Indirect Evaporative Cooling System
Our design also includes an indirect evaporative cooling system to pre-cool outdoor air to further reduce the building ’ s peak demand and overall chilled water consumption . The evaporative cooling coil is equipped with the ability to change over to heating duty ; utilizing one coil to perform both indirect cooling and heating eliminates the need for an extra heating coil , which reduces fan energy consumption . Additionally , since this coil is sized for the indirect evaporative cooling load , it provides exceptional heating hot water system ΔT , which reduces pump energy and enhances the overall heating system efficiency .
Process Path Narrative
The psychrometric diagram on the next page illustrates a summer cooling scenario where there may be lightly-loaded interior spaces within the building that require only a very mild amount of cooling . This condition may represent a substantial portion of the overall building on larger volume buildings such as the Ernest E . Tschannen Science
Complex . Under this condition , a space may only need a very mild supply air temperature ( i . e ., 70 ° F ) to maintain the room at its temperature setpoint to account for light fixtures , mild occupant activity , and mild equipment power loads within a space . A conventional VAV reheat system may be required to make air as cold as 55 ° F at the central air handling unit to satisfy the spaces with the highest demand for cooling . Simultaneously , the interior zones may need to reheat the air to ~ 70 ° F to avoid over-cooling the space . 4-Pipe VAV : Outside air comes in at point 1 , then is cooled by the indirect evaporative fluid cooler to point 1-A , then cooled by the central AHU to point 1-B and is distributed through the building supply air ductwork . The air is then cooled further at the zone 4-pipe VAV terminal unit to point 1-C and supplied into the zone served . Conventional VAV Reheat : Outside air comes in at point 1 , then is cooled by the central AHU to point 2 and is distributed through the building supply air ductwork . The air is then heated at the zone VAV reheat terminal unit to point 3 and is supplied into the zone served .
P2S EXTERNAL WINTER 2020
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