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Expert briefing
Publication date: 16 February 2022

A moderate northern hemisphere winter has resulted in weaker Asian gas demand, causing spot prices of liquefied natural gas (LNG) to fall back from record highs. Strong…

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DOI: 10.1108/OXAN-DB267357

ISSN: 2633-304X

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Geographic
Topical
Article
Publication date: 1 January 1992

J.I. RAMOS

A domain‐adaptive technique which maps the unknown, time‐dependent, curvilinear geometry of annular liquid jets into a unit square is used to determine the steady state…

Abstract

A domain‐adaptive technique which maps the unknown, time‐dependent, curvilinear geometry of annular liquid jets into a unit square is used to determine the steady state mass absorption rate and the collapse of annular liquid jets as functions of the Froude, Peclet and Weber numbers, nozzle exit angle, initial pressure and temperature of the gas enclosed by the liquid, gas concentration at the nozzle exit, ratio of solubilities at the inner and outer interfaces of the annular jet, pressure of the gas surrounding the liquid, and annular jet's thickness‐to‐radius ratio at the nozzle exit. The domain‐adaptive technique yields a system of non‐linearly coupled integrodifferential equations for the fluid dynamics of and the gas concentration in the annular jet, and an ordinary differential equation for the time‐dependent convergence length. An iterative, block‐bidiagonal technique is used to solve the fluid dynamics equations, while the gas concentration equation is solved by means of a line Gauss‐Seidel method. It is shown that the jet's collapse rate increases as the Weber number, nozzle exit angle, temperature of the gas enclosed by the annular jet, and pressure of the gas surrounding the jet are increased, but decreases as the Froude and Peclet numbers and annular jet's thickness‐to‐radius ratio at the nozzle exit are increased. It is also shown that, if the product of the inner‐to‐outer surface solubility ratio and the initial pressure ratio is smaller than one, mass is absorbed at the outer surface of the annular jet, and the mass and volume of the gas enclosed by the jet increase with time.

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International Journal of Numerical Methods for Heat & Fluid Flow, vol. 2 no. 1
Type: Research Article
ISSN: 0961-5539

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Expert briefing
Publication date: 17 April 2015

Turkmenistan's gas markets.

Article
Publication date: 16 March 2015

Robert Bogue

– This paper aims to provide details of the major optical gas sensing techniques and their applications.

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Abstract

Purpose

This paper aims to provide details of the major optical gas sensing techniques and their applications.

Design/methodology/approach

Following an introduction, this paper first identifies the major gas sensing technologies and provides an overview of optical sensing techniques. The sources and impact of the gases most frequently sensed by optical methods are listed. Three non-absorption-based and nine absorption-based methods and their main applications are then described in detail. Brief concluding comments are drawn.

Findings

All manner of optical gas sensing techniques have been commercialised and while the majority are absorption-based, several other methods also play a significant role. Some optical gas sensors offer advanced capabilities such as remote monitoring, the creation of 2D and 3D distribution maps, detection of parts per trillion levels and even the visualisation of gases in real time. They play a vital role in protecting workers from hazardous gases, controlling and minimising air pollution and monitoring the atmospheric environment, as well as being used in the food, medical, process, power generation and other industries.

Originality/value

This paper provides a detailed insight into optical gas sensing techniques and their uses.

Details

Sensor Review, vol. 35 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 1 March 1971

David Hawdon

Looks at models constructed for the gas industry domestic, central heating, cooling and industrial markets. Shows how these models can be used to permit the rapid…

Abstract

Looks at models constructed for the gas industry domestic, central heating, cooling and industrial markets. Shows how these models can be used to permit the rapid assessment of marketing targets for appliance sales and price levels against gas supply constraints. Concludes that although these models do not provide instant solutions to the marketing problems of the gas industry they do help to organize available data in a more efficient way.

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European Journal of Marketing, vol. 5 no. 3
Type: Research Article
ISSN: 0309-0566

Keywords

Article
Publication date: 10 August 2010

Sun Jingchun, Lv Ding and Wu Fan

The purpose of this paper is to model the trend of natural gas supply and demand in China in different circumstances from 1990 to 2050.

