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Benny Raphael
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Benny Raphael
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Benny Raphael
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Raphael, B.
Raphael, Benny
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3 results
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- PublicationPerformance evaluation of an integrated Personalized Ventilation-Personalized Exhaust system in conjunction with two background ventilation systems(01-01-2014)
;Junjing, Yang ;Sekhar, Chandra ;Cheong, DavidThe inhaled air quality in the breathing zone is strongly influenced by flow interactions around occupants. Personalized Ventilation (PV) aims to supply conditioned outdoor air directly to the occupants' breathing zone and thus improves the inhaled air quality. In this research, a Personalized Exhaust (PE) system is developed, which has two local exhaust devices installed with the chair, just above the shoulder level. Such a system placed in front of a PV system will introduce more PV air into the breathing zone of a seated person as well as exhausting part of the exhaled air from the free convective flow. This study investigates how the performance of a PV system will be affected after being integrated with the PE system. Experiments were conducted in an environmental chamber in Mixing Ventilation or Displacement Ventilation mode for the background air-conditioning system. A breathing thermal manikin was placed in the PE integrated chair in front of the PV air terminal device (ATD) to simulate a seated person in an office environment. The manikin was moved longitudinally away from the PV ATD as well as in an arc to 12 different locations. The performance of the PV-PE system at the 12 different locations was tested with regard to its ability in pulling the PV air towards a seated person moving within a small area in front of the workstation. Findings imply that the use of the combined PV-PE system for a seated person could provide more outdoor air than a PV system alone. © 2014 Elsevier Ltd. - PublicationExperimental and simulated energy performance of a personalized ventilation system with individual airflow control in a hot and humid climate(01-02-2016)
;Chen, Yixing; Sekhar, S. C.This paper presents the energy performance of a personalized ventilation (PV) system with individual control of airflow rate in a hot and humid climate. A set of experiments with 46 tropically acclimatized subjects were conducted with ambient temperatures of 23 and 26 °C and PV air temperatures of 20, 23 and 26 °C. It has been found that as the ambient temperature is increased, subjects prefer higher PV airflow rates. While the higher ambient temperature reduces the cooling load, this is partly offset by the increased ventilation load. Therefore, it is not straightforward to quantify the energy savings accurately. In this work, an EnergyPlus simulation model was developed and validated by measurement data. The model was normalized to take into account the effects of the variations of outdoor conditions and the number of occupants. It was then applied to evaluate the energy performance of the PV system. The results show that when the PV air temperature is kept at 20 °C, the energy consumption at an ambient temperature of 23 °C is 10.8% higher than that at 26 °C. The best results are obtained when the PV air temperature is 20 °C and the ambient temperature is 26 °C. It is therefore concluded that increasing the ambient temperature has good potential to reduce energy consumption, whereas increasing the PV temperature does not bring appreciable benefits. - PublicationPerformance evaluation of a novel personalized ventilation-personalized exhaust system for airborne infection control(01-04-2015)
;Yang, J. ;Sekhar, S. C. ;Cheong, K. W.D.In the context of airborne infection control, it is critical that the ventilation system is able to extract the contaminated exhaled air within the shortest possible time. To minimize the spread of contaminated air exhaled by occupants efficiently, a novel personalized ventilation (PV)-personalized exhaust (PE) system has been developed, which aims to exhaust the exhaled air as much as possible from around the infected person (IP). The PV-PE system was studied experimentally for a particular healthcare setting based on a typical consultation room geometry and four different medical consultation positions of an IP and a healthy person (HP). Experiments using two types of tracer gases were conducted to evaluate two types of PE: Top-PE and Shoulder-PE under two different background ventilation systems: Mixing Ventilation and Displacement Ventilation. Personalized exposure effectiveness, intake fraction (iF) and exposure reduction (ε) were used as indices to evaluate the PV-PE system. The results show that the combined PV-PE system for the HP achieves the lowest intake fraction; and the use of PE system for the IP alone shows much better performance than using PV system for the HP alone.