Modeling of Natural Ventilation in Built-in Photovoltaic-Trombe Wall

2013 ◽  
Vol 448-453 ◽  
pp. 1537-1541 ◽  
Author(s):  
Xiao Wei Xu ◽  
Ya Xin Su
Keyword(s):  
Solar Radiation ◽  
Natural Ventilation ◽  
Reverse Flow ◽  
Volume Flow Rate ◽  
Ventilation Rate ◽  
Volume Flow ◽  
Channel Width ◽  
Air Volume ◽  
Trombe Wall ◽  
Cfd Method

The natural ventilation in a novel built-in photovoltaic-Trombe wall (BiPV-TW) was numerically simulated by CFD method. The effect of solar radiation and channel width on the airflow pattern and ventilation rate was analyzed. Results showed that the solar radiation and channel width influenced the ventilation rate remarkably. As the solar radiation increased, the ventilation rate increased. As the channel width increased from 0.1m to 0.4m, the ventilation rate monotonously increased. However, when the channel width exceeded 0.5m, the reverse flow was formed in the tope zone and the ventilation rate decreased. A maximum air volume flow rate was achieved when the channel width was approximately equal to 0.4m in a 3m tall model.

Numerical Simulation on Air Volume Flow Rate Distribution of Stator Ducts for Salient Pole Synchronous Motor

2014 ◽  
Vol 644-650 ◽  
pp. 373-376
Author(s):  
Li Liu ◽  
Yi Ping Lu ◽  
Jia De Han ◽  
Xue Mei Sun
Keyword(s):  
Flow Rate ◽  
Volume Flow Rate ◽  
Domain Boundary ◽  
Air Flow ◽  
Flow Characteristics ◽  
Synchronous Motor ◽  
Volume Flow ◽  
Rate Distribution ◽  
Salient Pole ◽  
Air Volume

Air volume flow rate distribution of stator ducts along axial and circumferential for salient pole synchronous motor is strongly influenced by the air flow field in the air gap and rotor poles, which is completely different from the flow characteristics of non-salient pole motor and it directly relates to the peak temperature of stator bars and core and axial temperature difference which can affect the safety of the operation. A three-dimensional physical model of 1/8 motor was established and corresponding solution domain boundary conditions were given in this article. The air volume flow rate distribution of stator ducts along axial and circumferential was analyzed based on CFD. The study show that at the same position of the axial stator, the cooling air flow into stator ducts along the circumferential direction is uneven, the air volume flow rate distribution is largely influenced by rotor pole pieces, geometry and position of pole support block and rotor rotation direction.

scholarly journals Analysis of the potential use of Trombe walls in Brazil: design recommendations

2020 ◽  
Vol 5 ◽  
pp. 4
Author(s):  
Fernando Antonio de Melo Sá Cavalcanti ◽  
Rosana Maria Caram
Keyword(s):  
Solar Radiation ◽  
Computer Simulations ◽  
Thermal Performance ◽  
Natural Ventilation ◽  
Solar Heating ◽  
Heating And Cooling ◽  
Heated Air ◽  
Trombe Wall ◽  
Potential Use ◽  
Passive Strategy

In this paper, the thermal performance of a standard environment was evaluated based on the use of a Trombe wall with different configurations and types of use, as the potential for using this passive strategy is still little studied in Brazil. This device is capable of absorbing energy from solar radiation by heating the air in this greenhouse and this heated air can be directed to the interior or exterior of the building depending on the purpose. This air can be used to heat the room or cool it by means of natural ventilation. The analysis of this research was based on a series of computer simulations using the EnergyPlus software, version 7.0 in order to quantify and classify the thermal performance of a standard environment equipped with this component, under the various construction configurations. Both for heating and cooling environments. The use of Trombe walls improved the thermal comfort of users in buildings located in Brazil, depending on the climate where they are located, promoting natural ventilation and passive solar heating, allowing the potential of this device to be investigated in the most diverse Brazilian regions.

