The Experts below are selected from a list of 165 Experts worldwide ranked by ideXlab platform

Eckhard A Groll - One of the best experts on this subject based on the ideXlab platform.

  • application of second law analysis for the Environmental Control Unit at high ambient temperature
    Energies, 2020
    Co-Authors: Ammar M Bahman, Eckhard A Groll
    Abstract:

    This paper assesses the application of the second-law of thermodynamics in a military Environmental Control Unit (ECU) to evaluate the exergy destruction (or irreversibility) in each component when operating at high ambient temperature. Experimental testings were conducted on three ECUs, 1.5 (5.3 kW), 3 (10.6 kW), and 5 (17.6 kW) tons of refrigeration (RT), to assess the potential contribution of each component to enhance the overall energy efficiency of the system, and to determine the feasibility of the thermodynamic model presented herein. The analysis provided for extreme high ambient conditions up to 51.7 °C (125 °F). The results yielded that the highest irreversibility was associated with compressors (32.4% to 42.5%). This is followed by the heat exchanges (19.6% to 32.9%) in the case of 1.5-RT and 3-RT Units, whereas for the 5-RT Unit, the highest irreversibility was associated with the evaporator followed by the one of the compressors. In the 3-RT ECU, the condenser’s second-law efficiency enhanced due to an additional fan, yet the working refrigerant increased the irreversibility in the expansion device. The second-law analysis recognized the components with the highest exergy destruction and identified the direction to enhance the exergetic efficiency of any ECU operating at high-temperature climate.

  • Vapor injected compression with economizing in packaged air conditioning systems for high temperature climate
    International Journal of Refrigeration-revue Internationale Du Froid, 2018
    Co-Authors: Ammar M Bahman, Davide Ziviani, Eckhard A Groll
    Abstract:

    Abstract Operating packaged air conditioning systems at extremely high temperature ambient conditions result in severe performance degradation. In this paper, vapor injection (VI) with economization is proposed to improve system performance. An Environmental Control Unit (ECU) operating with R-407C has been retrofitted with an economized vapor injection (EVI) system and experimentally characterized in side-by-side psychrometric chambers. The performance of the EVI system for superheated and saturated injection conditions were compared to the case of without injection at different operating conditions. The results showed that the EVI system reduced the compressor discharge temperature by up to 5° C, and improved the cooling capacity and COP by up to 12.7% and 3.1%, respectively. The experimental data have been used to develop, tune, and validate a detailed steady-state cycle model. At last, the model has been employed to optimize the economizer geometry in order to maximize the system COP under such extreme weather conditions.

  • development of a carbon dioxide based field deployable Environmental Control Unit to replace hcfc 22 or hfc 134a Units
    2002
    Co-Authors: Joo S Baek, Eckhard A Groll, Patrick B Lawless
    Abstract:

    Abstract : This document reports on the design, construction, and testing of a piston-cylinder type expansion device with output work (ED-WOW) to be used in a transcritical carbon dioxide air conditioning system that is intended to replace R-22-based or R-134a-based Field Deployable Environmental Control Units (FDECUs). The ED-WOW is based on a highly modified small four-cycle, two-piston engine with a displacement of 2 x 13.26 cu cm that is commercially available. The ED-WOW replaced the expansion valve in an experimental transcritical CO2 cycle and increased the system performance by up to 10%. In addition, this document reports on the development of simulation models for the ED-WOW as well as for the transcritical CO2 cycle. The ED-WOW model was used to verify the proper operation of the device in the prototype application and to identify the major losses of the device. The model can be used to re-design the next generation ED-WOW. The cycle model was used to predict the performance of several modifications to the transcritical CO2 cycle and identify which modification is most suitable for implementation in a carbon dioxide-based FDECU.

  • simulation of the performance of a carbon dioxide based Environmental Control Unit ecu for the u s army
    Conférence IIR-Gustav Lorentzen sur les fluides actifs naturels à Purdue, 2001
    Co-Authors: D Li, Douglas M Robinson, Eckhard A Groll
    Abstract:

    Dans cette etude, les auteurs s'interessent a la conception, la construction, l'experimentation et la modelisation d'une Unite experimentale de Controle de l'environnement fonctionnant au dioxyde de carbone, destinee a remplacer les Unites existantes utilisant du HCFC22. Les resultats presentes dans l'etude ont ete obtenus grâce a un modele de simulation detaille appele ACCO 2 . ACCO 2 a servi a la modelisation d'un systeme de conditionnement d'air et de pompe a chaleur air-air utilisant du dioxyde de carbone comme frigorigene. Les resultats obtenus avec ACCO 2 ont ete compares avec des resultats de simulation obtenus avec PUREZ, PUREZ est un systeme de simulation public, qui a ete utilise pour prevoir la performance d'une Unite au HCFC22, d'une capacite de 3 tonnes, semblable a celle actuellement utilisee par l'armee americaine. Les resultats de cette comparaison ont montre qu'un systeme a base de dioxyde de carbone pouvait presenter les memes caracteristiques de performance et d'efficacite qu'un systeme utilisant du HCFC22.

