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Heating Ventilation and Air Conditioning Full Course - HVAC Course (Part 11)

 Reducer sizing in Duct Design :

         These are devices of fittings that connect through unsized ducts or sized ducts. or It is a cooling or heating joint which connects to the linearity of duct run or length which has to be sized.
The aspect ratio for duct reducer is 1: 4 to 1: 7, usually for low-velocity Aspect ratio duct reducer is taken low as 1: 4 and for high, it is taken as 1: 7.
As per SMACNA Reducers should be from 400 to 750mm of length for low and medium velocity duct, headloss, and friction loss should be 0.165.
                    As per SMACNA standard duct reducer length should be 800 to 1500mm for high velocity duct and head loss or friction loss should be 0.6.
There is another method known as " Australian Method or Australian Reducer Method" ranges from 150 - 1500mm of length.
There are two types of reducers:
* Concentric Reducers
* Ascentric Reducers.
w1 - w2 >= 100 (we will reduce)
w1 - w2 < 100 (There will be no reducer and there will be straight duct)

w1 - w2 = 600 - 400 = 200
Length of reducer = 4 x 200 = 800 approximately equal to 750.

Air Conditioning

        It is the conditioning of air according to human comfort zone condition. Criteria recommended by ASHRAE 76 °F, 50% RH , or 22 to 24 °C. or
                                                                        It is the simultaneous control of humidity, temperature, radiant energy, air motion, air quality and quantity within space, which satisfies human comfort condition criteria, is known as Air Conditioning.

Classification of Air Conditioning systems

* Direct Expansion System (DX type) or Non centralized system.
    - Window AC system
    - Split AC system
    - Ductable AC system
    - Package AC system
    - Cassette AC system

* Centralized AC system
    - Chiller System
        - Water Cooled Chiller System
        - Air Cooled Chiller System
    - Variable Refrigerant Volume System (VRV) or Variable Refrigerant Flow System (VRF)

Direct Expansion System (DX type) or Non centralized system.

DX Type air conditioning system is a kind of heat pump system that utilizes electricity to make ice water into vapor which then gets condensed after cooling down naturally.This technique can help with saving energy and reduce carbon emission.

DX-type air conditioner uses refrigerant gas that flows from compressor to condenser coil, where cold air outside surrounding the unit is cooled. Then the cold air passes through evaporator coil where the refrigerant changes back to liquid form and absorbs the heat from indoor space. This heat absorbed goes to the condenser coil where it is released to the environment as cold air again. Since cold air outside is needed for evaporation, this increases efficiency of the system.

DX type air conditioning system has two major advantages over conventional central air conditioning systems: firstly, DX type air conditioning systems are environmentally friendly since they do not have any freon emissions; secondly, DX type air conditioning units can provide both heating and cooling functions simultaneously, making them ideal for areas that experience extreme temperatures.

However, due to technological advancements and high cost, DX type air conditioning was rarely used until now. Due to its high price, its only use is mainly in healthcare facilities and luxury apartments. However, DX type air conditioning is expected to gain popularity in the near future as government regulations become more lenient towards environmental protection.

Window AC system

A window air conditioning system can keep your indoor space at a comfortable temperature without using much electricity. If you want to chill out and enjoy some peace while being productive, then this could be a good option for you. There are many different systems that might work for you, but if you really want to save money, then choose the correct unit as per your room size.
            For your money, you want efficiency from your cooling unit. Not only does it save money, but a well-designed window air conditioner can operate up to 20% cooler than any other type of A/C system. In addition, they are quiet, easy to install, and they do not impact the aesthetics of your home.
An efficient window air conditioner is made not just from quality materials, but also designed using the latest technology. This allows them to be compact enough to fit into most windows without taking up too much room. They are also light weight, weighing less than 4 pounds.
                If your home has a window air conditioner installed, you may not know that you can use this device to cool your house while saving energy. Window units usually have some fans inside them that circulate warm air into the room. You can take advantage of this by installing a fan outside of the window unit that blows cool air into the room. This can eliminate hot temperatures inside your home and lower power bills at the same time!

