Natural Ventilation Conditions Research Articles

Thermal Comfort in Naturally Ventilated Apartments in Surabaya, Indonesia

This study aims to investigate the detailed thermal environments in apartments of Surabaya, Indonesia and discuss their potential passive cooling strategies. Major thermal parameters, vertical distribution of air temperature and surface temperature of walls/ceiling were measured in one of the representative units of three types of apartments respectively, under different natural ventilation conditions. The results revealed that the unit in the old public apartment showed better thermal environments compared to those in the other two apartments. It is very difficult to achieve thermal comfort during most of the day particularly in the new public and private apartments by means of natural ventilation alone. Building orientation, insufficient shading devices, and building materials are some of the factors causing hot conditions particularly in the newly emerging middle-class apartments. Several passive cooling strategies were proposed based on the measurement results.

Natural Ventilation and Temperature Conditions in Some High-rise Building Flats in Bandung and Jakarta in Perspective of Adaptive Thermal Comfort

The effect of increasing RUSUNAMI high-rise and low cost building flats construction has brought about some problems. One of them is the use of air conditioning in many building flats. It shows that the objective of the RUSUNAMI is not fulfilled because it needs additional operational cost for air conditioning. Two RUSUNAMIs in Bandung and three RUSUNAMIs in Jakarta were selected and measured related to ventilation and indoor air temperature. This paper examines the performance of natural ventilation and indoor air temperature and their ability in thermal comfort with the adaptive approach. In general, all RUSUNAMI is not effective in utilizing the wind because it is designed for air conditioning. On this occasion, it is discussed the opportunities of natural ventilation associated with utilization approach of adaptive thermal comfort.

The Transient Simulation of Carbon Dioxide Emission from Human Body Based on CONTAM

Among the many types of indoor pollutants, carbon dioxide has always been overlooked. This paper simulated and analyzed the variety of the concentration of indoor carbon dioxide of the office room over time under steady-state conditions of natural ventilation based on CONTAM, and aims to understand the impact of the human body as a pollution source on indoor air quality produce, as well as the role of ventilation to improve indoor air quality. For the natural ventilation of a room, the airflow paths of upstream own far more effect on IAQ than that of downstream, so it is very important to make sure that the airflow paths of upstream is smooth. Furthermore, natural ventilation is not an optimal approach to eliminate indoor pollution. The mechanical ventilation must be introduced to effectively guarantee the IAQ.

Experimental Investigation of Assumptions Used to Quantify Airflows through a Window under Cross Natural Ventilation

As natural wind is continuously fluctuating in both speed and direction, quantifying instantaneous wind-driven natural ventilation rate can be difficult, and often an average effect is used to stabilize the fluctuations. This work performs an experimental investigation to assess the validity of assumptions often used in quantifying airflows through an opening under cross natural ventilation condition. In the experiment, the three velocity components are analyzed for flows approaching and through an open window exposed to natural wind. Detailed airflows are also examined across an open window to investigate velocity profiles at the opening. Finally, ventilation rates are calculated to assess the use of constant discharge coefficients for wind-driven natural ventilation, and show for the experimental conditions that the traditional orifice flow rate calculation using a constant discharge coefficient CD=0.65 results in an underestimate by 17% compared to a detailed calculation based on seven airspeed measurements within the window opening.

Investigation on Air Quality in Strawberry Greenhouse under Natural Ventilation

The effect of the air inlet and the air outlet of the strawberry greenhouse are very significant to the microclimate in greenhouse under the conditions of natural ventilation. This paper studied the numerical simulation and experiment of indoor temperature field of the strawberry greenhouse with natural ventilation in different areas of air inlet and air outlet. The impact of the natural ventilation on the microclimate of strawberry greenhouse has been explored. The results indicated that the air velocity and temperature in the air inlet effected on the temperature distribution within the greenhouse, and the temperature near the air inlet was susceptible to the outdoor environmental parameters. The general trend of the variation of the indoor temperature in the greenhouse decreased with increasing the sizes of the air inlet and the air outlet. The overall trend of temperature gradient is similar within the greenhouse.

