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To reduce the cost of oil exploitation, it is necessary to promote the development of cyclones for oil-water separation due to the increase of the water content in produced fluids. However, there are some limitations and disadvantages for the conventional separation device including bulky settling tanks and hydrocyclones. In this paper, a new axial inlet separator with two reverse flow outlets and a downstream flow outlet is introduced. In addition, an experimental system was designed and fabricated to investigate the effects of inlet flow rate, oil fraction, and a controlled split ratio on separation performance. The separator maintains high separation efficiency within the experimental range, namely water flow rate (4–7 m3/h), and oil fraction (1%–10%). Furthermore, the results show that a higher water flow rate and oil fraction will affect the separation efficiency. The change of a pressure drop in the separator was analyzed as well. Moreover, the controlled split ratio is a serious operating parameter, and a larger controlled split ratio is conducive to the separation performance.

Visualization experiments were carried out and sliding bubble coalescence behaviors were observed for subcooled flow boiling in a narrow rectangular channel. The results show that the consecutive coalescence process is composed of four steps based on the bubble morphological change: approaching, merging, adjustment, and stabilization, in which the more important are the merging and adjustment of the bubble. Bubble always slides along the heating surface and does not lift off in coalescence process. Bubble diameter and sliding velocity increase first, then decrease and finally stabilize. Bubble shape also oscillates from an irregular ellipse to a stable circle. In addition, a new small bubble may be induced in the coalescence process.

Gas-liquid separation technology is widely used in various fields of industrial production. In this research, a new kind of gas-liquid separator was proposed for the separation of gas-liquid mixture under different flow patterns. An inclined experimental system with an angle of 60 degrees from the vertical was established to test the new designed gas-liquid separator using of water and air as the working fluid. The experiment was conducted with the water flow rates covering 2.85–4.17 m3/h and the gas volume fraction covering 5–90%. Experiment results show that the separator can enable high efficient separation of gas-liquid mixtures under different patterns, especially under unstable flow patterns. The liquid level inside the separator is an important factor affecting the performance of the separator. On the basis of this, the critical liquid level of the separator was proposed for the practical application of the separator. This study fills the gap in the field of gas-liquid separation and provides a method for the separation of gas-liquid mixtures under different flow patterns.

The characteristics of bubble behavior have been in particular interest for decades due to its significant contribution to understanding the mechanism of heat transfer. In the present work, visualized experiment is conducted to study the bubble characteristics in subcooled flow boiling of a narrow rectangular channel under natural circulation. The experiments were performed at pressures of 0.2 MPa, with inlet subcooling ranging from 20 to 60 K and heat flux ranging from 100 to 300 kW/m2. A high-speed digital camera is used to capture the pictures of bubble behaviors. A sequence of image processing algorithms is used deal with the original bubble images to get relevant bubble parameters. We observe the whole process of a single sliding bubble lifetime and found most of bubbles slide along the heating surface after detaching the nucleation sites. Five typical sliding bubble growth paths are observed in the present experimental conditions. According to the analysis of the experimental data, it can be found that the liquid subcooling and wall superheat are the main factors that affect the bubble size during sliding in narrow rectangular channel under natural circulation condition. Due to the difference of driving force, the sliding velocity of bubble in forced circulation is always larger than that in natural circulation. At the same time, the bubble velocity changes significantly at different heat flux and shooting location.