Velocity Reduction Method of Duct Design in HVAC

   In this article of HVAC, We will learn about the Velocity Reduction Method of Duct Design in HVAC...

Velocity Reduction Method of Duct Design

What is Velocity Reduction Method of Duct Design?

Velocity reduction of a duct is the reduction of the forward pressure in the duct wall through the upward duct in response to the vertical pressure difference in the upper and lower walls.

Pre-tensioning allows duct to be loaded more than required for the current local duct flow and create a pressure difference between the upper and lower walls.

The process of the duct is to decrease the upward thrust into the duct through contraction of the duct and extension of the duct wall.

VMR has several advantages over other ventilation methods.

VMR duct can be run as isolated and constant-speed unit.

This allows the duct to run without the use of pressure regulators in conventional ventilation systems.

The duct can also be kept within its operational conditions such as air quality and pressure for longer duration.

VRM duct has less risk of cavity failure compared to conventional duct systems.

VRM duct can also deliver ventilation to a greater number of areas than other systems.

VMR duct requires less than 1.5% reduction in the convective flow velocity, which is 10 to 40 times lower than conventional duct systems.

Air quality is monitored in various ways with VRM duct systems.

These include the air quality monitors.

The sampling of VMR duct improves the air quality and carbon dioxide levels in the ventilating area.

VMR duct has more benefits as compared to conventional ventilation systems.

It is used in many applications in which high ventilation rate is required.

VRM duct is an option for the ventilation and cooling system as it allows the system to be free of the pressure regulators.

The benefits are:

Besides these many more benefits of VRM duct can be cited.

Velocity reduction can be done by temporary depressurization, or by temporary widening and compression of the duct.

Velocity reduction with depressedurization is the most basic form of VRM duct.

The motion of duct at the walls is completely stopped.

This allows duct to be loaded more than required for the current local duct flow.

The reduction of thrust is limited to the movement at the walls.

Such ducts require additional modifications to the ducts and can be installed under small pressure systems.

The ducts are installed above the main chimney to eliminate the flow to the shaft.

The main limitation for VRM duct installation is the duct height.

VRM duct can also be installed above and below the duct to permit greater airflow than just at the floor, wall, or ceiling.

Duct length of under VRM duct can be 10, 20, or 40 m.

Surface distance is the distance between duct and wall.

It is usually 25–50 m for the upper floor ducts and can be increased up to 100 m with the expansion/contraction of duct wall, in case of VRM duct.

Velocity reduction with expansion/contraction can only occur on a slab of concrete, other objects, air-handling devices, or pipe system.

Velocity reduction with temporary depressurization can be done with the VRM duct with the following modifications.

An extension is required to increase the velocity of air in the duct.

This method can be used to relieve problem areas or ducts.

A valve is required to open and close to control the pressure during the process.

Ducts in buildings are to ensure proper air flow.

Advantages of Velocity Reduction Method of Duct Design

Temperature – A result of velocity reduction can be obtained in designing cooling ducts.

Systematically – This method of ducts design is time saving, user friendly and easy.

Versatility – It can be customized according to desired uses.

Mode of Use – It is appropriate for all kinds of buildings

What is Standard Duct Design Method of Duct Design?

Standard Duct Design Method of Duct Design is quite simple. It has some benefits like:

Protection – This form of duct design is used to ensure the protection of valuable items, assets or personnel from smoke, dust or other environmental influences.

Sustainable – It is achieved by adopting the energy efficiency measures and eco-friendly mechanical equipment.

What is Type of R-value Used in Type A or Type B Capacitorized Duct System?

R-value in Duct System refers to the insulation value of the conduit. Types of R-value used for insulation are:

Type A – There are six types of type A of capacitorized duct systems:

Type A + Pure Air – Type A + Pure Air are the types of type A ducts that utilize a single type of R-value. There are two types of pure air in this system. Type A+Heat, Type A+High-Efficiency – These ducts utilize a system with different types of R-value to obtain both high-efficiency and low-emission of heat and smoke. Type A+Lux – These ducts utilize system with mixture of different types of R-value to achieve high efficiency.

