The variable refrigerant flow (VRF) model simulates the performance of VRF systems using either outdoor air or a water loop (heat transfer loop) as the source and sink for acquiring and rejecting heat. For simplicity, we refer to these as Air-source and Water-source VRF systems.
In the case of Water-source VRF systems, the building-level Heat Transfer Loop (HTL) typically serves as both heat source and heat-rejection sink for multiple VRF systems (e.g., one VRF system for each floor of a tall building) and normally incorporates a boiler and cooling tower to maintain the water loop within a set temperature range.
The VRF model uses performance characteristics at rated conditions along with thirty-one performance curves. Curve sets are provided for a default air-source VRF system and a number of manufacturer-specific air- and water-source VRF systems. The performance curve data for the manufacturer-specific VRF systems is provided by the manufacturers of those systems.
The contents of Variable Refrigerant Flow (VRF) Systems
