Predicting the Decompression Characteristics of Carbon Dioxide Using Computational Fluid Dynamics

2012 ◽  
Author(s):  
H. E. Jie ◽  
B. P. Xu ◽  
J. X. Wen ◽  
R. Cooper ◽  
J. Barnett
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Carbon Dioxide ◽  
Computational Fluid Dynamics ◽  
Shock Tube ◽  
Pipe Wall ◽  
Numerical Study ◽  
Wall Friction ◽  
Transfer Model ◽  
Dense Phase

In a previous paper, we reported the development of CFD-DECOM, a Computational Fluid Dynamics (CFD) model based on the Arbitrary Lagrangian Eulerian (ALE) approach and the Homogeneous Equilibrium Method (HEM) for simulating multi-phase flows, to predict the transient flow following the rupture of pipelines conveying rich gas or pure carbon dioxide (CO2). The use of CFD allows the effect of pipe wall heat transfer and friction to be quantified. Here, the former is considered through the implementation of a conjugate heat transfer model while the two-phase pipe wall friction is computed using established correlations. The model was previously validated for rich gas and to a limited extent dense phase CO2 decompression against the available shock tube test data. This paper describes the extension of the model to the decompression of both gaseous and dense phase CO2 with impurities. The Peng-Robinson-Stryjek-Vera Equation Of State (EOS), which is capable of predicting the real gas thermodynamic behaviour of CO2 with impurities, has been implemented in addition to the Peng-Robinson and Span and Wagner EOSs. The liquid-vapour phase equilibrium of a multi-component fluid is determined by flash calculations. The predictions are compared with the measurements of some of the recent gaseous and dense phase CO2 shock tube tests commissioned by National Grid. The detailed comparison is presented showing reasonably good agreement with the experimental data. Further numerical study has also been carried out to investigate the effects of wall friction and heat transfer, different EOSs and impurities on the decompression behaviour.

Under Pressure Welding and Preheat Temperature Decay Times on Carbon Dioxide Pipelines

2014 ◽  
Author(s):  
Simon Slater ◽  
Robert Andrews ◽  
Peter Boothby ◽  
Julian Barnett ◽  
Keith Armstrong
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Natural Gas ◽  
Cooling Rate ◽  
Gaseous Phase ◽  
Transfer Model ◽  
Dense Phase ◽  
Pressure Welding ◽  
One Dimensional ◽  
Decay Times

Whilst there is extensive industry experience of under pressure welding onto live natural gas and liquid pipelines, there is limited experience for Carbon Dioxide (CO2) pipelines, either in the gaseous or dense phases. National Grid has performed a detailed research programme to investigate if existing natural gas industry under pressure welding procedures are applicable to CO2 pipelines, or if new specific guidance is required. This paper reports the results from one part of a comprehensive trial programme, with the aim of determining the preheat decay times, defined by the cooling time from 250 °C to 150 °C (T250–150), in CO2 pipelines and comparing them to the decay times in natural gas pipelines. Although new build CO2 pipelines are likely to operate in the dense phase, if an existing natural gas pipeline is converted to transport CO2 it may operate in the gaseous phase and so both cases were considered. The aims of the work presented were to: • Determine the correlations between the operating parameters of the pipeline, i.e. flow velocity, pressure etc. and the cooling rate after removal of the preheat, characterised by the (T250–150) cooling time. • Compare the experimentally determined T250–150 cooling times with the values determined using a simple one dimensional heat transfer model. • Define the implications of heat decay for practical under pressure welding on CO2 pipelines. Small-scale trials were performed on a 150 mm (6″) diameter pressurised flow loop at Spadeadam in the UK. The trial matrix was determined using a one dimensional heat transfer model. Welding was performed on a carbon manganese (C-Mn) pipe that was machined to give three sections of 9.9 mm, 19.0 mm and 26.9 mm wall thickness. Trials were performed using natural gas, gaseous phase CO2 and dense phase CO2; across a range of flow velocities from 0.3 m/s to 1.4 m/s. There was relatively good agreement between the T250–150 cooling times predicted by the thermal model and the measured T250–150 times. For the same pipe wall thickness, flow velocity and pressure level, the preheat decay cooling times are longest for gaseous phase CO2, with the fastest cooling rate recorded for dense phase CO2. Due to the fast cooling rate observed on dense phase CO2, the T250–150 times drop below the 40 second minimum requirement in the National Grid specification for under pressure welding, even at relatively low flow velocities. The practical limitation for under pressure welding of pipelines containing dense phase CO2 will be maintaining sufficient preheating during welding. The results from this stage of the technical programme were used to develop the welding trials and qualification of a full encirclement split sleeve assembly discussed in an accompanying paper (1).

scholarly journals Numerical study on a heat transfer model in a Lagrangian fluid dynamics simulation

2016 ◽  
Vol 103 ◽  
pp. 635-645 ◽  
Author(s):  
Kazuya Takabatake ◽  
Xiaosong Sun ◽  
Mikio Sakai ◽  
Dimitrios Pavlidis ◽  
Jiansheng Xiang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Numerical Study ◽  
Heat Transfer Model ◽  
Dynamics Simulation ◽  
Transfer Model

Computational Fluid Dynamics Simulations of an Inertance Type Pulse Tube Refrigerator

2010 ◽  
Author(s):  
Dion Savio Antao ◽  
Bakhtier Farouk
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Heat Exchangers ◽  
Numerical Study ◽  
Working Fluid ◽  
Pulse Tube ◽  
Pulse Tube Refrigerator ◽  
Flow Recirculation ◽  
Temperature Heat

A numerical study is reported here for the investigation of the fundamental flow and heat transfer processes found in an inertance type pulse tube refrigerator (IPTR). The general design of an IPTR incorporates a pressure wave generator, a transfer line, an aftercooler, a regenerator, a pulse tube, a pair of heat exchangers for the cold and hot ends of the pulse tube, an inertance tube and a reservoir. The performance of the IPTR system is simulated using computational fluid dynamics (CFD) using cylindrical co-ordinates (r–z) and applying the axisymmetric assumption. The IPTR is driven by a cyclically moving piston at one end of the system operating at a fixed frequency with helium as the working fluid. Both constant temperature and convective heat transfer boundary conditions are examined along the external walls of the hot heat exchangers. The simulations reveal interesting steady-periodic flow patterns that develop in the pulse tube due to the fluctuations caused by the piston and the presence of the inertance tube. The secondary-flow recirculation patterns in the pulse tube reduce the heat pumping effect from the low-temperature heat exchanger to the high-temperature heat exchangers.

Sign in / Sign up

Export Citation Format

Share Document