Split AC system

Split AC systems are designed to provide a higher level of comfort than traditional central air conditioning units. These cooling devices use multiple compressors and evaporators to cool your home. Depending on what type of split AC system you have, they may run off of electricity, natural gas, propane, or even diesel fuel. When running on propane, these systems reduce carbon emissions compared to traditional AC units that use electricity. However, if you are looking for the best energy efficient split AC system, it would be better to go with a heat pump rather than a standard system. In both cases, the compressor unit is installed outside or inside the house while the condenser unit stays indoors. This means that your home’s internal environment is always kept at a comfortable temperature. Another advantage of having this kind of system is that you can install the equipment yourself and save money. In addition, a split AC system usually allows you to enjoy lower utility bills and costs less expensively.
                    The split air conditioner is a simple concept but can have some complex issues. When installing a split system you are giving yourself more options when you need to cool down your home. You can now easily control exactly how much cooling power your unit has and whether you want your units to run on gas or electricity. This means that you can choose if you want to save money or if you want to go green.
Split Air Conditioning Systems are becoming increasingly popular in today’s busy lifestyles. They have become more affordable and easier to install than traditional central systems, while still providing the same cooling power. However, they do come with some unique benefits that make them worthwhile to consider.
Split air conditioning systems utilize two separate components:

A. A condenser unit outside the building where the refrigerant is cooled down by evaporating water from the condensate and then condensed back into a liquid state.

B. An indoor unit inside the building, where a fan blows warm air over copper coils that cool the air. This cools the air and makes it cold enough to pass through your ductwork and enter your home. Split AC systems work best on homes with a single-layer roof, as this creates a low pressure area under the roof. In these cases, the warm air can flow out of the attic space at the bottom of the roof line and into the house via vents located near the top of the roofline.

Benefits of a split air conditioning system include:

Lower costs – As you only need to purchase one indoor unit instead of several units like in a regular central system, you save money overall. You could even get a free outdoor unit if you buy two indoor units!

With a split air conditioner, you can save around 40% of your energy consumption. This is due to the fact that the heat exchanger only needs to cool the inside of your home instead of cooling both the interior and exterior spaces. A single unit of an air conditioner cools both spaces at once.

You are probably aware of how much electricity your AC uses. When using a split unit, one side of the ductwork is used to cool your indoors space and the other is used to cool the outdoors. Because the outdoors area doesn't use the same amount of energy to cool your indoor air, there is less need to run the compressor.

Because the outdoor section of the duct runs across the roof line outside, condensation always collects on the cold surface. With a split unit, there is no longer any condensate build-up on the indoor coil, saving time and money on cleaning and maintenance.

Ductable AC system

Ducting your AC System
Ducting your AC system can make a huge difference in your energy bills. This is not only true for people that have central air systems but also for those who have ducted air conditioning units. Why? Well, if you are running your air conditioner continuously then you will require more power than if you’re running it less frequently. Also, keep in mind that the more often you run your air conditioner, the higher your demand on electricity consumption. So, if you are looking to save money on your energy bill, ducting may be exactly what you need. Here’s how to get started on ducting your air conditioner.

Benefits of ducting your unit
One of the greatest benefits of ducting your air conditioners is the reduction of humidity in your home. When your air conditioner is running constantly, it sucks out any moisture from outside the house making it into your home. If this happens constantly, then you could be experiencing high water damage on floors and walls inside your home. By ducting your air conditionner, all the moisture will stay outside where it belongs. This will help lower humidity levels inside your home while keeping dry areas drier and wet areas damp. This helps with mold growth and mildew formation which is why many states require homeowners to do duct work to their heating and cooling systems. However, even though this does help reduce mold growth and mildew, it doesn't necessarily mean that you won't get any mold problems inside your home. You should always check with your local building inspector to determine whether or not your home needs ductwork done before doing said ductwork.

How to install ductwork
When installing ductwork, you want to create a continuous line that runs from the floor to the ceiling. To begin, you will first need to cut a hole in the ceiling. Then, you will use a measuring tape to measure the length of the room. Next, you will take this measurement and add 2-4 inches to account for the width of the duct. After that, you will start cutting holes at regular intervals along the entire length of the wall. After each hole has been cut, you will put some kind of sealant on the edges of the hole. Once all of these steps have been completed, you will turn off the power and let the professional finish up installing the duct.

                    The Ducted Air Conditioner (AC) is a great way to cool down your room without needing to run fans continuously. All you need to do is open your window, and the air conditioner will cool the air inside. There are two types of ducted systems that people use, single-duct and double-duct. A single-duct system has only one supply duct from outside into the room. Double-duct systems have both supply and return ducts from the outside (Supply), through the ceiling (Return), and into the wall (Exhaust).
                The entire house runs off the ducted HVAC system. The way it works is that all the air coming into the house is pulled through a water cooling coil, after going through cooler and dehumidifier coils, before being pushed throughout the home. All the return air goes back to the outside environment, including the evaporator coil of the heater core where the heat energy from the home's furnace is transferred to the return air stream. Regulate the damper at the incoming air intake and you can control exactly how warm/cold your house gets.

