A PROJECT REPORT
AIR CONDITIONING AND AIR
CONDITIONING SYSTEM DESIGNING WITH
WHAT IS AIR CONDITIONING?
EQUIPMENTS USED IN AC SYSTEM
CLASSIFICATION OF AC SYSTEM
OBJECTIVE OF AC DESIGNING
WORKFLOW OF HVAC DESIGN
AutoCAD MEP SOFTWARE
AIR HANDLING UNIT
AIR DISTRIBUTION SYSTEM
COOLING LOAD ESTIMATION
• The first modern air conditioning system was developed in 1902 by a
young electrical engineer named Willis Havilland Carrier.
• It was designed to solve a humidity problem at the Sackett-Wilhelms
Lithographing and Publishing Company in Brooklyn, New York.
• The cooling is typically done using a simple refrigeration cycle, but
sometimes evaporation is used, commonly for comfort cooling in
buildings and motor vehicles.
• In construction, a complete system of heating, ventilation and air
conditioning is referred to as "HVAC".
• Many of our homes , offices and commercial facilities would not be
comfortable without control of the indoor environment. The "luxury
label" attached to air conditioning made practicality our live healthier
and more productive.
• AutoCAD MEP is the AutoCAD software for mechanical, electrical, and
plumbing designers and drafters. Creation and coordination of
constructional documents is more efficient with AutoCAD MEP’s more
intuitive systems drawing and design tools.
• With AutoCAD MEP we are able to make changes much faster, thus
help minimizing the financial impact, and make those changes in almost
• This project aims at studying the working phenomenon of Various AirConditioners and Designing an air-conditioning system in an
economical way using AutoCAD MEP.
• The goal of an HVAC system is to provide an energy efficient, cost
effective, healthy and comfortable indoor environment with acceptable
indoor air quality.
WHAT IS AIR CONDITIONING?
• The air conditioning is the branch of engineering science deals with the
study of conditioning of air, means supplying and maintaining desirable
internal atmospheric conditions for human comfort, irrespective of
• Heating ventilating and air-conditioning HVAC is one of the building
mechanical services that include plumbing, fire protection, and
escalators. Air-conditioning refers to any form of cooling, heating,
ventilation or disinfection that modifies condition of air.
• Air conditioning (aircon or AC) is the process of altering the properties
of air (temperature and humidity) to more favourable conditions. The
acronym HVAC&R stands for heating, ventilating, air-conditioning, and
refrigerating. The combination of these processes is equivalent to the
functions performed by air-conditioning.
EQUIPMENTS USED IN AC SYSTEM
• Circulation fan – to move air to and from the room
• AC unit – For Cooling, Heating, Humidifying and Dehumidifying
• Supply duct – Directs conditioned air from the circulating fan to space
• Supply outlets – Are grills which distribute the conditioned air evenly
in the required space
• Return outlets – Are the openings in the room surface which allow the
room air to enter the return duct
• Filters – For filtering dirt, dust and impurities
CASSIFICATION OF AC SYSTEM
ACCORDING TO PURPOSE
1. Comfort Air Conditioning System
2. Industrial Air Conditioning System
ACCORDING TO SEASON OF THE YEAR
1.Winter Air Conditioning System
2.Summer Air Conditioning System
3.Year Round Air Conditioning System
ACCORDING TO ARRANGEMENT OF EQUIPMENT
1.Unitary Air Conditioning System
2.Central Air Conditioning System
• It is based on vapor compression refrigeration cycle. It includes four devices,
• When hot air flows over the cold, low pressure evaporator coils, the refrigerant
inside absorbs heat as it changes from a liquid to a gaseous state
• To keep cooling efficiently, the air conditioner has to convert the refrigerant
gas back to a liquid again.
• To do that, a compressor puts the gas under high pressure, a process that
creates unwanted heat.
• All the extra heat created by compressing the gas is then evacuated to the
outdoors with the help of a second set of coils called condenser coils, and a
• As the gas cools, it changes back to a liquid, and the process
starts all over again.
• Thinking it as an endless, elegant cycle: liquid refrigerant,
phase conversion to a gas/ heat absorption, compression and
phase transition back to a liquid again.
Cooling-tower AC Units
• Cooling towers are heat removal devices used to transfer process
waste heat to the atmosphere.
• This technology is used in HVAC systems for cooling buildings.
• Cooling towers vary in size from small units to very large hyperboloid
structures that can be up to 200 metres tall and 100 metres in
diameter, or rectangular structures that can be up to 40 metres tall
and 80 metres long.
• Colling towers are classified into 2 types according to their use , such
1.HVAC cooling tower and
2.Industrial cooling tower.
The Objective of Air Conditioning System
• The objective of an air conditioning system design is to achieve a highly
quality system that functions effectively and is energy-efficient and costeffective.
• The following are essential for a system to function effectively:
1. All design criteria are fulfilled, and the requirements of the owner and the
user are satisfied.
2. A good indoor air quality is provided.
3. The system is reliable and has adequate fire protection level (e.g. smoke
DESIGN WORKFLOW OF HVAC SYSTEM
• The design procedure of an Air Conditioning system includes the following
1. Specifying the HVAC Parameters
2. Starting a Project
3. Linking System File to the Architectural Plan
4. Specifying Spaces and Zones
5. Calculating Loads
• Specifying the HVAC Parameters
In this step, you need to specify all the basic parameters required to create
an HVAC system. Some of the parameters are duct size, duct rise and drop,
flow rate, cut length, and so on. On the basis of these parameters, the
hierarchy of drawings in project will be decided.
• Starting a Project
In this step, you need to create a project file to link the drawings of a
system to each other. For example, the drawings related to HVAC system
will be interlinked and will be in the same project. As a result, you can
easily manipulate the parameters of the system.
