Numerical simulation for treatment of hypothermia based on vascular interventional direct heating system

Traditional chemical treatment methods have considerable operation costs and represent a risk to the environment. Since 1987 Norwegian oil companies have been investigating alternative electrical heating methods for prevention of hydrate and wax plugs. A joint industry project ‘Concept Verification – Direct Heating of Oil & Gas Pipelines’ was initiated in 1996 and terminated in October 1999. During this work an electrical heating system was proved to be feasible on several fields in the North Sea. It will be installed on 7 flowlines of 13% Chromium (Crl3) with lengths between 6 km and 16 km. Electrical heating is used to maintain or raise the thermally insulated steel pipe temperature above the critical value for hydrate formation (typically 15–25 °C) or wax formation (typically 20–40°C). A single-phase power supply for the heating system is based on commercial components and connected to the platform power supply. The qualification work for the direct heating system has included full scale testing for single and parallel pipes, end termination at the template, bypass of a template and aspects concerning corrosion control. The rating of the system is dependent on the magnetic and electrical characteristics of the steel material. Such data is not commonly available. Measurements performed during the qualification program confirm that the magnetic characteristic may vary within a wide range for a specific steel quality and that mechanical stress and heat treatment can effect the magnetic characteristic. The difference in magnetic characteristic of individual Crl3 pipes results in variation of the pipe temperature and problems concerning differential pressure during melting. The problem can be handled by dividing the pipeline into a number of sections, each with a limited variation of the magnetic characteristic, thus keeping the temperature for the whole pipeline within acceptable limits. As a part of the pipe specification both electrical and magnetic characteristic should be available. These data can be determined by measuring arrangements in the production line of the mill. Measures to limit the variation of magnetic characteristic should be discussed.

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M516 Performance Analysis of a Multi-Functional CO_2 Heat Pump Water Heating System by Numerical Simulation : Analysis Under a Daily Change in Hot water Demand

The Proceedings of Conference of Kansai Branch ◽

10.1299/jsmekansai.2015.90.342 ◽

2015 ◽

Vol 2015.90 (0) ◽

pp. 342

Author(s):

Takuya NAKAMATA ◽

Ryohei YOKOYAMA ◽

Masashi OHKURA ◽

Tetsuya WAKUI

Keyword(s):

Numerical Simulation ◽

Performance Analysis ◽

Heat Pump ◽

Water Demand ◽

Simulation Analysis ◽

Heating System ◽

Hot Water ◽

Water Heating ◽

Daily Change

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Numerical Analysis of the Heat Transfer in Passive Solar Composite Wall Collectors System With Porous Absorber

ASME 2007 Energy Sustainability Conference ◽

10.1115/es2007-36119 ◽

2007 ◽

Author(s):

Wei Chen

Keyword(s):

Heat Transfer ◽

Numerical Simulation ◽

Particle Size ◽

Temperature Field ◽

Room Temperature ◽

Heating System ◽

Thermal Insulator ◽

Composite Wall ◽

Unsteady Numerical Simulation ◽

Solar Wall

In this paper, heat transfer and flow in the composite solar wall with porous absorber has been studied. The unsteady numerical simulation is employed to analyze the performance of the flow and temperature field in the composite solar wall. The excess heat is stored within the porous absorber during solar radiation and there is stratification in the porous layer. So, the porous absorber works as thermal insulator in a degree when no solar shining is available. The heating characteristic of two types of the composite solar wall with porous absorber has been conducted. The influence of particle size, porosity and porous absorber arrange in the solar composite wall on the heating room temperature is significant. The results show that all these factors should be taken into account for a better design of a heating system.

