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Joseph Firrantello - One of the best experts on this subject based on the ideXlab platform.
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field measurement and modeling of uvc Cooling Coil irradiation for heating ventilating and air conditioning energy use reduction rp 1738 part 2 energy indoor air quality and economic modeling
Science and Technology for the Built Environment, 2018Co-Authors: Joseph Firrantello, William P. BahnflethAbstract:Ultraviolet germicidal irradiation of Cooling Coil airside surfaces is used to mitigate biofouling caused by viable microorganisms captured from the air. However, few peer-reviewed studies have investigated its effectiveness. Part 1 of this study presents the results of field measurements of changes in Coil performance after treatment with ultraviolet germicidal irradiation. Part 2 reports modeled energy use and indoor air quality impacts of Coil irradiation, as well as results of a life-cycle cost analysis that combines energy, indoor air quality, capital, and maintenance costs. Life-cycle costs with Coil ultraviolet germicidal irradiation are compared to life-cycle costs with mechanical Coil cleaning. Models from the U.S. Department of Energy Commercial Reference Buildings set were used to predict the benefit of ultraviolet germicidal irradiation treatment of fouled Coils for 7 buildings in 16 climate zones using pressure drop reduction estimates bounded by experimental results from Part 1 and results r...
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field measurement and modeling of uvc Cooling Coil irradiation for heating ventilating and air conditioning energy use reduction rp 1738 part 1 field measurements
Science and Technology for the Built Environment, 2018Co-Authors: Joseph Firrantello, William P. Bahnfleth, Paul A KremerAbstract:Wet Cooling Coil surfaces can provide opportunities for microorganism growth. This biological fouling (biofouling) increases airside pressure drop and decreases airside heat transfer coefficient. Ultraviolet germicidal irradiation is one method to eliminate biofouling. The current article reports field measurements of changes in pressure drop and heat-transfer characteristics of fouled Coils treated with ultraviolet germicidal irradiation designed for surface disinfection. Ultraviolet germicidal irradiation systems were installed in operating air-handling units with visibly fouled Cooling Coils at sites in Tampa, Florida and University Park, Pennsylvania. Pressure drop data were controlled for airflow and latent load, and overall heat-transfer coefficient data were controlled for heat exchanger entering conditions. Analysis of Tampa site data showed an initial mean 22.70% to 22.72% decrease (µ ± 2σ) in airside pressure drop and a mean 13.2% to 13.6% (µ ± 2σ) increase in overall heat-transfer coefficient. ...
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Effectiveness of an ultraviolet germicidal irradiation system in enhancing Cooling Coil energy performance in a hot and humid climate
Energy and Buildings, 2016Co-Authors: Yi Wang, Kok Wai Cheong, William P. Bahnfleth, Chandra Sekhar, Joseph FirrantelloAbstract:Biological fouling (biofouling) on wetted Cooling Coil surfaces decreases heat transfer efficiency, increases air-side flow resistance and may eventually lead to more energy consumption by fans and chiller plants. Applying ultraviolet germicidal irradiation (UVGI) systems in air handling units (AHUs) has the potential to clean Coils, improve Coil performance and save energy. In this study, the effectiveness of a Coil irradiation system in improving Coil performance and saving energy was investigated through a field test in a hot and humid climate. A commercially available Coil irradiation system was installed downstream of a Cooling Coil in a variable air volume (VAV) AHU. The duration of the field test was 14 months, with four months before UVGI intervention and 10 months after UVGI intervention. The effectiveness of UVGI was evaluated via a “before UV” and “after UV” comparison of Coil performance. The Coil overall thermal conductance increased by 10% and the pressure drop decreased by 13%, with the improvement being most rapid over the first month after UVGI intervention. Fan energy use fell by 9% over the ten months of UVGI operation. Savings in fan energy were 39% greater than the energy used by the UV lamps.
Shiming Deng - One of the best experts on this subject based on the ideXlab platform.
