TABLE OF CONTENTS

world. System Designs
The larger chiller system uses HFC air-cooled system: propane (R-290) chillers, each with a cooling
capacity of x kW (total capacity: x kW) and a free cooler with a capacity of x kW. The
AKV
• Parallel R404a system with very good load adaptation
glycol/water solution at 9°C and return at 15°C.
chillers have to deliver a 35% propylene
The units are built as two independent • Controlled circuits by ADAP-KOOL® with the two heat pack pumps controller operating and AKC
AKV
on
one frame. The R600a heat pumps 114A achieve case a controllers total heating with capacity electronic of about expansion x kW and a
cooling capacity of about x kW. valve type AKV
• 148 systems in operation
In the summer period a base load for heating of tap water and room heating was
identified in the range of 400 to
•
500
10 selected
kW is now
for
provided
the study
by the heat pumps. During the
winter a cooling load occurs which Transcritical is partly delivered 1 st generation by the system: heat pumps while the rest
is managed by the free coolers.
AKV
• Booster system with gas bypass
On the warm side the flow is • controlled 2 compressors to keep for MT up (33/67%) the condensing and 2 for temperature
LT (33/67%
and the
AKV
pressure in the local district • Mechanical heating gas system. bypass In valve the winter period the supply
temperature of water is 80°C and • Controlled in the summer by ADAP-KOOL® it is supplied at pack 70°C. controller, The return EKC is 326 40°C.
This requires the heat pumps to deliver controlling water ICMTS at 80°C high and pressure at the same valve, time and cool AK-CC water.
The whole system is connected 750 to a case local controllers generator with set to electronic ensure stable expansion supply valve and
independence of the local grid in type case AKV of a power blackout.
ICMTS
“The installed system • 32 solution systems in has operation been highly satisfying.
It has met and even • First exceeded 10 selected our for the expectations. study. This is
partly attributable to the fact that simulated conditions
differed from real-world Transcritical results 2 nd generation and because system: the design
AKV
criteria had been carefully • Booster defined system with in gas the bypass planning phase.”
• 2 compressors, one with AKD inverter for MT and 2
Says John Marston, Director of St compressors Anna Hospital. without inverter for LT
AKV
• Controlled by ADAP-KOOL® pack controller, EKC 326A
controlling ICMTS high pressure valve and CCM stepper
gas by pass valve, and AK-CC 750 case controllers
Results
with electronic expansion valve type AKV
Safety: By using ICMTS a hermetic design • 10 with systems no shaft in operation seals or semi-welded May 2010 and heat 29 exchangers
in December
2010
most flammability concerns were eliminated. If a leak is detected all power to the unit
CCM
is cut out and can only be restarted manually from the panel. Remote reset is disabled
• First 10 selected for the study.
to ensure that a personal verification will identify the cause of the interruption.
Danfoss
R64-2061.10
Danfoss
R64-2063.10
Danfoss
R64-2062.10
Installation: An important lesson learnt was that insulation needs more consideration
compared to normal refrigeration systems. In a standard refrigeration system the
liquid temperature needs to be kept as low as possible and any heat rejected from the
Results
discharge pipe and from the liquid line is welcome. In the heat pump this is considered
as a loss. Also, the insulation material used needs some careful selection. Normal cell
The rubber energy or foam data can in usually this study not was be used collected at the from high May temperatures. 2010 to April Mineral 2011. wool The or plot, other on
the sorts first of page, wool insulation shows energy become consumption more attractive per month options. for the Typically 3 different the systems thickness (HFC, will
Trans also increase 1 and Trans but 2) and the average ambient temperature for the month.
Application Energy Efficiency: Engineer Energy Kenneth savings B. Madsen have been from achieved Danfoss mainly explains by “Our running measurements
the system
indicate on a big scale approximately energy efficient 10% plant energy rather savings than many in Denmark smaller when plants. comparing Also the water the flow 2 nd
generation has now been transcritical upgraded and CO 2
it system is currently with monitored the HFC system so it can - constantly with the lowest be optimised. energy
consumption in the cold months”, and further “the results also show a technology
improvement Performance: since The new 2007 plants where have the first been generation performing transcritical better than system the old was R22 installed”. plants,
achieving approximately twice the Coefficient of Performance (COP).
CONCLUSIONS
The results show that the 2 nd generation transcritical systems in Fakta consume
approximately 10% less energy than the HFC packs installed until 2007. Energy
simulations indicate that the energy consumption in Denmark should be approx 10%
lower than HFC systems, which are very much in line with the test results.
The difference in energy consumption between the 1 st and 2 nd generation CO 2
transcritical systems can be explained by: improved part load capabilities and smooth
control of gas bypass as well as availability of components in smaller sizes to be able
to better match the capacity for smaller systems; and a new CO 2
injection algorithm in
AK-CC 750 and AK-CC 550a.
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