Large eddy simulation of thermal plume behavior in horizontally partitioned dual enclosure

The fire induced flow characteristics through horizontal passage between two enclosures are investigated under natural and forced ventilation conditions. The physical model consists of upper and lower enclosures with door openings through which forced air enters the dual enclosure. Transient three-dimensional simulations are performed by Large Eddy Simulations (LES) using Fire Dynamic Simulator (FDS) code. The assisting and opposing behavior of forced air stream in enclosure fire are investigated by varying fire source locations. The flow characteristics through horizontal and vertical passages are found to be oscillatory and bidirectional. In natural ventilation conditions, heat source location and thermal buoyancy force change the flow characteristics in dual enclosures. Under forced ventilation conditions, ambient air stream significantly affects fire transport phenomena by aiding or opposing the thermal buoyancy force. At higher velocity inlets, ambient air diffuses heat from fire and reduces temperature gradients inside dual enclosure. The forced air stream dominates buoyancy force and drives hot gases to propagate in reverse direction. The critical ventilation velocity that prevents the spreading of thermal plume from doorway opening is identified. The model employed has been validated with the existing experimental results available in literature.

A CFD Simulation of Indoor Natural Ventilation of a Residential District in Zhuzhou

With the promotion of building energy conservation, many residential areas are closely link with energy saving in design phase, and natural ventilation becomes the key to reduce building energy consumption. Thus, house design and building distribution of residential district is particularly important. Computational fluid dynamics (CFD) get rapid development in recent 20 years, especially in architectural design. This text established a model of part of a residential district in Zhuzhou based upon ANSYS FLUENT CFD software, and used numerical simulation method to simulate the condition of indoor natural ventilation under typical summer climate when the doors and windows of buildings were opened. The distribution regularities of indoor velocity field and pressure field and etc have been gotten. These data provide a theoretical basis to evaluate the building distribution of residential area.

A Numerical Simulation of VOCs Distribution in Indoor Environment of a Dormitory

This document utilizes CFD simulation method to confirm the distribution of a new dormitory under the condition of natural ventilation and get the visible result and analyses the result of simulation and monitor. Because of the sealing of the room is nice, the result of the simulation value well agree with the true monitor value. By use of CFD simulation method the detailed result of indoor velocity field and pollutant concentration can be get easily. This document provides a method and theory to do further research on indoor pollutant concentration of different conditions, such as different exhaust system, different exhaust volume and different pollutant resource location.

Natural ventilation of a room with an atmospheric-vent water heater in both on- and off-states

Instantaneous or tankless gas-fired water heaters are widely used in residential buildings to heat water for domestic use. For the combustion can process properly, a minimum amount of air is required, which can be obtained directly from outdoors or from inside the room. This latter case corresponds to the operation mode of the atmospheric-vent water heater, which is one of the most frequently encountered appliances to heat domestic water. As the room where the water heater operates is generally a living area, the installation design should account for the health and comfort requirements. Increasing the room airflow rates reduces the risk of harmful products from incomplete combustion but, as counterpart, important impacts on the thermal and energy performance of the room can occur. In this paper the natural ventilation conditions of a room with an atmospheric-vent water heater are investigated. Moreover, the effects on energy demand for thermal comfort are assessed. The study was conducted through the EnergyPlus simulation program, whose applicability to the problem was first tested. The results obtained are consistent with the expectations, allowing for a better insight into the level of compliance of the combustion air requirements and respective impacts on energy performance.

Application research of ECOTECT in residential estate planning

With the rapid development of China economy and the constant improvement of living standard in recent years, building energy consumption has already accounted for 46.7% of the total social energy consumption. It is urgent for China to explore the road of building energy conversation. In this paper, based on ECOTECT software, authors have done some beneficial explorations in the scheme design phase from the perspective of residential estate planning. Taking a residential estate in Ma’anshan City, Anhui Province as an example, authors have analyzed meteorological data and energy conservation strategies that are closely related to local environment. To realize the optimization of residential estate planning, some factors have been analyzed, such as building orientation, daylight on building, and natural ventilation condition. By the application of ECOTECT, designers could give full consideration to various ecological energy-saving methods in the early design stage. The results in this paper are useful for both building energy conversation and creating a comfortable living environment in future.

