the development of compact twisted tube heat exchangers.

Although YSZ ceramic coating has been used in the field of aeroengines for a long time to protect blades from high temperature erosion, its application on marine engines is still very rare. In this study, YSZ powder was sprayed onto the upper surface of the Al-Si alloy piston by atmospheric plasma spraying. The piston with or without ceramic coatings was applied to the diesel engine bench, and the ship propulsion characteristics test was carried out to study the effect of the coating on the performance of the diesel engine when the ship was sailing. The temperature field results show that under 25% load, the temperature of the top surface of the coated piston is about 30.91 °C higher than that of the conventional piston. The increase in the temperature of the combustion chamber is conducive to better combustion of the fuel in the cylinder of the diesel engine. Therefore, when the marine diesel engine is tested for propulsion characteristics, the thermal efficiency is increased by 5% under the condition of 25% load.

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