In an Air Handling Unit (AHU), the entering and leaving air temperatures refer to the temperature of the air as it enters and exits the AHU. The AHU is a device used in HVAC (Heating, Ventilation, and Air Conditioning) systems to condition and circulate air in a building.
The entering air temperature, also known as the outside air temperature or supply air temperature, is the temperature of the air as it is brought into the AHU from the outside environment. This air is typically drawn in from the outdoors or sometimes from a specific area like a ventilation duct.
The leaving air temperature, also referred to as the supply air temperature or discharge air temperature, is the temperature of the air after it has passed through the AHU and been conditioned. The AHU performs various functions, such as cooling, heating, humidification, dehumidification, filtration, and ventilation. Depending on the HVAC system's design and the requirements of the space being conditioned, the AHU adjusts the air temperature to achieve the desired comfort or process conditions.
The entering and leaving air temperatures in an AHU can vary depending on factors such as the specific HVAC system design, the building's requirements, and the environmental conditions. For instance, in a cooling mode, the AHU may aim to lower the entering air temperature by removing heat from the air, resulting in a lower leaving air temperature. In a heating mode, the AHU may increase the entering air temperature by adding heat to the air, resulting in a higher leaving air temperature.
It's important to note that the entering and leaving air temperatures can also be influenced by factors such as air flow rates, humidity levels, control strategies, and the setpoints established for the HVAC system. These parameters are typically determined based on the specific needs and comfort requirements of the building occupants or the process being served by the HVAC system.