https://uvadoc.uva.es/handle/10324/33219 Ingeniería de los Fluidos 2026-05-05T20:17:34Z https://uvadoc.uva.es/handle/10324/33204 This study evaluates the convenience of the use of four different mixing ventilation configurations in individual hospital rooms (IHR) based on ventilation performance and health workers (HW) exposure to the contaminants released by a confined patient (CP). Two supply configurations: grilles in the upper part of a wall (G) and swirl ceiling diffusers (S), combined with two different exhaust grilles positions in the opposite wall: upper part (U) and lower part (D) are tested using typical IHR set up. Occupants are represented by thermal breathing manikins, CP lies on a bed while HW stands close to it. Three air renewal rates are tested to determine their influence in the studied variables, 6, 9 and 12 ACH covering the whole range of ventilation requirements of such spaces. The experimental conditions considering the thermal comfort of the occupants are taken into account. Different ventilation configurations create different air distribution patterns inside the room. G configurations lead to high HW transient exposure values while S maintain low values that decrease when ACH is increased, so this second configuration is preferred for IHRs. Results are also compared with a displacement ventilation (DV) study highlighting the convenience of this strategy for IHRs. © 2018 Elsevier B.V. 2018-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/33066 When CFD is employed to design a ventilation system, one of the most delicate aspects is the modeling of the diffuser. The designer has different choices, which range from simulating the detailed geometry of the diffuser, including the plenum box, to use special boundary conditions to reproduce the velocity profile in each slot of the diffuser. This study is carried out to examine the influence of the plenum box on the turbulent airflow pattern generated by a swirl air diffuser from the experimental and numerical points of view. First, we perform experiments to evaluate such influence. Then, these experiments are contrasted with two numerical approximations to the problem using the Fluent 6.3.26 commercial CFD software. We first perform a simulation of the complete diffuser geometry – including the plenum box – and later a simplified simulation of the diffuser, where the whole geometry is simplified to a plane in which the velocity components and the slots positioning are specified via a particular boundary condition. The main findings of this study reveal that the simplified simulation is good enough at close range, while in the remote flow field the differences between both approaches practically disappear. © 2018 Elsevier Inc. 2018-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/33063 This study is focused on determining the convenience of the use of displacement ventilation strategy in airborne infection isolation rooms (AIIRs). Thermal comfort of the occupants of the chamber, ventilation and contaminant performance indices and the exposure of the health worker (HW) to the contaminants exhaled by the confined patient (P) are considered in a typical AIIR set up with two thermal breathing manikins and a radiant wall simulating an external wall. Three air renewal rates are tested to determine their influence in the studied variables. Results show that ventilation performance, contaminants and general comfort indices for both manikins perform well in the cases studied. Lockup phenomenon associated with displacement ventilation occurs above P but it has a low influence on contaminant exposure of HW because of the influence of the convective boundary layer of HW. The influence of the radiant wall could lock the air path near the exhaust grille. © 2017 Elsevier B.V. 2018-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/33058 It is common practice for operating rooms (OR) to have more pressure than the adjacent enclosures. This is to prevent the entry of potentially contaminated air and the consequent risk of wound infection. However, when the OR door is opened the pressure difference between the two areas disappears and can cause containment failures. If a person enters or leaves the OR during door operation, additional perturbations are also generated in the airflow pattern in the doorway. In this paper, instantaneous airflows are measured during the passage of a person through a sliding door in a real OR with the HVAC system working under operating conditions. An ultrasonic anemometer that measures the magnitude and direction of the instantaneous air velocity in the doorway is used. Results show that, even though the OR has a sliding door and an initial overpressure of 20 Pa, together with what is, a priori, a good HVAC system control strategy, a small volume of air enters the OR during a cycle of door opening and closing even without the passage of a person. Furthermore, if a person walks through the door the volume of air entering the OR is higher, especially if the person enters the OR. © 2016 Elsevier Ltd 2016-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/33056 CFD simulation is an accurate and reliable method to predict the risk of airborne cross-infection in a room. This paper focuses on the validation of a 3-D transient CFD model used to predict personal exposure to airborne pathogens and infection risk in a displacement ventilated room. The model provides spatial and temporal solutions of the airflow pattern in the room (temperature, velocity and turbulence), as well as contaminant concentration in a room where two thermal manikins simulate two standing people, one of whom exhales a tracer gas N2O simulating airborne contaminants. Numerical results are validated with experimental data and the model shows a high accuracy when predicting the transient cases studied. Once the model is validated, the CFD model is used to simulate different airborne cross-infection risk scenarios. Four different combinations of the manikins’ breathing modes and four different separation distances between the two manikins are studied. The results show that exhaling through the nose or mouth disperses exhaled contaminants in a completely different way and also means that exhaled contaminants are received differently. For short separation distances between breathing sources the interaction between breaths is a key factor in the airborne cross-infection for all the breathing mode combinations studied. However, for long distances the general airflow conditions in the room prove to be more important. 2016-01-01T00:00:00Z