An overview of HVAC: Heating, Ventilation and Air Conditioning

A Presentation on Overview of HVAC: Heating, Ventilation and Air Conditioning [With PDF]

HVAC or Heating, Ventilation, and Air Conditioning provide comfort for people & maintains an effective Environment for surroundings. Proper HVAC Allows humans to exist under adverse conditions. The requirement of HVAC Systems is a must for critical areas like Control rooms, Electronic Equipment Rooms, switchgear hall, Battery room, workshop area, etc. in a petrochemical plant.

The Primary Intent of HVAC-Comfort:

  • Comfort is the primary intent of HVAC systems.
  • Increase in Productivity.
  • Building & Equipment Durability.
  • Increase Life & Health.
  • Inside condition of 21–24 °C & 50–60 % Relative Humidity is most comfortable & purity of air.

Basic Refrigeration Cycle:

Vapour Compression Refrigeration Cycle
Fig. 1: Vapour Compression Refrigeration Cycle

Air Conditioning Capacity – The “Ton”:

  • One Ton of Refrigeration (TR) is defined as the quantity of heat removed to freeze 1 Ton (1 American short ton is 2000 pounds) of water into ice from and at 0°C in 24 hours.
  • 1 Ton of Refrigeration = 12000 Btu/hr or 3024 Kcal/hr

TR = Q x Cp x (Ti – To) / 3024

  • Q = mass flow rate of coolant in kg/hr
  • Cp = coolant specific heat in KCal /kg deg C
  • Ti = inlet, the temperature of the coolant to the evaporator (chiller) in °C
  • To = outlet temperature of coolant from the evaporator (chiller) in °C

Major Work in HVAC (Fig. 2):

  • The design HVAC system for plant buildings, which requires specific temp., humidity, internal pressure and cleanliness under various conditions.
  • Preparation of Heat load Calculations, System Diagram and Duct/Piping Plan.
  • Equipment Sizing & Selection.

HVAC Work Flow:

HVAC System Design
Fig. 2: HVAC System Design

Tools and Products:

E20-II, Elite

  • System Capacity Report (Fan, Cooling, Heating, Humidification)
  • Year Simulation (Power, Operation, Cost)
  • Load Analysis by Each Room
Simulation of HVAC using tools
Fig. 4: Simulation of HVAC using tools

Scope of work:

  • Preliminary Design
  • Vendor Print Checking
  • Engineering
  • Field Engineering

Basic HVAC Equipment:

  • Fans / Blowers
  • Air Handling Units (AHU)
  • Filters
  • Compressor
  • Condensing units
  • Evaporator (cooling coil)
  • Control System
  • Air Distribution System

Common HVAC System Types:

  • Window / Split AC
  • Duct-able Splits
  • Packaged Units
  • Fan Coil Units
  • VRV Units
  • Direct Expansion System
  • Chilled Water System

Split System:

An outline diagram of a typical split system
Fig. 5: An outline diagram of a typical split system

Air Handling Unit (AHU):

Diagram showing an AHU
Fig. 6: Diagram showing an AHU

Equipments (Fig. 7):

  • Chillers
  • Heat Exchangers
  • Cooling Towers
  • Humidifiers
Diagram Showing Major equipments
Fig. 7: Diagram Showing Major equipment

Air Distribution:

  • Ductwork
  • Metal
  • Flexible
  • Duct board
  • Grilles, Louvers, & Registers
  • Dampers
  • Shut off
  • Fire
  • Smoke
  • Sealants
  • Supports

HVAC Standards:

  • ASHRAE – The American Society of Heating, Refrigerating and Air-Conditioning Engineers
  • SMACNA – Sheet Metal & Air-conditioning National Contractor’s Association
  • NBC – National Building Code
  • IS – 12332 For Ventilation in Petrochemical Plants & Refineries
  • IS – 3103 For Industrial Ventilation
  • OISD – 163 Safety of Control room for the Hydrocarbon industry


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