Computational Fluid Dynamics (CFD)
Nader Pourmahmoud; Aydin Zabihi
Abstract
Cooling tubes are inserted into the desiccant dehumidifier liquid of a 3-fluid liquid-to-air membrane energy exchanger (LAMEE) in order to regulate the temperature of the dehumidifier liquid. As a result, the 3-fluid LAMEE's performance is significantly influenced by the refrigerated tubes. The numerical ...
Read More
Cooling tubes are inserted into the desiccant dehumidifier liquid of a 3-fluid liquid-to-air membrane energy exchanger (LAMEE) in order to regulate the temperature of the dehumidifier liquid. As a result, the 3-fluid LAMEE's performance is significantly influenced by the refrigerated tubes. The numerical analysis of the present work shows that the number of chilled tubes and their inner diameter affect the effectiveness (total, latent, and sensible) rate of moisture removal and adequate cooling power, and exergy loss. Additionally, the dehumidifier liquid channel receives the addition of wavy cooling tubes for the first time. The relationship between wave height and wave length is known as wave steepness, and its impact on efficiency and energy loss is also examined. Numerical studies show that the number and inner diameter of the cooling tubes have a direct correlation with the efficiency of the 3-fluid LAMEE. The improved the efficiency, the more cooled tubes there are and the larger their diameter. Furthermore, both exergy loss and without dimensions exergy loss increase with the quantity and diameter of refrigerated tubes. The sensible and latent effectiveness of the 3-fluid LAMEE is increased by the wavy refrigeration tubes as compared to straight tubes; the augmentation of the sensible and latent effectiveness increases with wave steepness.
Computational Fluid Dynamics (CFD)
Nader Pourmahmoud; Aydin Zabihi
Abstract
3-fluid liquid-to-air membrane energy exchangers (LAMEEs) are economic dehumidification systems; cooling tubes are put into dehumidifier liquid channels to regulate the internal temperature of the dehumidifier liquid. 3D computational fluid dynamics is used to simulate a 3-fluid LAMEE, and extra transfer ...
Read More
3-fluid liquid-to-air membrane energy exchangers (LAMEEs) are economic dehumidification systems; cooling tubes are put into dehumidifier liquid channels to regulate the internal temperature of the dehumidifier liquid. 3D computational fluid dynamics is used to simulate a 3-fluid LAMEE, and extra transfer of both heat and mass formulas, along with the essential equations that govern for viscous fluid flow, are compiled using external computer programs known as UDS (User Defined Scalar). This study thoroughly investigates the impact of the water inflow variables on system efficiency. The refrigeration fluid that runs inside the cooling tubes is water. The temperature distribution of the three fluids is investigated and the role of the refrigeration tubes based on their positions is evaluated on the desiccant solution cooling. Six tests are conducted to achieve the best arrangement of the inlet water conditions based on the tube’s geometrical location. At an intake water mass flow rate of 4.67 g/s, the latent and sensible effectiveness rise from51% to 78% and 60% to 130%, respectively, when the input water temperature drops from 24.6 °C to 10.1 °C.
Computational Fluid Dynamics (CFD)
Behnam Dilmaghani Hassanlouei; Nader Pourmahmoud; Pierre Sullivan
Abstract
In this article, an extracorporeal membrane oxygenator (ECMO) is simulated in 2D geometry using computational fluid dynamics (CFD). Momentum and mass transport equations were solved for the laminar flow regime (30 < Re < 130 for the blood channel) using the finite element method. In this study, ...
Read More
In this article, an extracorporeal membrane oxygenator (ECMO) is simulated in 2D geometry using computational fluid dynamics (CFD). Momentum and mass transport equations were solved for the laminar flow regime (30 < Re < 130 for the blood channel) using the finite element method. In this study, the software COMSOL was used as the solver. To this end, the main problem of ECMO devices is the pressure drop and the risk of thrombus formation due to blood stagnation, so to solve this problem, the oxygen transfer rate to the blood should be increased. Therefore, in the present study, to optimize the oxygen transfer rate of the blood, three basic parameters were examined: blood flow velocity, oxygen velocity, and membrane thickness. Blood flow was considered at five different velocities (0.2, 0.4, 0.5, 0.6, and 0.8 mm/s). Results showed that increased blood flow velocity adversely affected oxygen permeability, increasing oxygen permeability from about 60% at 0.2 mm/s to about 24% at 0.9 mm/s. In addition, five different membrane thicknesses (0.04, 0.06, 0.08, 0.2, and 0.3 mm) were investigated, and, as expected, better oxygen exchange occurred as the membrane thickness decreased. We also found that the diffusion rate is about 40% for the 0.4 mm/s thin films and about 25% for the same inlet velocity and larger film thickness. Furthermore, the oxygen diffusivity increases from 28% to 38% as the oxygen gas velocity increases. However, oxygen velocities above 0.8 mm/s should not be used, as the range of oxygen diffusivity variation decreases with higher oxygen gas velocities.
