scholarly journals Thermal Comfort Analysis for Overhead and Underfloor Air Distribution Systems

CFD Letters ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 113-132
Author(s):  
Firas Basim Ismail ◽  
Nizar F.O. Al-Muhsen ◽  
Ain Amira Johari
Keyword(s):  
Thermal Comfort ◽  
Distribution Systems ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Superior Performance ◽  
Air Distribution ◽  
Preventive Action ◽  
Ansys Fluent ◽  
Proposed Model ◽  
Underfloor Air Distribution

Underfloor and overhead air distributions are two types of Heating Ventilating and Air Conditioning (HVAC) system in which both differs in term of channelling the supplied air into a space. Underfloor air distribution (UFAD) system channels the supplied air from the underfloor plenum and goes to the return vent at the ceiling. On the other hand, the overhead air distribution (OHAD) system utilizes the ceiling-to-ceiling air pathway approach. In this study, A developed HVAC model was proposed. Ansys Fluent program was used to numerically investigate the best thermal comfort of the proposed model in terms of occupant satisfaction by referring to ASHRAE Standard. Two scenarios were designed and adopted in the computational investigation which is OHAD and UFAD. Three heat-generating parameters were involved which are a room lamp, personal computer and occupant. The attained computational fluid dynamic (CFD) simulation results were validated. Generally, the attained CFD results showed that the UFAD system could perform better compare to the OHAD system even though the OHAD system could have some benefits. Specifically, the UFAD system provided the best thermal performance whereas the OHAD system was found to be less efficient in providing thermal comfort to the occupant and consumed a greater amount of energy because it was required to cool down the whole room instead of being cooled partly. The CFD results confirmed that the UFAD system was capable of maintaining the room temperature at 26°C at a height below 2.0 m compared to 1.2 m of the OHAD system. In conclusion, the UFAD system could provide better indoor air quality, and it could have superior performance for the tropic weather regions such as Malaysia compared to that of the OHAD system. Besides, using the UFAD system could be represented a preventive action that could be proposed to solve the mould growth inside any occupied room.

Geometric Modeling of a Propeller Turbine Runner Using ANSYS BladeGen, Meshing Using ANSYS TurboGrid and Fluid Dynamic Simulation Using ANSYS Fluent

2016 ◽  
Vol 842 ◽  
pp. 164-177 ◽  
Author(s):  
Indra Djodikusumo ◽  
I. Nengah Diasta ◽  
Iwan Sanjaya Awaluddin
Keyword(s):  
Geometric Modeling ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Thickness Distribution ◽  
Ansys Fluent ◽  
Implementation Phase ◽  
Runner Blade ◽  
Modeling Process ◽  
Turbine Runner ◽  
Preparation Phase

This paper aims to demonstrate how to model, mesh and simulate a hydraulic propeller turbine runner based on the geometrical specification of the runner blade. Modeling process is divided into preparation and implementation phase. Preparation phase illustrates how to develop stream surfaces and passages, how to create and transform meanline and how to create an rtzt file. The profile in rtzt file has a certain fix thickness which has to be altered later. Implementation phase describes operations necessary in creating a propeller runner model in ANSYS BladeGen which consist of importing rtzt file, modifying the trailing edge properties and altering profile thickness distribution to that of 4 digits NACA airfoil standard. Grid is generated in ANSYS TurboGrid utilizing ATM Optimized topology. CFD simulation is done using the ANSYS Fluent with pressure inlet and pressure outlet boundary conditions and k-ε turbulence model. Hydraulic efficiency of the runner is calculated utilizing Turbo Topology module in ANSYS Fluent. The authors will share the advantages that may be obtained by using ANSYS BladeGen compared with the use of general CAD Systems.

scholarly journals Numerical Study on Coupled Operation of Stratified Air Distribution System and Natural Ventilation under Multi-Variable Factors in Large Space Buildings

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 8130
Author(s):  
Ziwen Dong ◽  
Liting Zhang ◽  
Yongwen Yang ◽  
Qifen Li ◽  
Hao Huang
Keyword(s):  
Thermal Comfort ◽  
Working Conditions ◽  
Distribution System ◽  
Distribution Systems ◽  
Natural Ventilation ◽  
Numerical Study ◽  
Air Distribution ◽  
Large Space ◽  
Air Conditioners ◽  
Air Supply

