Lijun Liu

Effects of crude oil’s variable physical properties on temperature distribution in a shutdown pipeline:

A partition method mathematical model was established for the shutdown process of an overhead pipe, and the effects of crude oil’s variable physical properties on the heat transfer performance were analyzed. The model and solving method were verified by the existing experimental data. The oil temperature distribution in pipe was simulated by FLUENT software, and the allowance shutdown time, which is the time of the oil temperature in the pipe center that it takes to drop to its freezing point, was discussed. In simulation, oil properties including densities, thermal conductivities, viscosities, and specific heat were modeled with their values as functions of temperature or set to their average values in the temperature range. Results show that compared with the latter (oil properties were average value), the allowance shutdown time using variable physical properties were shortened by 16.3%, 7.9%, 0.2%, and increased 61%, respectively; the influence of thermal conductivity was embodied in the second half of the shutdown process. In numerical simulation of the shutdown process for an oil pipeline, the effect of oil viscosity variation can be ignored and, the other properties must not be regarded as constant, especially heat capacity, whose change reflects the influence of latent heat.

Investigation of indoor thermal environment in a rural house in Daqing

At present, the rural population of China is large. The rural population accounts for about 50% of the total population in Heilongjiang Province, which is located in cold region. The winter is cold in severe cold region, for example, the average outdoor temperature in winter is about –25 °C in Daqing which is located in Heilongjiang Province, the indoor residential thermal environment is poor, people living there are uncomfortable. The existing rural residential building was researched in Daqing of Heilongjiang and the study of the indoor thermal environment was carried out. In this paper, the numerical simulation method is used to study the changes of indoor temperature field before and after adopting the wall insulation of existing house. The results show that the thermal environment of the existing rural house without wall insulation can not satisfy the requirements of human comfort, and the bedroom temperature is about 15 °C, and the temperature of the entrance hall is about 11 °C. However, the insulation of the building envelope has an obvious effect on the indoor thermal environment, and the temperature of the bedroom and the entrance hall increase about 5 °C and 3 °C with wall insulation, respectively.

Study on the Optimum Angle for Solar Collector

To increase the efficiency of solar energy, a method for setting the collector was established, which can enhance the solar thermal power in winter. The optimum angles of the quasi-fixed solar collector and fixed solar collector were calculated. For Daqing area, their values were given, the angle is 4945.51for quasi-fixed solar collector and it is 5355.97 for fixed solar collector. Comparing the quasi-fixed solar collector with fixed solar collector in Daqing area, the better choice is the quasi-fixed solar collector.

Gelled Crude Oil Particle Deformation under Hydraulic Suspension Transport Investigated by Numerical Simulation

In hydraulic suspension transport, the gelled crude oil particles are known to change shape in response to local flow conditions. The phase field method is used to simulate the deformation for the gelled crude oil particle with the same internal and external fluid viscosities. For this purpose, an Image Pro Plus software records the major and minor axises and thus, analyzes digitally its deformation degree. Initially spheroidal oil droplet is simulated and it is shown that the gelled crude oil particle exhibits deformation behavior as the movement and its final stable shape close to oval. The deformation behavior is response to shear stress with a time of 0.08s delayed. In the range of delayed time, the gelled crude oil particle deforms with a little degree and after the delayed time, the deformation degree increases seriously.

The Method of Computing the Thermal Conductivity of Heat-Insulation Oil Pipe Coupling

Based on the inverse problem theory of heat conduction, thermal conductivity of heat-insulation oil pipe coupling is researched in the paper. The finite volume method is extended to solve the direct problem, and the 0.618 method is used to solve the inverse problem by optimizing the objective function. The results show that by using the method, taking the outer wall’s temperature as the sample indicators, the thermal conductivity and the temperature distribution of heat-insulation oil pipe coupling and the temperature distribution of heat-insulation oil pipe can be obtained easily and accurately.

Testing research for oil-gas-water flow pattern in Daqing oilfield

During the period of the high water cut later stage, it is significant for decreasing energy consumption of gathering system to research oil-gas-water flow pattern. At the moment, the studies on oil-gas-water flow pattern are mainly focused on the temperature range of crude oil freezing point. A experimental system is designed, constructed and operated in oilfields in horizontal pipeline., which is used for experimental investigation and analysis of oil-gas-water flow pattern under freezing point in horizontal pipeline. According to the crude oil condition, the results show that oil-gas-water flow pattern includes four types that are oil contact wave flow, oil-oil particle dispersion flow, oil lamellar flow, oil puddle slugging flow.

The numerical simulation of oil-water two phase flow in horizontal pipeline based on the VOF model

Due to the existing phase interface between oil and water, it can form stratified flow, bubble flow, slug flow, annular flow and many kinds of flow patterns under different conditions. This paper adopts the VOF multiphase flow model to simulate the oil-water two phase flow during the period of high water cut in horizontal pipeline, and obtains the phase distribution profile of the oil-water two phase under the conditions of different volume oil content, flow velocity and viscosity, and compares numerical simulation with experiment results. the results show that the oil-water two phase flow tends to be stratified flow when the volume oil rate is in the range of 0.1 to 0.2m/s, the flow velocity is 0.3 to 0.5 and the viscosity is 0.02kg/ (m⋅s) to 0.06kg/(m⋅s). When the flow velocity is lager than 0.5m/s, it transits to the scattered flow from the stratified flow. The results of numerical simulation and test are same fundamentally.

Diagnosis for Thermal Defects of Pipeline Insulation in Refining Process

There are a lot of pipelines whose heat loss exceeds the limit of national standards after they are used a period of time in refining pipeline insulation engineering. Thermal defects are easily found on the pipeline surface by using a infrared thermal imager.There are two kinds of thermal defects on these pipelines. One is settlement of insulation layer; the other is seam in lap joints of insulation protection casing. Numerical simulation is developed in this paper for these two cases. Heat loss and surface temperature of pipelines are calculated to verify if the value has exceeded the limit of national standards. Some improving suggestions are also given in this paper.

Thermal Insulating System Design for the Wellhead of the Snubbing Service Equipment

The unsteady state mathematic model was utilized to compute the transient temperature field and determine the heating power, and then a set of thermal insulating system for the wellhead of the snubbing service equipment was designed and manufactured based on the mapping of the material object. The result shows that the numerical results of the cartridge heater’s temperature field agree with the testing values. The thermal insulating system for the wellhead of the snubbing service equipment meets the needs of the snubbing service in the winter; the system possesses the merits of rapid rate of temperature rise, well thermal insulating, safety and convenience.