International Journal of Civil Engineering and Technology (IJCIET) Volume 10, Issue 03, March 2019, pp. 691-712 Article ID: IJCIET_10_03_067 Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=10&IType=03 ISSN Print: 0976-6308 and ISSN Online: 0976-6316 © IAEME Publication Scopus Indexed DESIGN AND STUDY OF VENTILATION SYSTEMS FOR NATURAL AND PRIVATE BUILDINGS Nehayat H. Amin Ministry of Agriculture and Water Resources. Erbil, Iraq ABSTRACT Ventilation moves outdoor air into a building or a room and distributes the air within the building or room. The general purpose of ventilation in buildings is to provide healthy air for breathing by both diluting the pollutants originating in the building and removing the pollutants from it. The research summarized the following: 1) Ventilation is two types (natural and private). The private ventilation differs from the natural ventilation by adding filters and the work of blocking the air going out from the space and then putting it out by private ducts. Private ventilation also requires air rates and required ventilation models. The air is withdrawn from the zones according to the intensity of air pollution in the space. 2) This research showed the methods of air supplying which are through the air ducts, which are three methods (velocity reduction method, equal friction method, and static regain method) 3) Fans were identified as Centrifugal fans, Vaneaxial Fan, Tubeaxial Fan, and Propeller Fan. Vaneaxial fans were selected in the building model. It was identified the types of filters in the ventilation, including Input Filters, Pre-Filters, Primary, Final Filters, and High-efficiency particulate air (HEPA) filters used in the most polluted areas. Keywords: Study of Ventilation Systems. Cite this Article: Nehayat H. Amin, Design and Study of Ventilation Systems for Natural and Private Buildings, International Journal of Civil Engineering and Technology, 10(3), 2019, pp. 691-712. http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=03 http://www.iaeme.com/IJCIET/index.asp 691 editor@iaeme.com Design and Study of Ventilation Systems for Natural and Private Buildings 1. FIRST CHAPTER 1.1. Introduction Ventilation is defined as the process of providing or removing the air by nature or mechanical methods, from and to space. This air may either pre-treated or not pre-treated [1]. The quantities of required air for ventilation were a research field and controversy for many years and still exist [2, 3]. Various principles and ideas have led to the emergence of different ventilation standards. From these ideas and considerations of the adoption of quantities of exhalation air mainly to determine the requirements of ventilation, and remove moisture from internal air another basis and control the concentration of carbon dioxide, third basis [4]. The rates of ventilation currently accepted in home applications, commercial buildings, and others are based on the results of a number of scientific research began in the twenties and thirties of this century and some processes and immunological activities are characterized by the production of substances that may crumble or volatilize in the air, leading to producing air pollutants, Some of these pollutants may be harmful, toxic, or may be non-toxic, but are contaminated for air, flammable or explosive materials, or help them [5]. It is necessary for these industrial applications to know the characteristics of pollutants in some detail and the requirements of air purification and purifiers in the simple sense of the requirements of ventilation in air conditioning systems for comfort, the climatic factors (temperature, humidity, air movement, solar radiation) have a significant impact on the physiological comfort for humans. So ventilation is very necessary for the buildings, it is one of the main elements in the design of buildings, Natural conditioning and ventilation are important and have a great role in reducing heat stress and high temperatures [6]. They are the main solution for energy consumption crisis because the energy consumption crisis is due to mechanical adjustment, require interacting with these climate variables to remove the thermal accumulation and compensate it with a stream of refreshing moving air. The question that arises is why ventilation? The need to ventilate the spaces or provide them with fresh air is due to the following reasons: A. Oxygen is very necessary for human life and its continuity. B. Air acts as an energizer, and the level of air required depends on the size of the room to be conditioning because there are a lot of substances that release carbon dioxide (CO2) and other odors which emanate from human bodies or radiate from other substances present in the space. C. Ventilation allows the air movement through the spaces and this, in turn, affects the environment, here, Ventilation is considered a key to psychological comfort. D. Control of the air combustions in factories. 2. VENTILATION METHODS It is divided into two methods: 1. Natural ventilation. 