TUPDP student Jinghao Yang successfully defended his MS thesis, "Paraffin Deposition Mechanism: Influence of Thermal Driving Force," on July 18, 2019. Below is an abstract of his work. The full thesis is available to members in the "Member Access" section.

Abstract

A small scale flow loop was utilized to investigate the influence of thermal driving force on wax deposition with the variations of temperature condition and Reynolds number. Fifteen experiments were conducted using Caspian Sea condensate with 111° F wax appearance temperature and 9.5% wax content.

The first part of this study conducted seven flow loop experiments with same oil and coolant temperature, which means the thermal driving force equals to zero. Three temperatures (90° F, 94.5° F, 96° F and 101° F) and two Reynolds numbers (4000 and 6800) have been examined. Deposits have been observed to form at all conditions, with more deposits forming at lower temperatures and lower Reynolds number. No significant increase in the wax fraction of deposits has been observed due to insignificant aging. However, the temperature difference fluctuated between +2° F and -2° F along the test because of the facility limitation. Therefore, the molecular diffusion may still occur and contribute to the deposition.

In order to erase the effect of molecular diffusion, the second part of this study conducted eight flow loop experiments under the conditions that coolant temperatures are iv higher than the oil temperature. Two bulk temperatures (90 °F and 94.5 °F) and three Reynolds numbers (1800, 4000 and 6800) were selected, and the negative temperature differences explored are -3.5 °F, and -5.5 °F. Non-negligible amount of deposits have been observed at all eight conditions examined. The deposit mass has been observed to decrease with increasing bulk temperature and larger temperature difference. It also has been observed that deposit mass increases at lower Reynolds number while decreases when the Reynolds number reduces to laminar flow. Less insignificant increase in the wax fraction of deposits has been observed due to no aging. Significant fluctuations have been observed in the pressure drop profiles, indicating deposit formation and removal during the test.