Comfort At Work: Q&A: Evergreen Hermetic Centrifugal Chiller


What is the cooling capacity range of the 19XR/XRT hermetic centrifugal chiller?

The 19XR is available in cooling capacities ranging from 200 to 1500 tons (703 to 5357 KW) using HFC-134a refrigerant. The 19XRT is available in cooling capacities ranging from 350 to 525 tons (1231 to 1846 KW) using HFC-134a refrigerant.

What is the efficiency range of the 19XR/XRT centrifugal chiller?

At ARI (American Refrigeration Institute) standard conditions the efficiency of the 19XR ranges from .55 to .65 IKW/TON (.157 to .185 kW/kW) at full load. Integrated Part Load Value (IPLV) are equivalent to full load efficiencies. The 19XRT efficiency level approaches the .50 IKW/TON (.143 kW/kW) level.

What is the difference between the 19XR and 19XRT design?

The 19XRT incorporates Carrier's patented energy recovery turbine to reduce the power consumption of the chiller. We utilize the refrigerant pressure differential between the cooler and condenser to drive a turbine wheel attached to an extension of the motor shaft. By recovering this otherwise wasted potential energy we reduce the power consumption of the motor. Physically the 19XRT includes additional interconnecting piping between the turbine and the heat exchangers which does increase the size slightly.

What are the key features of the 19XR/XRT chiller?

The primary selling feature of the 19XR and 19XRT is these chillers are the highest efficiency chlorine free centrifugal chiller available on the market today. By optimizing the efficiency for HFC-134a refrigerant we are able to offer a higher efficiency HFC-134a chiller. The positive pressure design of the 19XR/XRT results in a significant reduction in product size when compared to a low pressure HCFC-123 chiller of the same capacity and efficiency. The volume can be 25 to 35% smaller than the equivalent HCFC-123 chiller. We also use a bolt together construction that allows each major component (Evaporator, Condenser, Compressor) to be disassembled, rigged into the plant room, and then reassembled which eliminates the need to knock down walls in most applications.

What is the sound level of the 19XR/XRT chiller?.

Sound levels for the 19XR/XRT range in the 87 to 89 dba range without any sound treatment. We offer an optional compressor discharge elbow sound reduction kit that can reduce the sound level by 2 dba. Also available, if required, is a sound blanket kit that covers the compressor, discharge elbow, and condenser. With this treatment sound levels in the 83 dba range are possible.

Will the 19XR/XRT work with my existing building energy management system (EMS)?

Yes, the 19XR/XRT will accept start/stop signals, chilled water setpoint reset, and demand limiting from your EMS system. Additional EMS functions can be easily achieved with the addition of an inexpensive optional interface.

What are the advantages of a hermetic compressor vs. an open drive compressor?

The hermetic 19XR/XRT compressor motor is cooled by the circulating liquid refrigerant. The motor operates in a clean and cool environment as opposed to a typical open drive compressor. The hermetic design eliminates heat rejection to the plant room which is characteristic of an air cooled open drive motor. The energy consumption to cool the motor is included in the 19XR/XRT power consumption. The heat rejected by an air cooled open motor must be accounted for in the building cooling or ventilation load. The hermetic compressor also eliminates the open drive shaft seal. Shaft seals wear and leak both oil and refrigerant and have to be replaced as the chiller ages. The 19XR/XRT hermetic design eliminates this operating concern.

Does Carrier offer performance testing for the 19XR/XRT?

Yes, both customer witnessed and Carrier certified performance testing is available. However you should be aware the 19XR/XRT is ARI certified. This certification is maintained through a stringent program of independently witnessed periodic performance testing.

What quality assurance programs do you have in place?

The 19XR/XRT is Underwriters Laboratories (UL) listed (CUL for Canada). Also the refrigerant side of the chiller is designed and built in accordance with ASME requirements, assuring pressure vessel integrity. The chiller is built in conformance with the latest version of ASHRAE 15 safety code for mechanical refrigeration units. The 19XR/XRT is also built in Carrier's ISO 9001 listed manufacturing facility.

What type of control system is used on the 19XR/XRT?

All Carrier centrifugal and rotary screw chillers utilize our microprocessor based Product Integrated Controls (PIC) as standard. This control system monitors over 100 functions and displays over 125 operating and diagnostic conditions. The human interface is a 16 line by 40 character backlit LCD display that allows simultaneous display of key chiller operating parameters on the same screen. The PIC can also be easily connected to the Carrier Comfort Network to interface with the entire building control system.

( top of page | back to Q&A menu )