2. Mechanical ventilation. In natural ventilation, there are two reasons that make the air move through space. The wind. The density difference between the outside air and the air inside. http://www.iaeme.com/IJCIET/index.asp 692 editor@iaeme.com Nehayat H. Amin 2.1. The wind effect wind is the result of different the pressure in the atmosphere, can determine the path of the wind through the trees and plants high and the velocity of the pressure transform to static and normal pressure, additional pressure will be generated (about 0.5 - 0.8 from the wind velocity ventilation) while low pressure is produced when (0.3 - 0.4 from the wind velocity ventilation), The difference between the two pressures will be generated through the building and lead to the entry of air to the space through the openings of windows or other openings [7]. 2.2. Stack Effect Hot air in the room tries to rise to the top because of its low density and take the place of cold air. Since pressure outside or inside is affected by wind, the process of stacking effect is partly controlled by wind pressure and partly by the design of the openings [8, 9]. 2.3. Natural ventilation and infiltration in industrial applications Natural ventilation is considered one of the cheapest ways to get moving air inside buildings, especially factories with small areas, which do not need large ventilation rates because they do not need capacity requirements such as air movement, there is also no noise, But there is a problem in the winter is caused by changes in the weather where cold air enters from the openings and it can be controlled through the roof or walls [1,10]. 2.4. Chimneys effect It depends on the power of producing natural ventilation in the buildings, which in turn results from changing the air due to differences in temperature. Due to the difference in pressure, the internal warm air is replaced by the external cold air while slow-moving air generated by thermal forces can be sufficient for both of the supply with fresh air and cooling with convection. These forces are very few and not enough to create the movement of air that can be obtained and necessary for some warm areas to provide thermal comfort [11]. Figure showing the chimneys effect on the velocity and movement of air. We can rely on the power of nature to display the dynamic impact of wind and to make the necessary efforts to catch a large amount of wind, thus we conclude the inevitable and http://www.iaeme.com/IJCIET/index.asp 693 editor@iaeme.com Design and Study of Ventilation Systems for Natural and Private Buildings essential importance of ventilation, which can be obtained in several ways, the most important of which are: * Stack effect as a result of changing temperatures * Mechanical methods * Pressure wind and air currents 3. MECHANICAL VENTILATION In mechanical ventilation systems, Fans are used to control air movement. In this case, the control is much more than natural ventilation. Mechanical ventilation is used in which the fan, the filter to clean the air, the batteries and the heater, where the air circulates through the air openings and goes to the rooms through the convection [12, 13]. Mechanical ventilation is a process of Disruptive in atmospheric pressure, where it is scientifically known that the air is moving from Positive pressure (+) to negative pressure (-), In other words, ventilation is: "Renewal, change, passage, replacement" for air in the space with pure air. This means that ventilation does not deal with the characteristics of the air, and this is done through Fans [13]. 3.1. Ventilation requirements 3.1.1. Air Requirements for Adequate Ventilation The Ventilation Rule of Thumb is an example of this (air change per hour, temperature rise between the inside and outside air in the system and the size for each square area) is meaningless to the effect of the thermal barrier unless the specific rate is constant for the successful exit of the systems similar to the suggestion of this standard that it is useful to give true change and confirmation of ventilation designs. Changing air flow rates at the upper level of the building is not necessary to secure equipped at the lower work areas [14]. Such ventilation should turn the roof air and turn it into the ground, making working conditions worse. Thermal barriers are reduced by a high temperature between the outside and supplied air, and the temperature rise of (50-60 °F) can easily carry the air about (30-25 °C), especially in areas with high roofs. A slight rise in temperature from (3 to 6 °C) is not suitable to provide comfort or discharge in hot weather and as low as the high temperature required by http://www.iaeme.com/IJCIET/index.asp 694 editor@iaeme.com Nehayat H. Amin large air volume and good design. For ventilation systems, maintain the working area within (2 ℃) for the temperature of the applied air with less air and higher temperature [14]. We can calculate the temperature rise in the following equation: H=1,08 Tq . q (H = 1.2 T .q) T: Temperature rise of the air (F°) (C°) H: The removed Heat (tu/h) (w) q: Air supply (CFM) (latter /sec) The amount of removed heat (H) shall include the internal heat for the equipment, processes, lighting, Solar cells and gain due to the transition through the roofs. Ventilation usually expresses about the size per square unit area and this relationship fails to calculate the true thermal discharge of the provided system. But it gives a relationship that not depending on the height of the building. It is the most logical approach to