A North America-based thermal energy utility will employ industrial heat pumps from German and American manufacturer of GEA Group for heating and cooling in a district heating project for 6 million ft2 (557,418m2) of building space. GEA’s American manufacturer is located in York, Pennsylvania, USA.
Details of the project were presented by German Robledo, Heat Pump Sales Manager at GEA, during a heat pumps case study session at the ATMOsphere (ATMO) America Summit 2023 on natural refrigerants. The conference took place June 12–13 in Washington, D.C., and was organized by ATMOsphere, publisher of Ammonia21.com.
The project will feature two 2MW (568TR), GEA RedGenium heat pump systems that use ammonia (R717) as a refrigerant. They will be connected to an existing district energy heating and cooling system.
Each unit will generate 2MW (568TR) of hot water at 85°C (185°F) and meet chilling requirements of 4.4°C (40°F) with 1.47MW (419.4TR) of chilled water. Operating with a COP of 3.09, these heat pumps ensure high energy efficiency for the sustainable operation of the buildings, said Robledo. Each heat pump weighs 26,762kg (59,000lbs) and has dimensions of 9.9m (32.5ft) in length, 3.29m (10.8ft) in width and 3.87m (12.7ft) in height.
The test facility showed impressive performance, energy efficiency and sustainability, noted Robledo. The data was collected under varying load conditions: 100%, 75% and 50%.
Operating at full throttle, the system produced 4,146kW (1,179TR) of heating and 2,881kW (818TR) of cooling power, requiring 1,202kW of shaft power and 1,306kW of input power, excluding water pump and oil pump power.
The COP of the installed system for heating and cooling is 3.17 and 2.21, respectively, after testing and modification, with a carbon footprint (CO2e) of 1.8 metric tons/hr.
At 75% and 50% total capacity, the COP of the system remained consistent with CO2e emissions of 1.3 and 0.8 metric tons/hr, respectively.
“Tested a full capacity, 75% and 50% loads, these units have shown remarkable consistency and adaptability, making them a truly efficient and suitable district heating options,” said Robledo.
“Even at full capacity, their carbon emissions are just 1.8 metric tons of CO2 per hour,” he added. “When operating at 50%, they still provide notable output, yet the emissions drop further to 0.8 metric tons per hour, making it a very environmentally friendly heating solution.”
Plate-and-shell heat exchanger
According to Robledo, the system has a high-side design pressure of 56.12bar (814psi) and is equipped with variable frequency drives for the electric motors. They feature a high-efficiency plate-and-shell heat exchanger.
These units employ an advanced evaporator design for the chilling process, delivering chilled water with an outlet temperature of 5°C (42°F) and an inlet temperature of 11°C (51.8°F). With a substantial flow rate of 424m3/hr (1,866gpm), the evaporator ensures efficient thermal exchange.
On the heating side, the hot water condenser operates with an inlet temperature of 65°C (149°F) and an outlet temperature of 85°C (185°F), handling flow rate of 180m3/hr(792gpm), said Robledo.
The system has two compressor units. The low-stage compressor, a GEA V1800HS model, features a six-cylinder 500hp motor with variable speeds between 600 and 1500rpm. The high-stage compressor, a GEA V550XHP model, operates with a slightly less powerful 450hp motor. Both compressors come with a NEMA12 variable frequency drive (VFD), vertical oil separators and air-cooled oil coolers and are designed for indoor installation.
The heat pump system also integrates an intercooler, a condenser, a sub-cooler, a desuperheater and an evaporator. The intercooler between the compressors gives higher efficiency and control on the high-pressure side.
The estimated refrigerant charge for these systems falls between 600 and 800kg (1,322 to 1,763lbs).
“Tested a full capacity, 75% and 50% loads, these units have shown remarkable consistency and adaptability, making them a truly efficient and suitable district heating options.”German Robledo, Heat Pump Sales Manager at GEA