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Research on Modeling Simultaneous Heat and Mass Transfer in a DX Cooling Coil and its Control Applications
Volume 1: Heat Transfer in Energy Systems; Theory and Fundamental Research; Aerospace Heat Transfer; Gas Turbine Heat Transfer; Transport Phenomena in, 2012Co-Authors: Liang Xia, Shiming Deng, Yulin SunAbstract:Extensive research work on modeling the simultaneous heat and mass transfer taking place in a direct expansion (DX) Cooling Coil which is a key element in a DX air conditioning (A/C) system has been carried out. A steady-state model (Coil model) has been developed for evaluating the equipment sensible heat ratio (SHR) and the total Cooling capacity (TCC) of the DX Cooling Coil in an experimental variable speed DX A/C system under different operating conditions based on known evaporating temperature and the air flow rate passing through the Cooling Coil. On the other hand, a previous mathematical model (system model) for the complete experimental DX A/C system has also been developed. The evaporating temperature of the DX A/C system may be predicated using this system model, and can then be used as an input to the Coil model. Therefore, by combining the Coil model and the system model, a new steady-state model for the DX A/C system, which links the compressor and fan speeds on the input side with the Equipment SHR and TCC on the output side, will be developed. The new model will be experimentally validated, and the validated model will be used as a base to develop a model-based controller for a variable speed DX A/C system to achieve the simultaneous control of indoor air temperature and humidity.Copyright © 2012 by ASME
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Effect of the Indoor Environment on the Condensing Rate and the Air-side Sensible Heat Transfer Resistance of a Direct Expansion Cooling Coil:
Indoor and Built Environment, 2010Co-Authors: Liang Xia, Shiming Deng, Mingyin ChanAbstract:Dehumidification and Cooling performance are two most important features of a direct expansion (DX) Cooling Coil, which works as an evaporator for a DX air-conditioning system. The condensing rate and the sensible heat transfer resistance of a DX Cooling Coil represent its capacity for dehumidification and is an important characteristic of the Cooling process. An experimental investigation on the effects of the indoor environment, that is, indoor air temperature and relative humidity (RH), on the condensing rate and the air-side sensible heat transfer resistance of a DX Cooling Coil has been conducted and is reported in this paper. It was found that both the condensing rate and the air-side sensible heat transfer resistance increased with increase of indoor air RH and decreased with an increase of indoor air temperature. Correlation of the experimental results of the condensing rate and the air-side sensible heat transfer resistance under different indoor air temperatures and RH were studied.
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Analytical solutions for evaluating the thermal performances of wet air Cooling Coils under both unit and non-unit Lewis Factors
Energy Conversion and Management, 2010Co-Authors: Liang Xia, Mingyin Chan, Shiming DengAbstract:Abstract Analytical solutions for evaluating the thermal performances of both chilled water wet Cooling Coils and direct expansion (DX) wet Cooling Coils, respectively, under both unit and non-unit Lewis Factors are developed and reported in this paper. The analytical solution was validated by comparing its predictions with those from numerically solving the fundamental governing equations of heat and mass transfer taking place in a wet Cooling Coil. With the analytical solutions, the distributions of air temperature and humidity ratio along air flow direction in a wet Cooling Coil can be predicted, and the differences in the thermal performances of the Cooling Coils under both unit and non-unit Lewis Factors can be identified. The analytical solutions, on one hand, can be a low-cost replacement to numerically solving the fundamental heat and mass transfer governing equations, and on the other hand, is able to deal with evaluating thermal performance for wet air Cooling Coils operated under both unit and non-unit Lewis Factors.
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a modified logarithmic mean enthalpy difference lmed method for evaluating the total heat transfer rate of a wet Cooling Coil under both unit and non unit lewis factors
International Journal of Thermal Sciences, 2009Co-Authors: Liang Xia, M Y Chan, Shiming DengAbstract:Abstract The logarithmic mean enthalpy difference, (LMED) method has been extensively used in evaluating the thermal performance of an air Cooling Coil under wet condition. The LMED method has been developed based on the assumption of unit Lewis Factor, i.e., Le 2/3 = 1. However, a number of previous studies have suggested that the Lewis Factor can actually deviate from being 1. Consequently, errors can be resulted in when calculating the total heat transfer rate of a wet Cooling Coil using the LMED method. Therefore, a modified LMED (m-LMED) method has been developed for calculating the total heat transfer rate under both unit and non-unit Lewis Factors and is reported in this paper. This m-LMED method has been validated by comparing its prediction of the total heat transfer rate to that from numerically solving the fundamental governing equations of heat and mass transfer of a wet Cooling Coil. The m-LMED method can therefore replace the LMED method for calculating the total heat transfer rate of a wet Cooling Coil under both unit and non-unit Lewis Factors.