air changes per hour. For the appropriate design, the desired heat will be equipped that independent from the height of the roof for the spaces with few exceptions [15]. If the ventilation rate is equal to (10 L/SM2), it will give acceptable and good results for many factories that have an internal shop ranging from (400-300 W/m2) / (125-100 ft2). When the outlet ventilation center requires contaminant control, the output rates are constantly increasing than the natural ventilation required to control the comfort under these conditions, and the outlet rate will determine the air rates of the simple extruder system with the minimum distribution (and the designer or manufacturer to equip the compensation air) without disturbances when booking the hood and desired processes. To ensure the effective power of the outlet system center, we need a wellorganized distribution for air [14,15]. 3.1.2. The need for air compensating In most industrial enterprises, the need for air compensating by replacing the large volume of air that should come out and to give personal comfort conditions and industrial safety more in the operational processes. It cannot use the windows and other entrances in the stormy atmosphere because they represent obstacles. In particular, the need is more important for the equivalent air and can be summed up by the following points [16, 17]: 1. To prove the amount required to remove from the processes, combustion and the removed heat of buildings [17]. 2. To delete the cross-currents by the proper regulation for the air and avoid leakage of doors and windows and small openings, that is, the coverings are unsafe and ineffective by eliminating the dominant effects such as mobile dust affecting cooling or disturbances [17]. 3. To get the air from a pure source, the applied Air, we can be filtering it or not filtering 4. Allow control of the pressure of the building and the flow of air from one area to another, This control is necessary for three reasons: A. To avoid positive pressure and negative pressure, when opening the doors at the same time, we will encounter difficulty and gravity and avoid the conditions in paragraphs (1, 2, 3) above. B. To allow the identification or capture of contaminants and the positive control of air, humidity and air movement. C. Allow the removed heat which will be removed by the air of ventilation. The heat will be contaminated unless it is properly identified and removed otherwise will be spread to work areas or interfere with the applied air for conditioning [17]. http://www.iaeme.com/IJCIET/index.asp 695 editor@iaeme.com Design and Study of Ventilation Systems for Natural and Private Buildings 4. FANS Fans are naturally used the device to drive and circulate air or other gases in air duct systems, including air conditioning applications. Fans are divided into four types depending on how they operate and place them [18]. 4.1. Type 1: Centrifugal fans Which are the most widely used in air conditioning applications. This fan is compatible with most uses and can pump large amounts of air with good pressure. The fan is operated by an electric motor, either with a single shaft for the engine and fan together or with pulleys and belts. There are three possible types of fan wheels: Frontward curved blade fans, Backward curved blade fans or Axial Blades. The fan characteristics vary depending on the type of blades. This type of fan extends to include most fields, the fan chamber cover with Gases and vapors that causing the corrosion, the fan chamber cover and blades are painted with Anticorrosion pigment and pitch, it is sometimes made of stainless steel [18, 19]. 4.2. Type II: Vaneaxial Fan It pumps the air by a pivotal current, and the blades are similar to the turbine blades. In some fans, the angle of the curvature of the blades can be changed to give different pumping rates. The blades are based on a large base similar to the Aircraft fan base, using with these types of fans an air flow control panels either in front or behind the fan [20]. 4.3. Type III: Tubeaxial Fan The blades are normal and larger than their predecessors. The center on which the blades are based is smaller and the direction of the blade cannot be changed, but they are fixed [21]. 4.4. Type IV: Propeller Fan It is characterized by the fact that it cannot provide great pressure and is often used to insert and remove the air from a particular place without pressure, such as applications fans vent air from kitchens and toilet room and placed in the walls with or without air ducts very short [22]. 