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A Comprehensive Heat Transfer Study Inside a Steam Turbine Valve: Experiment, Numerical Simulation and Simplified Model

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4050858 ◽

2021 ◽

Author(s):

Xu Zhang ◽

Hongyi Shao ◽

Wenwu Zhou ◽

Wei Zhe Wang ◽

YingZheng Liu

Keyword(s):

Heat Transfer ◽

Numerical Simulation ◽

Steam Turbine ◽

Transfer Process ◽

Electric Heating ◽

Heating System ◽

Heat Transfer Process ◽

Thermal Design ◽

Simplified Model ◽

Operational Flexibility

Abstract In a steam turbine system, one of the main factors limiting the operational flexibility is the thermal stress associated with a high temperature gradient within the control valves, which often leads to structural damage during frequent start-up and shut-down cycles. One possible solution is to utilize an electric heating system with appropriate insulation to decrease the warm-up time. Here, an experiment and a numerical simulation were performed using a scaled turbine valve equipped with an electric heating system to understand the heat transfer process. The experiment was conducted at Shanghai Jiao Tong University and had a duration of 100 hours, including three heating-cooling cycles and two heat preservation states. The simulation, which used the commercial software Ansys Fluent 2019 R1 with the finite volume method, was performed to model the experimental heat transfer process. The simulated results showed less than 10% deviation from the measured temperatures. To further improve the computing efficiency, a simplified model based on the lumped parameter method was proposed and validated. This model can predict the valve temperature in less than 1 minute and showed good agreement for all of the studied cases. The ability of the simplified model to simulate the valve heating-cooling cycles at a high efficiency could accelerate the thermal design process to improve the operational flexibility of steam turbines in the future.

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413 Performance Analysis of a Water Heating System with a Storage Tank Using Phase Change Material : Fundamental Performance Analysis by Numerical Simulation

The Proceedings of the Symposium on Environmental Engineering ◽

10.1299/jsmeenv.2012.22.281 ◽

2012 ◽

Vol 2012.22 (0) ◽

pp. 281-284

Author(s):

Ryouhei Yokoyama ◽

Yu Taeuchi ◽

Masashi Okura ◽

Tetsuya Wakui

Keyword(s):

Numerical Simulation ◽

Performance Analysis ◽

Phase Change ◽

Phase Change Material ◽

Storage Tank ◽

Heating System ◽

Water Heating ◽

Change Material

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Simulation of Airflow in the Burning Cave of an Auxiliary Heating System in a Greenhouse

Transactions of the ASABE ◽

10.13031/trans.12719 ◽

2018 ◽

Vol 61 (4) ◽

pp. 1405-1416

Author(s):

Zhanyang Xu ◽

Wenhe Liu ◽

Tieliang Wang ◽

Wei Yu ◽

Yuqing Zhang

Keyword(s):

Numerical Simulation ◽

Numerical Model ◽

Numerical Simulations ◽

Heating System ◽

Experimental Measurements ◽

Wall Function ◽

Auxiliary Heating ◽

Airflow Velocity ◽

Cave Entrance ◽

Turbulent Airflow

Abstract. In this study, numerical simulations of airflow were carried out in the burning cave of an auxiliary heating system. Experimental measurements were also conducted to verify the performance of the numerical model, and turbulent airflow in the burning cave was considered. The numerical simulation in the burning cave was performed for three cases:(1) with a baffle at the bottom of the burning cave entrance, (2) without a baffle at the burning cave entrance, and (3) with a baffle at the top of the burning cave entrance. The turbulent airflow was modeled using the realizable k-e turbulence model as well as the non-equilibrium wall function. The airflow velocity was assessed in the burning cave, and some suggestions were given to improve the performance of the burning cave. The results showed that the airflow entering the burning cave differed due to different positions of the baffle. The smoldering combustion was more even and the burning rate could be controlled more easily when the baffle was placed at the top of the burning cave entrance, making the airflow enter the burning cave through the bottom of the baffle. The results also showed that the maximum airflow velocity in the burning cave increased with increased distance between the baffle and the bottom of the burning cave. Keywords: Airflow, Burning cave, Greenhouse, Simulation.

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