Unsteady Analysis of Microvalves With No Moving Parts

2007 ◽  
Vol 23 (1) ◽  
pp. 9-14 ◽  
Author(s):  
C.-T. Wang ◽  
T.-S. Leu ◽  
J.-M. Sun
Keyword(s):  
Unsteady Flow ◽  
Flow Rate ◽  
Reverse Flow ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Pressure Amplitude ◽  
Flow Conditions ◽  
Unsteady Flow Condition ◽  
The Difference ◽  
Moving Parts

AbstractNo-moving-parts valves (NMPV) pumps produce the net volume flow due to the difference of pressure resistances between forward and reverse flow of a microchannel structure. NMPV has been developed by a number of research groups. However, most of NMPV in these studies are designed and based on steady state flow conditions. Little data is available regarding the NMPV in unsteady flow conditions. In this study, the performances of NMPV under both steady and unsteady flow conditions are investigated numerically. The NMPV used in this study is a diffuser-type microchannel with diffuser angle of 20° because of its outstanding production of net volume flow. By a series of numerical simulations, some useful results would be addressed for the performance of NMPV micropumps. First, Reynolds number confirmed by steady analysis should be greater than 10 (Re > 10) for the NMPV pumps to be more effective. Second, an optimal Strouhal number with maximum net volume flow rate is found at St = 0.013 for the unsteady flow condition. In addition, the relation between the driving pressure amplitude and net volume flow rate with a linear behavior found was helpful to the performance of the micropump system. According to these findings, it was easy for users to operate and design of NMPV micropumps.

scholarly journals Coupling Effect of Air Flow Rate and Operating Conditions on the Performance of Electric Vehicle R744 Air Conditioning System

2021 ◽  
Vol 11 (11) ◽  
pp. 4855
Author(s):  
Anci Wang ◽  
Jianmin Fang ◽  
Xiang Yin ◽  
Yulong Song ◽  
Feng Cao ◽  
...  
Keyword(s):  
Electric Vehicle ◽  
Flow Rate ◽  
Air Conditioning ◽  
Volume Flow Rate ◽  
Air Flow ◽  
Volume Flow ◽  
Air Flow Rate ◽  
Air Volume ◽  
Discharge Pressure ◽  
Air Conditioning Systems

The air flow rate on the gas cooler side is one of the key parameters affecting the performance and running safety of transcritical CO2 electric vehicle air conditioning systems. After experimentally analyzing the effects of the air volume flow rate in the gas cooler on the cycle parameters and system performance, a novel method to evaluate the optimal air flow rate was proposed. In addition, the effect of the gas cooler air volume flow rate on the key performance parameters of the system (e.g., optimal discharge pressure) was explored. Finally, the coupling effects of the compressor speed, ambient temperature and optimal air flow rate on the system performance was also exhaustively assessed. It was found that as the discharge temperature, the CO2 temperature at the gas cooler outlet and the discharge pressure did not vary more than ±2%, the corresponding gas cooler air volume flow rate was optimal. For the single-row and dual-process microchannel evaporator used in this work, the recommended value of the optimal gas cooler air volume flow rate was 2500 m3·h−1. The results could provide reference for the fan speed design of electric vehicle CO2 air conditioning systems, especially for the performance under idling model.

scholarly journals Numerical Analysis of the Energy Consumption of Ventilation Processes in the School Swimming Pool

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1023
Author(s):  
Piotr Ciuman ◽  
Jan Kaczmarczyk
Keyword(s):  
Energy Consumption ◽  
Flow Rate ◽  
Energy Demand ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Swimming Pool ◽  
Specific Humidity ◽  
Total Energy Consumption ◽  
Air Volume ◽  
Indoor Swimming Pool

Ventilation of an indoor swimming pool is a very energy consuming process. This is a result of, among other things the required high value of the ventilation air volume flow rate, calculated on the basis of the moisture gains in the facility. The total energy consumption consists of the heat required to heat this air and the electricity needed to transport it. It is possible to reduce the ventilation air volume flow rate by assuming the correct value of specific humidity of the supply and indoor air, but then a deterioration of thermal-moisture conditions in the building can be expected. The aim of this paper was to examine how the reduction of the supply air volume flow rate affects the energy consumption for indoor swimming pool ventilation. It was also checked how this consumption can be reduced by using two-stage heat recovery in the air handling unit. Multi-variant simulations of energy consumption for indoor swimming pool ventilation were carried out using the IDA ICE software for day and night operation of the swimming pool throughout the year. The results of the research proved that reduction of the supply air volume flow rate resulted in the lower energy expenditure on ventilation. The variant with additional local air supply to the lifeguard zone was also analysed, which caused only a slight increase in energy demand for ventilation.