4.5. Fan power and air power The flow of air in the air ducts system is due to supplying the power to the system by a fan, the fan receives power from its operating engine. The goal of calculating the loss of energy (pressure) through the air ducts is to obtain sufficient information to determine the engine power and the velocity at which the fan should rotate, The selection of the fan for a specific system to pump a known air flow rate against computed pressure loss is the total loss of pressure in the system. Each fan has a net input power is a Fan Power [23]. There is dissipation in the fan's ability to overcome friction in the wheel bearings and dissipate in the friction form and disturbance through blades of fan chamber cover. The remaining is called Air Power, it is the net power that reaches the air current to overcome on the pressure drop in the air duct system, parts of the air conditioning unit, distribution slots and other parts of the whole system and accelerate the air to drive it quickly required, that is, it provides the static pressure and required Dynamic pressure [23]. PA = mg Ht = Q Pt Pt : total pressure http://www.iaeme.com/IJCIET/index.asp 696 N/M2 editor@iaeme.com Nehayat H. Amin Q: M3 /see The percentage between fan power and air power = The fan power Pf, which is the net power reaching to the fan axis, is calculated from the multiply the power that the engine used by its efficiency when negligible the loss in the process of movement transfer between them [23]. 4.6. Types of ventilation Ventilation is divided into two types: 1. natural ventilation 2. private ventilation 4.6.1. Natural ventilation Natural ventilation refers to the removal or supplying of the air supplied for comfort or replacement of The air coming out (Achieving ventilation refers to pollution control), the used systems can equip the air equation with the external system which is in the process of air conditioning to replace the outside air and represented by areas of comfort for people or remove the air that leaks out of the structure of the building as a whole [1, 15]. 4.6.2. Ventilation for the Storage Room, toilet room and showrooms This ventilation is important in the modern industrial facilities to remove the unacceptable smell and high humidity, in some industries, appropriate control of pollution in the workplace requires to avoid inhalation, as well as the appropriate health facilities with the appropriate ventilation needed for storage rooms, dining rooms, and rest rooms and showrooms. The entering air through doors or through walls In some cases factory air is polluted, Therefore air is filtered by preferred mechanical methods for ventilation, when we control the components in the work rooms is not appropriate or useless, the total exposure of workers and users certainly reduces the level of contamination of storage rooms and dining rooms and Break room is low by reducing the area with excessive of the supplied air. When using mechanical ventilation, the applied system can regulate the distribution of diffusers from ceilings and walls, or by supplying air from plenums to suit the distribution through the producing areas. In the storage rooms, the Air discharge must begin from the sanitary facilities and showrooms and the remaining draws from the roofs and storage rooms. These assumptions for the conditioning areas, which are produced from the edges of the doors and the most important different distributions, which allow the moving air in the storage area to the sanitary facilities and then to the showrooms [24]. 4.7. Private ventilation and their requirements 4.7.1. Ventilation and filtration for private buildings The system of ventilation and filtration for any factory working on radioactive decay materials is an integral part of us natural arrangements for the handling or transportation of these materials. There are two inherent risks are radiation and pollution [25]. The main function of the ventilation system is personal protection from the transferred pollution in the air. This function is common practice and isolating an effective building into zones and classifying each of these zones depends on the safety factors associated with the operations performed [1, 6]. There are four types of areas that are usually similar, each with a distinct trait in the required ventilation. The relationship between the types of areas is an important http://www.iaeme.com/IJCIET/index.asp 697 editor@iaeme.com Design and Study of Ventilation Systems for Natural and Private Buildings factor. The require to transport material through the boundaries of the designated area is one of the central problems to give a convincing system design. As well as, it is the basic principle of air duct between areas must be cleaning for most areas full pollution. While the reverse flow has not an important risk and is not desirable at the same time the relationship of size between zones represented by the limits of the process of air velocity and the need for a system that eliminates safety in the dangerous latent parts of the experimental project, which makes the design of the system very complex [26, 27]. It is for the modern methods that have been completed and are changing from a project and there are no standard and acceptable designs. The growth curve of the effective projects is the same in terms of figures for these projects [26, 27]. The invention of Radioactive Decay involves use that leads to a broad discussion with the admission laws which should in the future highlight the protection of workers in radiological institutions. This confirms and emphasizes the need to review experimental information and operational experience which are clustered in projects over the past two decades with the purpose of authorizing common problems and developing broad lines and convincing solutions for them in the future. In some projects, where the conditions are variable and where the original design is necessary to consider the suitability of existing ventilation systems [26, 27]. 