FEATURE
INCORPORATING COLD CHAIN
At this point, he described one victory leading to increased efficiency.
as bringing on-line “the first synthetic Technologies that enhance the
refrigerant free store in the USA, with zero efficiency of transcritical systems include
ozone depletion and low global warming parallel compression, ejectors, adiabatic
potential.” He noted refrigeration is condensers and subcooling.
contributing to “an expected whole
the cascade system, with R407A on
than 60% above the ASHRAE 90.1-2007 the high side, at the Castro location,
baseline.” He added the store has and the transcritical CO 2 system with
earned GreenChill Platinum and LEED an absorption chiller at the Alameda
Platinum recognition, the highest levels in location performed most efficiently in
both programmes. high ambient temperatures.
The case study called ‘Comparing
provides a useful system comparison.
System Types’, looked at the way that However, a look at the Total Equivalent
transcritical CO 2 and cascade systems Warming Impact (TEWI) of the five
perform in variable climates and stores systems paints a different picture. After
around California. Coffin said that direct refrigerant emissions are taken into
building type and climate zone are account, the Castro system, using R407A
the two most important considerations (with a GWP of 2107) on the high side,
when deciding which type of natural proves to have the highest TEWI of the
refrigerant system to use. He added that installations discussed.
make the state an effective place to UNITED KINGDOM
conduct case studies on how different A Sainsbury supermarket chain reported
systems work in varied climate types. it was testing an Epta ECP2 small CO 2
At the two locations where transcritical
Kingdom. CO 2 is used in all refrigerated
ambient temperature increased beyond addition, the store was using 42 solar
the critical point of CO 2 : 88°F (31°C). panels to generate electricity and
However, at the Alameda location,
the CO 2 system was able to remain in
cases in the convenience store. In
double glazing for its LED lighting.
The innovations were part of what
subcritical mode when the absorption Sainsbury said was an effort to make the
chiller was in operation. store “the greenest convenience store in
Cascade systems, the study
confirmed, are generally more efficient in
www.coldlinkafrica.co.za
system in one of its stores in the United
CO 2 systems were installed, energy
efficiency decreased significantly as the
40
The comparison of energy efficiency
the Performance of Different Advanced
the many microclimates in California
The ammonia/CO 2 systems installed the world over show good benefits, not only for the clients
but for the environment too.
The case study also showed that
building design energy savings greater
the U.K.”
Star Refrigeration installed a CO 2
climates with high ambient temperatures plant at Lineage Logistics, project
because transcritical operation is which consists of a 15 000-pallet frozen
avoided. It was noted, however, that warehouse supporting Lineage's plan
transcritical system design is improving, for growth together with the industry's
COLD LINK AFRICA •
March/April 2020