Suitability and optimisation of analytical indoor shelter model used for infiltration of carbon dioxide for typical dwellings

Carbon Capture Utilisation and Storage (CCUS) schemes involve transporting large quantities of carbon dioxide (CO2). A release of CO2 from CCUS transportation infrastructure could cause severe consequences for the surrounding population if the risk is not appropriately managed. Following a release of CO2, people in the surrounding environment could move away and seek shelter. The CO2 plume could drift past buildings causing the concentration of CO2 inside these buildings to build up. How much CO2 accumulates inside the buildings is key to the safety of their occupants. Previously an analytical infiltration model, based on wind and buoyancy driven ventilation, and a CFD infiltration model were created which can be used to predict the effect of CO2 exposure on building occupants following a release from an onshore CO2 pipeline [1]. These models can be used to determine the consequences of failure the dispersion behaviour of CO2 and the infiltration rate of a plume of CO2 into buildings and can form part of a Quantitative Risk Assessment (QRA) process for a CO2 pipeline. The models were validated against an experimental test of CO2 infiltration into a small enclosure. Comparisons were made between the analytical model, CFD model and experimental data for the build-up of CO2 in the enclosure and the changes in internal temperature. This paper investigates the suitability of the analytical model for buildings geometries more closely resembling domestic abodes and against a wider range of conditions by comparing its results to those of the CFD model for a set of representative case studies. It also tunes the parameters used in the model. Thirty test cases were created which explore the key parameters affecting the CO2 ventilation rate: wind speed, the area and height of the openings, internal temperature and building height, width and length. The analytical model’s predictions of the accumulation of CO2 inside a building are shown to be extremely close to the CFD results for all cases except one, where it makes an over prediction of the level of CO2. Furthermore, it is recommended that the analytical infiltration model is used with the tuned set of coefficients identified in this paper