• Linking System File to the Architectural Plan
To create an HVAC system, you need to have an architectural plan. In this
step, you will link the HVAC system file to the architectural plan file using
the Project Navigator. After the completion of this step, you can reroute the
HVAC lines according to the architectural plan.
• Specifying Spaces and Zones
In this step, you need to create spaces and zones using the tools available in
AutoCAD MEP. These spaces are used for exporting the building information
related to the heating and cooling loads. The spaces are further divided into
zones which represent the actual heating and cooling loads.
• Calculating Loads
In this step, you need to calculate the heating and cooling loads for the
building. These calculations are performed by using the analysis tools
available in AutoCAD MEP.
• According to ASHRAE (American Society of Heating, Refrigerating
and Air- Conditioning Engineers), AutoCAD MEP software & building
information modeling (BIM) software, is used to design a central air
conditioning system. Building engineering data have to be exported
from architectural plans, using gbXML format, to Load soft 6.0
software for cooling load analysis. Then the total cooling load is to be
• The calculated cooling load was imported to the AutoCAD MEP
software which is used to design a central air conditioning system.
AutoCAD MEP Software
• AutoCAD MEP is the AutoCAD software for mechanical, electrical,
and plumbing designers and drafters.
• In AutoCAD MEP software, it is possible to test design considerations
in the virtual building model before anything, literally, gets set in
concrete which is expensive to fix in the field.
• AutoCAD MEP also assessing our vision and enhance our efficiency
because of its purpose-built software for MEP designers and drafters.
FEATUTRS OF AutoCAD MEP
• One of the major benefits of AutoCAD MEP is the improved
coordination with the architectural and structural designs (mechanical,
• Better Design Accuracy ,
• Coordinate Design Information ,
• Collaborate More Effectively ,
• Single/Double-Line Design and
• AutoCAD MEP enable us to make zones boundaries
DESIGN OF CENTRAL AIR CONDITIOING SYSTEM
Central air conditioning systems basically consist of three major parts
1. An air system or air handling unit (AHU), air distribution
system (air ducts) and terminals(resisters and diffusers).
2. Water system – chilled water system, hot water system, condenser
3. Central plant – refrigeration (chiller) plant, boiler plant.
Central air conditioners circulate cool air through a system of supply and
return ducts. Supply ducts and registers carry cooled air from the air
conditioner to the home. This cooled air becomes warmer as it circulates
through the home; then it flows back to the central air conditioner through
return ducts and registers
AIR HANDLING UNIT(AHU)
We can arrange AHU separately to each floor or to the whole buildings.
AIR DISTRIBUTION SYSTEM
Air Supply Ducts & Air Return Ducts
• The size of ducts can be decreased by increasing the air velocity. Hence
it is more common to use large ducts and the resultant low velocity air
flow because high velocity air flow requires more fan power to generate
and is much noisier.
• Ducts are either round, rectangular, flat oval or square in cross-section.
Round ducts are preferable for high velocity system and rectangular
ducts are very popular for the typical low velocity system.
• Aspect Ratio
• Duct material
Terminal devices presents at the end of supply ducts. The supply air enters
into the room through either a grille, resister or diffuser.
• Grilles & Resisters
A supply grille has adjustable vanes for controlling the direction of
air entering the room. A resister is a grille that also has a damper behind it, so
that the amount as well as the direction of air entering can be controlled.
They should be located where occupants will not block them.
Diffusers are used to mix the supply air with the room air rapidly.
They can be round, rectangular or linear.
• The total heat required to be removed from the space in order to bring it
at the desired temperature by the air conditioning is known as Cooling
Load. The purpose of a load estimation is to determine the size of the air
• Sensible Heat Gain
• When there is a direct addition of heat to the enclosed space, a gain in
the sensible heat is said to occur. This sensible heat is to be removed
during the process of summer air conditioning.
• Latent Heat Gain
• When there is an addition of water vapour to the air of enclosed space, a
gain in latent heat is said to occur. This latent heat is to be removed
during the process of summer air conditioning.
Sensible Heat Gain through
Building by conduction
Heat Gain due to Infiltration
Heat gain due to Ventilation
• The ventilation is provided to the air conditioned space in order to
minimise odour, concentration of smoke, carbon dioxide and other
undesirable gas so that freshness of air should be maintained.
• For analysis purpose we considered the installation of central air
conditioning unit in our college conference hall.
• No. of person=250, td2=22ᵒc,Ф2=60%, td1=40ᵒc,tw1=27ᵒc
• The floor diagram for the given air conditioning system is shown in
figure. The various points on the psychrometric chart, are shown in
figure are marked as discussed below.
• First of all, mark the outside condition of air that is 40ᵒc DBT and
27ᵒcWBT on the psychrometric chart as point 1, as shown in figure.
Now mark the inside condition of air in the room i.e. 22ᵒc dbt and
60% relative humidity as point 2. Locate point A by drawing vertical
and horizontal lines through point 1 and 2 respectively.
• In this project, AutoCAD MEP program, building information modeling
(BIM) software, is used to design a central air conditioning system. Building
engineering data have been exported from architectural plans, using
gbXML format, to Loadsoft 6.0 software for cooling load analysis. The
software obtained a total cooling load of 53.22 KW.
• The calculated cooling load was imported to the AutoCAD software which
is used to design a central air conditioning system. The software analyzed
the imported data and used it for duct sizing and equipment selection.
• Air conditioning course notes, university of Khartoum.
• Walter T.Grondzic, Air conditioning system design manual, second edition.
• An Introduction to building information modeling, 2009.
• Autodesk Company, autocad mep brochure, 2009.
• Autodesk Company, AutoCAD MEP 2010 user’s guide, March 2009.