Ventilation of the administrative and domestic building

Contents

Contents:

Job for Course Project

Introduction

Climatological data

Characteristics of space-planning solution of the building

3.

Purpose of rooms, characteristics of building structures, characteristics of technological processes in rooms

3.2. 

Characteristics of pollutants released in the premises

Calculation of air exchange by multiplicity, by sanitary devices

5.     

Calculation of air exchange from emitted contaminants

Substantiation of decisions taken to create normal sanitary and hygienic conditions in the premises

6.

Provision of optimum temperatures in the working areas of the room

6.

Ensuring optimal air mobility in the working areas of the room

6.

Provision of optimum relative indoor air humidity

6.

Calculation and selection of devices for air distribution and removal

Aerodynamic calculation of ventilation system ducts

7.

Aerodynamic calculation of air ducts of plenum ventilation system

7.

Aerodynamic calculation of air ducts of mechanical exhaust ventilation system

7.

Aerodynamic calculation of air ducts of gravity exhaust ventilation system

Calculation and selection of equipment

 11.    

Split System Selection

List of used literature

Introduction

The work of modern enterprises in many industries is inconceivable without creating a strictly set temperature, humidity and air speed in their premises. An urgent issue is the use of air ventilation in public and residential buildings, in buildings of theaters, cinema, meeting rooms, industrial buildings and. etc.

Modern ventilation is an important and complex branch of technology. It serves to solve the problems related to the creation of such meteorological and hygienic conditions of the air environment in industrial and other premises that would ensure the normal well-being of people, harmless work, and contribute to improving the productivity and quality of products.

Of all the tasks solved by ventilation, the most important is the task of ensuring normal sanitary and hygienic conditions of the air environment in production rooms, the technological processes in which are associated with various emissions (dust, gases, etc.) harmful to the human body.

Another important task of ventilation is to create constant meteorological air conditions in rooms with a large population, regardless of the time of year and weather. Such meteorological conditions should ensure the best possible well-being or, in other words, comfortable conditions for a person.

Ventilation units used to maintain certain predetermined meteorological indoor air conditions are called air conditioning units. 

Ventilation also plays a very important role in the technology of many industries, where the quality of products depends on meteorological conditions.

Fans are used in all sectors of the national economy. The most widely used fan plants are for ventilation, aspiration, air harvesting , air heating in industry, public and residential buildings (ventilation fan plants), for traction and blowing in boiler plants (traction fan plants), for traction and blowing in boiler plants (traction fan plants) for ventilation of mines and shafts (mine fan plants), as well as for maintenance. 

 The production of many  industries      : electronic, instrument-making, chemical, textile, radio, optical, food, engineering, etc., make certain requirements for the state of the air in the premises for  technological processes . 

The main  normalized  parameters in the rooms    are: temperature, relative humidity and air speed.

To meet these requirements    , air conditioning systems are  designed, the tasks of which in the production   rooms are to create  and automatically  maintain the specified parameters of the air medium under changing  meteorological  conditions and various heat and moisture inputs  .     

In accordance with the stated tasks , the Building Codes and Regulations (SNiP 2.04.0591) provide for ventilation and air conditioning to be used for the following purposes:

Achievement of standard meteorological conditions and air cleanliness in rooms, if they cannot be provided with natural and mechanical ventilation;

Creation and maintenance of meteorological conditions and air cleanliness in rooms or parts thereof according to technological requirements;

Creation and maintenance in production premises of optimal meteorological conditions or intermediate conditions between optimal and permissible meteorological conditions, if economically justified;

Creation  and maintenance of optimal meteorological  conditions  and air cleanliness established for   premises of residential and public  buildings and auxiliary   buildings and enterprises  . 

To ensure the specified air        conditions, supply air with certain   parameters must be supplied to the conditioned rooms, subjecting it to special   treatment in units called  air conditioners . 

Climatological data 

Construction area: Lviv;

Humidity zone: dry;

Geographical latitude: 49 ° s.;

Temperature: 26.4/19 ° С;

Barometric pressure: 745 mmHg;

Enthalpy: 13.7/4.2 kcal/kg;

Wind speed: 1/5.1 m/s;

The course project provides for the design of ventilation of the administrative building. The building consists of one floor, each 3.8 m high. The basement is absent. 510 mm thick structural walls consist of five layers:

limestone sand solution;

silicate brickwork;

polystyrene foam (insulation);

brickwork;

cement sand mortar.