Package AC system

A package AC system is a complete enclosed climate control unit that provides air conditioning or heating, humidity control, lighting, ventilation, and filtration depending on application requirements. PAS units are typically used for commercial applications such as indoor cultivation. These systems also require less energy than other HVAC options; however, they do not have the capacity to provide outdoor ventilation.
                The Package Air Conditioning Unit (PAU) is a standalone unit that provides both cooling and heating functions. This unit can be placed anywhere indoors or outdoors where temperature extremes are likely. Depending on the product, the heating/cooling function may be either the primary or secondary function. Some products are capable of providing bi-directional airflow to improve efficiency.

Cassette AC system

The cassette AC system is an amazing technology that allows us to control the temperature at any given time. The cassettes are interchangeable and can be installed into any other cassette system.

To get started, you need to purchase the cassettes (which are pretty cheap) and then install them into your existing setup. They require no wiring and work beautifully! You can choose from both heat and cold temperatures and they come in many different colors.

Centralized AC system :

The centralised air conditioning unit is a single unit designed to cool several rooms at once, while keeping them isolated from outside influences. A centralized cooling system can reduce operational costs by providing efficient air conditioning and heating. There are several different types of centralised systems that include chillers, heat pumps, etc.
                Centralized air conditioning systems are becoming increasingly common in buildings in order to provide cost-effective heating and cooling solutions that make use of energy efficiently. They can increase building comfort and reduce utility costs. However, they have their drawbacks too.
The centralization of these systems increases carbon dioxide emissions through refrigerants, compressors and electrical power. In addition, centralized air conditioners require complex controls and piping networks, increasing maintenance costs and electricity consumption.
                    Centralized air conditioners usually require high-powered fans to circulate cool air throughout a building. These fans produce noise, which can disturb occupants. In addition, cold air from centralized units tends to move down, rather than upwards. Thus, this type of cooling system may not effectively keep people comfortable in areas where temperature decreases.

Water Cooled Chiller System

Why do we need water cooled chillers?
Modern air conditioning systems are expensive. They use large amounts of energy and can cost hundreds of dollars per year to operate. If the equipment isn't using enough electricity to offset those costs, then you may have to pay even more money. One way to reduce this expense is to use a chiller that uses less energy than traditional evaporative systems. A chiller system has two major components: the condenser and compressor.

The condenser is where heat from the cooling coils is turned into cool water vapor. This allows you to use less energy to run the air conditioner. A system without a condenser would just suck the hot air out of the room through a fan. Because our planet's temperature is rising due to climate change, we need to find ways to conserve energy.

How does a water-cooled chiller work?
A water cooled chiller works by passing cold water over the outside coil. As the hot surface heats up, the water absorbs some of the heat. However, unlike evaporative systems, the water never actually touches any other parts of the unit. So the water doesn't get warm like it would if it were passed through a radiator. This means less energy is used to run the machine.
                Chillers are used in many different applications from refrigerating food products to cooling electronic equipment. While they are often thought of as luxury items, chillers have become a necessity due to increasing energy costs and decreasing fossil fuel reserves. Chillers can range in size from small air conditioning units that cool only one room to large systems that provide heat to entire office complexes.

Important points about Water Cooled Systems:

1. Water cooled chiller air conditioning systems are designed to provide comfort through cooling by using water instead of conventional refrigerants.

2. They use the same basic components that we know from traditional air conditioners and refrigerators but work differently. In a water cooled system the compressor uses a closed cycle that runs continuously drawing heat out of the environment and discharging it into the water. As this cools the water it causes the external coil (the evaporator) to chill the air passing over it. The chilled air then passes back to the living space where it can be used to provide conditioned air. This cycle continues until either the temperature of the water drops below some threshold or enough energy has been extracted from the environment to make running the compressor worthwhile.

3. There are two major differences between traditional air conditioning systems and water-cooled ones. Firstly, they do not require any moving parts - meaning that no motors are needed to drive compressors or fans. Secondly, unlike traditional air conditioners, water cooled systems produce their own electricity rather than relying on mains power. This is achieved by extracting energy from the ambient conditions around them, usually via solar panels mounted on the roof.

4. Water cooled air conditioning systems have many advantages over other types of air conditioning systems. They are typically less expensive to purchase and maintain, consume less power than other forms of technology and last longer while requiring much smaller physical footprints.

5. Like all air conditioning systems, water cooled air condensers produce a significant amount of waste heat. This wastes energy and increases fossil fuel use. However, the water cooled method is particularly inefficient at heating water compared to other methods of air conditioning. This is due to the fact the process requires large amounts of water to extract just a small amount of useful energy, thus increasing the overall rate of entropy production relative to a similar sized unit that heats air directly.

