Time filter

Source Type

Montreal, Canada

Farhanian D.,Concordia University at Montreal | Haghighat F.,Concordia University at Montreal | Lee C.-S.,Concordia University at Montreal | Lakdawala N.,Dectron Internationale
Building and Environment | Year: 2013

Ultraviolet photocatalytic oxidation (UV-PCO) is regarded as one of the promising technologies for air purification. Previous studies on UV-PCO of ethanol were performed in an ideal bench top reactors. However, this research is focused on UV-PCO of ethanol in full-scale open test rig which closely resembles the real application of this technology. Ethanol mineralization was investigated under several conditions including two types of UV-lamps (UVC and VUV) for two different photocatalysts under varied concentrations, airflow rate and relative humidity. In each case, removal efficiency and by-products yield were compared. Furthermore, possible mechanism for by-product formation is presented. Experimental results show that acetaldehyde and formaldehyde are the main by-products of ethanol. VUV lamps increase photocatalytic oxidation of ethanol compared to UVC lamps. The increase of relative humidity decreases UV-PCO of ethanol using both VUV and UVC lamps; however, the yield of by-products in the presence of VUV lamps increases while it decreases in the presence of UVC lamps. Higher flow rate results lower removal efficiency and consequently formation of less by-products. Improvement of reaction section by increasing the number of reactors leads to higher ethanol removal efficiency, less partial oxidation, lower amount of by-products and the complete mineralization of acetaldehyde. © 2013 Elsevier Ltd.

Zhong L.,Concordia University at Montreal | Haghighat F.,Concordia University at Montreal | Lee C.-S.,Concordia University at Montreal | Lakdawala N.,Dectron Internationale
Journal of Hazardous Materials | Year: 2013

Photocatalytic oxidation (PCO) is a promising technology that has potential to be applied in mechanically ventilated buildings to improve indoor air quality (IAQ). However, the major research studies were done in bench-top scale reactors under ideal reaction conditions. In addition, no study has been carried out on the investigation of the ozonation and photolysis effect using a pilot duct system. The objective of this study is the development of methodologies to evaluate the performance of PCO systems. A systematic parametric evaluation of the effects of various kinetic parameters, such as compound's type, inlet concentration, airflow rate, light intensity, and relative humidity, was conducted, and new interpretations were provided from a fundamental analysis. In addition, the photolysis effect under vacuum ultraviolet (VUV) irradiation for a variety of volatile organic compounds (VOCs) was examined for the first time in a pilot duct system. The performance comparison of ultraviolet C (UVC)-PCO and VUV-PCO was also discussed due to the presence of ozone. Moreover, the formation of by-products generated with or without ozone generation was fully compared to evaluate the PCO technology. © 2013 Elsevier B.V.

Farhanian D.,Concordia University at Montreal | Haghighat F.,Concordia University at Montreal | Lee C.-S.,Concordia University at Montreal | Zhong L.,Concordia University at Montreal | Lakdawala N.,Dectron Internationale
7th International Cold Climate HVAC Conference | Year: 2012

The quantity of the outdoor air brought into the building can have a direct negative effect on the energy cost of ventilation and the climate. There is cost to heat, cool, humidify or dehumidify the outdoor air depending on the location and season. This leads to a balancing act between indoor air quality (IAQ) and energy cost. Ultraviolet photocatalytic oxidation (UV-PCO) has been acclaimed as one of these innovative technologies for purifying indoor air by decomposition of pollutants, especially volatile organic compounds (VOCs). Although numerous studies have been carried out in this field, UVPCO performance under real life applications is still questionable. Experimental conditions of most previous works focused on ppm level of VOCs in ideal bench-top-scale reactor with low flow-rate and high residence time conditions. On the other hand, limited research has been devoted to investigate generation of the UV-PCO toxic by-products and this issue is one of the main drawbacks and obstacles in its wide applications and design of immune buildings. This paper represents the outcomes of an experimental study which was performed to investigate the generation of the by-products under single pass through duct system. By-products in photodegradation of n-hexane as a result of ozone producing VUV lamps with 254nm+185nm wavelength radiations have been compared with UVC lamps with 254nm wavelength radiation. Two types of catalyst media were used to investigate the feasibility of UV-PCO technology. Removal efficiency and by-products identification results are presented and discussed. © 2012 ASHRAE.

Lee C.-S.,Concordia University at Montreal | Lakdawala N.,Dectron Internationale | Haghighat F.,Concordia University at Montreal
7th International Cold Climate HVAC Conference | Year: 2012

Major air contaminants of concern in indoor swimming pools are vaporized disinfection byproducts (DBPs) formed in the swimming pool water. Conventionally we rely on ventilation to control indoor air contaminant levels. ASHRAE Standard 62.1 Ventilation for Acceptable Indoor Air Quality (2010) specifies the required minimum outdoor air ventilation rate for indoor swimming pools in Ventilation Rate Procedure (VRP). However, swimming pools compliant to the required ventilation rate can still face unacceptable airborne DBP levels. In order to improve the indoor air quality (IAQ) in swimming pools, the World Health Organization (WHO) and US Center for Disease Control (CDC) recommend much higher outdoor air ventilation rate than ASHRAE Standard 62.1. Under the presence of strong sources of specific air contaminants like swimming pools, air cleaning can be a promising technique to improve IAQ. ASHRAE Standard 62.1 Indoor air Quality Procedure (IAQP) allows a reduced outdoor air ventilation rate when it is combined with air cleaning. This paper presents brief review on ventilation requirement by standard and guidelines for indoor swimming pools, and the results of mass balance analysis carried out to investigate the effects of ventilation and air cleaning on the indoor air pollution levels in a typical public swimming pool. Ventilation rates given by ASHRAE Standard 62.1 VRP as well as those by other guidelines were considered and compared with ASHRAE Standard 62.1 IAQP, which has the lowest ventilation rate in combination with air cleaning. © 2012 ASHRAE.

Khazraei Vizhemehr A.,Concordia University at Montreal | Haghighat F.,Concordia University at Montreal | Lee C.-S.,Concordia University at Montreal | Kholafaei H.,Concordia University at Montreal | Lakdawala N.,Dectron Internationale
Clean - Soil, Air, Water | Year: 2015

Adsorption-based granular activated carbon (GAC) filter is one of the common techniques for removing gas phase contaminants. However, a large group of gas phase contaminants is present in indoor environment and limited studies have been carried out to investigate the impact of contaminants type, their mixture and indoor air humidity on the GAC performance. This paper reports the outcomes of a series of experimental work which was carried out on a full-scale system to study the impact of gas phase contaminant type (toluene, n-hexane, and methyl ethyl ketone (MEK)), their mixture, and indoor air relative humidity (RH) level on the performance of GAC filter. It was observed that the GAC filter performed well in removing toluene in both scenarios (single and mixture) due to its high molecular weight, boiling point, and polarizability to ion formation with the GAC, followed by n-hexane and MEK. It was also noted that the GAC filter did not perform well in removing MEK due to its weak attractive forces with GAC as compare to n-hexane and toluene. Among the different physical properties of indoor contaminant, removal performance and service life of the tested GAC filter were positively correlated to the contaminant molecular weight. In addition, the lower dipole moment and interaction energy made the adverse effects of indoor air RH on n-hexane more visible than toluene and MEK. Finally, a significant difference was observed between quantification indexes of the filter in removing indoor air contaminants as a single gas and as a mixture gas. The removal efficiency of GAC filter for the mixture was significantly reduced compared to those for the single gases due to the presence of other compounds in gas mixture competing for the same free space on carbon media. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Discover hidden collaborations