TABLE OF CONTENTS

To choose the future systems a comparison was made between R600a and R744. Had
warming of the water to higher temperatures been a requirement the R744 would
have come out as the best candidate but for this application and site the R600a looked
more promising for the heat pumps.
kW
Cooling chillers 2250
Cooling HP as chiller 150
Cooling from HP 150
Freecooler 300
Heating capacity 450
Results
The system is running perfectly well after some surprises on the regulation side. There
are some conditions that have to be thought through. One of the essential questions
was: is a heat pump primarily a refrigeration unit or is it a heat pump? The lesson
learned is that it is essential to know if the heating load exists at the same time as the
cooling load.
At the end of the project the customer was very happy with the new system and is
pretty impressed with what has been achieved within the project, which also has a
value in it self.
For the chillers the preferred solution was R290. The 9 chillers each have a cooling
capacity of 250 kW at 9˚C/15˚C using 27˚C as ambient design temperature. The cooling
media circulated to the hospital is 35% propylene glycol and this is to cover the needs
for the existing build area that covers 160.000m 2 . The future extension will cover
another 190.000m 2 .
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The replaced R22 chillers were reaching the end of their service life and the experienced
leak rates were making an exchange necessary because it was becoming more difficult
to keep getting recycled R22 in a market where most of the recycled material was
imported from other countries where the R22 era was coming to an end when it comes
to virgin R22.
The required hot water supplies are 70˚C in the summer period and 80˚C in the winter
period. It is important to note that there is always a cooling need also in the winter
months, to some extent generated by locally installed refrigeration systems.