Decarbonization of the energy sector is still one of the most urgent challenges the world must deal with, and hydrogen can play an important role in the global energy transition. To make a significant contribution to this purpose, hydrogen must be adopted in sectors where now it is almost absent, such as the domestic heating sector. The present work deals with an experimental and numerical analysis of the diffusion and evaporation phenomena in a wet drum gas meter, used as reference meter for certifying new domestic gas meters suitable for accurate and traceable hydrogen flow measurements. The wet drum gas meter is a volumetric gas flow meter. It consists of a cylindrical and rotating measuring drum which is partitioned into different measuring chambers. Also, this is partially submerged in the packing liquid, water in this study, whose level defines the volume of the measuring chambers. The aim of this study is the impact assessment of the mutual influence of water and hydrogen flowing into the wet drum gas meter on the flow measurement. Specifically, the study of hydrogen solubility and diffusivity in water is performed through two analytical models and a numerical model implemented in MATLAB. While water evaporation investigation is performed through a mathematical analysis of the experimental data. Moreover, the whole analysis regarding hydrogen is carried out by comparing it with air, used as calibration gas of the wet drum gas meter. Since hydrogen and air dissolve little in water and the time required to reach the saturation condition is on the order of years, the diffusion phenomenon can be considered negligible. In its turn, water evaporation has more impact on the flow measurement, leading to significant measurement errors both during air calibration and normal use with hydrogen. To overcome the evaporation issue, calculations to retrieve the effective gas volume flow rate at the outlet of the wet drum gas meter are provided. Specifically, the volume occupied by the evaporated water is subtracting from the total measured outlet volume. In parallel to water, an equivalent analysis on ionic liquids as alternative fluids to water in the wet drum gas meter is developed. It results that hydrogen is more soluble in ionic liquids than in water, leading to higher measurement biases. While the negligible vapor pressure of these innovative fluids would minimize the evaporation problem.
La decarbonizzazione del settore energetico è ad oggi una delle sfide più impellenti da affrontare e l'idrogeno può svolgere un ruolo importante nella transizione energetica globale. Tuttavia, per dare un contributo significativo l'idrogeno dovrebbe essere adottato in settori dove è ancora pressoché assente, come quello del riscaldamento domestico. Il presente lavoro affronta un'analisi sperimentale e numerica dei fenomeni di diffusione ed evaporazione in un “wet drum gas meter”, utilizzato come strumento di riferimento per la certificazione di nuovi contatori di gas domestici idonei a misure di flusso di idrogeno accurate e tracciabili. Il “wet drum gas meter” è un misuratore volumetrico di portata. È costituito da un tamburo di misurazione cilindrico rotante suddiviso in diverse camere di misura. Inoltre, il tamburo è parzialmente immerso in un liquido di impacchettamento, in questo studio acqua, il cui livello definisce il volume delle camere di misura. Lo scopo di questo studio è la valutazione dell'impatto sulla misura di portata dell'influenza reciproca dell'acqua e dell'idrogeno all’interno del “wet drum gas meter”. Nello specifico, lo studio della solubilità e diffusività dell'idrogeno in acqua viene eseguito attraverso due modelli analitici e uno numerico implementato in MATLAB. Mentre l'evaporazione dell'acqua viene studiata attraverso un'analisi matematica dei dati sperimentali. Inoltre, l'intera analisi relativa all'idrogeno viene effettuata confrontandola con l'aria, utilizzata come gas di taratura del “wet drum gas meter". Poiché l’idrogeno e l’aria dissolvono poco in acqua e il tempo necessario per raggiungere la condizione di saturazione è nell’ordine degli anni, il fenomeno della diffusione può essere considerato trascurabile. Mentre l'evaporazione dell'acqua ha un impatto maggiore sulla misurazione del flusso, portando a errori significativi sia durante la calibrazione in aria sia durante il normale utilizzo con idrogeno. Per risolvere il problema dell'evaporazione, sono forniti i calcoli per ricavare la portata volumetrica di gas effettiva all’uscita del wet drum gas meter. Nello specifico, il volume occupato dall’acqua evaporata viene sottratto dal volume totale misurato in uscita. Parallelamente all'acqua, viene sviluppata un'analisi equivalente sui liquidi ionici come fluidi alternativi all'acqua nel “wet drum gas meter”. Ne risulta che l'idrogeno è più solubile nei liquidi ionici che nell'acqua, portando a distorsioni di misura più elevate. Mentre la pressione di vapore trascurabile di questi fluidi innovativi ridurrebbe al minimo il problema dell'evaporazione.
Analysis of diffusion and evaporation phenomena in wet drum gas meters for accurate and traceable hydrogen flow measurement
Russo, Matteo;SORANNO, CATERINA
2020/2021
Abstract
Decarbonization of the energy sector is still one of the most urgent challenges the world must deal with, and hydrogen can play an important role in the global energy transition. To make a significant contribution to this purpose, hydrogen must be adopted in sectors where now it is almost absent, such as the domestic heating sector. The present work deals with an experimental and numerical analysis of the diffusion and evaporation phenomena in a wet drum gas meter, used as reference meter for certifying new domestic gas meters suitable for accurate and traceable hydrogen flow measurements. The wet drum gas meter is a volumetric gas flow meter. It consists of a cylindrical and rotating measuring drum which is partitioned into different measuring chambers. Also, this is partially submerged in the packing liquid, water in this study, whose level defines the volume of the measuring chambers. The aim of this study is the impact assessment of the mutual influence of water and hydrogen flowing into the wet drum gas meter on the flow measurement. Specifically, the study of hydrogen solubility and diffusivity in water is performed through two analytical models and a numerical model implemented in MATLAB. While water evaporation investigation is performed through a mathematical analysis of the experimental data. Moreover, the whole analysis regarding hydrogen is carried out by comparing it with air, used as calibration gas of the wet drum gas meter. Since hydrogen and air dissolve little in water and the time required to reach the saturation condition is on the order of years, the diffusion phenomenon can be considered negligible. In its turn, water evaporation has more impact on the flow measurement, leading to significant measurement errors both during air calibration and normal use with hydrogen. To overcome the evaporation issue, calculations to retrieve the effective gas volume flow rate at the outlet of the wet drum gas meter are provided. Specifically, the volume occupied by the evaporated water is subtracting from the total measured outlet volume. In parallel to water, an equivalent analysis on ionic liquids as alternative fluids to water in the wet drum gas meter is developed. It results that hydrogen is more soluble in ionic liquids than in water, leading to higher measurement biases. While the negligible vapor pressure of these innovative fluids would minimize the evaporation problem.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/176206