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8/18/2019 Module 1 HVAC
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Module 01
HVAC SystemInstructor:
Engr. Haris Alam
Department of Civil Engineering
CECOS University, Peshawar.
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What is HVAC System??
CECOS University, Peshawar. 2
H V A C S y s t e m H- Heating
V- Ventilation
AC – Air Conditioni
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Few people think that HVAC is allLuxury, Waste of money &
Valuable Energy.
But…….!!!
HVAC System
3CECOS University, Peshawar.
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Of Course,
It is Right of Every Individualto live in Comfort & HVAC
Serves the industrial segment
to great extent.
HVAC System
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• Control of Air Temperature.
• Control of Moisture Content in Air.
• Proper Air Movement.
• To Hold the Air Contamination Within Acceptable limits
Functions of HVAC
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6CED, CECOS University, Peshawar.
Humidity & Temperature:
• Humidity:
• Humidity is the amount of water vapor in the air. Water vapor is th
gaseous state of water and is invisible.
• There are three main measurements of humidity:
• Absolute humidity is the water content of air.
• Relative humidity , expressed as a percent, measures the current absolut
humidity relative to the maximum for that temperature.
• Specific humidity is a ratio of the water vapor content of the mixture to th
total air content on a mass basis.
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• Electrical Hygrometers• Hygroscopic films detect atmospheric moisture
• Dew point impedance from partial pressure of water vapor
• Chilled mirror
• Optically sense presence of dew or frost on mirror
• Measure temperature of mirror for dew point or frost point
• Recent optical sensing improvements
Humidity Instruments:
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Problems due to Humidity:
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• Electrical: . High voltage short-circuit occurs when the insulation is moist.
• Archive: Films and papers will stick together if stored in moist place. Paper turn
yellow and disintegrates.
• Metal: A lot of metals are free from corrosion if the environment is dry.
• Food: Drying is usually part of food processing. Food exposed to moisture are
subject to fungal growth.
• Military: A lot of military gears must be stored at low RH to keep away from rus
forming. Gun powder and explosive are particularly sensitive to moisture.
• Batteries production: Extremely low RH is required to batteries production.
• Photography material: Most films are moisture sensitive.
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Humidity Levels:
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Humidity & Temperature:
• Temperature:
• A temperature is a comparative measure of hot and cold.
• It is measured, typically by a thermometer, through the bulk behavior o
a thermometric material, detection of heat radiation, or by particl
velocity or kinetic energy.
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Electrical Thermometers
•
Thermocouple: A Thermocouple is a sensor used to metemperature. Thermocouples consist of two wire legs made from different metalswires legs are welded together at one end, creating a junction. This junction is whetemperature is measured.
• Resistance temperature detector (RTD):RTD are devices used to metemperature by correlating the resistance of the RTD element with temperature. Moselements consist of a length of fine coiled wire wrapped around a ceramic or glass cor
element is usually quite fragile, so it is often placed inside a sheathed probe to protect• Thermistor :A thermistor is a type of resistor whoseresistance varies significantly with temperature, more so
than in standard resistors.
Temperature Instruments
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Manual Thermometers:
• Liquid in glass thermometers
• Bi-metallic sensor
Temperature Instruments
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Comfort Levels:
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• The Cooling load calculation begins with the determination of he
loss through a variety of building envelope components an
situations.
• Walls , Roofs , Windows, Doors, Exposed Floors, Slab-on-Grade , Baseme
Walls, Infiltration Ventilation ,Duct Loss , Electric Appliances, Humans & other
Cooling Load Calculation:
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Cooling Load Calculation:
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16CED, CECOS University, Peshawar.
Temperature & Humidity Controls:
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Components….
