Indoor air distribution in a room with underfloor air distribution and chilled ceiling: Effect of ceiling surface temperature and supply air velocity

2019 ◽  
Vol 29 (2) ◽  
pp. 151-162 ◽  
Author(s):  
Jie Gao ◽  
Haichao Wang ◽  
Xiaozhou Wu ◽  
Fenghao Wang ◽  
Zhen Tian
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
Indoor Air ◽  
Residential Buildings ◽  
Air Distribution ◽  
Cooling Load ◽  
Air Velocity ◽  
Underfloor Air Distribution ◽  
Chilled Ceiling ◽  
Cooling Loads

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.

Influence of sensible cooling load on indoor air distribution in an office room with ceiling cooling and mixing ventilation

2020 ◽  
pp. 1420326X2092481
Author(s):  
Xiaozhou Wu ◽  
Haichao Wang ◽  
Jie Gao ◽  
Fenghao Wang
Keyword(s):  
Air Temperature ◽  
Temperature Difference ◽  
Turbulence Intensity ◽  
Indoor Air ◽  
Cooling System ◽  
Ventilation System ◽  
Air Distribution ◽  
Cooling Load ◽  
Contaminant Removal ◽  
Vertical Distributions

A mixing ventilation system integrated with a ceiling cooling system is a potential advanced heating, ventilation and air conditioning system for modern office buildings with a high sensible cooling load. This paper presents an evaluation of the effect of sensible cooling load on the indoor air distribution in a typical office room with mixing ventilation and ceiling cooling. The vertical distributions of indoor air temperature, air velocity and contaminant (CO2) concentration were evaluated by the vertical air temperature difference, turbulence intensity and contaminant removal effectiveness. The results showed that when the chilled ceiling surface temperature was increased from 15.0°C to 23.0°C and supply air temperature was decreased from 22.0°C to 19.0°C, the average vertical air temperature difference, turbulence intensity and contaminant removal effectiveness were 0.2°C–0.3°C, 27%–32% and 0.53–0.81 as both internal and external sensible cooling loads were 41.5 W/m2. Moreover, these evaluation indices varied slightly as the external sensible cooling load was increased from 41.5 W/m2 to 69.5 W/m2, whereas they varied greatly as the internal sensible cooling load was increased from 41.5 W/m2 to 69.5 W/m2. Hence, the external sensible cooling load could slightly affect the indoor air distribution, whereas the internal sensible cooling load could clearly affect the indoor air distribution in an office room with mixing ventilation and ceiling cooling.

Impact of chilled ceiling in a high sensible cooling load room with underfloor air distribution

2019 ◽  
Vol 25 (6) ◽  
pp. 705-715 ◽  
Author(s):  
Xiaozhou Wu ◽  
Jie Gao ◽  
Haichao Wang ◽  
Fenghao Wang ◽  
Zhen Tian
Keyword(s):  
Air Distribution ◽  
Cooling Load ◽  
Underfloor Air Distribution ◽  
Chilled Ceiling

Experimental Modeling of Air Temperature and Velocity Distribution in an Engine Compartment

2006 ◽  
Author(s):  
A. A. Mozafari ◽  
M. H. Saidi ◽  
J. Neyestani ◽  
A. E. Sany
Keyword(s):  
Heat Transfer ◽  
Velocity Distribution ◽  
Air Temperature ◽  
Gasoline Engine ◽  
Point Of View ◽  
Vehicle Body ◽  
Air Distribution ◽  
Wind Effect ◽  
Engine Compartment ◽  
Air Velocity

Investigation of air distribution and wind effect on a vehicle body from the point of view of underhood heat transfer effect and proper positioning of vehicle elements such cooler, condenser and engine configuration is an important area for engine researchers and manufacturers as well. In this research, the effect of air velocity distribution and wind effect around a vehicle is simulated and temperature and velocity distribution around engine block which is influenced by the wind effect is investigated. Thermal investigation of the engine compartment components is performed using results of underhood air temperature and velocity distribution. The heat transfer from engine surface is calculated from the engine energy balance in which their input data are obtained from a comprehensive experimental study on a four cylinder gasoline engine.

scholarly journals MEAN SURFACE TEMPERATURE OF JAPANESE QUAIL EXPOSED TO DIFFERENT LEVELS OF AIR VELOCITY AND TEMPERATURE AT START OF LAY