4.8. Building Zones There are four zones within the building that are naturally numbered (1-4), which were developed by the International Organization for Standard item (ISO). The higher number indicates the high radiation risk in Ref 10. The number zones, unlike AEA, represent a natural similarity of these zones with the building by color laws. (ISO) does not make a specific reference to the outside of the building, but the AEA refers to these white areas as well as the changing areas that need to safely transport materials to and from the building. 4.8.1. Red Zone (ISO No4) The red zones include the indoor areas of the cell which are closed from normal working conditions and which are contaminated from operating load outside the area and reduce the level of pollution too (10-3 .cm-2) which can be exceeded in the continuity of red rays. Opening the port to allow it to turn Amber color under control conditions and there is no direct outlet to reach the Green Zone (Radiation Workspace). 4.8.2. Amber Zone (ISO Zone3) Services and maintenance zones for work equipment, cells and related to this zone, become contaminated when the doors of the cell are open and the cell surface is shut off from the transmission of materials, maintenance and for similar purposes. The connection between the amber and green zones must be under control conditions using the necessary interconnections and zones. 4.8.3. Green Amber (ISO Zone3) Which are within the radiation work area, which includes the natural works and the zone facing the cell working with the treatment of the decay of radioactive materials in the building, but should not become contaminated under normal conditions [27]. http://www.iaeme.com/IJCIET/index.asp 698 editor@iaeme.com Nehayat H. Amin 4.8.4. White Zone (ISO Amber) The offices and control rooms, where ventilation rates are determined by traditional measurements, they are located in the private contaminated building, classified as a green area under the AEA color system [27]. 4.9. The outside Zones for Active Building The pollution of Beta-radiation in green zones with active buildings should not exceed (10-3 μ.cm-2) with a radiographic design that does not exceed (2.5 Millirems Per Hour) 5 rems per year - and airborne radioactive gaseous material exceeding (1Mcp and 40 hour -week), Active spaces presence outside active buildings are defined as Active, which has the same limits as radiation and airborne pollution as green zones. The nuclear isolates are regulated so that the highest permissible dose to which people are exposed is (1/10) and by means of the indication of conformity to the minimum permitted airborne concentration. These zones are classified as white zones and within the active zones there are data designed as green zones, (Offices) where airborne considerations and airborne effectiveness are similar to (0.1 Mcp) but should not exceed (1 Mcp). Here ventilation only needs to equip the comfort conditions to work. Green zones shall be in contact with the red or amber zones within the building and shall contain a gradual pressure for the gradation and maintenance within the boundaries of the area and the deletion of the impact of the wind [26, 27]. 4.10. Pressure difference The direction of runoff should be maintained from the less polluted areas to those areas with high pollution. This is achieved by maintaining on the least air pressure in the most polluted zones and with the direction of the air duct. Acceptable measurements of how pressure varies between zones to ensure that there is no opposite flow of contaminants, but we maintain the double differences (local doors and openings for ventilation) in the formation of the changing zones needed at the boundary of the zone for the transfer of material and character [28, 27]. 4.11. Air Changes The number of air changes per hour within the zone depends on the maintenance of the acceptable process to people in the zone and in the case of the implementation of operations in the red zone and the qualitative values are classified as follows [29]: 1. Ventilation of the red zone: The rate of air change as a minimum limit is (6 times/ hour) 2. Maintenance of Amber zone: Naturally, the acceptable level of air change is (20 times/ hour) 3. Work zones of Green Radiation: The rate of air change (12 times/ hour) [27]. 4.12. Ventilation Models Ventilation system designs are used to achieve operating conditions and are affected by the interaction degree of the booking zone. There are two types of ventilation models [1]: A. The appropriate design of the new system or project in which the interaction is good for the reservation zones; B. Suitable designs for existing projects where good interaction is not impossible for these designs which are considered the systems of (Fresh Input) as shown in figures (1, 2, 3) where: http://www.iaeme.com/IJCIET/index.asp 699 editor@iaeme.com Design and Study of Ventilation Systems for Natural and Private Buildings Figure 1: illustrates a good interaction model for ventilation is shown where all extraction fans are attached to extraction filters and the extraction is 100% until it reaches the main extraction fan. Figure 2: illustrates the basis of simplified ventilation models where extraction is from the most polluted zone. Figure (3): illustrates a model for ventilation where extraction of this model from two different zones in the intensity of the pollution [27]. Figure 1 illustrates a good interaction model for ventilation is shown where all extraction fans are attached to extraction filters and the extraction is 100% until it reaches the main extraction fan. Figure 2 illustrates the basis of simplified ventilation models where extraction is from the most polluted zone. http://www.iaeme.com/IJCIET/index.asp 700 editor@iaeme.com Nehayat H. Amin Figure 3 illustrates a model for ventilation where extraction of this model from two different zones in the intensity of the pollution [27]. 