scholarly journals Study of Four Passive Second Skin Façade Configurations as a Natural Ventilation System During Winter and Summer

2021 ◽  
Vol 28 (1) ◽  
pp. 94-105
Author(s):  
Youssef Hamidi ◽  
Mustapha Malha ◽  
Abdellah Bah
Keyword(s):  
Flow Rate ◽  
Fossil Fuels ◽  
Natural Ventilation ◽  
Climate Models ◽  
Energy Savings ◽  
Volume Flow Rate ◽  
Ventilation System ◽  
Volume Flow ◽  
Design Strategies ◽  
The Difference

The fight against climate change is a significant challenge, resulting mainly from the linear and extensive exploitation of natural resources, particularly fossil fuels. Its impacts are now recognized. The current climate models are neither sustainable nor ecological in economic and social terms, especially as we live in a century marked by galloping demography and urbanization. Researchers worldwide have paid great attention to passive solar design strategies such as double skin or Second Skin Façade.  From this point, the present work aims to contribute to a better understanding of the feasibility of using a passive façade as a useful technology for natural ventilation to achieve potential energy savings and improve thermal comfort and indoor air quality. For this purpose, a parametric study was conducted for a room with four different southern facade configurations in six Moroccan climatic zones; the difference between each lies in the vent's position in the entrance and exit. This process was done by using COMSOL Multiphysics software. Velocity and volume flow rate fields were analyzed. The proposed configurations provided an average volume flow rate between 200 m3/h and 400 m3/h for a surface of 1 m2 of southern façade with an air vent area of 0.1mx0.2m.

scholarly journals C INVESTIGATION OF HEAT TRANSFER COEFFICIENT AUGMENTATION IN DIVERGENT RECTANGULAR DUCT FOR TWO PHASES FLOW (AIR-WATER)

2020 ◽  
Vol 20 (2) ◽  
pp. 111-121
Author(s):  
Hadi O . Basher ◽  
Riyadh S Al-Turaihi ◽  
Ahmed A. Shubba
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Water Volume ◽  
Maximum Heat ◽  
Air Volume ◽  
The Heat Transfer Coefficient

In this project, the flow distribution for air and water, and the enhancement of the heattransfer coefficient are experimentally studied. Experimental studies have been performed totest the influence of discharge, pitch, the height of ribs at a constant heat flux on thetemperature and pressure distributions. Along the channel of the test and the heat transfercoefficient, the water volume flow rate was about (5-12 L/min), the air volume flow rate wasabout (5.83-16.66 L/min), and heat were (80, 100,120, watt). An experimental rig wasconstructed within the test whole system. On the other hands, the channel has a divergentsection with an angle =15o with vertical axis. The study included changing in the ribs heightby using three values (12, 15, 18 mm) and changing the ribs pitch into three values (5, 8, 10mm).The results indicated an increasing in the local heat transfer coefficient as a result ofincreasing the discharge. While there was an inverse influence for the temperature distributionalong the test channel which drops when the discharge rise. The results also confirm that theincreasing in the pitch distance leads to reduce the heat transfer coefficient. Increasing theribs height increases the coefficient of heat transfer. However, the experiment heat transfercoefficient improves about (15.6 %) when the water volume flow rate increased from (5 to 12L/min), and about (18.7%) when the air volume flow rate increased from (5.83 to 16.66L/min). The best heat transfer coefficient was about (35.6 %) which can be achieved whenthe pitch decreased from (10 to 5mm). The increasing of the height from (12 to 18) mmimproves the heat transfer coefficient about (11.2 %). The best rib dimension was 18 mmheight, and 5 mm pitch, which give a maximum heat transfer coefficient (1212.02 W/m2. oC).

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