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• Source Components
• Distribution Components
• Delivery Components
Components of HVAC System:
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• Source Components:
Heating :• Combustion of some flammable material (a fuel)
• Conversion of Electrical energy to heat
• Solar radiation or other renewable energy resources
• Removal of Heat from material on site and transferred into a building
Cooling:• Natural Heat Sinks (Outside air, the night sky, on-site water bodies,
and on-site soil)
• Artificial Heat Sinks (Vapor compression (mechanical) refrigeration, ,absorption (chemical) refrigeration, evaporative cooling)
Components of HVAC System:
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• Natural Heat Sink
Components of HVAC System:
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• Artificial Heat Sink:
Components of HVAC System:
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• Commonly used Heating & Cooling system for active control
• Fireplace:• Wood Strove:
• Furnace:
• Boilers
• Solar Thermal Collector
• Vapor Compression Refrigeration Unit• Absorption Refrigeration Unit.
• Chillers
• Cooling towers
Components of HVAC System:
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• Distribution Component:
•
Heating or cooling effect produced must be transmitted to thevarious spaces in a building
• Three transmission media are commonly used in central systems:
air, water, and steam.
• Air & Steam Based System
Two Ducts are required one for Conveying the air & Other for taking theair back to the system
• Water Based System:
Minimum of 3 pipe system is required.
• High Pressure & Low Pressure System
Components of HVAC System:
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• Distribution Component:
• Dampers are used to control air flow ,they balance
flows throughout a system
• Specialized fire dampers and smoke dampers are
used to reduce the spread of fire and smoke through
the building air distribution system.
• Splitters and turning vanes are used to reduce
friction losses by reducing turbulence within the
ductwork; they also can reduce noise generated
within the ducts.
Components of HVAC System:
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• Delivery Component:
• Devices designed to provide the interface between
occupied building spaces and distribution
components are collectively termed delivery
devices.
Diffusers.
Registers.
Grille.
Components of HVAC System:
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Assignment #01
Climatic Control System
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Ventilation….
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•
Process of "processing" or replacing air in any space to providhigh indoor air quality.
• Used to remove unpleasant smells and excessive moisture, introduc
outside air, to keep interior building air circulating, and to preven
stagnation of the interior air.
• Ventilation includes both the exchange of air to the outside as well a
circulation of air within the building.
Ventilation System:
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• Maintain human comfort and health.
• Provide sufficient oxygen (approx. 21%) for human during overcrowding inoffice (Remove Heat generated).
• Remove products of respiration and bodily odor.
• Remove contaminants or harmful chemicals.
• Create air movement (feeling of freshness/comfort)
• Moisture problems, as indicated by visible fungal growth in corners.
• Staining and discoloration of false ceilings, walls or carpets.
• Smoking in the office..
Purpose of Ventilation:
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• Basic elements of Ventilation system:
• Ventilation Rate: The amount of outdoor air
that is provided into the space.
• Airflow direction: From clean zones to dirty zones
• Air distribution or Airflow pattern: Deliverance of air to each part of
the space in an efficient manner ----- Airborne pollutants removed in
an efficient manner.
Ventilation System:
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Natural Ventilation:
•
Natural movement of air enteringand leaving openings such aswindows, doors, wind towers, roofventilators.
• Heated air rises, cool air below.( wind
towers/ high ventilators)
• Mainly rely on pressure difference----placement of Openings to circulatewind.
Types of Ventilation:
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Mechanical Ventilation:
• Alternative to Unreliable Natural Source. Also known as Forc
• Usually accepted as being the use of ducted air distributed to
centrally located fans with the addition of air filtration, heatin
cooling, humidification or heat recovery.
• Case of Hospital ----- Need Sterilized places ----- Can’t provid
opening like windows.
• Components involves: Exhaust Fans , Filters, Ductworks & Diffu
Types of Ventilation:
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Propeller inside to enhance up-flowair movement
Some without propeller and some install it in wrong orientation
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Hybrid Ventilation:
•
Introduction of outdoor air ventilation into a building bmechanical and Natural.
• It is sometimes called mixed-mode ventilation.
• The Changeover Type
• The Concurrent (or zoned) Type:
• Changeover variant, controls could switch between mechanipassive ventilation seasonally, diurnally, or based on a meparameter.
• Concurrent variant, appropriate controls are needed to p“fighting” between the two ventilation methods.
Types of Ventilation:
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