A discharge air temperature control system (DATCS) is a heating unit with a closed loop feedback control system. A schematic drawing of a typical system is shown in Fig. 1. The heating unit is a serpentine tube and fin heat exchanger supplied with hot water from a boiler. The air temperature is controlled by varying the water flow rate while the temperature of the inlet water to the heat exchanger remains constant.
The requirements placed on a DATCS vary from full heatlng load in the winter to part heating load in the spring and fall. In the design of a DATCS the heat exchanger and hot water boiler are sized and selected primarily to provide the heat required by the full heating load,. The feedback control loop is designed generally to give acceptable performance of the DATCS during the winter months. This implies that the feedback loop is designed to control the DATCS when it is operating under approximately 75% to 100% of full load. This design procedure poses a potential problem of poor DATCS performance when demands for less than 75% full heating occur.
The purposes of this paper are:
- To explore via computer simulation the performance characteristics of a typical DATCS under various loads.
- If poor perforance exists, to determine whieh components in the DATCS are responsible,
- To recommend possible methods for good DATCS performance when experiencing a part load.
Citation: ASHRAE Transactions, Volume 80, Part 1, Los Angeles, CA
Product Details
- Published:
- 1974
- Number of Pages:
- 14
- File Size:
- 1 file , 610 KB
- Product Code(s):
- D-LA-2303