2020 ◽  
Vol 4 (2) ◽  
pp. 15-18
Author(s):  
Tatiany Carvalho dos Santos ◽  
Richard Stephen Gates ◽  
Ilda De Fátima Ferreira Tinôco ◽  
Sérgio Zolnier ◽  
Letícia Cibele da Silva Ramos Freitas
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
Japanese Quail ◽  
Systems Engineering ◽  
Air Velocity ◽  
Agricultural Engineering ◽  
Initial Stage ◽  
Different Temperatures ◽  
The Mean ◽  
Different Levels

The objective of this study was to evaluate the effect of different air velocities and temperature at the feeder on mean surface temperature of Japanese quail during the initial stage of laying. The experiment was carried out at the Center for Research in Environment and Agroindustry Systems Engineering (AMBIAGRO), Department of Agricultural Engineering, Federal University of Viçosa, Viçosa/MG, Brazil. A total of 216 Japanese quail in the initial laying phase were placed in four environmental chambers with different temperatures and air velocity, where they were housed and distributed randomly in 2 galvanized wire cages, with 3 partitions each and 27 birds/cage, and a density of approximately 155.6 cm²/bird. The experimental design consisted of randomized blocks with replications of two treatments (air velocity at the feeder: 0, 1, 2, and 3 m/s and air temperature: 17, 23, 29 and 35°C). The mean surface temperature was analyzed by Two-Way ANOVA, with treatment means separated by the Tukey test (P < 0.05). There was a significant positive correlation between air temperature and mean surface temperature (MST). Air velocity is important in removing heat from the surface of birds.

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

Energies ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 693 ◽  
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.

scholarly journals A NILM method for cooling load disaggregation based on artificial neural network

2019 ◽  
Vol 111 ◽  
pp. 05020 ◽  
Author(s):  
Ziwei Xiao ◽  
Jiaqi Yuan ◽  
Wenjie Gang ◽  
Chong Zhang ◽  
Xinhua Xu
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Energy Management ◽  
Residential Buildings ◽  
Building Energy ◽  
Cooling Load ◽  
Building Energy Management ◽  
Load Disaggregation ◽  
Artificial Neural ◽  
Cooling Loads

The demand of building energy management has increased due to high energy saving potentials. Load monitor and disaggregation can provide useful information for building energy management systems with detailed and individual loads of the building, so corresponding energy efficient measures can be taken to reduce the energy consumption of buildings. The technique is investigated widely in residential buildings known as Non-Intrusive Load Monitoring (NILM). However, relevant studies are not sufficient for non-residential buildings, especially for the cooling loads. This paper proposes a NILM method for cooling load disaggregation using artificial neural network. The cooling load is disaggregated into four categories: building envelope load, occupant load, equipment load and fresh air load. Two approaches are used to realize the load disaggregation: one is based on the Fourier transfer of the cooling loads, the other takes the cooling load, dry-bulb temperature and humidity of outdoor air, and time as inputs. By implementing the methods in a metro station, the performance of the proposed method can be obtained. Results show that both approaches can realize the load disaggregation accurately, with a RMSE less than 11.2. The second approach is recommended with a higher accuracy.

Prediction and Analysis of Building Energy Efficiency Using Artificial Neural Network and Design of Experiments

2016 ◽  
Vol 819 ◽  
pp. 541-545 ◽  
Author(s):  
Sholahudin ◽  
Azimil Gani Alam ◽  
Chang In Baek ◽  
Hwataik Han
Keyword(s):  
Neural Network ◽  
Energy Efficient ◽  
Residential Buildings ◽  
Building Energy ◽  
Cooling Load ◽  
Simulation Data ◽  
Heating And Cooling ◽  
Heating Load ◽  
Input Variables ◽  
Cooling Loads

Energy consumption of buildings is increasing steadily and occupying approximately 30-40% of total energy use. It is important to predict heating and cooling loads of a building in the initial stage of design to find out optimal solutions among various design options, as well as in the operating stage after the building has been completed for energy efficient operation. In this paper, an artificial neural network model has been developed to predict heating and cooling loads of a building based on simulation data for building energy performance. The input variables include relative compactness, surface area, wall area, roof area, overall height, orientation, glazing area, and glazing area distribution of a building, and the output variables include heating load (HL) and cooling load (CL) of the building. The simulation data used for training are the data published in the literature for various 768 residential buildings. ANNs have a merit in estimating output values for given input values satisfactorily, but it has a limitation in acquiring the effects of input variables individually. In order to analyze the effects of the variables, we used a method for design of experiment and conducted ANOVA analysis. The sensitivities of individual variables have been investigated and the most energy efficient solution has been estimated under given conditions. Discussions are included in the paper regarding the variables affecting heating load and cooling load significantly and the effects on heating and cooling loads of residential buildings.

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

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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