Exergy-based analysis of gas transmission system with application to Yamal-Europe pipeline

This paper presents a thermodynamic analysis of a gas transmission system consisting compressor stations and pipeline sections. It has been assumed that the compressor station comprises a gas turbine-driven compressor and a gas cooler, and the irreversibility of the processes associated with the gas transmission was investigated. The exergy method was used to determine the amount of work supplied to the components of the pipeline system and the amount of work that is lost during the gas transmission. For the case study, the Yamal-Europe pipeline is chosen. In this study, a nonisothermal, steady-state gas flow model was used for comparing the performance of the gas transmission system under different cooler operating set points. The pipeline flow and the compressor station processes were governed by the equations which include real-gas model based on virial equation of state.Gas transmission system Compressor station Gas cooler Gas pipeline Exergy Efficiency

Comparison of the WRF and SODAR Derived Planetary Boundary Layer Height

In this work we compare the Planetary Boundary Layer Height (PBLH), calculated with the Weather Research and Forecasting (WRF) model, with the measurements from an acoustic remote sounding system (SODAR) gathered at Wrocław, SW Poland. The comparison is done for 15-30 November 2011. During this period, very high concentrations of PM2.5 were observed in SW Poland. For 9 days, 24-hour average PM2.5 concentrations reached the level “unhealthy for sensitive groups” and for 2 days “unhealthy” level according to Air Quality Index. Four simulations were run with different planetary boundary layer schemes for the innermost domain. The PBL schemes tested were: Yonsei University (sim1), Mellor-Yamada Nakanishi and Niino Level 3 (sim2), Asymmetric Convective Model 2 (sim3) and Bougeault-Lacarrère (sim4). The results show that all the schemes tested overestimate the PBLH, with the largest mean error for sim1 and sim2 (215 and 225m, respectively). The mean error is significantly smaller for sim3 and sim4 (109 and 72m, respectively). The agreement between the WRF and Sodar PBLH has diurnal pattern and changes with the Pasquill stability classes. The overestimation of the PBLH might lead to the underestimation of air pollutants concentrations modelled with the air quality models