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Condensate retention on a louver-fin-and-tube air Cooling Coil
International Journal of Refrigeration, 2007Co-Authors: Chunwah Leung, Mingyin Chan, Shiming DengAbstract:This paper presents a study of condensate retention on a louver-fin-and-tube air Cooling Coil, which is commonly used in air conditioning (A/C) systems. Compared to previously related work focusing on the influence of condensate retention on the heat and mass transfer between air and a Cooling Coil, the present study emphasizes the impacts of operating parameters on condensate retention on a Cooling Coil. A new method to describe the steady-state condensation has been suggested and a new mathematical model to represent the force balance of retained condensate developed. The mass of condensate retained has been measured experimentally under various operating conditions of a direct expansion (DX) air Cooling and dehumidification system. The influences of air dry-bulb temperature, moisture content and Reynolds Number on condensate retention are discussed. The model developed relates the mass of condensate retained to condensing rate, and is successful in predicting the trends of condensate retention under normal operating conditions for air Cooling applications.
William P. Bahnfleth - One of the best experts on this subject based on the ideXlab platform.
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field measurement and modeling of uvc Cooling Coil irradiation for heating ventilating and air conditioning energy use reduction rp 1738 part 2 energy indoor air quality and economic modeling
Science and Technology for the Built Environment, 2018Co-Authors: Joseph Firrantello, William P. BahnflethAbstract:Ultraviolet germicidal irradiation of Cooling Coil airside surfaces is used to mitigate biofouling caused by viable microorganisms captured from the air. However, few peer-reviewed studies have investigated its effectiveness. Part 1 of this study presents the results of field measurements of changes in Coil performance after treatment with ultraviolet germicidal irradiation. Part 2 reports modeled energy use and indoor air quality impacts of Coil irradiation, as well as results of a life-cycle cost analysis that combines energy, indoor air quality, capital, and maintenance costs. Life-cycle costs with Coil ultraviolet germicidal irradiation are compared to life-cycle costs with mechanical Coil cleaning. Models from the U.S. Department of Energy Commercial Reference Buildings set were used to predict the benefit of ultraviolet germicidal irradiation treatment of fouled Coils for 7 buildings in 16 climate zones using pressure drop reduction estimates bounded by experimental results from Part 1 and results r...
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field measurement and modeling of uvc Cooling Coil irradiation for heating ventilating and air conditioning energy use reduction rp 1738 part 1 field measurements
Science and Technology for the Built Environment, 2018Co-Authors: Joseph Firrantello, William P. Bahnfleth, Paul A KremerAbstract:Wet Cooling Coil surfaces can provide opportunities for microorganism growth. This biological fouling (biofouling) increases airside pressure drop and decreases airside heat transfer coefficient. Ultraviolet germicidal irradiation is one method to eliminate biofouling. The current article reports field measurements of changes in pressure drop and heat-transfer characteristics of fouled Coils treated with ultraviolet germicidal irradiation designed for surface disinfection. Ultraviolet germicidal irradiation systems were installed in operating air-handling units with visibly fouled Cooling Coils at sites in Tampa, Florida and University Park, Pennsylvania. Pressure drop data were controlled for airflow and latent load, and overall heat-transfer coefficient data were controlled for heat exchanger entering conditions. Analysis of Tampa site data showed an initial mean 22.70% to 22.72% decrease (µ ± 2σ) in airside pressure drop and a mean 13.2% to 13.6% (µ ± 2σ) increase in overall heat-transfer coefficient. ...