Ammar M Bahman - One of the best experts on this subject based on the ideXlab platform.

  • application of second law analysis for the Environmental Control Unit at high ambient temperature
    Energies, 2020
    Co-Authors: Ammar M Bahman, Eckhard A Groll
    Abstract:

    This paper assesses the application of the second-law of thermodynamics in a military Environmental Control Unit (ECU) to evaluate the exergy destruction (or irreversibility) in each component when operating at high ambient temperature. Experimental testings were conducted on three ECUs, 1.5 (5.3 kW), 3 (10.6 kW), and 5 (17.6 kW) tons of refrigeration (RT), to assess the potential contribution of each component to enhance the overall energy efficiency of the system, and to determine the feasibility of the thermodynamic model presented herein. The analysis provided for extreme high ambient conditions up to 51.7 °C (125 °F). The results yielded that the highest irreversibility was associated with compressors (32.4% to 42.5%). This is followed by the heat exchanges (19.6% to 32.9%) in the case of 1.5-RT and 3-RT Units, whereas for the 5-RT Unit, the highest irreversibility was associated with the evaporator followed by the one of the compressors. In the 3-RT ECU, the condenser’s second-law efficiency enhanced due to an additional fan, yet the working refrigerant increased the irreversibility in the expansion device. The second-law analysis recognized the components with the highest exergy destruction and identified the direction to enhance the exergetic efficiency of any ECU operating at high-temperature climate.

  • Vapor injected compression with economizing in packaged air conditioning systems for high temperature climate
    International Journal of Refrigeration-revue Internationale Du Froid, 2018
    Co-Authors: Ammar M Bahman, Davide Ziviani, Eckhard A Groll
    Abstract:

    Abstract Operating packaged air conditioning systems at extremely high temperature ambient conditions result in severe performance degradation. In this paper, vapor injection (VI) with economization is proposed to improve system performance. An Environmental Control Unit (ECU) operating with R-407C has been retrofitted with an economized vapor injection (EVI) system and experimentally characterized in side-by-side psychrometric chambers. The performance of the EVI system for superheated and saturated injection conditions were compared to the case of without injection at different operating conditions. The results showed that the EVI system reduced the compressor discharge temperature by up to 5° C, and improved the cooling capacity and COP by up to 12.7% and 3.1%, respectively. The experimental data have been used to develop, tune, and validate a detailed steady-state cycle model. At last, the model has been employed to optimize the economizer geometry in order to maximize the system COP under such extreme weather conditions.

James P. Lucas - One of the best experts on this subject based on the ideXlab platform.

Gregory F. Brainard - One of the best experts on this subject based on the ideXlab platform.

Kenichiro Noda - One of the best experts on this subject based on the ideXlab platform.

  • google home smart speaker as Environmental Control Unit
    Disability and Rehabilitation: Assistive Technology, 2018
    Co-Authors: Kenichiro Noda
    Abstract:

    Environmental Control Units (ECU) are devices or a system that allows a person to Control appliances in their home or work environment. Such system can be utilized by clients with physical and/or functional disability to enhance their ability to Control their environment, to promote independence and improve their quality of life. Over the last several years, there have been an emergence of several inexpensive, commercially-available, voice activated smart speakers into the market such as Google Home and Amazon Echo. These smart speakers are equipped with far field microphone that supports voice recognition, and allows for complete hand-free operation for various purposes, including for playing music, for information retrieval, and most importantly, for Environmental Control. Clients with disability could utilize these features to turn the Unit into a simple ECU that is completely voice activated and wirelessly connected to appliances. Smart speakers, with their ease of setup, low cost and versatility, may be a more affordable and accessible alternative to the traditional ECU. Implications for Rehabilitation Environmental Control Units (ECU) enable independence for physically and functionally disabled clients, and reduce burden and frequency of demands on carers. Traditional ECU can be costly and may require clients to learn specialized skills to use. Smart speakers have the potential to be used as a new-age ECU by overcoming these barriers, and can be used by a wider range of clients.