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Basics of ventilation by jj

Basics of ventilation with classification

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Basics of ventilation by jj

  1. 1. “VENTILATION SYSTEM” PREPARED BY JITENDRA JHA
  2. 2. What is HVAC….??? • H • V • AC
  3. 3. Ventilation :- Ventilation moves outdoor air into a building or a room, and distributes the air within the building or room. The general purpose of ventilation in buildings is to provide healthy air for breathing by both diluting the pollutants originating in the building and removing the pollutants from it.
  4. 4. Purpose of Ventilation • Maximum indoor air quality to control temperature, • Remove odours, • Replenish oxygen, • Remove moisture, smoke, heat, dust, carbon dioxide and airborne bacteria from the indoor space.
  5. 5. Types of Ventilation System: NATURAL VENTILATION • Natural ventilation is the process of supplying air to and removing air from an indoor space without using mechanical system • It refers to the flow of external air to an indoor space as a result of pressure differences arising from natural forces. FORCED VENTILATION • A building ventilation system that uses powered fans or blowers to provide fresh air to rooms when the natural forces of air pressure and gravity are not enough to circulate air through a building. HYBRID VENTILATION • Hybrid (mixed-mode) ventilation relies on natural driving forces to provide the desired (design) flow rate. It uses mechanical ventilation when the natural ventilation flow rate is too low
  6. 6. Selection Parameters • Calculation of Ventilation capacity. • Selection of techno-economical system. • Equipment selection. • Designing Air distribution system. • Evaluation of system to be used. • Need/Requirement of client • Use of Space • Outside condition • Aesthetic • Floor layout • Location and dimension of beam/Column • Power availability • Water availability • Space availability • And many more…
  7. 7. Natural ventilation: DESIGN ASPECTS :  Building orientation and location.  Building form and dimensions.  Window typologies and operations.  Types, shapes and size of openings  Construction methods and detailing. PRINCIPLE : STACK EFFECT: Internal and solar heat gain results in a higher temperature inside the building. This causes an updraft. If a opening, which is the constriction in the inlet-exhaust system, is located at the highest point of the roof, a plenum of air with a positive pressure is built up below the constriction and an assured exhaust through this opening is obtained. ASPIRATING EFFECT DUE TO THE WIND: The difference in wind velocities between the outside and inside of the buildings causes a pressure differential. Since the velocity outside is much higher than that of the internal air movement, a negative pressure zone results at certain locations on the external face of the building envelope.
  8. 8. Advantage : Improved Indoor air quality (IAQ) Energy Shavings Reduction of greenhouse gas emissions Occupant control Reduction in occupant illness associated with Sick building syndrome(SBS) Increased worker productivity Dis-advantage : Lack of Control Building Location & Orientation Difficult to correct problems Dependency on ambient condition i.e. Geography
  9. 9. Forced ventilation: FORCED VENTILATION SYSTEMS :  Evaporative Cooling Unit(ECU)  Fresh Air Fan unit  Exhaust Unit  Exhaust Fans  And many more…. A building ventilation system that uses powered fans or blowers to provide fresh air to rooms when the natural forces of air pressure and gravity are not enough to circulate air through a building.
  10. 10. Advantage : Improved Indoor air quality (IAQ) Control on ventilation capacity Reduction of greenhouse gas emissions Occupant control Reduction in occupant illness associated with Sick building syndrome(SBS) Increased worker productivity Dis-advantage : Capital cost and Operating Cost is high. Power consumption is more.
  11. 11. Evaporative cooling : 1 2 • Evaporative cooling works by employing water's large enthalpy of vaporization. • The temperature of dry air can be dropped significantly through the phase transition of liquid water to water vapor (evaporation), which can cool air using much less energy than refrigeration.
  12. 12. Generally lower initial purchase & Operating costs It cools up to 15 ºC lower than ambient temperature based on efficiency of Cooling pad. Lower peak energy usage Zero greenhouse gas production. Allows flow through ventilation, with plenty of fresh air In dry areas, the higher humidity is beneficial (Refrigerated systems dehydrate the air too much on a dry day) Some people prone to allergens find the wet air less irritating There is not necessary to have isolated area, door or window to be closed etc. Evaporative system depends on ambient condition i.e. dry bulb and wet bulb. It does not have control on humidity. In monsoon season it does not work properly as air conditioning does. Temperature and humidity is not that much achievable as compare to air conditioning system ADVANTAGE DISADVANTAGE
  13. 13. Water evaporates directly into the air stream, thus reducing the air temperature while humidifying the air. DIRECT EVAPORATIVE COOLING (DEC) Primary air is cooled sensibly with a heat exchanger, while the secondary air carries away the heat energy from the primary air as generated vapor. INDIRECT EVAPORATIVE COOLING (IEC) There are two approaches to evaporative cooling 1 4
  14. 14. Two stage ECU(IDEC): • In two stage cooling (also referred to as indirect / direct evaporative cooling), the primary air stream is first pre-cooled sensibly by indirect evaporative cooling. Since this pre-cooling adds no humidity to the air, it can still be subsequently direct evaporative cooled, which is carried out in a direct evaporative section with a rigid pad. However, since the pre-cooled air can hold less moisture, the final relative humidity is lower (about 60% to 65%) than that reached with direct evaporative cooling. • In the first stage, hot outside air passes inside a heat exchanger that is cooled by evaporation on the outside. During this initial cooling phase, the incoming air stream doesn't pick up any extra moisture. In the second stage, the same air stream passes through a water-soaked pad where the additional cooling takes place and the air picks up some additional humidity.
  15. 15. : Working of Two Stage ECU system
  16. 16. Types of Fans: Centrifugal fans use the kinetic energy of the impeller to increase the volume of the air stream, which in turn moves them against the resistance caused by ducts, dampers and other components. Centrifugal fans displace air radially, changing the direction (typically by 90°) of the airflow. They are sturdy, quiet, reliable, and capable of operating over a wide range of conditions. Axial fans The blades of the fan force air to move parallel to the shaft about which the blades rotate. Axial fans are typically used for exhausting dirty air or fumes from processes (such as paint spray booths), supplying fresh air, and general spot cooling of people, rooms or machinery.
  17. 17. HVLS Fans (High Volume low speed fan) • An HVLS fan is a large ceiling fan that moves a High Volume of air at a Low Speed. The low speed delivers gentle air movement rather than disruptive wind, and circulating a high volume of air effectively distributes airflow over a large area. Fan Size(Dia.) Area Coverage 10-feet 5000 Sqft 12-feet 7200 Sqft 16-feet 14400 Sqft 20-feet 25000 Sqft 24-feet 39500 Sqft
  18. 18. HVLS Fans(as per Interior)
  19. 19. HVLS Fans Working:
  20. 20. Hybrid ventilation: Hybrid (mixed-mode) ventilation relies on natural driving forces to provide the desired (design) flow rate. It uses mechanical ventilation when the natural ventilation flow rate is too low Hybrid ventilation solutions will use a mixture of both natural and mechanical ventilation, but should utilise the natural ventilation as much as possible, as this is based on the principle of providing healthy indoor climates and comfort, delivered with minimal energy consumption and therefore at minimal cost. For example, in periods of low wind, mechanical ventilation systems will take over in order to maintain the internal thermal temperatures and to ventilate the spaces.
  21. 21. Jitendra Jha
  • KhaledAhmed38

    Jun. 4, 2020
  • jeetjha90

    Aug. 5, 2019

Basics of ventilation with classification

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