Type B – There are seven types of type B of capacitorized duct systems:

Type B + Pure Air – Type B + Pure Air are the type of type B ducts that utilize a single type of R-value. Type B + Heat, Type B + High-Efficiency – These ducts utilize system with different types of R-value to obtain high efficiency and low emission of heat and smoke. Type B+Lux – These ducts utilize system with mixture of different types of R-value to achieve high efficiency and low emission of heat and smoke. Type B+High-Efficiency – These ducts utilize system with mixture of different types of R-value to obtain high efficiency and low emission of heat and smoke. Type B+Flux – These ducts utilize system with mixture of different types of R-value to obtain high efficiency and low emission of heat and smoke. Type B+Heat – These ducts utilize system with mixture of different types of R-value to obtain high efficiency and low emission of heat and smoke. Type B+High-Efficiency – These ducts utilize system with mixture of different types of R-value to obtain high efficiency and low emission of heat and smoke.

Type C – There are four types of type C of capacitorized duct systems:

Type C + Pure Air – Type C + Pure Air ducts utilize a system with combination of different types of R-value to achieve high efficiency and low emission of heat and smoke. Type C+Heat – These ducts utilize system with mixture of different types of R-value to obtain high efficiency and low emission of heat and smoke. Type C+Lux – These ducts utilize system with mixture of different types of R-value to achieve high efficiency and low emission of heat and smoke. Type C+High-Efficiency – These ducts utilize system with mixture of different types of R-value to obtain high efficiency and low emission of heat and smoke.

Type D – There are two types of type D of capacitorized duct system:

Type D + Pure Air – Type D + Pure Air ducts utilize a system with combination of different types of R-value to achieve high efficiency and low emission of heat and smoke. Type D + Heat – These ducts utilize system with mixture of different types of R-value to achieve high efficiency and low emission of heat and smoke.

Type E – There are only three type E of capacitorized duct system:

Type E+ Pure Air – These ducts utilize a system with combination of different types of R-value to achieve high efficiency and low emission of heat and smoke. Type E+ Heat – These ducts utilize a system with combination of different types of R-value to achieve high efficiency and low emission of heat and smoke.

Type F – There is no type F of capacitorized duct system.

Types of R-Value Used in HVAC System:

When it comes to the R-value used in the HVAC system, there are three types of R-value:

Type 1 – Type 1 R-value, also known as Half-V-Value, is the most common type of R-value used in HVAC system. It is obtained from capacitorized duct system having 30 to 65% of the R-value. These ducts have been installed with mix of different type of R-value to obtain high efficiency and low emission of heat and smoke.

Type 2 – Type 2 R-value, also known as Full-V-Value, is obtained from ducts having above 70% of the R-value. These ducts have been installed with mix of different type of R-value to obtain high efficiency and low emission of heat and smoke.

Type 3 – Type 3 R-value, also known as Total-V-Value, is obtained from ducts having above 85% of the R-value. These ducts have been installed with mix of different type of R-value to obtain high efficiency and low emission of heat and smoke.

The concept of velocity reduction method is used to reduce the speed of objects in the heat conduction system.

The major challenge faced in all design of ducts, especially in new construction, is in determining the appropriate duct selection by a reduction of the effective length of ductwork in a system.

The ducts are not equally distributed over the floor spaces with increased length in areas requiring interior connections, particularly kitchen and bathroom.

There is a disproportion of ductwork in some areas where more than 60% of the floor space is used for living area.

Impedance shall be minimized and system airflow optimized.

The ductwork design should minimise the circuit complexity of high-performance ducts for the purpose of energy reduction.

Overhead ductwork may also cause environmental problems by absorbing or transferring a great deal of carbon dioxide.

The ductwork are constructed with precision, and finish work with an anti-corrosive coating is a prerequisite of high performance ductwork.

Decorative or smooth ductwork along the length of a wall, often found in older houses, should be removed to avoid delays and costs.

