Abstract
Ventilation for underground carparks is critical to indoor air quality (IAQ) due to carbon monoxide (CO) emissions from cars. The IAQ within a multi-level underground carpark of a shopping mall has been investigated using computational fluid dynamics (CFD) model based on ANSYS-FLUENT (18.1) software. The effects of car engines types, porosity of supply and exhaust air louvers and ventilation flow rates on IAQ were examined. A mesh sensitivity study was conducted and the CFD model was validated against the fully mixed mathematical formulations of IAQ with a maximum difference in values of 1.5 ppm and an error of 3.4%. The results showed that the ventilation system must be operated at ACH value of more than 2.7 in order to meet the required CO concentration of 50 ppm within the carpark and should be based on running cars within each level rather than the parking capacity of each level. Porosity of louvers affected air flow distribution between parking levels and led to higher dilution of CO. Therefore, modelling a multilevel underground carpark requires closer attention to cross level interaction across Ramps which could affect the CO concentration within a given level.
Highlights
The rapid increase in the population within urban areas and limited ground spaces have increased the need for multilevel car parking facilities, either aboveground or underground
Hybrid cars were found to emit 117.4 g/km of CO2, which resulted in 45% reduction in CO2 emissions when compared with gasoline vehicles
It is estimated that compact, mid-size, mid-size sport utility, and SUV hybrid cars emits less CO2 than conventional cars by 10%, 15%, 19%, and
Summary
The rapid increase in the population within urban areas and limited ground spaces have increased the need for multilevel car parking facilities, either aboveground or underground. An underground carpark is an enclosed space located below ground level due to better utilization of the building space. Indoor air quality (IAQ) is a critical element when designing an underground carpark as it directly affects the health of human beings using it. Car emissions are the main source of air pollution in underground carparks were exposure to high levels of these emissions, such as Carbon Monoxide (CO), could cause respiratory and heart diseases [1,2,3]. Car emissions might increase during start-up and at lower speed and health effects might become worse in poor ventilation, which make underground carparks not favorable for long-term stays [4,5]. Carpark users may become feel uncomfortable at temperatures of 32 ◦ C to 35 ◦ C and air velocity between 0.2 and 0.4 m/s for 80% satisfaction [6]
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