Stratified air distribution systems are commonly used in large space buildings. The research on the airflow organization of stratified air conditioners is deficient in terms of the analysis of multivariable factors. Moreover, studies on the coupled operation of stratified air conditioners and natural ventilation are few. In this paper, taking a Shanghai Airport Terminal departure hall for the study, air distribution and thermal comfort of the cross-section at a height of 1.6 m are simulated and compared under different working conditions, and the effect of natural ventilation coupling operation is studied. The results show that the air distribution is the most uniform and the thermal comfort is the best (predicted mean vote is 0.428, predicted percentage of dissatisfaction is 15.2%) when the working conditions are 5.9% air supply speed, 11 °C cooling temperature difference and 0° air supply angle. With the coupled operation of natural ventilation, the thermal comfort can be improved from Grade II to Grade I.

scholarly journals Experimental Investigation of Ventilation Performance of Different Air Distribution Systems in an Office Environment—Heating Mode

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1835 ◽  
Author(s):  
Arman Ameen ◽  
Mathias Cehlin ◽  
Ulf Larsson ◽  
Taghi Karimipanah
Keyword(s):  
Thermal Comfort ◽  
Distribution Systems ◽  
Cold Climate ◽  
Air Distribution ◽  
Temperature Pattern ◽  
Office Environment ◽  
Ventilation Effectiveness ◽  
Local Thermal Comfort ◽  
Heating Mode ◽  
Occupied Zone

A vital requirement for all-air ventilation systems are their functionality to operate both in cooling and heating mode. This article experimentally investigates two newly designed air distribution systems, corner impinging jet (CIJV) and hybrid displacement ventilation (HDV) in comparison against a mixing type air distribution system. These three different systems are examined and compared to one another to evaluate their performance based on local thermal comfort and ventilation effectiveness when operating in heating mode. The evaluated test room is an office environment with two workstations. One of the office walls, which has three windows, faces a cold climate chamber. The results show that CIJV and HDV perform similar to a mixing ventilation in terms of ventilation effectiveness close to the workstations. As for local thermal comfort evaluation, the results show a small advantage for CIJV in the occupied zone. Comparing C2-CIJV to C2-CMV the average draught rate (DR) in the occupied zone is 0.3% for C2-CIJV and 5.3% for C2-CMV with the highest difference reaching as high as 10% at the height of 1.7 m. The results indicate that these systems can perform as well as mixing ventilation when used in offices that require moderate heating. The results also show that downdraught from the windows greatly impacts on the overall airflow and temperature pattern in the room.

A CFD SIMULATION OF PM1 AND CO AIR CONTAMINANTS IN A BUS PASSENGER COMPARTMENT

2015 ◽  
Vol 77 (30) ◽  
Author(s):  
Noor Emilia Ahmad Shafie ◽  
Haslinda Mohamed Kamar ◽  
Nazri Kamsah
Keyword(s):  
Carbon Monoxide ◽  
Particulate Matter ◽  
Distribution Systems ◽  
Cfd Simulation ◽  
Ventilation System ◽  
Air Distribution ◽  
Passenger Compartment ◽  
Displacement Ventilation ◽  
Three Dimensional Model ◽  
Air Contaminants

Air distribution systems inside a bus compartment are important for providing healthy and comfortable environment for passengers. Lack of ventilation inside the bus passenger compartment causes an increase level of air contaminants concentration. Particulate matters and carbon monoxide are indoor air contaminants which can affect the passenger’s health such as respiratory problem and lung cancer. This article reports the results of a CFD simulation on transport of carbon monoxide and particulate matter 1 inside a passenger compartment of a university’s shuttle bus. Fluent CFD software was used to develop a simplified three-dimensional model of the bus passenger compartment. Flow analysis was carried out using RNG k-e turbulent model for air flow, discrete phase and species transport for the air contaminants. Four variations of ventilation system namely two mixing ventilation types, combined mixing with displacement ventilation and combined mixing ventilation with underfloor air distribution was examined. The CFD simulation results show that the use of the combined mixing and displacement ventilation and also the combined mixing and underfloor ventilation types are capable of reducing the concentration of carbon monoxide and particulate matter 1 inside the bus passenger compartment by 81% and 54%, respectively.