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Effectiveness of an ultraviolet germicidal irradiation system in enhancing Cooling Coil energy performance in a hot and humid climate
Energy and Buildings, 2016Co-Authors: Yi Wang, Kok Wai Cheong, William P. Bahnfleth, Chandra Sekhar, Joseph FirrantelloAbstract:Biological fouling (biofouling) on wetted Cooling Coil surfaces decreases heat transfer efficiency, increases air-side flow resistance and may eventually lead to more energy consumption by fans and chiller plants. Applying ultraviolet germicidal irradiation (UVGI) systems in air handling units (AHUs) has the potential to clean Coils, improve Coil performance and save energy. In this study, the effectiveness of a Coil irradiation system in improving Coil performance and saving energy was investigated through a field test in a hot and humid climate. A commercially available Coil irradiation system was installed downstream of a Cooling Coil in a variable air volume (VAV) AHU. The duration of the field test was 14 months, with four months before UVGI intervention and 10 months after UVGI intervention. The effectiveness of UVGI was evaluated via a “before UV” and “after UV” comparison of Coil performance. The Coil overall thermal conductance increased by 10% and the pressure drop decreased by 13%, with the improvement being most rapid over the first month after UVGI intervention. Fan energy use fell by 9% over the ten months of UVGI operation. Savings in fan energy were 39% greater than the energy used by the UV lamps.
Esmail M. Saber - One of the best experts on this subject based on the ideXlab platform.
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adaptable Cooling Coil performance during part loads in the tropics a computational evaluation
Energy and Buildings, 2018Co-Authors: Chandra Sekhar, Prashant Anand, Stefano Schiavon, Kwok Wai Tham, David Cheong, Esmail M. SaberAbstract:Air conditioning and mechanical ventilation systems may be oversized in commercial buildings in the Tropics. Oversized Cooling Coils may lead to reduced dehumidifying performance, indoor air quality and thermal comfort and increased energy consumption. In this paper, an adaptable Cooling Coil design is assessed with a general-purpose Coil selection software tool, in which the number of active rows changes as a function of the load. For a 100% oversized Coil, it is shown that the adaptable Cooling Coil is able to provide small but relevant improved humidity control down to 25% of the design load. This was obtained without affecting energy performance in typical variable air volume design and control. For specific applications, where variable air volume systems mainly control space humidity, there are also energy savings. The adaptable Cooling Coil could be seen as providing additional flexibility in the operation of HVAC systems, particularly in the tropics.
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Adaptable Cooling Coil performance during part loads in the tropics—A computational evaluation
Energy and Buildings, 2018Co-Authors: Chandra Sekhar, Prashant Anand, Stefano Schiavon, Kwok Wai Tham, David Cheong, Esmail M. SaberAbstract:Air conditioning and mechanical ventilation systems may be oversized in commercial buildings in the Tropics. Oversized Cooling Coils may lead to reduced dehumidifying performance, indoor air quality and thermal comfort and increased energy consumption. In this paper, an adaptable Cooling Coil design is assessed with a general-purpose Coil selection software tool, in which the number of active rows changes as a function of the load. For a 100% oversized Coil, it is shown that the adaptable Cooling Coil is able to provide small but relevant improved humidity control down to 25% of the design load. This was obtained without affecting energy performance in typical variable air volume design and control. For specific applications, where variable air volume systems mainly control space humidity, there are also energy savings. The adaptable Cooling Coil could be seen as providing additional flexibility in the operation of HVAC systems, particularly in the tropics.
Mingyin Chan - One of the best experts on this subject based on the ideXlab platform.
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Effect of the Indoor Environment on the Condensing Rate and the Air-side Sensible Heat Transfer Resistance of a Direct Expansion Cooling Coil:
Indoor and Built Environment, 2010Co-Authors: Liang Xia, Shiming Deng, Mingyin ChanAbstract:Dehumidification and Cooling performance are two most important features of a direct expansion (DX) Cooling Coil, which works as an evaporator for a DX air-conditioning system. The condensing rate and the sensible heat transfer resistance of a DX Cooling Coil represent its capacity for dehumidification and is an important characteristic of the Cooling process. An experimental investigation on the effects of the indoor environment, that is, indoor air temperature and relative humidity (RH), on the condensing rate and the air-side sensible heat transfer resistance of a DX Cooling Coil has been conducted and is reported in this paper. It was found that both the condensing rate and the air-side sensible heat transfer resistance increased with increase of indoor air RH and decreased with an increase of indoor air temperature. Correlation of the experimental results of the condensing rate and the air-side sensible heat transfer resistance under different indoor air temperatures and RH were studied.
