TABLE OF CONTENTS

Dorin, CO 2
transcritical compressors
Introduction
Carbon dioxide (R744 - CO 2
) is nowadays considered one of the most attractive
long-term solutions for many kind of application. The compressor represents one
of the most critical components in CO 2
transcritical applications. In designing CO 2
compressors several challenges have to be overcome, mainly linked to the refrigerant
thermodynamic characteristics, like high discharge temperatures (up to 200°C), which
impacts on both oil temperature and refrigerant suction temperature and density. This
affects lubrication as well as the compressor volumetric and isentropic efficiency.
Different design concepts impact on compressor heat transfer and dissipation.
Improving discharge gas heat rejection it is possible to increase both compressor
reliability and efficiency. The main results of several design experiments are summarised
and described below.
About the company
Dorin entered the field of refrigeration in 1932 with its
first open-drive compressor range. The first CO 2
transcritical
type was commissioned in 1999. Today, Dorin
produces more than 70,000 compressors per year.
More information at:
http://www.dorin.com
Contact Information
Giacomo Pisano
g.pisano@dorin.com
About the System
A new generation of CO 2
transcritical compressors has been developed, with
displacements ranging from 1.1 m 3 /h to 26.6 m 3 /h and motor power ranging from 1.5
hp to 40 hp. The newly developed compressor ranges (CD200, CD300, CD400) offer the
largest choice in terms of available models, making it possible to realize installations
of any size, from residential to commercial and industrial ones. Compressors are
developed in semi-hermetic platforms with 2 and 4 cylinders. Compressors are able
to operate in a very broad application envelope, with working pressures up to 150 bar;
qualifcation life testing highlighted how robust the compressors are, able to work with
differential pressures up to 120 bar and 200°C discharge temperatures.
The compressor model tested was CD1900H, 11.62 m 3 /h, 20 hp. Due to the very high
end of compression temperature, particular focus has been given to the heat rejection
at the high pressure side of the compressor. Two main design experiments (A and B)
were carried out and tested, shown in Figure 1 and Figure 2.
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