Abstract

Purpose

The purpose of this paper is to model the trend of natural gas supply and demand in China in different circumstances from 1990 to 2050.

Design/methodology/approach

The related factors were selected from references and classified into three categories such as endogenous, exogenous, and excluded factors. The three sub‐models of supply, demand and their interconnection were built and integrated. The impacts of natural gas resources, the investment of gas industry and the energy structure over natural gas supply and demand were analyzed based on scenario analysis.

Findings

The impact of energy structure in China is more evident compared to natural gas resources and the investment level.

Research limitations/implications

Import and transportation of natural gas will have growing impacts on the supply and demand in China when the model is applied.

Practical implications

A very useful method to analyze the equilibrium of natural gas supply and demand.

Originality/value

The paper presents a new prediction model of natural gas supply and demand in system dynamics. The paper is aimed at the researchers and decision makers in energy industries, especially in the fields of energy prices.

Details

Kybernetes, vol. 39 no. 8
Type: Research Article
ISSN: 0368-492X

Keywords

Article
Publication date: 1 January 2014

Asis Sarkar

This paper aims to evaluate nine types of electrical energy generation options with regard to seven criteria. The analytic hierarchy process (AHP) was used to perform the…

Abstract

Purpose

This paper aims to evaluate nine types of electrical energy generation options with regard to seven criteria. The analytic hierarchy process (AHP) was used to perform the evaluation. The TOPSIS method was used to evaluate the best generation technology.

Design/methodology/approach

The options that were evaluated are the hydrogen combustion turbine, the hydrogen internal combustion engine, the hydrogen fuelled phosphoric acid fuel cell, the hydrogen fuelled solid oxide fuel cell, the natural gas fuelled phosphoric acid fuel cell, the natural gas fuelled solid oxide fuel cell, the natural gas turbine, the natural gas combined cycle and the natural gas internal combustion engine. The criteria used for the evaluation are CO2 emissions, NOX emissions, efficiency, capital cost, operation and maintenance costs, service life and produced electricity cost.

Findings

The results drawn from the analysis in technology wise are as follows: natural gas fuelled solid oxide fuel cells>natural gas combined cycle>natural gas fuelled phosphoric acid fuel cells>natural gas internal combustion engine>hydrogen fuelled solid oxide fuel cells>hydrogen internal combustion engines>hydrogen combustion turbines>hydrogen fuelled phosphoric acid fuel cells> and natural gas turbine. It shows that the natural gas fuelled solid oxide fuel cells are the best technology available among all the available technology considering the seven criteria such as service life, electricity cost, O&M costs, capital cost, NOX emissions, CO2 emissions and efficiency of the plant.

Research limitations/implications

The most dominant electricity generation technology proved to be the natural gas fuelled solid oxide fuel cells which ranked in the first place among nine alternatives. The research is helpful to evaluate the different alternatives.

Practical implications

The research is helpful to evaluate the different alternatives and can be extended in all the spares of technologies.

Originality/value

The research was the original one. Nine energy generation options were evaluated with regard to seven criteria. The energy generation options were the hydrogen combustion turbine, the hydrogen internal combustion engine, the hydrogen fuelled phosphoric acid fuel cell, the hydrogen fuelled solid oxide fuel cell, the natural gas fuelled phosphoric acid fuel cell, the natural gas fuelled solid oxide fuel cell, the natural gas turbine, the natural gas combined cycle and the natural gas internal combustion engine. The criteria used for the evaluation were efficiency, CO2 emissions, NOX emissions, capital cost, O&M costs, electricity cost and service life.

