If you are asked to design a pipe system for an HVAC system

If you are asked to design a pipe system for an HVAC system, what aspects you need to consider, what parameters you may need to know and what parameters you may need to decide? Briefly describe the design procedures referring to technical literature.

Solution

Aspects need to consider in designing a pipe system for HVAC system are :

1 . Heating - To maintain conditions in responce to thermal heat loss.

2 . Cooling - To maintain conditions in response to thermal heat gain.

3 . Effectiveness - To achieve the desired thermal energy transfer, filtration, humidity control.

4 . Humidifying -To maintain moisture content by adding water vapour.

5 . Dehumidifying -To maintain moisture content by removing water vapour.

6 . Ventilation - Maintaining sufficient outside air and pressure.

The parameters we need to know and to decide for the design of HVAC pipe system are :

1 . Pressure drop - For the proper performance of the system the prressure loss of each component must be subtracted from the available static pressure of the equipment.

2 . Room by room supply requirements - The volume of conditioned air needed to satisfy the load of each room can be calculated by using heating and cooling of room by room estimation of values.

3 . Return air design - A well desined strategy is critical for designing a HVAC system with lower airflow requirements to meet the load. Direct rreturn from each room to the equipment is not desirable when we are trying to minimize the duct lenghts and prressure losses in the system. Rooms without an adequate return path will be pressurized which results in comfort complaints.

4 . Supply air outlets - The supply of air outlets are critical to the comfort with in the space.The air must be delivered in which it mixes the supply air with room air without introducing or accepting any other noise.Placement of the air outlet is as important to the comfort in the room as the type of air outlet used.

5 . Duct layout - From the integrated design work and the room by room air flows, a layout on the ductwork can be completed in the floor plans.

6 . Duct size - The duct size is selected relative to the amount of air pass through the ductwork.The variables which define the airflow of duct are friction loss in the duct, cross-sectional area of the duct, and average velocity of air moving in the duct.