4.13. Filters The principle of dividing the building into booking zones and maintaining air movement in these areas to prevent the spread of radioactive elements within the chosen building. Collect the resulting efficiency within the building and avoid the spread of activity outside the building, it is achieved by using different types of filters, including [30]: 4.14. Input Filters The input filters are used to stabilize the amount of air dust inside the building as low as possible. If the entering air is not filtered, the external filters need to be changed continuously because they will be exposed to the materials generated in the project and using good quality for internal filtration [30]. 4.15. Pre-Filters When the high amount of transmitted radiation from the worktable uses filters with a good filter for the working zone. The dust carries to the most hazardous zone and the Highefficiency particulate air (HEPA) extractors remove the dust until it remains at a concentration of (1 mg.m-3). The used isolators for high dust levels are re-filtered before the first HEPA filter is used. Ventilation Extraction is done by removing a large number of particles. The degree of re-filtration depends on the materials carried out and the cost of changing the filters [31]. 4.16. Primary and Final Filters In order to prevent the leakage of air containing radioactive materials to the ocean and reduce the proportion of these substances to prevent their access to the air and the first filter (HEPA) in the extraction area is designed to prevent the departure of pollutants to the outside area. The filters must be constantly changed. In the case of high radiation of the filters must be removed by the treatments of the cell (Manipulators) and filling for the purpose of disposal of radioactive materials and put the insulators in the first stage of extraction filters before helping extraction of air ducts to keep the ducts from becoming contaminated, in addition to the first stage of the nomination we add two High efficiency particulate air filters (HEPA) for the necessary considerations [31, 32]. To avoid leakage of dust from air ducts and building filters, place a final filter before the extraction fan as shown in figure (4). http://www.iaeme.com/IJCIET/index.asp 701 editor@iaeme.com Design and Study of Ventilation Systems for Natural and Private Buildings 5. SECOND CHAPTER 5.1. Building specifications The building consists of five workshops which are as follows: 5.1.1. Plumbing workshop: It consists of the melting furnace, the casting section, the sand section, the finished products section. The number of persons for this workshop is 10 person. The administrative section consists of the preparation of models and store management and the number of persons for this workshop is 7 person. 5.1.2. Turning workshop It consists of 6 lathes, 4 grinders, 4 drills; the number of persons for this workshop is 14 person. The administrative section consists of a rest room, store and administration. 5.1.3. Carpentry workshop It consists of 4 woodworking drills, 4 woodworking lathe, and 4 saws with 4 grinders. The administrative section consists of a rest room, store and administration. 5.1.4. Electricity workshop It contains a motor winding section and a department of maintenance of electrical equipment, contains a battery room in addition to the room management and rest room. 5.1.5. Welding and Blacksmithing of Workshop It consists of five welding machines, five welding (Tungsten Arc Welding) with a blacksmith. The administrative section contains a management room and a rest for workers The length of the building is 75 m The wide of the building is 17 m The height of the workshop Roof is 5.5 m The height of administrative sections is 3.5 m http://www.iaeme.com/IJCIET/index.asp 702 editor@iaeme.com Nehayat H. Amin 6. THIRD CHAPTER 6.1. Design of air ducts The air distribution system can be high, medium or low in air ducts. This depends on the spaces of the air ducts, the cost, the type of used windows and when there is a wider area for air ducts, It is recommended to use the system of low velocity because the construction of air ducts for this system is not critical and the cost of operating the fans of pumping the air is less If you use a high-velocity air system. When the need for the use of the central system or highvelocity with high pressures resulting from the use of this system, must considering the durability, sound and air leakage. In this case, circular air ducts and accessories are usually ideal for medium or high-velocity systems. As for the points to be considered in the design of ducts can be identified