Analysis of the influence of the return position in the vertical temperature gradient in displacement ventilation systems for large halls

Gil López, Tomás and Gálvez Huerta, Miguel A. and O'Donohoe, Paul G. and Castejón Navas, Juan and Diéguez Elizondo, Pedro M. (2017). Analysis of the influence of the return position in the vertical temperature gradient in displacement ventilation systems for large halls. "Energy and buildings", v. 140 ; pp. 371-379. ISSN 0378-7788. https://doi.org/10.1016/j.enbuild.2017.02.017.

Description

Title: Analysis of the influence of the return position in the vertical temperature gradient in displacement ventilation systems for large halls
Author/s:
  • Gil López, Tomás
  • Gálvez Huerta, Miguel A.
  • O'Donohoe, Paul G.
  • Castejón Navas, Juan
  • Diéguez Elizondo, Pedro M.
Item Type: Article
Título de Revista/Publicación: Energy and buildings
Date: 2017
ISSN: 0378-7788
Volume: 140
Subjects:
Freetext Keywords: Displacement ventilation, High ceiling space, Return point height, Roof temperature
Faculty: E.T.S. de Edificación (UPM)
Department: Tecnología de la Edificación
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

Displacement ventilation systems are widely used in spaces of small and medium heights (up to 7.5 m), taking advantage of their high efficiency in removing contaminants by means of the air stratification. This outcome usually hides major drawbacks compared to admixture systems, such as inadequate temperature gradient in the occupied zone and low cooling capacity. On the contrary, its use in large spaces with high ceilings displays the best features of the system, provided the return is placed near the ceiling. When, due to architectural reasons, this option is not feasible, alternatives for the return position are assessed using simulation tools that result in excessive time consumption during the design stage. In this article a simple Mundt?s equation based iterative process is proposed to quickly evaluate the influence of the return height in the vertical temperature gradient and the additional cooling load due to overheated ceiling. It has been applied to the case of Madrid airport new terminal, and their results have been compared to a CFD simulation, with a reasonable degree of accuracy for an initial stage of a design process. The results show that the higher the return is placed, the lesser airflow rate is needed to match the additional cooling load due to radiation from the ceiling. The calculation process also shows that Mundt?s radiant heat exchange coefficient is far from being constant, for it is affected by the height of the return point, and takes values much greater than the usually accepted.

More information

Item ID: 48704
DC Identifier: http://oa.upm.es/48704/
OAI Identifier: oai:oa.upm.es:48704
DOI: 10.1016/j.enbuild.2017.02.017
Official URL: https://www.sciencedirect.com/science/article/pii/S0378778816318722
Deposited by: Memoria Investigacion
Deposited on: 18 Jun 2018 09:05
Last Modified: 18 Jun 2018 09:05
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