A FLUIDODINÂMICA COMPUTACIONAL UTILIZADA PARA MAPEAR O CONFORTO TÉRMICO DE SUÍNOS NA FASE DE MATERNIDADE

2017 ◽  
Vol 32 (1) ◽  
pp. 32
Author(s):  
Beatriz Kenickel Nunes ◽  
Silvia Regina Lucas de Souza ◽  
Arilson José de Oliveira Júnior ◽  
Enedy Allan Rodrigues Cordeiro ◽  
Reginaldo Apolinário de Almeida
Keyword(s):  
Thermal Comfort ◽  
Computational Fluid Dynamic ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Thermal Conditions ◽  
Simulation Software ◽  
Santa Cruz ◽  
Facilities Design ◽  
Comfort Condition ◽  
Made In

As observações geradas em estudos sobre instalações de suínos têm demonstrado que o desempenho térmico das instalações comumente utilizadas pelos produtores vem apresentando um quadro de desconforto térmico na fase da maternidade, devido às adaptações construtivas feitas com a finalidade de atender tanto as necessidades da matriz quanto dos leitões. Sendo assim, o objetivo deste trabalho foi utilizar a ferramenta de fluidodinâmica computacional (CFD) para realizar o mapeamento do microambiente de duas instalações de suínos, visando o bem-estar dos animais. As simulações foram obtidas em uma maternidade da Fazenda Experimental Lageado, UNESP, Botucatu/SP e de uma granja comercial localizada em Santa Cruz do Rio Pardo/SP. Para as simulações utilizou-se o software Autodesk® CFD Simulation juntamente com o AutoCAD 3D, para desenho das instalações. As condições de conforto térmico foram analisadas por meio da aplicação do índice de voto médio estimado – PMV. Na instalação comercial simulada observou-se que as aberturas laterais não são suficientes para manter uma condição de conforto térmico, segundo o índice PMV. Com o uso da fluidodinâmica computacional foi possível modificar o ambiente mediante a elevação do seu fluxo de ar, o que demonstrou ser uma solução na diminuição da temperatura do ar e alcance de uma condição de conforto térmico.PALAVRAS-CHAVE: Conforto térmico, bem-estar de suínos, fluidodinâmica computacional, CFD, simuladores. FLUIDODYNAMICS COMPUTATIONAL USED FOR THE MAPPING OF THERMAL CONDITIONS IN INSTALLATION OF SWINE MATERNITIESABSTRACT: Studies have shown that the thermal performance of facilities commonly used by producers has presented an environmental discomfort picture in the maternity phase due to constructive adjustments made in order to meet needs of both piglets and sow. Therefore, this work aimed to use the computational fluid dynamic tool for mapping the microclimate of two facilities, which purpose of improving the animal welfare. The simulations were conducted at experimental farm “Lageado”, UNESP, Botucatu/SP and a commercial facility, located in Santa Cruz do Rio Pardo/SP. For simulations were used the Autodesk® CFD Simulation software along with AutoCAD 3D (facilities design). Thermal comfort conditions were analyzed by means of predicted mean vote – PMV. In simulated commercial facility was observed that side vents are not sufficient to establish a thermal comfort condition, according to PMV. With computational fluid dynamic was possible to change the environment through air flow increase, showing to be a solution in decrease of air temperature and reach of thermal comfort condition.KEYWORDS: Thermal comfort, swine welfare, computational fluid dynamic, CFD, simulators.

scholarly journals Earth Air Tunnel Heat Exchanger for Building Cooling and Heating

2021 ◽  
Author(s):  
Nasim Hasan ◽  
Mohd Arif ◽  
Mohaideen Abdul Khader
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Numerical Algorithms ◽  
Ansys Fluent ◽  
Helical Pipe ◽  
Complex Fluid ◽  
Set Up ◽  
Building Cooling

The computational fluid dynamic (CFD) is an influential method for measuring Heat transfer profiles for typical meteorological years. CFD codes are managed by numerical algorithms that may undertake fluid glide headaches. CFD offers the numerical results of partial differential equations with main airflow and heat transfer in a discretized association. The complex fluid glide and the warmth transfer publications worried in any heat exchanger can be determined with the help of the CFD software program (Ansys Fluent). A study states and framework which implicitly rely on the computational fluid dynamics, which is being formulated for computing the efficiency-related parameters of the thermal part and the capability of the EATHE system for cooling. A CFD simulation program is being used for modeling the system. The framework is being validated with the help of the simulation set-up. A thermal model was developed to analyze thermal energy accumulated in soil/ground for the purpose of room cooling/heating of buildings in the desert (hot and dry) climate of the Bikaner region. In this study, the optimization of EATHE design has been performed for finding the thermal performance of straight, spiral, and helical pipe earth air tunnel heat exchanger and Heat transfer rate for helical pipe was found maximum among all designs.

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