DOE-2 Reference Manual Version 2.1 - DOE2.com

IV.SYSTEMS PROGRAMA. INTRODUCTION1. Program DescriptionThe SYSTEMS program simulates the operation of the equipment and systemsthat distribute cooling and/or heating directly to the spaces being conditioned.In the case of the "packaged systems," RESYS, PSZ, PMZS, PVAVS, andPTAC, or any system with a furnace, the SYSTEMS program simulates not only theheating and cooling distribution systems but also that equipment which wouldnormally be part of the PLANT program, i.e., heating source, cooling source,pumps, etc. The reason for this approach is because in "packaged systems" itis difficult to clearly separate the primary systems from the secondarysystems. Most such systems are treated by manufacturers in their performan,cedata as a unit anyway. SYSTEMS also simulates the control of temperatureand/or humidity in these spaces. These are sometimes called "secondary" or"terminal" energy distribution systems, to differentiate them from "primaryenergy distribution" or "energy conversion" systems. This latter category ofequipment and the program that simulates its operation, called PLANT, aredescribed in Chap. V.The hourly space loads calculated by the LOADS program are not necessarilythe loads that are imposed on the heating and cooling "plant." Because of outsideventilation air requirements, HVAC equipment operating schedules, and thetemperature fluctuations required for control actuation, each building's hourlyheating and/or cooling requirements will be different from the summation of theexternal and internal hourly space loads calculated in LOADS. The purpose ofthe SYSTEMS simulation program is, therefore, twofold:a. To provide information for sizing of components in the "secondary"energy distribution system, based upon peak (or design day) heatingand cooling requirements.b. To simulate each distribution system as it responds to space thermalrequirements, and to determine the demand it is imposing upon thecen tral heatin g an d coo 1 i ng plan t.The SYSTEMS program mathematically simulates the heat and moistureexchange processes that occur in HVAC distribution systems. The user mustselect a system from a menu of "familiar" types of distribution systems.Additionally, optional component and control features, available for each typeof system, can be selected. The systems are described in Sec. B of thischapter.The SYSTEMS program receives, as input, a list of the hourly loads foreach space from the LOADS programs, and requires a sequence of user-definedSDL input instructions. The output of the SYSTEMS program provides input tothe PLANT program and information for the REPORT Generator Program.I V.1 (Revised 5/81)