6. Water cooled air conditioners are only suitable for well insulated spaces. If a building isn't well insulated then the amount of heat stored in its walls will cause the temperature of the water to rise. This will reduce the effectiveness of the system and may even lead to damage caused by overheating. To avoid this problem, water cooled units should only be installed in unheated buildings or areas of the house with a high level of insulation, such as attics.

Air Cooled Chiller System

An air cooled chiller is a device that cools using evaporation and convection. Air cooled chillers are usually much smaller and quieter than other types of cooling devices, but they can't reach as high of temperatures.
                    Chillers are used primarily to cool air in greenhouses. They are usually powered by electricity or gas. A fan draws outside air through a heat exchanger where the air is cooled before passing back into the greenhouse. Most chillers use fans that force cold air over metal coils to cool the air. This creates condensation. To prevent this from happening, the air is sometimes passed through wetted pads. When using electric chillers, they can have either a constant power output or a variable output. To save money, some people choose to buy an electric chiller with a variable output. These may not work well if the ambient temperature around the chiller is constantly changing. There are many different types of fans; the most common ones include centrifugal blowers, axial blowers, cross-flow fans, and propellers. Some models of chillers have cooling towers that are designed to provide additional cooling capacity and to help lower operating costs.

How do they work? 
When the temperature rises above 70 degrees Fahrenheit, the fan starts spinning and pulls cool air from outdoors through holes in the side of the unit. This air passes over an evaporator coil, where water gets vaporized out of the coils. As this happens, the water condenses back into liquid again. The condensed water runs down into a reservoir located at the bottom of the unit. Once the reservoir is full, the pump kicks in and pushes the water back up to the top of the unit, where it drips back onto the evaporator coil. You can change the amount of time your chiller runs by adjusting your thermostat. Typically, you'll run them 8 hours longer than your standard heating setup.

What are their benefits ?
If you are looking at installing air-cooled chillers for your business, you need to know that they can provide many benefits. One of the biggest advantages of these air conditioners over conventional air conditioners is their ability to conserve energy. This is due to the fact that this type of cooling system uses 80% less electricity than traditional ones. Another great advantage of these coolers is that they do not produce smog, thus making them much safer for indoor environments. A third benefit of using these devices is that they can run continuously 24/7 without any downtime. They have no moving parts that require lubrication, and this means that they are maintenance-free.

Variable Refrigerant Volume System (VRV) or Variable Refrigerant Flow System (VRF)

The Variable Refrigerant Volume System (VRF) has been around since the early 1980s but has only recently started gaining popularity in modern indoor cultivation facilities. VRFs are used to provide variable airflow throughout a facility. This can help regulate temperatures and humidity levels while maintaining optimal CO2 concentrations. They are also commonly used in greenhouses and other controlled environments.
            The VRF system was designed from the ground up to be able to operate at variable refrigerant volumes (VRVs) without any loss of capacity or efficiency. This eliminates the need to switch between different modes of operation, which can get costly if you want to run your VRF at different temperatures or at different times throughout the day. Variable refrigerant volume systems are becoming popular because they offer higher energy efficiency, lower running costs, and ease of installation. However, these benefits come with some drawbacks. These include the fact that VRV systems require significant changes to existing HVAC equipment and installations.

1. Vrf's are refrigeration systems that can change their volume based off of pressure changes throughout the compressor. They are commonly used on commercial refrigerations but they have been adapted to small residential applications as well. These systems are able to adjust its output based on the amount of heat absorbed from the condenser coil. This makes the system work like a variable capacity unit, where it can increase or decrease it's output capacity based on the ambient temperature. In this way there is no need for a thermostat and any type of manual control. This allows for easier installation and less maintenance.

2. Variable Refrigerant Volume (VRV) Systems are designed to be used in conjunction with a conventional air conditioning unit. They allow the user to manually control the cooling performance of the AC unit. A VRV system consists of two components: 1. Control Valve 2. Sensor(s).

The control valve is what actually controls the flow rate of refrigerant through the system. With VRV systems the control valves do not regulate the flow rate of refrigerants through the system. Instead, they sense the temperature of the outdoor environment and respond accordingly.

A VRV system has three basic characteristics. First, it is designed to run at low speeds. Second, it uses a relatively large amount of oil. Third, it operates in the range of approximately 1.5 - 4% load. 
                        VRF system can also be used in buildings that need variable temperature control with improved comfort. A VRF unit can save over 50% on electric bills at full capacity while still providing excellent humidity regulation and air quality.

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