Variable air volume is described along with categories, different kinds of properties, types of metals, etc.
Let’s explore the Properties of Metals and types of metals!
Let’s understand the basics of variable air volume or VAV system. Some systems provide an immense advantage to humanity. It acts as shielding and offers maximum comfort.
Though the variable air volume is the core process that entails effective functioning, the whole system helps get maximum benefit. An overview of this variable air volume entails that it is equipped with a supply duct that cools down the environment by providing supply air at any desired temperature.
The first and foremost thing that holds massive importance is the core definition of this system.
Let’s delve into the practical introduction of this system.
A VAV system is an effective way by which appropriate room temperature in the desired environment by a dynamic change in air quantity rather than varying or changing the temperature.
A system is defined as a series of individual parts that interact and function accordingly to ensure a specific or desired design.
The VAV system mainly consists of a,
It also includes some of the subsidiary parts such as,
The above parts or pieces of machinery synchronize in a way and provide a comfortable and cozy environment. This can be attained in a specific building or any covered zone.
It is vital to understand the different parts that make this VAV system an efficient one. We will provide a brief description of all the components that make the VAV system a success.
While understanding the VAV system concept, it is imperative to get knowledge of some essential terms. These terms will provide an easy understanding of the whole system.
This is simply a box controlled with the help of a thermostat, which regulates the air quantity. This system provides conditioned air to the desired zone or environment.
It is simply a box consisting damper, inlet, outlet, actuator, controller, heater (as applicable)
Remember, the VAV box is a part of the VAV system.
This is the equipment that helps in providing hot air in the desired zone. With this apparatus, heat can be produced, which ultimately helps provide the desired heat for the zone or produce steam.
A designated passage or a pipe of fiberglass or sheet metal through conditioned or heated air passes.
This equipment has numerous slats at various angles, which helps in deflecting heated or conditioned air in different directions from an outlet.
This is safety equipment installed in the VAV system. The fire damper has an efficient function that provides automatic blockage to the smoke and fire if it happens. It is required in those places where the duct is in the vicinity of a fire-rated shaft, a firewall, or other fire-prone areas.
The chiller or condensing unit is among the vital parts of the VAV system that provides a compelling advantage by providing a compressive refrigeration cycle. This helps to chill the water that helps to cool the desired zone.
The air handler is a set of machineries that contains different equipment, which helps the inefficient distribution of conditioned air in the specific zone. It generally comprises filters, fans, etc.
The ductwork comprises different parts that help in the overall process of the VAV system. Mainly it has a system of ducts, dampers, and connectors. The processes involved are air conditioning, heating, and ventilation.
This is among the essential parts of the VAV system that automatically performs actions to temperature change. This helps activate the switches that control all the other parts of the VAV system, such as refrigerators, furnaces, and air conditioners.
The above are some of the critical parts of the VAV system that performs different functions. Here we are also providing some of the efficient processes that are related to these parts.
Moreover, this system provides thermal comfort, which is nothing but the body’s ability to release heat and moisture due to several metabolic actions.
Different processes constitute thermal comfort; some of them are as follows:
A place that is closed and doesn’t have any openings needs an effective VAV system. These areas experience massive surges of humidity, which can be lethal. Places like conference halls, auditoriums, etc., need a VAV system to eliminate the humidity. The VAV system performs this action by releasing air into that area.
Heating is the core function of a furnace that is present in the VAV system. Specifically, there are heating coils that are located in the ducts which provide effective heating.
Thermal comfort has a fair share of the cooling aspect, and the VAV system distributes it according to the demand. This cold air can be preheated to maintain the desired ventilation requirements.
The volume of air delivered to the zone at a set temperature helps in controlling the temperature of the zone. When it comes to the mechanism, the volume of air distributed by the VAV boxes is controlled by a thermostat located in the zone.
VAV systems are also capable of depressurizing as different areas need to be depressurized to provide sufficient thermal comfort.
The VAV system provides effective measures by providing a dynamic approach to the volume of air, which helps in those places that are not equipped with appropriate pressurization requirements.
Understanding these core processes makes it relatively easy to grab a fair share of knowledge about VAV systems further. One will get hands-on help in understanding the overall concept with this.
Let’s try to understand how does VAV system work. The main feature in the VAV system is it allows zoning of buildings.