While ductwork costs can vary considerably, a majority of new ductwork is intended to be installed above the floor.

About half of the cost of installation is for the ductwork itself.

The costs for ductwork installation depend on the size of the ductwork, the type of ductwork, and the individual needs and requirements of the facility.

Advantages of using ductwork include protection from dust, dirt, and moisture penetration, as well as energy efficiency and reduced operating cost.

Disadvantages include the need for frequent maintenance and replacement, and potential safety concerns from ductwork that overhangs a wall.

Damage to the ductwork can cause the flow of air to be interrupted, causing a buildup of heat, and a loss of efficiency.

Installations of ductwork can become unsightly if they are not installed correctly.

Designing ducts by the Velocity Reduction Method takes into account the full lifecycle of duct systems, providing you with the best design for your new building project.

How to design HVAC ducts by Velocity Reduction Method?

To deal with high cost of cutting and welding, before getting any HVAC ducts manufactured in your home or office premises, you may use the "Velocity Reduction Method" as the design tool. This can be used before purchasing any duct system which can save your your funds and time as you will have to redesign the ducts with a new design. This will make the process easier and also save your time.

Ducts will be designed by using a CAD software and the correct size will be kept and all the ducts can be accurately measured and then manufactured.

As the manufacturing of HVAC ducts has reduced in India, it is a better idea for you to have the cheapest option which comes with all the good features. It is not easy to cut and weld HVAC ducts at the time of installation. This can be reduced and less costly and also it will give you all the good design and durable HVAC ducts.

The main purpose of this HVAC duct modeling is to identify and reduce the heat loss, thus creating more energy efficiency for the homes. Here, heat loss and air movement have been used as a pair to create the proper response for cooling a home. These are crucial factors in HVAC designs as you have to adapt to the real life situation. This means that you have to match the amount of air that is circulating with the actual energy utilization of the home.

How to design HVAC ducts by Velocity Reduction Method?

Do duct designers have to spend time looking for outdated textbooks or unsafe designs? Not a chance! Discover how Velocity Reduction Method (VRM) can enhance design accuracy and decrease cost.

When it comes to hot and cold air distribution, a good HVAC designer knows the importance of proper ductwork design. If you're one of the thousands of HVAC industry designers who's never heard of Velocity Reduction Method, what are you waiting for?

The key to accurate ductwork design is fitting the flow correctly into the finished ductwork. A bad fitting can throw off the direction of flow, decrease airflow, or even damage the wall components around it. If you don't know the right way to go about your ductwork design, why not try Velocity Reduction Method?

This innovative method makes it easy to design the perfect ductwork for your home. From sizing to kinks, shaft flow, cross-ventilation, or other technical challenges, Velocity Reduction Method will provide you with all the information you need to design HVAC ductwork to protect your home from leaks and save you money.

Advanced VRM tool features:

Accurately measure and calculate a ductwork project's final size and length

Based on research into the products' properties and applications, calibrate for accurate flow

Calculate accurate dimensions and slopes for ductwork in a fraction of the time using a simple process

Improve the design efficiency of any ductwork project by designing with VRM

Create and test different duct models with instant and accurate dimensional visualization

Provide easy-to-follow formulas and diagrams for your designs, to help you get your ductwork up to standard in a fraction of the time

Vertical duct specialist Velocity Reduction Method uses advanced airflow and duct design simulation technology to help you design better ductwork. This innovative ductwork design tool can help you achieve accurate and optimal performance of all types of ductwork. With its ability to calculate airflow and kinks, shaft flow, and cross-ventilation, along with shaft and baffle dimensions, you can meet your ventilation needs with confidence.

There is a direct correlation between duct efficiency and energy efficiency. Effective ductwork is an essential component of your home's overall HVAC system, so it pays to make sure your ductwork is installed to best suit your HVAC installation needs. When you are ready to create your ductwork design, we've got you covered.

Flying in the wrong direction? No problem!

Proper ductwork design can improve efficiency, which saves energy. HVAC professionals can use VRM to create custom solutions that maximize the efficiency of your entire HVAC system.

