Frascold Blog

Frascold now offers a full range of compressors for both subcritical and transcritical CO2 applications
The solutions offered by Frascold for CO2 applications, include semi-hermetic reciprocating compressors for use in both subcritical and transcritical operation, single-cycle cascade and booster.
The compressors can run in a wide operating range, ensuring excellent performance and efficiency with a high reliability. Besides, the compressors are designed to withstand high standstill pressures in order to ensure an immediate restart of the plant.
Frascold continues to invest significant resources in the search for solutions leading to the reduction of indirect emissions and energy consumption.

Subcritical applications:
The range of SK3 series for subcritical CO2 applications consists of 13 models with cooling capacity from 1,8 kW to 101 kW at 50Hz. Their particular compact construction allows to operate at maximum operating condensing pressure of 50 bar(a) and withstand a standstill pressure Pss equal to 80 bar.
Operating range: condensing temperature up to 15°C, evaporation temperature up to -15°C.
The SK3 series is available with the innovative RSH system (Frascold patent) for capacity reduction: this system is available both for 4-cylinders compressors and 2-cylinders. Compared to the traditional CC control system (cylinder head part-loading) the RSH system allows to reduce the displacement of each single cylinder with the following benefits: no limitation of the operating time, a better adaptation to the thermal load of the system, only a small temperature rise of discharge gas, a steady piston lubrication, no noise increase.
All models of SK3 series are equipped with the electronic protection device “Diagnose” with many diagnostic and communication functions.
The SK3 compressors are applied to cascade systems and booster systems.

Transcritical applications:
The range of TK series compressors for CO2 transcritical applications consists of 19 models with cooling capacity from 9,5 kW to 112 kW.
The construction is designed to operate with condensing pressures up to 140 bar(a) and 80 bar(a) evaporating.
These compressors, in combination with the SK3 series, are installed in multi-compressor systems for medium and low temperature applications (booster systems) with plant standstill pressure of 80 bar.
TK series includes models designed for specific applications in heat pump systems.
All models are equipped with the electronic protection device “Diagnose” with many diagnostic and communication functions.

Support to application of the compressors
Frascold Selection Software CO2: The new Frascold software dedicated to CO2 processes within refrigeration, air conditioning and heat pumps, is one of the most complete tools available today.
The software has been designed and developed by the Frascold’s technical and research team. It is based on many years of experience in the production of compressors and their application in simple or more complex systems.
The software allows to choose a specific refrigeration cycle, sub-critical or transcritical, to choose or select the CO2 compressors, verify their performance.

This powerfull program, other than typical refrigerant cycles, includes other systems, such as:

Thermodynamic cycle with flash-gas bypass
Compared to the basic thermodynamic cycle, it is possible to define a mid working pressure to be maintained inside a liquid receiver placed between the gas cooler and the evaporator. In this way there is an independent control of the discharge and evaporation pressures. This solution improves the operation of expansion devides, reduces the risk of liquid slugging and allows the compressors to run always at max efficiency.
Thermodynamic cycle with flash-gas bypass and booster sub-critical stage
Compared to the previous cycle, an additional evaporative stage is add for the LT utilities. In this stage, a compressor will operate between a given evaporative pressure and the pressure in the suction line of the medium temperature compressors. In such a way, it is possible to serve with a single system both, low and medium temperature utilities, without using the cascade systems.

In the software, each cycle is presented in a simple and intuitive manner, allowing to make multi-compressor selections, at fixed or variable speeds (inverter use). Once the calculation is done, the software provides accurate thermodynamic information, that can be used by the designer for the installation dimensioning.

The FSS3 can be free-downloaded from Frascold website
The program will create a shortcut on the desktop for easy start-up.

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