scholarly journals Numerical Study on the Performance of a Fin-and-Tube Condenser with Non-Uniform Air Distribution and Different Tube Types

2012 ◽  
Vol 24 (12) ◽  
pp. 858-866 ◽  
Author(s):  
Da Young Cho ◽  
Hyung Chang Hahm ◽  
Chang Yong Park
Keyword(s):  
Numerical Study ◽  
Air Distribution ◽  
Tube Condenser

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 Numerical study of the air distribution in the Crew Quarters on board of the International Space Station

2019 ◽  
Vol 85 ◽  
pp. 02015 ◽  
Author(s):  
Charles Berville ◽  
Matei-Răzvan Georgescu ◽  
Ilinca Năstase
Keyword(s):  
Numerical Simulations ◽  
International Space Station ◽  
Numerical Study ◽  
Ventilation System ◽  
Space Station ◽  
Air Distribution ◽  
Thermal Manikin ◽  
Airflow Rate ◽  
International Space ◽  
Airflow Distribution

The current concept of Crew Quarters on board of the International Space Station has several issues according to the crew member’s feedback. Major issues concern noise levels, the accumulation of CO2 and the quality of the air distribution. Our study targets the airflow distribution, to diagnose this issue, we realise a series of numerical simulations (CFD) based on a real scale replica of the Crew Quarters. Simulations were set with a zero-gravity mode and with the theoretical air parameters inside the SSI. The geometry includes a thermal manikin having the neutral posture of a body in the absence of gravity. Numerical simulations were run for the three different air flow rates provided by the current ventilation system. Results have shown that the air distribution inside the Crew Quarter is insufficient for low airflow rates but becomes acceptable for the higher airflow rate, however the higher airflow rate can potentially produce draught discomfort.

Numerical Study of Air Distribution in Combustion Chamber

2016 ◽  
Vol 832 ◽  
pp. 218-223
Author(s):  
Michal Špilaček ◽  
Martin Lisý ◽  
Zdenek Skala
Keyword(s):  
Numerical Model ◽  
Turbulent Flow ◽  
Combustion Chamber ◽  
Numerical Study ◽  
Air Distribution ◽  
Secondary Combustion ◽  
Laminar And Turbulent Flow ◽  
Secondary Air

The main goal of this article is to analyze the distribution of primary and secondary combustion air in a combustion chamber. The fuel for the combustion chamber is biomass and the main characteristics the combustion chamber must meet is to be simple, reliable, cheap and ecological. A brief summary of the importance of primary and secondary air is made and then it is compared with the results from the numerical model. The numerical model is based upon a simplified chamber geometry and the results are computed for laminar and turbulent flow. From the comparison are determined flaws of the design of the combustion chamber and outlined possible solutions for their removal and further direction of the study.

A Study on Evaluation of ADPI and Ventilation Performance of a Small Auditorium with Unevenly Arranged Return Diffusers

2017 ◽  
Vol 25 (04) ◽  
pp. 1750029
Author(s):  
Yong-il Kwon
Keyword(s):  
Distribution System ◽  
Distribution Systems ◽  
Numerical Study ◽  
Side Wall ◽  
Air Distribution ◽  
Rear Wall ◽  
System Parameters ◽  
Ventilation Efficiency ◽  
Ventilation Performance ◽  
Air Diffusion

The ventilation performance and thermal comfort characteristics on placing the supply or return diffusers for the air distribution systems applied to an auditorium with high ceiling heights must be inherently considered. A numerical study has been conducted to simulate the airflow and ventilation characteristics in a small auditorium with the uniformly installed supply diffusers on the ceiling surface, and with the unevenly installed return diffusers on the side wall of the stage, the left and rear wall. It is the objective of the present study to investigate the effects of various air distribution system parameters on air diffusion performance index (ADPI), air change efficiency and scale of ventilation efficiency NO.4 (SVE4) of return diffusers in the auditorium with the movable audience seat on the flat floor. This paper focuses mainly on the effect of the unevenly installed return diffusers on the low part of the side wall of the auditorium with the movable audience seat.