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Analytical solutions for evaluating the thermal performances of wet air Cooling Coils under both unit and non-unit Lewis Factors
Energy Conversion and Management, 2010Co-Authors: Liang Xia, Mingyin Chan, Shiming DengAbstract:Abstract Analytical solutions for evaluating the thermal performances of both chilled water wet Cooling Coils and direct expansion (DX) wet Cooling Coils, respectively, under both unit and non-unit Lewis Factors are developed and reported in this paper. The analytical solution was validated by comparing its predictions with those from numerically solving the fundamental governing equations of heat and mass transfer taking place in a wet Cooling Coil. With the analytical solutions, the distributions of air temperature and humidity ratio along air flow direction in a wet Cooling Coil can be predicted, and the differences in the thermal performances of the Cooling Coils under both unit and non-unit Lewis Factors can be identified. The analytical solutions, on one hand, can be a low-cost replacement to numerically solving the fundamental heat and mass transfer governing equations, and on the other hand, is able to deal with evaluating thermal performance for wet air Cooling Coils operated under both unit and non-unit Lewis Factors.
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A New Viewpoint to Studying the Condensate Retention and Drainage Process on Air Cooling Coil
Volume 1: Heat Transfer in Energy Systems; Thermophysical Properties; Heat Transfer Equipment; Heat Transfer in Electronic Equipment, 2009Co-Authors: Mingyin Chan, Sm DengAbstract:Normally simultaneous air Cooling and dehumidification takes place in an air Cooling Coil. The condensate accumulated on the Cooling Coil surfaces could significantly affect its thermal and hydraulic performance. The condensate retention and drainage has bee usually regarded as a static process. The total mass of condensate retained was viewed as being influenced by the balance among gravitational, air flow drag forces and surface tension retaining force only. With fixed geometric and surface characteristics and under a constant air Reynolds Number, a Cooling Coil was therefore considered to have a fixed amount of condensate retained. However, some researches pointed out that the total mass of condensate retained could be influenced by system operating parameters such as temperature and moisture content of inlet air. A previously related study by authors developed a mathematic model and considered this process as being a dynamic but without giving a detailed discussion. In this paper, through a further analysis of data obtained in the previously study, a new viewpoint on condensate retention and drainage process has been suggested in order to better explain the experimental results and to provide a base for proposing some future related research work.Copyright © 2009 by ASME
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Dehumidification effects in the superheated region (SPR) of a direct expansion (DX) air Cooling Coil
Energy Conversion and Management, 2009Co-Authors: Xia Liang, Mingyin Chan, Deng Shiming, Xu XiangguoAbstract:A DX air Cooling Coil may normally be assumed to have two regions in its refrigerant side, according to refrigerant status, a two-phase region (TPR) and a superheated region (SPR). Dry air side surface of the SPR in a DX air Cooling Coil has been normally assumed in lumped-parameter mathematical models previously developed without however being validated. Therefore, an experimental study has been carried out to examine such an assumption under different operating conditions. The experimental results suggested that the air side surface of the SPR in a DX air Cooling Coil was either fully or partially wet under all experimental conditions and assuming dry air side of the SPR could lead to an underestimated total amount of water vapor condensed on the entire DX Coil surface. Therefore, it is recommended that the assumption of dry air side in a SPR be no longer used in future lumped-parameter models to be developed for improved modeling accuracy.
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Condensate retention on a louver-fin-and-tube air Cooling Coil
International Journal of Refrigeration, 2007Co-Authors: Chunwah Leung, Mingyin Chan, Shiming DengAbstract:This paper presents a study of condensate retention on a louver-fin-and-tube air Cooling Coil, which is commonly used in air conditioning (A/C) systems. Compared to previously related work focusing on the influence of condensate retention on the heat and mass transfer between air and a Cooling Coil, the present study emphasizes the impacts of operating parameters on condensate retention on a Cooling Coil. A new method to describe the steady-state condensation has been suggested and a new mathematical model to represent the force balance of retained condensate developed. The mass of condensate retained has been measured experimentally under various operating conditions of a direct expansion (DX) air Cooling and dehumidification system. The influences of air dry-bulb temperature, moisture content and Reynolds Number on condensate retention are discussed. The model developed relates the mass of condensate retained to condensing rate, and is successful in predicting the trends of condensate retention under normal operating conditions for air Cooling applications.