Multi-Functional, High-Performance Run Around Energy Recovery Systems in Cold Climate Zones

While the thermodynamics of a run-around energy recovery system are relatively simple, it is critical that high-performance systems operate at optimum performance under varying operating parameters. With several variable input parameters (outside air/supply air/return air temperatures; air volumes; fluid volumes & temperatures), controlling and optimizing a system requires a numerical simulation based controller ('performance mapping') that allows variable amounts of heat transfer fluid to be circulated throughout the system. In multi-functional systems, additional heating and/or cooling is introduced into the fluid circuit, either to increase the heating/cooling capability of the energy recovery system from waste heat/cooling sources, or to control the supply air temperature to the building to eliminate separate heating/cooling coils in the supply air handlers. These features add yet another level of complexity to the controller function.