【 Weak current College 】 in air-conditioning environment of ventilator features the how to apply

In the air-conditioned environment, generally refers to the fresh air in enclosed or semi-enclosed environment human being fed into the outside world natural air. the surface of the Earth, wrapped in the atmosphere close to the thickness of the surface of the Earth is approximately 12 to 16 km of a layer called the troposphere. This is the Earth's surface of human and creature has adapted and survival of the air layer, he dissolved oxygen, nitrogen, carbon dioxide and other gases. In non-closed environment or cave, poor ventilation, it has been widely used in various types of ventilation equipment into the outside air which directly to ensure air purifiers and replace the exhaust, and also have a certain temperature conditioning functions. In the air-conditioned environments, due to thermal moisturizing, environment and external air natural convection cannot be exchanged. Need to transfer into the external nature air to maintain the environment air quality requirements, into the air called fresh air.
The importance of fresh air for air conditioning environment is a result of temperature humidity or purification treatment, outside air to join must also undergo treatment to maintain temperature and humidity clean original ambient air of constant values for the parameter. Therefore the Fed no longer only fresh air ventilation device dissipation problem, but a large flow of fresh air temperature of continuous feed into moisture large amounts of reactive power consumption. It's in the air conditioning energy occupies a considerable proportion. Fresh air is must and strive to achieve a low energy consumption, and therefore more attention should be paid to the analysis.
The need for fresh air
1. air pollution
In the practical application of the air environment, including human habitat or industrial process plants, even in a closed condition nor as fresh, because all kinds of environments have different sources, for example:
(A) human settlement or other organisms present in the environment, life cycle process be aspirated deflated processes such as smoked oxygen and exhale CO2 exhaust smell, smokers put smoke, etc.
(Ii) environment furniture and walls decorated release harmful gases and volatile substances.
(3) production process emissions of harmful gas or oxygen consumption.
(4) breeding mildew and moisture in the dead material disseminated smell.
In closed in long accumulation will be the original deposit air metamorphic hypoxia. People in closed air conditioning environment dizziness not so-called air conditioning sickness is due to the original deposit of air quality deterioration and lead to consequences.
Second, the means of improving air quality
Air modification can have two channels, one: by Oxygenator artificial oxygen and chemical decomposition, physical adsorption, ionization and photocatalytic and other means of addressing the Elimination of harmful gas and supplementary oxygen. But this way technology complex energy-consuming large only suitable space spaceship and underwater diving submarines, the special needs of the laboratory and other small space. Second: to large civil space, better approach is to use the natural rocks of air to dilute the original replacement substitution or keep out air, the air conditioning environment within the overall air quality improvements. This method is relatively easy to implement, less energy consumption, so widely used, but also our air-conditioning environment fresh air system engineering methods.
Fresh energy
Air conditioning environment of outdoor air project, essentially closed environment of new year sent the old works. Due to the existing air conditioning environment is as people require temperature humidity, purification, so as to maintain a specific State. Outside into the air must be the same treatment to ensure the integration of environmental air stays constant. Continuous access to large amounts of fresh air handling large amounts of energy, it is possible to achieve the air conditioning system total energy consumption by 25% to 40%.
Fresh air applications
The fresh air entering meet air conditioning environment requirements, there are three ways to implement.
(A) full replacement, with continuous feed into the outside for fresh air discharged squeeze in place of the former environmental air. In air-conditioning environment in this way is used only for the specific needs of small environment. For example, environmental chambers, special wards, less application. But in mine tunnel operation area of ventilation systems, and other non-air conditioning in the number of applications.
(2) partial replacement, in the big air conditioning environment that need to be focused on ensuring the high demands of the region, with directional set post blowing fresh air. For example, some industrial production processes with this on-demand blowing fresh air to the station to ensure higher requirements. In this way can improve the utilization reduced fresh air consumption, reducing energy consumption.
(3) mixed adjustment, on the original large air-conditioning environment exceeding air (such as oxygen is small, the noxious gas content too high), into the fresh air of the method mix, after dilution air environment of stability in qualified content.
This means easy to implement, easy to use, it is calculated as common way.
