PSI - Issue 59

Ya. Grudz et al. / Procedia Structural Integrity 59 (2024) 750–756 Ya. Grudz et al. / Structural Integrity Procedia 00 (2019) 000 – 000

752

3

st Q - the volume flow of gas in the gas pipeline is reduced to sr sr P T  , , - average pressure and temperature in the gas pipeline and gas density sr

where M - mass flow of gas in the gas pipeline;

st st P T , );

standard conditions (

under these conditions. Using (3) and (4) we obtain for the useful work assigned to a unit of time

P P

T T

( z P P  

)

N Q 







st

sr

k

st

sr

p

k

st (5) The total energy consumption for the gas flow per unit of time will be somewhat higher due to losses in local resistances that occur in the network in the form of liquid accumulations, and the deterioration of the technical condition of the pipelines of the network itself. Therefore, taking into account that the hydraulic losses are proportional to the coefficient of hydraulic resistance, respectively, of the new network t  and in its actual technical condition f  , the efficiency factor of the gas network can be written in the form sr .

k N N N 

t 







f 

k

vtr

,

(6)

where vtr N - irreversible energy losses per unit of time. As is known (Grudz (2012)), the technical and hydraulic condition of gas pipelines is assessed by the coefficient of hydraulic efficiency, which shows the degree of reduction in throughput due to the increase in hydraulic resistance and is determined by the ratios

Q

t 

f

E

 

Q

f 

t

. (7) Comparison (6) and (7) allows us to obtain a relationship between the coefficient of useful action of the gas pipeline of the network and the coefficient of its hydraulic efficiency in the form 2 E   . (8) Dependence (8) is important because it shows the difference between the coefficient of useful action and the coefficient of hydraulic efficiency. In the works of Grudz et. al. (2014a), the concepts of the efficiency coefficient and the hydraulic efficiency coefficient are equated, which, as we can observe, is an erroneous assertion. This is because the hydraulic efficiency coefficient is a characteristic of the technical condition of the gas pipeline (its diagnostic feature), while the efficiency coefficient characterizes the gas network from an energy perspective. On the other hand, the use of dependence (8) allows us to characterize the gas network from the point of view of energy consumption and connects energy efficiency with the characteristics of the technical condition. If, for example, the coefficient of hydraulic efficiency of the network gas pipeline has decreased to 0.9, this means a deterioration of the technical condition by 10%. At the same time, the characteristics of the network from the energy point of view worsened by 19%. Therefore, to determine the efficiency of the gas network or its elements, it is important to assess the technical condition using the hydraulic efficiency coefficient. The gas network is a complex system of gas pipelines with road selections, parallel and serial connection of elements. Therefore, the task of determining the overall coefficient of hydraulic efficiency of the gas network, if the coefficients of hydraulic efficiency of its elements are known, as well as establishing the influence of the