Impact of chilled ceiling on indoor air distribution in a room with mixing ventilation

An underfloor air distribution (UFAD) system integrated with a chilled ceiling (CC) cooling system may be a potential advanced heating, ventilation and air conditioning system in modern non-residential buildings with high sensible cooling loads. This article presents an experimental study concerning the effect of ceiling surface temperature and supply air velocity on the indoor air distribution in a room with UFAD as the internal and external sensible cooling loads change. The vertical distributions of indoor air temperature, air velocity and contaminant (CO2) concentration were evaluated by vertical air temperature difference (VATD), turbulence intensity (TI) and contaminant removal effectiveness (CRE), respectively. The results showed that the average VATD, TI and CRE levels were 0.5°C–1.0°C, 31%–41% and 0.85–1.06 when both internal and external sensible cooling loads were 41.5 W/m2. These evaluation indices varied clearly when the external sensible cooling load increased from 41.5 W/m2 to 69.5 W/m2, whereas they remained almost the same when the internal sensible cooling load increased from 41.5 W/m2 to 69.5 W/m2. The maximum TI coincided with the minimum CRE under the condition of a constant sensible cooling load. Moreover, an air diffusion performance index clearly reduced with an increase in the heat removal effectiveness. It is recommended that it is important to balance the indoor air quality and energy consumption in a room with UFAD + CC.

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An Experimental Study of Indoor Air Distribution Characteristics in a Room with Mixing Ventilation and Chilled Ceiling

Environmental Science and Engineering - Proceedings of the 11th International Symposium on Heating, Ventilation and Air Conditioning (ISHVAC 2019) ◽

10.1007/978-981-13-9520-8_23 ◽

2020 ◽

pp. 211-220

Author(s):

Jie Gao ◽

Pin Lv ◽

Xiaozhou Wu ◽

Shugang Wang ◽

Fenghao Wang

Keyword(s):

Experimental Study ◽

Indoor Air ◽

Air Distribution ◽

Distribution Characteristics ◽

Chilled Ceiling

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Kitchen and Toilet of the Residence Exhaust Flow Field Analysis

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.354-355.726 ◽

2011 ◽

Vol 354-355 ◽

pp. 726-731

Author(s):

Yue Ren Wang ◽

Cong Xue ◽

Jing Zhang

Keyword(s):

Indoor Air ◽

Cfd Simulation ◽

Simulation Software ◽

Field Analysis ◽

Air Distribution ◽

Volume Changes ◽

Air Volume ◽

Secondary Pollution ◽

Comparison Results ◽

Flow Field Analysis

Adopting the k-ε standard model, the CFD simulation software to simulate the indoor kitchen and toilet different row of indoor air volume air distribution in natural ventilated circumstance, by comparison results show that different row of indoor air volume changes in the rate of secondary pollution rate, and then to provide the change rule of indoor air quality protection reference basis.

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DESIGNING A SMALL CLIMATE CHAMBER TO CHARACTERIZE PEOPLE AS A SOURCE OF DETERIORATION OF INDOOR AIR QUALITY BY RESPIRATION

CBU International Conference Proceedings ◽

10.12955/cbup.v7.1484 ◽

2019 ◽

Vol 7 ◽

pp. 954-959 ◽

Cited By ~ 1

Author(s):

Detelin Ganchev Markov ◽

Sergey Mijorski ◽

Peter Stankov ◽

Iskra Simova ◽

Radositna A. Angelova ◽

...

Keyword(s):

Carbon Dioxide ◽

Water Vapor ◽

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Carbon Dioxide Concentration ◽

Air Distribution ◽

Vapor Concentration ◽

Cfd Simulations ◽

Climate Chamber

: People are one of the sources for deterioration of the indoor air quality. They worsen indoor air quality by their presence (respiration, bio-effluents), activities and habits. Through respiration, people decrease the oxygen concentration in the air of the occupied space and increase carbon dioxide and water vapor concentration in the indoor air as well as its temperature. The goal of the AIRMEN project is to find out if the rate of consumption of oxygen and emission of carbon dioxide (and water vapor) by people depends on the indoor air temperature as well as carbon dioxide concentration in the inhaled air. In order to achieve this goal a small climate chamber must be designed and constructed which allows for controlling and measuring both inflow and exposure parameters as well as for measuring outflow parameters. The principal goal of this paper is to present some important details, obtained by CFD simulations, from the design process of the climate chamber which precondition the air distribution in the chamber and hence the exposure parameters.