Windows accept wooden with double glazing                      

Characteristics of space-planning solution of the building

This course project presents the building (bishop's house), which is equipped with an artificial supply ventilation system.

In rooms with a single air exchange and less, natural plenum ventilation is allowed. 

Both mechanical and natural ventilation is provided in this building.

As air intakes, louver grilles were selected.

The structural elements of the building are walls. Therefore, part of the ducts are combined with building structures .

Purpose of rooms, characteristics of building structures, characteristics of technological processes in rooms

The course project provides for the design of ventilation of the administrative building. The building consists of one floor, 3.8 m high. The building has an attic. The basement is missing .

The walls are made of red brick. Thickness of external walls is 510mm. The thickness of the internal walls is accepted as 150mm.

We accept wooden windows with double glazing. The dimensions of the windows are (depending on the space area):

1600 × 1200 mm

Structural walls consist of 4 layers:

lime-sand solution;

brickwork made of solid clay brick on cement sand mortar;

soft mineral wool slabs;

brickwork made of solid ceramic hollow brick on cement sand mortar.

Characteristics of pollutants released in the premises      

The building in my version is an administrative building. It has showers, washes,... therefore, no harmful technical pollutants can be released. During the operation of the building , CO2 will be released from people who are in the building, a large amount of moisture and heat is also released. 

Calculation of air exchange by multiplicity, by sanitary devices 

The amount of ventilation air is determined for each room on the basis of released hazards, or is determined on the basis of studies.

If the nature and number of hazards cannot be taken into account, ventilation air exchange is determined by multiplicities.

Substantiation of decisions taken to create normal sanitary and hygienic conditions in the premises

In this course design, the ventilation system for the public building was calculated. In the premises of public buildings and in auxiliary rooms it is necessary to arrange a plenum ventilation system with mechanical inducement. In this building, the air supply is carried out by one plenum ventilation system. The plenum chamber is installed on the 1st floor in the corridor. Air is filtered in the plenum chamber of the ventilation system, and heated in winter. 

For all rooms, the exhaust ventilation system is designed with mechanical and natural thrust. Natural ventilation systems are used if it is necessary to remove a small amount of air from the room. With significant volumes of removed air, mechanical drawing is used. Since it is unacceptable to combine latrine ventilation systems with exhaust ventilation systems of other rooms, separate mechanical exhaust ventilation from bathrooms is provided. 

Provision of optimum temperatures in the working areas of the room

Room microclimate is characterized by internal air temperature, relative humidity of air and speed of its movement. The combination of these parameters, which ensures the best well-being and highest performance of a person, is called comfortable conditions. It is especially important to maintain certain temperature conditions in the room. Relative humidity and air velocity usually have slight fluctuations. The temperature in the rooms is taken depending on the category of work (light, medium and heavy) and excess apparent heat. The specified temperature in cold and transient periods of the year is ensured by means of a heater installed in the plenum chamber. In the warm period of the year, it is not advisable to pass air through the air heater, since suspended impurities (soot, dust...) will be deposited on its cold surface, so the air heater is equipped with a bypass valve, which is in the open position in the warm period of the year.

Ensuring optimal air mobility in the working areas of the room

The required air mobility is achieved with the help of the calculated number of plenum diffusers and the specified optimal speeds in the air ducts and channels of the plenum and exhaust ventilation systems of the building. Set the air speed when leaving the diffuser 2 m/s (for inflow) and 3 m/s (for drawing). 

In the course project, the following apply:

TROX louvres;

When designing plenum and exhaust ventilation systems, it is necessary to follow the principle of maximum air circulation in the room, i.e. air must enter the room on the one hand, pass through it and be discharged from the room on the other hand, this is the most acceptable option.

Provision of optimum relative humidity in the working areas of the room

The calculated optimum values of relative humidity are taken within 6030%, with large values corresponding to lower temperatures. The permissible relative humidity for the cold period of the year shall not exceed 75%, and for the warm period of the year it shall be taken depending on the temperature of the internal air .

In our case, dry air is supplied to the rooms through plenum systems, which can be saturated with water vapors using stationary humidifiers or air conditioners.

Aerodynamic calculation of ventilation system ducts

Air distribution in ventilation systems is carried out according to more or less complex system of air ducts. Air distribution networks shall meet certain requirements:

- Ensure air performance;

- Have minimum head loss;

- Have an air flow rate that meets the requirements of sanitary standards;

- Have a noise level not exceeding the permissible level according to sanitary standards;

- Be airtight;

- If necessary, air ducts shall have appropriate heat , sound or steam insulation;

- The space occupied by the duct shall be minimal.