But fine analysis of the way, is to ensure the whole swimming pool in which to drink drinking is not exceeding the amount containing the entire pool of water are used new water dilution to qualified, new amount of wind is big, reaching the time slowly, greater energy consumption.
So far, new theories, new value is selected, you can press the environmental function to determine the outdoor air distribution mode, instead of simple press space volume multiplied by the value of the new amount of wind theory units.
The new air volume V determines the principles
New air flow value selection based on the three major premise. Aim to reduce consumption.
(A) pursuant to the air conditioning environment features and requirements
If the process flow of production workshop, cold storage warehouse, little or no space environment, you can determine, based on environmental realities overall ventilation rate whether you must, or need a small amount (m3/h). If it is a living environment, you should ensure that staff needs and comfort of a normal request, press people determine the air flow values m3/h. To ensure that the oxygen supply and reduce harmful gas concentration ratio, to meet the requirements.
(B) basis of fresh air in the form of layout and regulation
Should follow all local displacement ventilation, ventilation or hybrid adjustable displacement ventilation and Jet air and so different forms but use different values for the new amount of wind.
(3) air conditioning intensity of environmental groups and the staff of active determine per capita needed new air flow (m3/h.).
VI to control carbon dioxide levels to determine the new amount of wind
United States, in recent years has implemented the rule, that is, DCV "on-demand-controlled ventilation" DemandControlVentIlation this is adopted in recent years, energy-saving ventilation is in principle to control environmental CO2 concentration in the air, and outdoor CO2 concentration difference to determine the value of the new amount of wind.
General air conditioning ventilation system is a hybrid air ways, sent to outdoor fresh air to dilute the original indoor air to ensure that air quality does not fall below the required targets. Indoor air quality indicators are many, including oxygen must value and variety of harmful gases of maximum limits. DCV strategy is to "CO2 concentration difference" to determine the new amount of wind
CO2 from human and other animal and plant life cycle release fumes, indicating its contents in physical units is ppm, expressed as a per unit volume 106 of containing CO2 gas in the air of the same number of unit volume. Visible is a dimensionless value 10-6.
The Earth's natural environment in different areas of different height of ppm values are different, usually in the range 200ppm to 1000ppm. Natural fresh air around 400ppm. Indoor environment and features related to the people in situation of static and dynamic, the amount of CO2 emitted will differ by several times. Buildings, CO2 content may have 1000 ~ 3000ppm, air-conditioning environment should take less than 1000ppm.
According to the United States as a standard, indoor ASHARE 1000ppm, and outdoor air is CO2 as the difference is that 300ppm 700ppm, as practices take fresh air value for each human person 25.5m3/h..
The actual value from fresh air VII principles
(A) of indoor and outdoor environments, the difference between the concentration of CO2 is also different, the time can be selected by pressing the value:
2000ppm corresponds with 8.5m3/h.
700ppm corresponds with 25.5m3/h.
500ppm corresponds with 34m3/h.
350ppm corresponds with 50m3/h.
(Ii) the actual selection should be based on actual environmental requirements and the actual air quality and other harmful gases and amendments.
(3) select the fresh air, it should be noted that, if the actual environment outdoors outside air pollution is serious, the quality is poor, the introduction of fresh air Wolf doing time. It should be used when cleaning measures and appropriate application of fresh air.
Comprehensive analysis of reference instance selected value
In the actual design of the new amount of wind to 25.5m3/h reference datum. According to the different requirements and extend selection, to ensure functional condition, makes every effort to save energy. The following is a reference to the actual position of various types of projects:
Large stadium, theatre 8.0 ~ 8.5m3/h.
Grocery stores, classroom 8.5 ~ 10m3/h.
Places of amusement, common rooms and 17 ~ 20m3/h.
Restaurant, meeting room for 20 ~ 25m3/h.
Office 25m3/h.
Advanced hotel rooms 30m3/h.
Function does not explicitly select 25.5 ~ 30m3/h reference datum. human.
Conclusions of the
Fresh air applications is the central air conditioning system as an integral part of the entire central air conditioning system using effects and operating power consumption. Must seek to the correct value of appropriate programmes,, reasonable layout, to achieve good results and energy-saving purposes.