BASICS OF AIR CONDITIONING

AIR CONDITIONING

HVAC

HEATING:- It is form of energy which transfer form one body to another due to change in temperature.

VENTILATION:- Providing out side air or Fresh air inside the room from outside to improve the indoor Air quality (IAQ) there by removing bad odor gases called as ventilation.

AIR CONDITIONING:-  It is conditioning of air according to human comfort zone condition & human comfort zone criteria as mentioned by ASHRAE (American Society of  Heating Refrigeration & Air Conditioner Engineer)  

Comfort zone temperature are 76 ℉ / 24 ℃ & 50% RH (Relative Humidity)

                        The term Air conditioning can also be defined as conditioning the air by conditioning the temperature humidity air motion, air quality & quantity within the space for satisfying the requirement of the comfortness is known as air conditioning 

Application of Human Comfort Zone:-

1. Residential Buildings.
2. Commercial Buildings.
3. Hotels & Restaurants.
4. Supermarket & Malls.
5. Airports.
6. Hospitals.
7. Theater, Cinema Halls.
8. Auditorium & Seminar Halls. 

DESIGNING OF HVAC SYSTEMS

Designing of HVAC system involves following things.

1. Building survey.
2. Selection of system.
3. Load calculation.
4. Machine selection.
5. Fan selection.
6. Chilled water pipe design.
7. Fittings selection.
8. Pump selection.
9. Selection of equipment's. 
10. Planning of each equipment's in building.

In air-conditioning system, the air must undergo one or several of the following processes:

1- Cooling

2- Heating

3- Dehumidification 

4- Humidification

Psychometrics can be used to predict changes in the environment when the amount of heat and/or moisture in the air changes. Use of psychrometric analysis is also important to determine the volume flow rates of air to be pushed into the ducting system and the sizing of the major system components.

                In designing air conditioning systems, the first challenge is to understand the components that affect the building heat gain or heat loss - this process is called heating or cooling load estimation. The reactive challenge is to "design" controlled processes to maintain the desired condition or state-point within the occupied space - these are usually called the system processes that use psychometrics.

ESTIMATION OF COOLING & HEATING LOAD

Load estimates are the summation of heat transfer elements into (gains) or out of (losses) the spaces of a building. Each heat transfer element is called load components, which can be assembled into one of three basic groups, external space loads, internal space loads and system loads. To properly understand the workings of the various external, internal and system load components, the following items need to
be gathered from a set of plans, existing building surveys or occupant interviews.

1. Building square-footage and volume
2. Orientation of the building (sun effects on surfaces)
3. Year round weather data (design conditions, heat transfer)
4. Use of the spaces within the building (offices, conference room, lab, datacenter)
5. Hours of operation (occupied and unoccupied)
6. Thermostat set points (main comfort parameter)
7. Dimensions of walls, roofs, windows and doors
8. Construction materials (gather densities, external color and U-factors or describe material type layer by layer (R-values)
9. Stairways and elevators (floor-to-floor openings)
10. People occupancy and activity, and when they are present
11. Lighting intensity and hours used
12. Motor and appliance sizes or kW and times they are used
13. Ventilation needs (IAQ and exhaust makeup)
    

The total cooling load is than determined in kW or tons* by the summation of all of the calculated heat gains. Along with psychometrics, load estimating establishes the foundation upon which HVAC system design and operation occur.

Tons of Refrigeration:- 

                                                        A tone of refrigeration is defined as amount of cooling effect produce by uniform melting of 1000 KG (1 Tone) of ice from 0 ℃ in 24Hr.