Showing 6 results for Natural Ventilation
Volume 11, Issue 3 (11-2021)
Abstract
Aims: Wind Catchers, as a traditional method of cooling, are compatible with the environment, on the one hand, and reduce energy consumption which is a major global challenge, on the other hand. This study evaluates the thermal and ventilation performance inside different floors of a four-story residential building by using three one-sided, two-sided, four-sided wind catcher models in hot and dry weather in open window mode.
Methods: The analysis by computer modeling or computational fluid dynamics (CFD) to evaluate the cooling potential and flow rate during the summer solstice
Finding: The results show that one-sided wind catchers are not efficient due to the low average inlet air and the negative airflow in the central shaft. Two-sided wind catchers have a positive airflow rate in the warm months, but a four-story building, cannot have the amount of air needed for ventilation on the first and second floors. Among three samples, the simulated four-sided Wind Catchers model has higher refrigeration power and optimal efficiency because it can provide airflow with appropriate speed and volume for the first to fourth floors
Conclusion: Among the three wind catcher modeled in software, it has been determined that only the four-way model can have the necessary efficiency to perform ventilation in different floors. designers can design an optimized design and a building that is more compatible with natural ventilation to provide comfort for residents, according to some special points for the use of wind catchers.
Mohammad Kazemi Esfeh, , ,
Volume 13, Issue 1 (4-2013)
Abstract
In the present study, the ventilation performance of a one-sided wind-catcher positioned in the wake of an upstream structure is experimentally investigated by measuring the induced airflow rates and employing smoke flow visualization techniques. Wind-catchers are usually used in places of high urban densities in Middle East regions; however, their potential to provide natural ventilation depends on the presence of upstream structures. The present study focuses on the ventilation performance evaluation of a one-sided wind-catcher located in the wake of an upstream structure model. The influence of the upstream structure height and its distance relative to the wind-catcher on the flow structure within and around the wind-catcher is investigated. Moreover, the ventilation performance is evaluated by measuring the ventilation flow rate using a hot wire anemometer for upstream air velocities of 10 and 15 m/s. The results show that the presence of an upstream object influences the rate and the direction of air flowing from the wind-catcher to the house. Placing a short upstream object increases the induced air flow rate. However, by increasing the height of upstream object, the airflow direction is reversed inside the wind-catcher and the air may flow backward from the ventilated space to the wind-catcher.
Volume 13, Issue 2 (6-2023)
Abstract
Aims: Today, the energy crisis has become a global problem, and all countries are involved in this crisis, so solutions with small results can lead to significant changes on a macro scale. Passive cooling strategies are a method to reduce energy consumption in buildings and help improve and promote energy management in hot climates.
Methods: The current study analysis ventilation performance related to constructing four-story buildings. Furthermore, there is a heavy investigation into the mechanical aspects of ventilation; hence this research is going to fill the gap in the architectural view of the ventilation system. The modeling uses energy software (Design-Builder).
Findings: Studies have been conducted to investigate the position of the stack, and the earth's rotation, in addition to changes in the materials of the stack in the residential area of Dezful city. The most frequent residential land size in the residential area of Dezful is 10x20 square meters. In addition, changing materials has a direct impact on stack ventilation.
Conclusion: The simulation outcomes demonstrated that material and site rotation changes could alter the stack's performance, meaning that glass can be more effective than aluminum. Still, the position of the stack in the plan does not make a significant difference in the stack's performance. The result is outstanding for architects and all people working in this field, which can be a guideline in designing energy-efficient.
Amin Haghighi Poshtiri, Safura Bahar, Azadeh Jafari,
Volume 16, Issue 6 (8-2016)
Abstract
In this paper, a natural cooling system composed of domed roof and solar adsorption chiller is presented and its performance to provide the thermal comfort conditions in Yazd, Kerman, and Tehran is investigated based on ISO 7730. Furthermore, the effects of environmental parameters, wind speed, and geometric characteristics on the system performance are studied. To calculate the number of air changes of the room, Ansys Fluent software is used. Additionally, to estimate the room inlet temperature, the governing equations of the adsorption chiller and cooling channel are solved based on the forth order Runge-kutta and finite difference methods, respectively. The results show that increasing the incision diameter of the domed roof as well as the width of the cooling channel causes to increase the number of air changes of the room. Alternatively, increasing the width of the inlet air vent up to a threshold value will cause to increase the number of air changes. However, increasing beyond the threshold value has no significant effect on the number of air changes. Additionally in the aforementioned cities, the room inlet air temperature is almost constant when the chiller operates. Finally, the environmental conditions are determined which accordingly the system is able to provide the thermal comfort conditions in the test room on July 15.
Hossein Dehghani Mohamadabadi, Seyyed Abbas Yazdanfar, Aliakbar Dehghan, Abolfazl Aehghani Mohamadabadi,
Volume 16, Issue 12 (2-2017)
Abstract
In this study, hydrodynamic behavior of four-sided wind tower attached to parlor and courtyard of a scaled model form existing historical house with wind incident angel as variable was numerically investigated. Hazire-ei house wind tower, which has six channels with rectangular cross section, integrated with parlor and courtyard is considered among the most typical ones in the vernacular architecture of Yazd city. This article seeks to investigate the performance of four-sided wind tower regarding suction and supply amount of air and the way it was used as a vernacular solution for natural ventilation in order to provide engineers with design guidelines for contemporary use. Numerical study was conducted on a 1:25 scaled model and for 13 wind incident angels with 15 degrees intervals and interested parameters are mass flow rate and flow direction in each channel. A structured mesh was generated and ANSYS Fluent software was used for numerical simulation. Numerical modeling results were validated against experimental tests conducted on the same scaled model and good agreement was observed. Results indicate that in 68.5% of incident angels, four-sided wind tower acts as sucking the air out of building and in other incident angels with approximately equal amount of supply and extract rate, it operates as an air exchange unit. Accordingly it can be concluded that putting aside stack effects, four-sided wind towers in dry regions of Iran are mostly employed for heat dissipation elements rather than inducing outdoor cool breezes.
Volume 19, Issue 1 (1-2017)
Abstract
Net-screen covered greenhouses operating on natural ventilation are used as a sustainable approach for closed-field cultivation of fruits and vegetables and to eliminate insect passage and the subsequent production damage. The objective of this work was to develop a real-time assessment framework for evaluating air-temperature inside an insect-proof net-screen greenhouse in tropical lowlands of Malaysia prior to cultivation of tomato. Mathematical description of a growth response model was implemented and used in a computer application. A custom-designed data acquisition system was built for collecting 6 months of air-temperature data, during July to December 2014. For each measured air-Temperature (T), an optimality degree, denoted by , was calculated with respect to different light conditions (sun, cloud, night) and different growth stages. Interactive three-dimensional plots were generated to demonstrate variations in values due to different hours and days in a growth season. Results showed that air temperature was never less than 25% optimal for early growth, and 51% for vegetative to mature fruiting stages. The average in the entire 6 months was between 65 and 75%. The presented framework allows tomato growers to automatically collect and process raw air temperature data and to simulate growth responses at different growth stages and light conditions. The software database can be used to track and record values from any greenhouse with different structure design, covering materials, cooling system, and growing seasons and to contribute to knowledge-based decision support systems and energy balance models.
