Nowadays, under unstable prices scenarios, the oil and gas industry is looking for improvement in its production processes, either by increasing the production and/or lowering the operational costs. Aircoolers, particularly, are key equipments in the natural gas industry, and are frequently the bottleneck of gas conditioning processes.
To improve air cooling efficiency and increase their gas volume capacity, several solutions are commonly implemented such as: fan blade angle change, air inlet section modification, fogging cooling system, among others.
The present study shows the CFD (Computational Fluid Dynamics) analysis of an air cooler, under an air flow with an evaporative cooling system, in order to quantify the effect of this cooling process on its overall equipment performance.
Simulations were carried out using sing the ANSYS CFX v-14® software, in a simplified multidomain which consider fluid and solid blocks:
1.- External two-phase flow (air + water droplets) with heat and mass transfer
2.- Heat transfer through the pipe wall
3.- Single phase natural gas flow inside the tubes
In order to stablish an operational range of the fogging system, the influence of parameters like: inlet temperature and relative humidity of the air, water flow rate, water droplets mean diameter, water injection position, were studied [9, 10].
The results show a good agreement (around 5%) respect to the reported values on the literature. The best performance for the equipment was reported with a droplet diameter of 20 μm and for low relative humidity (less than 65%), which guarantees the complete evaporation of the droplets within the studied domain. For the analyzed operating conditions, a reduction of the gas outlet temperature of up to 1.5°C can be achieved.