Numerical study of different ceiling-mounted air distribution systems for a virtual classroom environment

2016 ◽  
Vol 26 (10) ◽  
pp. 1382-1396 ◽  
Author(s):  
Eusébio Z. E. Conceição ◽  
Cristina I. M. Santiago ◽  
Hazim B. Awbi
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Air Temperature ◽  
Distribution Systems ◽  
Numerical Study ◽  
Virtual Classroom ◽  
Comfort Level ◽  
Air Distribution ◽  
Air Supply ◽  
Distribution Index

This paper presents a comparative numerical study of different ceiling-mounted-localized air distribution systems placed above students in a virtual classroom in summer conditions. The influence of four different ceiling-mounted-localized air distribution systems, using vertical descendent jets, on the thermal comfort, local thermal discomfort, and air quality levels was numerically evaluated. The air distribution index, developed previously, was used for non-uniform environment. This index considers the thermal comfort level, air quality level, effectiveness for heat removal, and effectiveness for contaminant removal. Numerical simulations were conducted for a virtual classroom equipped with one of four different ceiling-mounted-localized air distribution systems and with 6 desks, 6 or 12 students, and 2 upper airflow outlets. Inlet air supply temperature of 20 and 24℃ and an outdoor air temperature of 28℃ were used. The simulation results show that the air supply system having a vertical air jet placed at 1.8 m above the floor level (Case III), and with an inlet area of 0.01 m2 and a supply air velocity of 3 m/s would represent the best option in comparison with other air supply methods. In general, the air distribution index value decreases with an increase in inlet air temperature and the number of occupants. The air distribution index values are highest for Case III representing a classroom with 6 or 12 occupants with an inlet air temperature of 20 or 24℃.

Fluid Flow, Heat and Contaminant Transport in a Ventilated Enclosure due to the Presence of Thermosolutal Body

2017 ◽  
Author(s):  
Neha Gupta ◽  
Ameeya Nayak
Keyword(s):  
Mass Transfer ◽  
Fluid Flow ◽  
Contaminant Transport ◽  
Richardson Number ◽  
Numerical Study ◽  
Vertical Wall ◽  
Air Distribution ◽  
The Core ◽  
Flow Heat ◽  
Higher Temperature

A numerical study is performed for the fluid flow, heat and mass transfer in a ventilated enclosure where a thermally and solutally activated square block is placed for heat and solute exchanges. The block is maintained with higher temperature and concentration than that of inlet flow and the walls are impermeable and adiabatic to heat and solute. Cold fluid is entered through a slot of left vertical wall and flushes out at the different slots of opposite wall to study the mixed air distribution due to the thermosolutal source present in the core of the enclosure. The dynamic, thermal and solutal transport phenomena are computationally visualized through the streamlines, isotherms and iso-concentration lines. The efficient cooling activities are studied by changing the locations of inlet and outlet ports with the variation of Richardson number (Ri) and Reynolds number (Re) for a fixed Prandtl number (Pr = 0.71).

scholarly journals Evaluation of Integral Effect of Thermal Comfort, Air Quality and Draught Risk for Desks Equipped with Personalized Ventilation Systems

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3235
Author(s):  
Eusébio Conceição ◽  
Hazim Awbi
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Numerical Study ◽  
Heat Removal ◽  
Thermal Conditions ◽  
Air Distribution ◽  
Pv Systems ◽  
Integral Effect ◽  
Personalized Ventilation ◽  
Air Removal

This work evaluates the integral effect of thermal comfort (TC), indoor air quality (IAQ) and Draught Risk (DR) for desks with four personalized ventilation (PV) systems. The numerical study, for winter and summer thermal conditions, considers a virtual chamber, a desk, four different PV systems, four seats and four virtual manikins. Two different PV configurations, two upper and two lower air terminal devices (ATD) with different distance between them are considered. In this study a coupling of numerical methodology, using one differential and two integral models, is used. The heating, ventilating and air conditioning (HVAC) system performance in this work is evaluated using DR and room air removal effectiveness (εDR) that is incorporated in an Air Distribution Index (ADI). This new index, named the Air Distribution Turbulence Index (ADTI), is used to consider simultaneously the TC, the IAQ, the DR and the effectiveness for heat removal (εTC), contaminant removal (εAQ) and room air removal (εDR). The results show that the ADI and ADTI, are generally higher for Case II than for Case I, increase when the inlet air velocity increases, are higher when the exit air is located at a height 1.2 m than when is located at 1.8 m, and are higher for summer conditions than for winter conditions. However, the values are higher for the ADI than ADTI.

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