Thermal Comfort Evaluation of a Mixed-mode Ventilated Office Building with Advanced Natural Ventilation and Underfloor air Distribution Systems

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.

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Analysis on the impact of mean radiant temperature for the thermal comfort of underfloor air distribution systems

Energy and Buildings ◽

10.1016/j.enbuild.2010.07.030 ◽

2010 ◽

Vol 42 (12) ◽

pp. 2353-2359 ◽

Cited By ~ 16

Author(s):

Jae Dong Chung ◽

Hiki Hong ◽

Hoseon Yoo

Keyword(s):

Thermal Comfort ◽

Distribution Systems ◽

Air Distribution ◽

Mean Radiant Temperature ◽

Underfloor Air Distribution ◽

Radiant Temperature ◽

The Impact

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Thermal Comfort Analysis for Overhead and Underfloor Air Distribution Systems

CFD Letters ◽

10.37934/cfdl.13.12.113132 ◽

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.

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Thermal Comfort Evaluation of Under Floor Air Distribution Space Using EDT Index

Journal of The Korean Society of Living Environmental System ◽

10.21086/ksles.2017.12.24.6.777 ◽

2017 ◽

Vol 24 (6) ◽

pp. 777-784

Author(s):

Byung-Yoon Park ◽

Yong-Ho Jung

Keyword(s):

Thermal Comfort ◽

Air Distribution ◽

Distribution Space ◽

Comfort Evaluation

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

Energies ◽

10.3390/en12101835 ◽

2019 ◽

Vol 12 (10) ◽

pp. 1835 ◽

Cited By ~ 5

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.

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Air Flow Modelling of a Multi-Storey Office Building

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.361-363.833 ◽

2013 ◽

Vol 361-363 ◽

pp. 833-844

Author(s):

Chong Jie Wang ◽

Wei Wei Liu

Keyword(s):

Temperature Distribution ◽

Natural Ventilation ◽

Air Flow ◽

Comfort Level ◽

Office Building ◽

Temperature Stratification ◽

Air Distribution ◽

Flow Modelling ◽

Ventilation Strategies

Indoor fresh air distribution, temperature stratification and temperature distribution are consider to be the essential indicators when comes to evaluation of the comfort level for internal ventilation environment, particularly for natural ventilated space as target office building. It can be identified that the targeting building has been well designed in the respect of natural ventilation strategies where both cross and stack strategies have been adopted, but it is also obvious that under combined buoyancy and wind driven mode alternative problems appears.

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