CO2 heat pump with variable-displacement compressor/expander in the pipeline

Last August, The United State Energy Department announced 12 projects aimed at developing innovative heating, cooling and insulation techniques as well as open source energy-efficiency software to help homes and businesses to make energy savings.

 

 

 

 

One of the blueprint projects is an oil-free heat pump using no high GWP refrigerants. Leading partner in the project S-RAM Dynamics will deliver a 20-ton cooling and 240 000 BTU/h heating capacity heat pump for commercial buildings and industrial applications.

It is expected to operate between -35°C and 85°C, allowing for excellent performance in both cold climates and high-temperature work environments.

 

It will use oil-free variable-load compressor and variable expander technology, currently tested at Purdue University’s Herrick Laboratories.

The variable displacement compressor/expander systems enable varying the hot-side and cold-side temperatures as desired. This allows the pre-production heat pump to demonstrate significant energy-efficiency improvement as compared to current state-of-the-art heat-pump systems.

 

The unit will be able to run at constant speed while still allowing for variable temperatures and capacity, which removes the need for variable frequency drivers.

These innovations are made possible by a variable stroke compressor and the use of a mechanical expander that can recover a significant amount of energy, allowing for energy consumption savings up to an expected 50%, as compared to classic systems.