Abstract
Water hammer on transient flow of hydrogen-natural gas mixture in a horizontal pipeline is analysed to determine the relationship between pressure waves and different modes of closing and opening of valves. Four types of laws applicable to closing valve, namely, instantaneous, linear, concave, and convex laws, are considered. These closure laws describe the speed variation of the hydrogen-natural gas mixture as the valve is closing. The numerical solution is obtained using the reduced order modelling technique. The results show that changes in the pressure wave profile and amplitude depend on the type of closing laws, valve closure times, and the number of polygonal segments in the closing function. The pressure wave profile varies from square to triangular and trapezoidal shape depending on the type of closing laws, while the amplitude of pressure waves reduces as the closing time is reduced and the numbers of polygonal segments are increased. The instantaneous and convex closing laws give rise to minimum and maximum pressure, respectively.
Highlights
Most analysis of flow in pipelines and networks has assumed the flow to be at steady state conditions
From (11), the celerity pressure wave of compressible gas flow can be expressed based on the hydrogen mass ratio
The relationship between the pressure waves of hydrogennatural gas mixture with the different types of closing valve laws is determined based on the type of closing laws, closure times, and the polygonal segments of the closing function
Summary
Most analysis of flow in pipelines and networks has assumed the flow to be at steady state conditions. Water hammer is a kind of transient phenomenon that occurs when rapid valve closure suddenly blocks the flow in pipelines It depends on the fluid compressibility where there are sudden changes in pressure. Have been presented by different investigators to obtain the transient pressure and discharge in water hammer situations These methods are time consuming, especially for gas network analysis. Our main objective is to determine the relationship between the pressure waves of hydrogen-natural gas mixture with different modes of closing and opening of valves, most commonly referred to as convex, concave, linear, and instantaneous closing law. The water hammer on transient flow of hydrogen-natural gas is analysed based on the types of closing laws, closure valve times, and the number of polygonal segments in the closing function
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