FR3091334A1 - Energy transfer in the same air handling unit for temperature and hygrometry regulation - Google Patents

Abstract

[The system presented consists in taking advantage of the simultaneous need for hot and cold. The attached diagrams show the configuration of an air handling unit (AHU) equipped with the system. On a conventional air handling unit only two hot and cold batteries connected to independent productions are installed. Here, an internal brine exchange battery system has been added to the AHU. This invention relates to the field of air treatment and aims to reduce the energy consumption on the production of chilled water and hot water intended to provide the necessary power in a treatment plant for temperature regulation. and humidity of a room.]

Description

Description

Title of the invention: Energy transfer in the same air handling unit for temperature and hygrometry regulation

Presentation of the classic air dehumidification process

The outdoor air contains, in the form of sustenance vapor, a certain variable amount of water. This amount of water is expressed as a percentage (relative humidity), and or by weight of water (g _water / kg _air ) (absolute humidity).

For comfort, the optimal relative humidity conditions in the air are between 30% and 60%. But some industries need to maintain a specific humidity level for their manufacturing process.

The most common method of dehumidifying air is to lower the temperature of the air below the dew point corresponding to the desired humidity level.

[0005] [fig. 1] Below is a psychrometric diagram of humid air schematizing the transformations undergone during the process:

Point E - Outdoor air at 28 ° C and 70% relative humidity

Transformation E to X - Air cooling to reach the saturated air temperature corresponding to the desired absolute humidity (here 10.5 ° C for 8 g _water / kg _air )

Transformation X to S - Air heating in order to reach the desired supply air temperature

Point S - Supply air at 16 ° C and 70% relative humidity

The process is particularly energy intensive since it consists of cooling and then heating the air accordingly. In the case cited above we find ourselves for example in the need to provide heat to the air to obtain a temperature of 16 ° C even when the outside temperature is 28 ° C.

In a conventional configuration, the cooling is carried out through a cold battery supplied by the production of chilled water, and the heating by a hot battery supplied by a separate production of hot water.

Presentation of the innovative process

The system presented consists in taking advantage of the simultaneous need for hot and cold. The attached diagrams show the configuration of an air handling unit (AHU) equipped with the system. On a conventional air handling unit only two hot and cold batteries connected to independent productions are installed. Here, an internal brine exchange battery system has been added to the AHU.

[Fig-2] In the diagram below, these batteries allow you to use the calories of the outside air (38 ° C) to heat the air at the outlet of the cold battery (4 ° C at

21 ° C). The savings achieved are twofold since this makes it possible to limit or even eliminate the need for subsequent heating. But also to reduce the need for cold by pre-cooling the air (from 38 ° C to 21 ° C)

This internal recovery battery set at the CTA therefore allows significant energy savings, both hot and cold. The savings vary according to the external climatic conditions. But they are especially important in summer when the temperature and humidity are high.

Potential gains

To assess the potential savings, a simulation of the consumption of a practical case with and without the recovery system was carried out on the basis of actual climatic conditions in 2017. The hourly hourly weather data used are those of Beauvais (60) .

Simulation hypothesis

System: all-fresh air treatment unit

Air flow to be treated: 50,000 m ³ / h

Air temperature set point: 21 ° C

Maximum humidity setting: 45% or 7 g _ea u / kg _air

[Fig-3] This gives the following results in gross consumption (without considering production yields)

Table generated using MS Word tools:

[Fig.4] is a comparison table of consumption with and without heat recovery.

The simulation of this practical case highlights a total gross gain of around 20% on energy consumption.

Claims (1)

[Claim 1] Claims The air handling unit (CTA) has 4 water batteries allowing temperature and humidity to be treated outside air to blow it into a room. There is a cold battery which allows both to cool and dehumidify the outside air, and a hot battery which allows to heat the air before entering the room after passing through the cold battery. Upstream and downstream of the cold battery, there are two internal heat exchange batteries in the air handling unit which transfer calories from the outside air after the cold battery, and also reduce the temperature of the air arriving on the cold battery.