Subject:- Refrigeration and Air Conditioning

Topic:- Design of air conditioning systems

Difficulty:- Low

The DBT and WBT along with relative humidity of the area where the library is located must be determined.

The library room specifications must be known like room size, no. of doors and windows, door and window sizes, size of bricks and wall plaster, etc.

The materials used for the construction of room must be known like roof material and thickness, flooring, etc.

Presence of insulation must be accounted. The heat exchanged through walls, floors, and windows must all be considered. Climate will play a role as well because humidity and air movement can affect temperature.

The number of people expected to work in the room must also be estimated because living bodies produce heat. Large electronics like computers, washing machines, and televisions also produce heat and should be accounted for when figuring refrigeration load. This also includes lighting devices.

The heat gained through roofs, walls, glass; heat from conduction, convection, radiation, infiltration; heat gained from people, appliances, light, all are calculated and summed up into Effective Room Sensible and Latent Heat. Considering a safety factor in these calculations, gives us the Grand Total Heat which is the cooling load.

RSHF

It is defined as the ratio of room sensible heat to room total heat. The supply air having conditions given by any point on this line will satisfy requirements of the room with quantity of air supplied different for different points.

GSHF

It is defined as ratio of total sensible heat to the grand total heat which the cooling coil is required to handle after the outside fresh air and recirculated air mixing has taken place.

$GSHF=\frac{(Room sensible heat+Outside air sensible heat)}{((RSH+ouside air sensible heat)+(RLH+outside air latent heat))}$