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International Journal of Quality & Reliability Management, vol. 31 no. 1
Type: Research Article
ISSN: 0265-671X

Keywords

Article
Publication date: 1 March 1994

Ray Kocache

Summarizes some of the most commonly used gas sensors and describes howeach one works. Covers solid state gas sensors; aqueous electrochemicalgas sensors; paramagnetic gas

Abstract

Summarizes some of the most commonly used gas sensors and describes how each one works. Covers solid state gas sensors; aqueous electrochemical gas sensors; paramagnetic gas sensors, photometric gas sensors; thermal conductivity gas sensors and fibre‐optic gas sensors.

Details

Sensor Review, vol. 14 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 29 August 2019

Wei Long, Mimi Wu, Fasha Li, Jiyao Wang and Wei Deng

The purpose of this paper is to develop the micro-electro-mechanical systems (MEMS) technology has created the conditions for the study of microfluidic technology…

Abstract

Purpose

The purpose of this paper is to develop the micro-electro-mechanical systems (MEMS) technology has created the conditions for the study of microfluidic technology. Microfluidic technology has become a very large branch in the MEMS field over the past decade. For aerostatic thrust bearing, the micro-fluidic gas flow in a small-scale gas film between two parallel plates is the subject of many studies. Because of the thin gas in the film, velocity slip occurs at the interface, which causes the gas flow pattern to change in the lubricating film. So, it is important to clarify the mechanism and pressure characteristics in thin firm gas flow.

Design/methodology/approach

First, a new assumption and corresponding models for the flow regime were established by theoretical analysis. Second, computational simulations about pressure distribution and velocity were given by a large-scale atomic/molecular massively parallel simulator (LAMMPS). Third, comparison of the results of LAMMPS simulation and direct simulation Monte Carlo calculation were made to verify the reliability of above results.

Findings

The gas flow mechanism and corresponding regulations are significantly different from traditional pneumo dynamics, which can be described by Navier–Stokes equations accurately. Combining theatrical study and computational results, the stratification theory of the gas film was verified. The research shows that when the gas flow rate increased, the pressure of the gas film decreased, the thickness of the continuous flow layer increased, the thickness of the thin layer decreased and the layered pressure in the gas film disappeared. In this case, velocity slippage could be ignored.

Originality/value

First, this paper established an analytical model of the gas film support and proposed a film stratification theory. The gas film was divided into the near wall layer, the thin layer and the continuous layer, which was proved by the calculation of LAMMPS flow simulation. The velocity slip boundary conditions theory is feasible. Second, the gas film size of the flat plate is at the micron level, which cannot be observed in its flow regimen, only determined by calculation and simulation. This paper proposes a new model and a new tool to analyze gas flow in gas films.

Details

Industrial Lubrication and Tribology, vol. 73 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Open Access
Article
Publication date: 31 May 2002

Sang Jang Kwon and Soo Jong Kwak

In this paper, we theoretically examine the optimal hedge strategy for a natural gas company. The use of natural gas derivatives to minimize consumers' per unit cost of…

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Abstract

In this paper, we theoretically examine the optimal hedge strategy for a natural gas company. The use of natural gas derivatives to minimize consumers' per unit cost of natural gas consumed, or to minimize the upside risk associated with extreme bills would be the strategy being considered by local distribution companies (LDCs) and regulators. The objective is, therefore, to stabilize the summer and the winter months' natural gas prices as well as to improve the level of customers' welfare. In general, during the summer injection period, April through October, utility companies purchase a certain amount of natural gas and keep in storage facilities and, hence, during the winter withdrawal months, November through March, utility companies supply natural gas at a predetermined minimal fuel cost rate to residential and commercial customers. Therefore, to manage these conflicts of interests efficiently should natural gas companies be supported by accurate forecast of the natural gas price for the winter months. Otherwise, natural gas companies will trade natural gas derivatives in order to reduce costs charged to customers. The results show that customers benefit from the use of natural gas derivatives. If the natural gas market is deregulated, the typical risk-return trade off shows that natural gas derivatives would provide the most efficient tools for utility companies to minimize the natural gas price volatilities.

Details

Journal of Derivatives and Quantitative Studies, vol. 10 no. 1
Type: Research Article
ISSN: 2713-6647

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