As you know, chillers are typically considered cold water providers. With advancements in technology, that has been changing. As energy efficiency becomes more and more important, chillers are being optimized for heat recovery across markets that demand more from their HVAC systems. Paul Crisman, a Daikin Application Engineer, recently shared a white paper detailing heat recovery’s advantages in HVAC. Today, we’ll share a few of his key insights.
Heat recovery reclaims energy normally rejected during heating and cooling processes from air or water applications using an enthalpy wheel or energy recovery ventilator. The engineering concept is to extract the otherwise wasted energy of exhaust air and use it to preheat cold outdoor air.
In air-cooled chillers, the heat exchanger is called a desuperheater. In heat recovery mode, hot refrigerant gas leaves the compressor and enters the heat exchanger where the energy in the refrigerant gas is transferred to the incoming hot water loop. As a result, the refrigerant is pre-cooled prior to entering the condenser coil section, reducing fan energy and further improving energy efficiency.
The efficiency improvements seem obvious: why isn’t everyone doing it? Heat recovery in chillers requires additional design considerations, since greater infrastructure and controls are needed. Control of the heat recovery loop is performed by the chiller controller to ensure the leaving water temperature does not influence the refrigerant temperature limits. As conditions change, the controller sends a signal to modulate the device selected by the engineer.
As the leading innovator in HVAC, Daikin is ready for the challenge. With Daikin’s Trailblazer® air-cooled scroll chiller, control of the three-way valve or pump from the unit controller helps simplify installation and ensure proper operation. Without this ability, additional sensors and control strategies would have to be added thus increasing costs and the probability of operation outside proper safety range values.
What applications are best fit for heat recovery? While it can vary depending on geographical location, the hospitality industry has the highest demand due to domestic hot water needs, high utility rates and stints of simultaneous heating and cooling. For example, schools, health care facilities, and office buildings.
Interested in learning more? Check out Paul’s whitepaper, Delivering Hot Water with a Chiller, for the full story.