This software can calculate the ventilation space that will be needed. As you enter your design requirements, the software will calculate the ductwork required to achieve those performance requirements. For maximum efficiency, you'll need a duct system with extra space to meet the required airflow capacity. In some cases, the system can provide multiple paths for the air to travel to and from your home.

Step by step guide to duct design by Velocity Reduction Method

I present a step by step guide to designing ducts with by velocity reduction method.

It is a revolutionary method of designing ducts and involved a complex amount of process which can be really time-consuming.

The new method is simple and easy to understand and it may reduce the overall design time by 50%.

Also you can share your experience on duct design by Velocity Reduction Method.

Duct design by Velocity Reduction Method with Combiners

Step-by-step approach for duct design by velocity reduction method

Now you know the strategy behind implementing velocity reduction method in duct design, the major thing that you should keep in mind while choosing the material and where you want to place them.

In this article, I am going to present you a process of selecting the right material for your ducts.

The tool you are going to use is Combiners. I also explained how to configure it.

You can either use a variable amount or the number of combs for your configuration, you can also use your own.

It is very simple, it requires 4 clicks and you can compare the result in very few seconds.

You can easily see the difference in the flow between the two configurations.

If you use the two configurations for the selection purpose, then it may require 2 clicks.

Another thing is the range of tessellation, it can be either two, three or five.

However you can configure it so that it shows the results on the screen for 2-3 seconds and again, you can see the flow of that condition in the next 3-5 seconds.

I would recommend you to start with a configuration of two combs for measuring the flow.

Two Combs

Each combs has two parameters like FID and BP.

FID is the heat capacity, it indicates how much heat the duct can dissipate, which in turn lets you know how much energy loss you can expect when ducting.

BP is the pressure, it means how much pressure you can get in the ducts.

Designing flow through a duct by Velocity Reduction Method

I will explain how to design a flow through a duct with velocity reduction method.

First you need to place the propreties first. Then, let’s see the first configuration.

A flow through duct diagram

The whole process is pretty simple, all you need to do is

First click on the design panel, in the “Grid” area, click on the “Components”, then click on “Comma”, then click on “Figure Out”

The flow through duct is to be used to transfer hot and cold liquids. The “gas” section may be connected in case you want to do some gas control.

As you can see, there is a lot of stuff you can do to design the flow.

If the tube has a pressure differential (say, in case of air pipe), you may use the pressure to increase the size of the flow.

However you cannot do that in case of liquid duct, because the gradient wouldn’t be continuous and therefore wouldn’t be usable for you.

If the tube is not rigid (a liquid pipe, for example), then you can use variable resistance to generate the gradient.

The flow direction can be used to fine tune the flow.

Designing flow through duct diagram, using velocity reduction method

With the help of the Combiners, we can build up the flow in a duct and see its effect on the design.

In this way, you can have better understanding of the design and can take the necessary actions to make things happen in the design.

You can see how the Combiners work for your flow-through duct.

You should notice the different configurations in the visualization area, while placing the combs there.

In case of two combs, the velocity reduction method may require two clicks to change. However, in case of three or more combs, it will be 4 clicks.

There are multiple settings in the “Shape” area.

The flow direction should be set up to be in the horizontal direction, i.e. opposite the direction of flow.

If the flow is in the vertical direction, you may click on the right arrow and there will be settings for the vertical direction as well.

The flow direction should be set up to be in the horizontal direction, i.e. opposite the direction of flow. If the flow is in the vertical direction, you may click on the right arrow and there will be settings for the vertical direction as well. You can go into the “Friction” area. The selection of friction can be based on the flow. In case of two combs, the flow is not in the vertical direction, so you can choose a higher friction.

The selection of friction can be based on the flow. In case of two combs, the flow is not in the vertical direction, so you can choose a higher friction. Finally, if the flow is in the vertical direction and high pressure, you can choose the “Friction Power Limit” in order to maximize the performance of your duct.

That’s it. You now know how to design a flow through duct using the velocity reduction method.

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