as follows [12]: * Placing the air equipped unit in terms of placement in the appropriate place for the average of air ducts * Areas of the building that are ventilated * placing the exits and entrances in terms of obtaining an integrated air distribution * Suitable sizes for air inlets and outlets * The sizes of Air ducts and their distribution * placing air regulator valves in natural areas The fresh air drawn into the heating and cooling air machines is an important factor in increasing the capacity of the cooling machines in summer and winter, and this is more obvious in our country in summer where the temperature of the air is relatively high. The air flow through the ducts is accompanied by pressure loss due to friction. The larger the air volume, the greater the friction loss. Similarly, the smaller the area of the duct, the greater the friction loss. The initial cost of the air ducts depends on its size. The small air ducts are initially cost-effective but the capacity required to pumping the air through these ducts is high and therefore the operating costs are high. Therefore, air duct designs depend on the balance between initial costs and operating costs 6.2. Methods of air duct design 1. velocity reduction method 2. equal friction method 3. static regain method 6.2.1. Velocity reduction method In this method, the Velocity is chosen for each section of the duct network, So that the speed is high at the outlet of the air intake fan, decreases at the branches, and it is the lowest possible at the end of the duct. The Velocity is selected according to the used air conditioning systems and their applications and by using the friction curve for the specified air size, the size of the duct and loss in friction is determined at each section, The process of collecting losses is then used by friction in each section and this method is usually used in simple air ducts systems such as rooms and small shops [33]. 6.2.2. The equal friction method In this method, the friction factor (friction loss per meter of equivalent length) remains constant during the air ducts system. The total loss of friction is calculated by multiplying the http://www.iaeme.com/IJCIET/index.asp 703 editor@iaeme.com Design and Study of Ventilation Systems for Natural and Private Buildings friction factor by the equivalent length of the duct network. The friction factor is determined at the primary velocity in the main duct and air volume [34]. 6.2.3. Static regain method The basic principle for this method is determining the size of the duct so that the increase in static pressure due to the decrease in velocity at each branch to overcome on the loss by friction at the successive sections for the duct or in other meaning, The pressure of the velocity decreases and the static pressure increases, so that there is a conversion from the velocity pressure to the static pressure called the re-dormancy from this method as in the equal friction method. The friction factor is calculated from the size and velocity of the air and the loss is in friction calculated by multiplying the friction factor in the equivalent length, From the beginning of the air-conditioning fan to the beginning of the first sub-duct and the design of the air ducts to the length of the air duct for the longest duct in the air duct system, so that the loss of friction at each start of the sub-duct is equal. This method is used in highspeed air-conditioning systems and air ducts designed in this method are smaller in size compared to the equal friction method but the friction loss is high [12, 23]. 6.3. Calculating the rates of Ventilation for persons Zone Number of persons Ventilation rate / sec Plumbing Workshop 10 75 Preparation of models 4 30 Administration 3 22.5 Turning workshop 14 105 Restroom for Worker 16 240 Administration 3 22.5 Carpentry workshop 16 120 Restroom for Worker 16 240 Administration 3 22.5 Electricity workshop 10 75 Restroom for Worker 10 150 Administration 3 22.5 Welding and Blacksmithing of Workshop 13 97.5 Restroom for Worker 13 195 Administration 3 22.5 The ventilation rate for each person in the workshops = The ventilation rate for each person in the restroom = The ventilation rate for each person in the Administration office = (3) 6.4. A model of calculating 1. We find the velocity and diameter of the air by knowing the air flow and from the Ashre design for the air ducts, considering (P = 1.0 pa / m) [12]. 2. The dimensions of the duct (w * b) for the knowing the area (A) where A=b w http://www.iaeme.com/IJCIET/index.asp 704 (1) editor@iaeme.com Nehayat H. Amin A = d2/4 = 225 / (4 106) = 0.0397 m2 ⇒ 4b = w = (2) Sub the equation (2) in the (1) b = 100 mm w = 400 mm Calculating the dimensions of takeoff (b1 and w1 from the first table) b2 = b1 b2 = 100 * = 20.75 mm As well as for (w2) considering (R = 1.5 m) = 0.25 R = b and w from the table = = 3.76 From scheme (2) we use the equation n = - 2.13 ( ) 0.126 = - 2.13 ( 0.25 ) 0.126 = -1.787 From scheme (2) we use the equation L/W = ( 0.33 )-1.787 = 0.68 = ( 0.33 The equivalent length L = 0.331 m Calculate fan power Total length equivalent = 0.525 + 0.525 + 0.53 + 0.54 Length of bend = 0.27 Total length of duet = 30 T . P . L (Total Pressure Loss) = 1.0 Pa/m Power of the fan = T . P . L = 32.39 (30 + 0.27 + 