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Air Distribution and Air Handling Unit Configuration Effects on Energy Performance in an Air-Heated Ice Rink Arena

Energies ◽

10.3390/en12040693 ◽

2019 ◽

Vol 12 (4) ◽

pp. 693 ◽

Cited By ~ 3

Author(s):

Mehdi Taebnia ◽

Sander Toomla ◽

Lauri Leppä ◽

Jarek Kurnitski

Keyword(s):

Temperature Gradient ◽

Air Temperature ◽

Indoor Air ◽

Energy Demand ◽

Energy Performance ◽

Air Distribution ◽

Air Handling Unit ◽

Cooling Coil ◽

Indoor Conditions ◽

Cooling Energy Demand

Indoor ice rink arenas are among the foremost consumers of energy within building sector due to their exclusive indoor conditions. A single ice rink arena may consume energy of up to 3500 MWh annually, indicating the potential for energy saving. The cooling effect of the ice pad, which is the main source for heat loss, causes a vertical indoor air temperature gradient. The objective of the present study is twofold: (i) to study vertical temperature stratification of indoor air, and how it impacts on heat load toward the ice pad; (ii) to investigate the energy performance of air handling units (AHU), as well as the effects of various AHU layouts on ice rinks’ energy consumption. To this end, six AHU configurations with different air-distribution solutions are presented, based on existing arenas in Finland. The results of the study verify that cooling energy demand can significantly be reduced by 38 percent if indoor temperature gradient approaches 1 °C/m. This is implemented through air distribution solutions. Moreover, the cooling energy demand for dehumidification is decreased to 59.5 percent through precisely planning the AHU layout, particularly at the cooling coil and heat recovery sections. The study reveals that a more customized air distribution results in less stratified indoor air temperature.

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Operation Testing of an Advanced Personalized Ventilation System

Energies ◽

10.3390/en12091596 ◽

2019 ◽

Vol 12 (9) ◽

pp. 1596 ◽

Cited By ~ 3

Author(s):

Csáky ◽

Kalmár ◽

Kalmár

Keyword(s):

Air Quality ◽

Thermal Comfort ◽

Indoor Air Quality ◽

Indoor Air ◽

Distribution System ◽

Noise Level ◽

Background Noise ◽

Ventilation System ◽

Air Distribution ◽

Personalized Ventilation

Using personalized ventilation systems in office buildings, important energy saving might be obtained, which may improve the indoor air quality and thermal comfort sensation of occupants at the same time. In this paper, the operation testing results of an advanced personalized ventilation system are presented. Eleven different air terminal devices were analyzed. Based on the obtained air velocities and turbulence intensities, one was chosen to perform thermal comfort experiments with subjects. It was shown that, in the case of elevated indoor temperatures, the thermal comfort sensation can be improved considerably. A series of measurements were carried out in order to determine the background noise level and the noise generated by the personalized ventilation system. It was shown that further developments of the air distribution system are needed.

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Role of Indoor Air Distribution in Performance of Heat Pump Systems in Energy-Efficient Residential Buildings

Advanced Energy Systems ◽

10.1115/imece2006-15079 ◽

2006 ◽

Author(s):

Ali A. Jal-Alzadeh-Azar ◽

Ren Anderson ◽

Keith Gawlik

Keyword(s):

Energy Consumption ◽

Heat Pump ◽

Indoor Air ◽

High Performance ◽

Energy Use ◽

Residential Buildings ◽

Comfort Level ◽

Air Distribution ◽

Air Mixing ◽

Heating Mode

This paper demonstrates the potential impact of indoor air distribution on the energy consumption of central HVAC systems with cognizance of human thermal comfort. The study focuses on a hypothetical high-performance house incorporating a split heat pump system. The air distribution of this building incorporates high sidewall supply-air registers and near-floor, wall-mounted return-air grilles. Heating-mode stratification resulting from this prevalent configuration is a prime example of situations in which challenges regarding energy efficiency, comfort, and ventilation effectiveness emerge. These challenges underline the importance of adopting a comprehensive design strategy for high-performance buildings. Two indoor air distribution scenarios were analyzed: (1) theoretically well mixed and (2) poorly mixed, representing a realistic case. The former scenario was evaluated using an analytical approach, whereas the latter was investigated through computational fluid dynamics (CFD) simulations. For heating mode, the results indicated the presence of a pronounced thermal stratification resulting from poor air mixing. At 50% of the design heating load, for the well-mixed case, the HVAC system energy consumption was significantly higher. Considerably better air distribution performance was observed with cooling mode, in which the relative energy penalty for the well-mixed scenario was noticeably less. In real-world applications where measures must be taken to achieve near perfectly mixed indoor conditions for better comfort, the energy use is expected to be even higher. However, in the absence of such measures, the thermostat setpoint is likely to be readjusted, leading to a higher energy use without necessarily improving the overall comfort level, as demonstrated in this paper. The limitation of increasing the supply-air flow rate to enhance air mixing and diffusion is also discussed in terms of the system moisture removal capability.

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