The Process and Mechanism of Electrolytic Manganese Anode Slime Lead Removal

Production of electrolytic manganese metal inevitably produces a certain amount of solid wasteelectrolytic manganese anode slime, with a high manganese content, but its difficult to recycle due to the presence of other impurities. Firstly, the washing method was used to remove the anode slime soluble salts, then its chemical composition and phase were analyzed. The flame atomic absorption spectrometer and X-ray fluorescence (XRF) analysis showed the anode slime mainly contained Mn, Pb, Ca, Fe, Cr, K, Se and other metal elements, with the average manganese content 45% and the lead 3.5%;X-ray diffraction (XRD) preliminary analysis showed that the anode slime was a colloidal system mainly containing the spinel structure of MnO2 and complex salts PbMn8O16xH2O phase, by high temperature roasting, the anode slime transformed from hexagonal system to cubic system , and the basic structure unit from edges connection to surfaces connection,the change of length,angle and fracture of manganese-oxygen bond provided the channel for the lead leaching;TG-DTA analysis showed that anode slime was dominated by water loss below 400°C,and started to lose oxygen beyond 425°C, and clear endothermic peak was observed at 500°C and 700°C, which showed the anode slime crystal structure changed at 500°C, anode slime weight loss tending to be gentle with some Mn2O3 generation at 700°C, and roasted crystal stabilizing to Mn2O3. Preliminary roasting and leaching purification technology route was proposed according to the above analysis results, and analysis of the purification process related factors was made. Under the condition of natural ventilation, anode slime was roasted at 700°C, and fully leached in 2mol/L HAc , with liquid-solid ratio 10:1, then leached anode slime was characterized by XRD and flame atomic absorption test, the results showed that anode slime manganese content increased from 45% to 67.5%, the lead content decreased from 3.5% to 0.1%, XRD indicated that the anode slime existing phase was Mn2O3. Anode slime after purification treatment can be further used for battery manganese source material, which provides an effective approach for the recovery of manganese anode slime utilization.

Temperature Field-Wind Velocity Field Optimum Control of Greenhouse Environment Based on CFD Model

The computational fluid dynamics technology is applied as the environmental control model, which can include the greenhouse space. Basic environmental factors are set to be the control objects, the field information is achieved via the division of layers by height, and numerical characteristics of each layer are used to describe the field information. Under the natural ventilation condition, real-time requirements, energy consumption, and distribution difference are selected as index functions. The optimization algorithm of adaptive simulated annealing is used to obtain optimal control outputs. A comparison with full-open ventilation shows that the whole index can be reduced at 44.21% and found that a certain mutual exclusiveness exists between the temperature and velocity field in the optimal course. All the results indicate that the application of CFD model has great advantages to improve the control accuracy of greenhouse.

Effectiveness of horizontal air flow fans supporting natural ventilation in a Mediterranean multi-span greenhouse

Natural ventilation is the most important method of climate control in Mediterranean greenhouses. In this study, the microclimate and air flow inside a Mediterranean greenhouse were evaluated by means of sonic anemometry. Experiments were carried out in conditions of moderate wind (≈ 4.0 m s-1), and at low wind speed (≈ 1.8 m s-1) the natural ventilation of the greenhouse was supplemented by two horizontal air flow fans. The greenhouse is equipped with a single roof vent opening to the windward side and two side vents, the windward one being blocked by another greenhouse close to it, while the leeward one is free of obstacles. When no fans are used, air enters through the roof vent and exits through both side vents, thus flowing contrary to the thermal effect which causes hot air to rise and impairing the natural ventilation of the greenhouse. Using fans inside the greenhouse helps the air to circulate and mix, giving rise to a more homogeneous inside temperature and increasing the average value of normalized air velocity by 365 %. These fans also increase the average values of kinetic turbulence energy inside the greenhouse by 550 % compared to conditions of natural ventilation. As the fans are placed 4 m away from the side vents, their effect on the entrance of outside air is insufficient and they do not help to reduce the inside temperature on hot days with little wind. It is therefore recommended to place the fans closer to the side vents to allow an additional increase of the air exchange rate of greenhouses.