The purpose of aerodynamic calculation is to determine optimal ratios of capital costs and operating costs by means of reasonable selection of optimal diameters of air ducts and air flow rates. As a result of the aerodynamic calculation, the pressure loss in any direction of the gas flow is linked.

Aerodynamic calculation sequence:

1. We calculate air exchange by rooms (by heat, moisture, impurities).

2. We select the ventilation scheme and apply the duct route on the ventilation plan.

3. Draw an axonometric diagram of the ventilation system. On the axonometric diagram is applied: section numbers; length of calculated sections; number of ducts that pass through the section. 

4. At the end sections we apply volumetric air flow rates.

Volumetric air flow rate - the maximum value of air flow rate obtained during calculation of air exchange (by heat, by moisture and gas).

Air flow rates at end sections are determined based on calculation of air exchange. In prefabricated areas - the sum of expenses of the corresponding end sections.

5. Select the calculated direction. 

Design direction - the direction of serially connected sections, the total length of which is maximum.

6. We select and number the calculated sections. The sections are numbered starting from the outermost end section towards the flow increase along the main line.

The calculated section is a section of the duct, on which the flow rate, size and shape of the cross section, as well as the material from which the duct is made, do not change.

Lengths of horizontal sections are taken according to the building plan.

7. According to the flow rate (L, m ³), we find in the table "Data for the calculation of ducts" the nearest flow rate at the corresponding speed and calculate the values ​ ​ of the equivalent diameter (de), specific pressure losses (R, Pa/m), dynamic pressure (Rdin, Pa).

Recommended air speed in mechanical ventilation in main sections is not more than 8 m/s, and in branches 5 m/s. To prevent noise in ventilation systems of civil buildings, the actual speed in the main section is not more than 4-5 m/s, on branches - 3 m/s.

Air velocity in live section of louver screens is not more than 2 m/s.

In gravity systems, the air velocity shall not exceed 1.5 m/s. Moreover, for multi-storey buildings with collector ventilation schemes, the air speed for the upper floor is not more than 0.6 m/s. For each floor below, the speed increases by 0.1 m/s, but not more than 1 m/s.

In aerodynamic calculation equivalent diameter is taken by resistance.

dэ=2ab/(a+b)

a; b are the cross-sectional sides of the rectangular duct air.

8. We find pressure losses along the length of R·ℓmn, (Pa).

Rectangular ducts differ from circular ducts in that their perimeter is larger. In civilian buildings, rectangular air ducts are used, which allows you to achieve good aesthetic qualities in the interior of the room.

In this case, a coefficient m is introduced, which takes into account the fact that the friction surface of the rectangular duct is larger than the surface of the round section. This factor is taken from the Duct Side Guide .

Differences in channel roughness take into account the factor n. This factor is also taken from the directory.

9. We find the sum of local resistances (Αο). These include taps, tees, sudden expansion/constriction, process ventilation equipment.

10. We find pressure losses on local resistances Z = Αο· Pg, (Pa).

11. We find pressure losses on the site ΔРуч = Z+ R · mn, (Pa).

12. We find losses in the amount of sections ΔP.

In the process of aerodynamic calculation, the diameters of the air ducts and the gas flow rate are taken so that the total pressure loss does not exceed the available one. Therefore, the available pressure should be at least 10% more than the pressure loss of the ducts.

Rr =0.9ΔÉ

For mechanical ventilation systems, Pp is equal to the total pressure created by the fan.

For naturally induced systems:

Pp = gh (α1ο2)

The available pressure is due to the difference in air densities (cold and heated).

If the pressure loss in a section is greater than 10% of the pressure loss than in adjacent sections, it is necessary to link the pressure loss by changing the section of the channels with less pressure loss, or to install diaphragms or throttles.

Throttling washers of smaller diameter than air duct. Throttle washer is installed in the area with lower pressure losses. Note here that pressure loss difference is used to overcome throttle resistance. It is better to install throttle washers in vertical sections.

The calculation of the duct network in general is limited to the determination of pressure losses in the ducts at a given air flow rate.

They are defined by the section or diameter of the ducts and determine the air velocity at the projected flow rate and the corresponding pressure loss in the duct by 1 meter of length.

In areas where the non-binding exceeds 15%, we install shut-off devices with rotary flaps of the throttle type-air valves. Air valve is a device for control of air flow in plenum and exhaust ventilation units. Air valve is designed for proportional control and uniform distribution of air flow along cross section area behind valve of section.

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