Mechanical System For Engineering And Information Technology college in Arab American University

HVAC system:

HVAC (pronounced either ‘H-V-A-C” or “H-VAK”) is an acronym that stands for “Heating, ventilation and air-conditioning.” Often installed into a single system, these three functions of the HVAC system are closely interrelated to provide thermal comfort and to maintain good indoor air quality. HVAC is sometimes referred to as climate control because it provides heating, cooling, humidity control, filtration, fresh air, building pressure control, and comfort control.

All occupied buildings require a supply of outdoor air. Depending on outdoor conditions, the air may need to be heated or cooled before it is distributed into the occupied space. As outdoor air is drawn into the building, indoor air is exhausted or allowed to escape, thus removing air contaminants. Heating, ventilating, and air conditioning is based on the basic principles of thermodynamics, fluid mechanics, and heat transfer, and two inventions and discoveries made by Michael Faraday, Willis Carrier, Reuben Trane, James Joule, William Rankine, Sadi Carnot, and many others. The invention of the components of HVAC systems goes hand-in-hand with the industrial revolution, and new methods of modernization, higher efficiency, and system control are constantly introduced by companies and inventors all over the world.

The term “HVAC system” is used to refer to the equipment that can provide heating, cooling, filtered outdoor air, and humidity control to maintain comfort conditions in a building.

Building Details:

Information Technology and Engineering College is consist of four floors, There are different applications inside the Building as the table (1) shows.

Table 1: Building floors applications

2.3 Building Location

Country: Palestine.

City: Jenin

Elevation: 322 m above sea level Latitude: 32˚.

Building face sits at the North orientation.

The wind speed in Jenin above 5 m/s. 

Inside Design Condition:

The name inside design conditions refer to temperature, humidity, air speed and cleanliness of inside air that will induce comfort to occupants of the space at minimum energy consumption. There are several factors that control of selection of the inside design conditions and expenditure of energy to maintain those conditions:

1. The outside design condition.

2.  The period of occupancy of the conditional space.

3. The level of activity of the occupants in conditional space.

4. The type of building and its use.

Usually the range of temperature difference between inside and outside is  11 C . the relative humidity range from the conditioned space varies from 30% - 60% . a dry environment  will be felt when the relative humidity falls below 30%, and sickness will be felt  at relative humidity above 60%.

The Indore air speed is not designed as a parameter for comfort as long as it moves the treated air to the desired corners and edges of the spaces. However, it is desirable to keep it within the range of 0.1 to 0.35 m/s for comfort. In Palestine the inside design condition is:

For winter:

Dry bulb temperature Td =23 C

Relative humidity RH = 50 %

For summer:

The dry bulb temperature Td = 23 C

Relative humidity RH = 50%

Out Side Design Conditions:

Outside design conditions are very important parameters, they must be evaluated correctly since they will determine whether the air conditioning system will provide the desired comfort or not, whether the system will be undersized or oversized. an undersized system will not provide the desired indoor conditions for comfort. an oversized system will cost more than it should for a proper  economical engineering system.

Outside design condition vary considerably with the location they are determine by averaging conditions with occur over a number of years, and they generally exclude usually high or low values that are reached for a period of time less than 10 days for the summer and winter seasons.

 in Palestine, the outside design conditions are :

For winter:

Dry bulb temperature Td = 6 C

Relative humidity RH = 73 %

For summer:

The dry bulb temperature Td = 31 C

Relative humidity RH = 49%