CUSTOM LIQUID REFRIGERANT OVERFEED ENERGY RECOVERY SYSTEM
Three sets of redundant exhaust systems serving a high-tech production facility required fan replacements. One dedicated system for each type of exhaust; corrosive, solvent and heat. This presented our client with an opportunity to incorporate a fully integrated, retrofit liquid refrigerant overfeed energy recovery system. Energy recovery coils were designed into the existing exhaust systems and a local make-up air handling unit. Energy recovery is obtained year round by reversing the refrigerant cycle. This reduced overall operating cost while restoring some additional capacity to the make-up air handling unit. Our design also resolved a long standing problem with snow entrainment at the make-up air handling unit.
- Full sequence of operations for all new equipment including all interface points with existing equipment and systems.
- Designed modifications to an existing 20,000 CFM make-up air handling unit to integrate new energy recovery coil, filter section and outdoor air inlet section to eliminate snow entrainment during winter conditions.
- Designed and integrated new energy recovery coils for each set of new exhaust fans. New fans designed and arranged for N+1 redundancy with controls and dampers for automatic changeover. Detailing included discharge configuration, inlet and outlet conditions, support, and sound attenuation.
- New refrigerant pumps and receivers designed with fully integrated controls including automatic changeover. Refrigerant cycle reverses based on adjustable outdoor air temperature setpoints with built in deadband. A typical design requires only a single pump and receiver with refrigerant flowing by gravity under one condition. However, the unique circumstances associated with geometry relative to equipment locations in the field required two  pumps and receivers. One pump and receiver set each for cooling and heating.
- Designed power for refrigerant pumps including feeders, disconnect switches, and motor controllers.
- Fully integrated energy recovery system provided year round operational energy savings for make-up air handling unit with a total load reduction of 371 MBH (108 kw) wintertime and 198 MBH (16 tons) summertime.
- Served clients original need of fan replacements for exhaust systems and also incorporated a custom liquid refrigerant overfeed energy recovery system for overall operational savings and efficiency.