Suppose a building has two rooms,
Now, if we consider a CAV system, we cannot maintain three different temperatures in different areas but if we consider a VAV system, it can be possible.
The main difference between a CAV & VAV system is that an additional VAV box or VAV terminals are included in the VAV system.
Let’s try to understand the main working philosophy.
Now, let’s see how the VAV box works in the system.
Check a very nice video from The Engineering Mindset,
Let’s see the basic differences between the CAV system and the VAV system.
The difference between the CAV system and the VAV system, are as follows,
|CAV System||VAV System|
|CAV system stands for constant air volume system, means the air supply is constant with different temperature.||VAV system means air flow rate will be different at a constant temperature.|
|It can use for the single zone as well as multi-zones, however, efficiency is more in case of a single zone.||It can use for the single zone as well as multi-zones, however, efficiency is more in case of multi-zones.|
|System efficiency for multi-zone is less||System efficiency for multi-zone is high|
|In case multi-zones, zone wise heater needs to be considered and it reduces efficiency||In case of multi-zones, VAV boxes are used to control the temperature. In case, heating is required, the same shall be served by the heating element in the VAV box.|
|Normally, where load variation is less, the CAV system is preferable. Like, industrial buildings, control buildings, etc.||Normally, where load variation is more, the VAV system is preferred. Like, malls, concerts, hotels, etc.|
There are some of the specific features that define the overall benefits of this system.
Following are some of the efficient ones that help humankind in the best possible ways.
Let’s consider two rooms that have been provided with a VAV system. This example is just to illustrate the VAV system basics only. The room has a heat load of 50.0 kW and it needs to be maintained at 22 oC temperature to be maintained.
Outside design temperature is 45 deg. C.
Let’s try to understand the system.
q = Cp X ρ X Q X dt
q = Cp X ρ X Q X dt
Q = q / (Cp X ρ X dt )
Hence, we get,
Now, the VAV system will adjust normally this 1770 lps air quantity.
Let’s check how the VAV system works if the load changes say in the summer season it is increased to 60 kW and in the winter season it is reduced to 40 kW.
Option-1: Heat Load Increased to 60 kW
Air quantity, Q1
Here, the temperature difference is constant and the VAV system, as well as the VAV terminal, increases the air quantity by increasing the damper opening area and maintain the required air quantity of 2150 lps.
Option-2: Heat Load Decreased to 40 kW
Air quantity, Q2
Here, the temperature difference is constant and the VAV system, as well as the VAV terminal, decreases the air quantity by decreasing the damper opening area and maintain the required air quantity 1440 lps, and saves energy.
The versatility of the VAV system is its forte. The common usage of this system is in large to medium office buildings.
Apart from these, it is also used in,
Some of the core usages of this system are in hospitals and nursing facilities, as these facilities need a specific level of pressurization that can be achieved with this system.
However, this attribute can be cumbersome as it is difficult to maintain a specific pressure in any zone.
It can also be used in large offices as this system helps in achieving maximum efficiency of the HVAC system. The customized control of the environment makes it quite apt for usage.
One should use this system as there can be problems with latent heat loads when used in massive auditoriums. The major problem that occurs is sound pollution if the equipment is located on the ceiling.
The benefits of the VAV system make it quite efficient and provides all-around help for desired areas.
Here we are providing some of the core benefits:
The simplistic design of the VAV system
While installing a VAV system, it is recommended to consider this attribute as the foremost fault that comes in the VAV system is the complexity.
Coordination while implementation
Implementation at the initial stage for any system is vital and complicated. Sometimes it is quite hard to attain proper communication.
The VAV system is among those systems that are effective in critical climatic conditions.
It is quite essential to consider numerous factors while installing the VAV system, as there are numerous delicate pieces of equipment. In addition to that, attaining optimal efficiency is vital; it can only be achieved by proper installation.
The all-round analysis of the VAV system provides all the information. Being one of the most advanced and proven temperature modulation systems, one can get optimal benefits. With this information, you will get a holistic view of the different terms associated with VAV systems. In addition to that, the applications of this system help to use vividly. The advantages and disadvantages are the foremost information that holds the crux of the system.
This genre of dynamic temperature modulator system has a bulk load of information. The VAV system has wide applications, and that needs further elaborative analysis.
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