2.12) = 32.39 Pa ( volumetric flow rate ) 0.180 = 5.83 Kw http://www.iaeme.com/IJCIET/index.asp 705 editor@iaeme.com Design and Study of Ventilation Systems for Natural and Private Buildings 6.5. Design of air ducts for workshops and offices We use the equal friction loss method, Considering the difference in pressure per meter is P (1.0 Pa / m), which is the average of maximum limit (1.5 Pa / m) and the minimum limit (0.5 Pa / m) Fan (A, c) for workshops, fan (B, D) for offices and rooms Section A – R1 R1 – R2 R2 – R3 R3 – R4 B – R5 R5 – R6 R6 –R7 R7 – R8 R8 – R9 D – R10 R10 – R11 R11 – R12 R12 – R13 R13 – R14 R14 – R15 R15 – R16 C – R17 R17 –R18 R18 – R19 R19 – R20 R20 – R21 R21 – R22 Q/sec P Pa/m Length M 180 142.5 105 52.5 315 292.5 172.5 52.3 30 652.5 630 435 412.5 262.5 240 120 292.5 232.5 172.5 135 97.5 48.75 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 12 6 6 6 5 3 4 7 5 6 4.5 5 4.5 10 3.5 3 12.5 6.5 6.5 6.5 4 4 http://www.iaeme.com/IJCIET/index.asp Velocity m/sec 4 3.75 3.5 3 5 4.75 4 3 2.75 5.75 5.5 5 4.5 4.25 4 3.75 4.75 4.5 4 3.75 3 2.5 706 Diam Area M2 (mm) 225 0.0397 200 0.0314 175 0.024 150 0.071 300 0.070 275 0.059 225 0.039 150 0.017 125 0.0138 400 0.125 350 0.096 300 0.070 275 0.059 250 0.049 225 0.0397 200 0.0314 275 0.059 250 0.049 225 0.039 200 0.031 175 0.024 150 0.0176 Dimension W * b (mm*mm) 488 * 100 400 * 79 400 * 60 400 * 44 531 * 133 447 * 133 300 * 133 133 * 133 104 * 133 709 * 177 543 * 177 399 * 177 353 * 177 277 * 177 224 * 177 177 * 177 488 * 122 488 * 101 488 * 82 488 * 64 488 * 49 488 * 36 editor@iaeme.com Nehayat H. Amin 6.6. Calculations of Bends Take off R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R19 R/W 2.50 2.50 2.50 2.50 1.88 2.23 3.34 7.52 9.62 1.41 1.84 2.50 2.98 3.6 4.45 5.64 2.05 2.05 2.05 2.05 2.05 2.05 n -1.46 -1.46 -1.53 -1.61 -1.78 -1.82 -1.92 -2.13 -2.19 -1.78 -1.84 -1.92 1.96 -2.01 -2.06 -2.13 -1.46 -1.42 -1.40 -1.40 -1.49 -1.53 http://www.iaeme.com/IJCIET/index.asp L/W 1.31 1.31 1.33 1.35 2.34 1.75 0.82 0.14 0.07 3.92 2.49 1.44 1.05 0.91 0.45 0.26 1.770 1.776 1.728 1.73 1.79 1.82 707 b/w 0.052 0.052 0.075 0.111 0.250 0.297 0.444 1.000 1.279 0.250 0.326 0.444 0.528 0.639 0.79 1.000 0.051 0.053 0.036 0.037 0.061 0.074 L(m) 0.525 0.525 0.530 0.540 1.243 0.782 0.247 0.0195 0.008 2.779 1.35 0.577 0.353 0.254 0.100 0.047 0.862 0.86 0.84 0.84 0.87 0.88 editor@iaeme.com Design and Study of Ventilation Systems for Natural and Private Buildings 6.7. Fan power calculation Total length equivalent(m) 2.120 2.290 5.176 5.469 Length of Bend(m) 0.27 1.8 0.33 4.02 Fan A B C D Total length duct (m) 30 24 40 36.5 Total pressure Power of fan T.P.L (Pa) (kW) 32.39 5.83 28 8.85 45.4 13.29 45.98 30 6.8. Fan power calculation We calculate fan power on welding and Blacksmithing of Workshop, the drag rate of each welding machine is 7.5 L / sec From the right side of the workshop [25] 6.8.1. Inlet losses K ( U2 / 2g ) Head loss = 0.061 K = 0.43 U = 3 m/sec Head loss = 0.062 0.43 (9/2 9.81 ) = 0.012 m 6.8.2. Calculations of Bends = = 0.5 = n = - 2.13 ( = ( 0.33 = 2.5 )0.126 = - 2.13 ( 0.5 ) 0.126 = - 1.95 m ) n = ( 0.33 2.5 ) -1.95 = 1.455 L = 0.873 m Total length = 2 + 2 0.873 + 0.012 = 3.758 We take the amount of pressure losses (1.0 Pa / m) T.P.L = 1.0 3.758 = 3.758 Pa Power of each fan = flow rate http://www.iaeme.com/IJCIET/index.asp 708 T.P.L editor@iaeme.com Nehayat H. Amin = 3.758 0.075 = 0.281 Kw The left side is similar to the right side but added to the losses is the length of the duct amounted of (8 m) Total length = 3.758 + 8 = 11.758 T.P.L = 11.758 Power of each fan = 11.758 0.075 = 0.881 Kw A section of the duct at the rectangle inlet (0.3 0.6) (b workshops a fans to outside, the power of each fan (1 Kw) http://www.iaeme.com/IJCIET/index.asp 709 w), placing in the rest of the editor@iaeme.com Design and Study of Ventilation Systems for Natural and Private Buildings 7. CONCLUSIONS Ventilation is two types (natural and private). The private ventilation differs from the natural ventilation by adding filters and the work of reserving the air outside the space and then putting it out by private ducts. The private ventilation also requires air rates and required ventilation models. The air is withdrawn from the zones according to the intensity of air pollution in the space. Air is withdrawn from areas according to the intensity of air pollution in the space From this research we know the methods of air supplying which are through the air ducts, which are three methods 1. velocity reduction method 2. equal friction method 3. static regain method Fans were identified as Centrifugal fans, Vaneaxial Fan, Tubeaxial Fan and Propeller Fan. Vaneaxial fans were selected in the building model. Through this research we identified the types of filters in the ventilation, including Input Filters, Pre-Filters, Primary, Final Filters and High efficiency particulate air (HEPA) filters used in the most polluted areas REFERENCES [1] [2] [3] [4] [5] [6] Chartier, Y., and Pessoa-Silva, C. L. (2009). Natural ventilation for infection control in health-care settings. World Health Organization.ISO 690 Reed, W., and Taylor, C. (1900). Factors affecting the development of mine face ventilation systems in the 20th century. Taylor, R. W. (2007). 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