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  1. Article ; Online: Numerical Study on Indoor Environmental Quality in a Room Equipped with a Combined HRV and Radiator System

    Aminhossein Jahanbin / Giovanni Semprini

    Sustainability, Vol 12, Iss 10576, p

    2020  Volume 10576

    Abstract: Heat recovery ventilation (HRV) systems can be integrated with an additional air heater in buildings with low energy demand in order to cover space heating demand. The employment of coupled HRV-heater systems is, therefore, gaining increasing interest ... ...

    Abstract Heat recovery ventilation (HRV) systems can be integrated with an additional air heater in buildings with low energy demand in order to cover space heating demand. The employment of coupled HRV-heater systems is, therefore, gaining increasing interest for the improvement of the indoor environmental quality (IEQ), as well as the reduction of ventilation energy loss. The present paper analyses the efficacy of a HRV system, coupled with a low-temperature radiator, in satisfying the IEQ indices inside a retrofitted dormitory room. A computational fluid dynamic (CFD) model based on the finite volume method is established to investigate IEQ characteristics including indoor air quality and thermal comfort condition. The presented CFD code provides a practical tool for a comprehensive investigation of the IEQ indices in spaces employing a coupled HVAC system. In an analysis of indoor air quality, parameters such as age of the air, air change efficiency, and ventilation efficiency in removal of gaseous contaminants, namely VOCs and CO 2 , are evaluated. The results obtained by the numerical model allow addressing the interaction between HRV and radiator systems and its effects on airflow field. The results show the decrease of the indoor operative temperature with increment of the supply air flow rate, which is mainly due to the decreased thermal efficiency of the HRV system. The obtained results indicate that, while higher ventilation rates can significantly decrease the age of the air and gaseous contaminants level, at the same time, it would cause a local discomfort in some parts of the room.
    Keywords indoor environmental quality ; thermal comfort ; indoor air quality ; HVAC systems ; heat recovery ventilation ; radiators ; Environmental effects of industries and plants ; TD194-195 ; Renewable energy sources ; TJ807-830 ; Environmental sciences ; GE1-350
    Subject code 690
    Language English
    Publishing date 2020-12-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Numerical Analysis on the Optimisation of Thermal Comfort Levels in an Office Located inside a Historical Building

    Eleonora Palka Bayard de Volo / Beatrice Pulvirenti / Aminhossein Jahanbin / Paolo Guidorzi / Giovanni Semprini

    Applied Sciences, Vol 13, Iss 2954, p

    2023  Volume 2954

    Abstract: The present study examines the possibility of thermal comfort optimisation inside an office room where, due to historical heritage, it is possible to modify neither the energetic characteristic of the envelope nor the position of the inlet air vents. The ...

    Abstract The present study examines the possibility of thermal comfort optimisation inside an office room where, due to historical heritage, it is possible to modify neither the energetic characteristic of the envelope nor the position of the inlet air vents. The distribution of global and local thermal comfort indices is evaluated in both heating and cooling conditions by establishing a computational fluid dynamics (CFD) model validated against experimental data. The obtained results demonstrate a striking asymmetry of the air velocity and temperature distribution due to the low energy efficiency of the building. In heating mode, the predicted mean vote ( <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>P</mi><mi>M</mi><mi>V</mi></mrow></semantics></math> ) values were improved if the discharged air from the fan coil was at its maximal velocity. However, at the same time, the vertical air temperature gradient increased by around 0.5 <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mo>°</mo></msup></semantics></math> C in each working station. In the cooling condition, in the absence of the solar radiation, the minimal air-flow rate satisfied the acceptable range of the draught rate ( <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>D</mi><mi>R</mi></mrow></semantics></math> ), whereas in the presence of a solar load, it could not meet the required cooling load in all positions, leading to higher floor temperature. The findings of this study allow for identifying and rearranging the optimal position of working stations in terms of thermal comfort.
    Keywords indoor environmental quality ; thermal comfort ; historical buildings ; HVAC ; numerical simulations ; CFD ; Technology ; T ; Engineering (General). Civil engineering (General) ; TA1-2040 ; Biology (General) ; QH301-705.5 ; Physics ; QC1-999 ; Chemistry ; QD1-999
    Subject code 690
    Language English
    Publishing date 2023-02-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  3. Article: Simple equations to evaluate the mean fluid temperature of double-U-tube borehole heat exchangers

