The buzz about CO2 compressors at Chillventa 2014

By Janet Thompson, Oct 21, 2014, 19:15 6 minute reading

With a record breaking 30,000+ visitors, Chillventa 2014 proved to be a key meeting place for refrigeration, air conditioning, ventilation and heat pump industry players. Leading manufacturers such as GEA Refrigeration Technologies, Dorin, Bitzer, Emerson Climate Technologies, Frascold and Howden were on site to present their latest CO2 compressor innovations.

Fresh insights from GEA Refrigeration Technologies & GEA Bock

GEA Refrigeration Technologies proudly exhibited its Grasso 5HP series reciprocating compressors for use in CO2 cascade freezing systems in industrial refrigeration applications. The series features a high stage design pressure of 50 bar and includes four single stage models with 3 to 6 cylinders and a range of capacities. The extremely low volume flow in relation to the cooling capacity is one of the things that make this series a big performer.

Another stand out at GEA Refrigeration Technologies’ booth was the GEA Grasso screw compressor LT series, which distinguish themselves by their robust design. The components are specially engineered for long operational life, high availability and easy maintenance. The compressors in this series are available for both CO2 and ammonia applications.

GEA Bock showcased its impressive product range for CO2, including its semi-hermetic CO2 compressors for subcritical cascade systems and transcritical CO2 applications. The main highlight was the HG46 CO2 T semi-hermetic 6 cylinder compressor with a displacement of 21,8 to 30,2m3/h. With operating pressures of up to 130 bar, it is one of the biggest semi-hermetic compressors for transcritical CO2 currently available on the market. Its robust design enables maximum standstill pressures of 150 bar on the high pressure side and 100 bar on the low pressure side. Another highlight was GEA Bock’s 4 cylinder HGX34 transcritical CO2 compressor series with a range of displacements from 9,9m3/h to 25,5m3/h. The series includes the HGX34/290-4 model with a displacement of 25,5m3/h at 50 Hz.

Dorin exhibits its flagship CO2 compressors

Transcritical & subcritical CO2 compressors stood in the spotlight at Dorin’s Chillventa 2014 booth. One of the star performers was Dorin’s CD500, a 6 cylinder model for CO2 transcritical commercial refrigeration. The largest compressor in the CD range, it reduces the number of compressors needed on the racks and is able to accommodate larger cooling capacity requirements. It has a displacement from 39,8 to 53,2m3/h, one of the widest on the market, a design pressure of 100 bar (LP) and 150 bar (HP) and nominal power from 50 to 80 HP.

Dorin also exhibited its CDS series for both cascade and booster systems, which boasts one of the highest standstill pressures for CO2 subcritical compressors worldwide. The CDS series was recently extended with CDSI series, which operates from 20 to 70 Hz. Models include the CDSI 11:5 with 2 cylinders and displacement from 1,90 to 5,53m3/h at 50 Hz, the CDSI 35:3 with 4 cylinders and displacement from 10,61 to 16,19 m3/h at 50 Hz and the CDSI 41:2 with 4 cylinders and displacement from 29,49 to 33,63m3/h at 50 Hz.

Bitzer’s new compressor ranges draw a crowd

For over ten years, Bitzer’s CO2 transcritical compressors have been highly successful.. At Chillventa 2014, Bitzer exhibited the latest additions to its product series: new 2 cylinder and 6 cylinder models with optimised oil management that increase the range of applications and provide even higher energy efficiency and operational reliability. The new capacity range covers displacements from 3.3.m3/h to 37.9m3/h. The compressors feature housing with high pressure strength and no bottom plate, with maximum permissible pressure levels of 160 bar for the high pressure side and 100 bar for the low pressure side. They are particularly well suited for operation with frequency inverters to increase and control capacity.

The 2KTE – 7K 2 cylinder semi-hermetic reciprocating compressor in particular drew quite a crowd. This compressor for transcritical CO2 applications offers high energy efficiency, low vibration and pulsation and displacements from 3.3 to 4.8m3/h.

Bitzer also showcased its new line of semi-hermetic reciprocating compressors specifically developed to meet the requirements of subcritical CO2 applications with high demands on standstill pressures and condensing temperatures. Compared to Bitzer’s proven SL compressors, this new series has an increased pressure strength of 100 bar at the high and low pressure sides and an extended application range. It includes eight models with a geometric displacement capacity of 1.73 to 9.22m3/h. The two motor versions allow for efficient use in conventional CO2 low temperature systems or in applications with elevated condensing temperatures. The compressors are particularly suited for use in cold-water networks with condensing temperatures of up to 25°C.

Durability and performance with Emerson’s Copeland compressors

Emerson Climate Technologies proudly exhibited its Copeland brand compressors for both transcritical and subcritical CO2 applications. The CopelandTM Stream series of 4 cylinder CO2 compressors is designed for durability and performance in CO2 transcritical applications. Characterised by a design pressure of 135 bar, the compressors are ideal for medium temperature cascade and booster systems, as well as for low temperature cascade and booster applications requiring high standstill pressures up to 90 bar suction. Both the refrigerant flow and heat transfer are optimised and all compressors are equipped with CoreSenseTM, with offers the possibility to diagnose system-related problems faster or even before they occur.

The ZO compressor range for low temperature refrigeration is optimised for high efficiency in CO2 subcritical cascade and booster systems. The compressors have a compact design and half the weight of equivalent semi-hermetic compressors. They feature high condensing temperature limits allowing for better overall design. The Copeland ScrollTM compressors are available as a digital model offering simple, stepless 10 to 100% capacity modulation.

Frascold compressors cover transcritical and subcritical applications

Semi-hermetic reciprocating compressors for CO2 subcritical and transcritical applications were also a hit at the Frascold booth. With its high design pressures, the SK2 series for subcritical CO2 can be installed in most cascade and booster systems with standstill pressures of up to 60 bar. The compressors have a maximum condensing temperature of 15°C (55 bar) and a maximum allowable standstill pressure of 30 bar (models with 60 bar are available upon request). In addition to the use of a variable frequency drive, Frascold has also developed a unique capacity control head that provides the system with different levels of cooling capacity. This new RSH head is available for all models of the D and Q series.

For transcritical CO2 applications, Frascold presented its TK series compressors, which are suitable for use in single-stage and booster (in combination with SK2 series compressors) applications. The series includes 11 models for commercial refrigeration applications, 8 of which are also suitable for heat pumps. The maximum allowable pressures are 140 bar on the discharge side and 80 bar on the suction side.

The model Q9-5.3STK is a two-stage CO2 transcritical compressor designed to operate in a flash-gas-by-pass cycle with either one temperature level or two different temperature levels, medium and low temperature. It has a first stage displacement of 5,3m3/h and a second stage displacement of 3,5m3/h. At an evaporating temperature of -30°C and a discharge pressure of 87 bar with a gas cooler outlet temperature of 35°C, it is able to provide a cooling capacity of about 8kW.

Howden, a specialist manufacturer of twin screw compressors

Howden was present at the 2014 Chillventa show to exhibit its range compressors. The company offers oil injected and oil free rotary twin screw compressors and supplies bare shaft oil injected screw compressors for the refrigeration, gas processing and other industries. Howden’s compressors are capable of operation with all known refrigerants including CO2, with which the company has over 30 years of experience. Howden is actively increasing its range of products to match customer requirements, such as high pressure gas boosters for aeroderivative gas turbines, which now typically require gas supply at pressure above 50 bar.


By Janet Thompson

Oct 21, 2014, 19:15

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