Influence of atrium roof geometries on the numerical predictions of fire tests under natural ventilation conditions

The use of computational fluid dynamics (CFD) as a tool for the design of smoke control systems and fire protection in large spaces has become more frequent as accuracy and computational speeds increase. In the present work Fire Dynamic Simulator (FDSv5) has been used to study two full-scale experiments conducted in Murcia (Spain) of 1.36MW and 2.34MW pool fires burning inside a 20m cubic atrium under natural ventilation conditions. Different cartesian-grid approximations to the real geometry of the pyramidal roof have been investigated in order to assess the effect of stair stepping on the smoke layer and the temperature field. In general terms, good agreement between experiments and numerical simulations is found for all model roof geometries, especially far away from the fire source and the centreline. For example, at a height of 15m, the temperature differences between all geometry approximations are lower than 10%. This shows that the cartesian-grid simplifications proposed here are a good choice and allow for saving some computational resources. In order to extend the results to different designs, the model has then been applied to study a range of 16 different atrium geometries, varying the area-to-height-squared ratio from 0.4 to 3.8. In addition, a comparison with simulation with a previous version of the code, FDSv4, shows that it predicts higher temperatures and slower ascends of the smoke layer than FDSv5, the difference being lower than 12% and 100s respectively.

Natural ventilation and surface temperature distribution of piglet crate heated floors

This research had the objective of evaluating the influence of the natural ventilation on the surface temperature distribution of heated crates. The research used six crates from a farrowing room in a commercial swine production farm located in the state of São Paulo, Brazil. Three crates were heated using a heat mat while the other three had the environment heated by incandescent light bulbs (200W) fixed on the lateral wall. The surface temperature of the crate's floor (1.55x0.55m) was registered in 36 points, distributed in 18 quadrants (0.26x0.18m) using an infrared thermometer in three different conditions of the room's natural ventilation: opened, semi-opened, and closed lateral curtain. The isotherms and the temperature distribution of the floor heat were processed using the SURFER® (1995), and the statistical analysis was done using the MINITAB® (Statistical..., 2002). It was found that the room's natural ventilation had a significant influence on crate floor surface temperature distribution. The crate with a heat mat system provided higher temperatures and led to a more homogeneous surface temperature distribution.

Determinations of the fire smoke layer height in a naturally ventilated room

According to the case-based reasoning of natural ventilation designs in recommended Green Buildings, an investigated model space was proposed in this study. FDS simulations and full-scale experiments were carried out to measure the impact of natural ventilation conditions and the installation of a natural ventilation shaft on smoke layer descent during different fire scenarios. The feasibility of using the N-percentage rule to determine the fire smoke layer height in a naturally ventilated space was also investigated.In a non-fire room, the smoke descent curve determined from the FDS simulated temperatures is consistent with the experimentally measured temperatures and visual observation of the smoke layer. However, the thermocouples in the fire room are affected by direct burning and fire radiation, and the experimentally measured temperatures cannot be used to determine the smoke height. Under these conditions, FDS simulations can be used to compensate for the lack of experimental measurements. In fire scenarios without outdoor winds blowing into the building's interior, FDS simulations can reliably model the fire smoke layer height. When outdoor air blows into the interior, it causes the smoke layer temperature to become unstable. Thus, the temperature will not be thermally stratified, and the use of the N-percentage rule is not recommended.