    Zanchini, Enzo / Aminhossein Jahanbin

    Applied energy. 2018 Dec. 01, v. 231

    2018  

    Abstract: The design of ground-coupled heat pump systems requires the knowledge of the mean temperature Tfm of the working fluid in borehole heat exchangers. This quantity is usually approximated by the arithmetic mean of inlet and outlet temperature. The ... ...

    Abstract The design of ground-coupled heat pump systems requires the knowledge of the mean temperature Tfm of the working fluid in borehole heat exchangers. This quantity is usually approximated by the arithmetic mean of inlet and outlet temperature. The approximation yields an overestimation of the thermal resistance of the heat exchanger in thermal response tests, as well as errors in the estimation of the outlet fluid temperature in the dynamic simulation of ground-coupled heat pumps. Recently (Applied Energy 206, 2017, 1406–1415), Zanchini and Jahanbin determined, by finite element simulations, correlations that allow an immediate evaluation of Tfm in any working condition, with reference to double U-tube boreholes with length 100 m and shank spacing 85 mm. In this paper, the analysis presented there is extended to double U-tube boreholes with any length, between 50 and 200 m, and any shank spacing, between 65 and 105 mm. The results hold for every thermal conductivity of the sealing grout between 0.9 and 1.6 W/(m K), every volume flow rate between 12 and 24 L per minute, every diameter of the BHE and every working condition (heating, cooling, thermal response test), both in quasi-stationary and in transient regime.
    Keywords arithmetics ; energy ; equations ; finite element analysis ; heat ; heat exchangers ; heat pumps ; temperature ; thermal conductivity ; thermal stability
    Language English
    Dates of publication 2018-1201
    Size p. 320-330.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2000772-3
    ISSN 0306-2619
    ISSN 0306-2619
    DOI 10.1016/j.apenergy.2018.09.094
    Database NAL-Catalogue (AGRICOLA)

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  4. Article: Correlations to determine the mean fluid temperature of double U-tube borehole heat exchangers with a typical geometry

    Zanchini, Enzo / Aminhossein Jahanbin

    Applied energy. 2017 Nov. 15, v. 206

    2017  

    Abstract: In the evaluation of thermal response tests and in the dynamic simulation of ground-coupled heat pumps, the mean temperature Tm of the working fluid in a borehole heat exchanger is usually approximated by the arithmetic mean of inlet and outlet ... ...

    Abstract In the evaluation of thermal response tests and in the dynamic simulation of ground-coupled heat pumps, the mean temperature Tm of the working fluid in a borehole heat exchanger is usually approximated by the arithmetic mean of inlet and outlet temperature. In thermal response tests, this approximation causes an overestimation of the thermal resistance of the heat exchanger. In the dynamic simulation of ground-coupled heat pumps, this approximation introduces an error in the evaluation of the outlet temperature from the ground heat exchangers. In this paper, by means of 3D finite element simulations, we provide tables of a dimensionless coefficient that allows an immediate evaluation of Tm in any working condition, with reference to double U-tube borehole heat exchangers with a typical geometry. These tables allow a more accurate estimation of the borehole thermal resistance by thermal response tests and a more accurate evaluation of the outlet temperature in dynamic simulations of ground-coupled heat pump systems. Criteria for the extension of the results to other geometries are also provided.
    Keywords arithmetics ; finite element analysis ; geometry ; heat exchangers ; heat pumps ; heat tolerance ; temperature
    Language English
    Dates of publication 2017-1115
    Size p. 1406-1415.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 2000772-3
    ISSN 0306-2619
    ISSN 0306-2619
    DOI 10.1016/j.apenergy.2017.09.120
    Database NAL-Catalogue (AGRICOLA)

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    Order via subito

    This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.

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