Natural Safety Analysis of the Spent Fuel Residual Heat Removal in Loading and Storage Process of HTR-10

For the 10 MW High Temperature Gas Cooled Reactor (HTR-10), the residual heat of the spent fuel could be removed by natural ventilation in loading process. The spent fuel storage tank could shield radiation; the outside is covered by an iron sleeve, the spent fuel tank would be stored in atmosphere after fully loaded, and the residual heat could be discharged by natural ventilation in interim storage stage. The calculation showed that, the maximum temperature locates in the middle of the fuel pebble bed in the spent fuel tank in loading process and interim storage stage, and the temperature decrease gradually with radial distance, the temperature in the tank body and sleeve is evenly, it is feasible to remove the residual heat of the spent fuel tank by natural ventilation, and in the natural ventilation condition, the temperature of the spent fuel and the tank is lower than the temperature limit, which provides theoretical evidence for the choice of the residual heat removal method in loading process and interim storage stage.

Indoor Thermal Environment and Energy Conservation of Seaside Resident Building in Xiamen in Summer

The good and comfortable environment is beneficial to the health, and can improve working efficiency, make people imbued with more creativity. This means strengthening the competitiveness, increase economic efficiency. So, creating the good building environment not merely has a meaning on technology, and has social effect and economic meaning. In order to understand the situation of indoor thermal environment of the seaside residential building generally, a field measurement on the condition of summer was made in Xiamen from the last ten days of July to the first ten day of Aug, 2005, 2006 and 2008. Test the thermal environment and investigate the thermal comfort in residential buildings of natural ventilation condition, analyze the main influence factors of indoor thermal environment, and evaluate indoor thermal comfort with effective temperature (ET). The curves of indoor air temperature and relative humidity reflect the character of high temperature and high relative humidity in summer in Xiamen residential buildings. Discuss the methods of building energy saving. Suggest that, for seaside city in hot days, the natural ventilation and interval natural ventilation should be the main fundamental methods of improving the resident building thermal environment.

How a Natural Ventilation Shaft Affects Smoke Layer Descent in Room Fires

In this study, full-scale experiments were conducted to observe the influence of a natural ventilation shaft on smoke layer descent in room fires. An oil pan with a heat release rate of 50 kW was ignited in a model space to generate fire smoke for the observation of smoke layer descent and flow conditions under various natural ventilation conditions. It is found that when there is no natural ventilation shaft available in a room that is on fire, the height of the descending smoke layer in the fire room has nothing to do with whether the natural ventilation shaft has been set up or not in the adjacent non-fire room. However, when a natural ventilation shaft has been set up in the fire room, it is able to effectively raise the smoke layer height.

Full-scale measurements of indoor environmental conditions and natural ventilation in a large semi-enclosed stadium: Possibilities and limitations for CFD validation

The use of Computational Fluid Dynamics (CFD) to study complex physical processes in the built environment requires model validation by means of reduced-scale or full-scale experimental data. CFD studies of natural ventilation of buildings in urban areas should be validated concerning both the wind flow pattern around the buildings and the indoor airflow driven by wind and buoyancy. Reduced-scale wind tunnel measurements and full-scale on-site measurements both have particular advantages and disadvantages. A main disadvantage of reduced-scale experiments is the difficulty to fulfill the similarity requirements, especially when wind flow and buoyancy effects are combined. This paper presents the results of unique full-scale measurements for a situation in which accurate wind tunnel experiments are not possible: natural ventilation and thermal, humidity and CO2 concentration conditions inside a large semi-enclosed multifunctional stadium with relatively small ventilation openings. The emphasis is on three consecutive evenings on which concerts took place in the stadium. Although the repeatability of full-scale on-site measurements is in general quite low, nearly identical meteorological and indoor environmental conditions were present on the three concert evenings. Furthermore, the calculated air exchange rate based on CO2 concentration decay measurements shows that also the natural ventilation on the three evenings was almost equal. The paper addresses the possibilities and limitations of this type of experimental data for the validation of CFD simulations. The data will be used in future studies for validation of CFD models for wind flow, natural ventilation and indoor environmental conditions in buildings.