TABLE OF CONTENTS

for data centre air conditioning systems in London. Both
the ABN Amro data centre and Imperial College University
E-Science Computer Suite are cooled using CO 2
plants
to absorb the intense heat loads produced by the computer
blade servers.
In addition, the Office Building of EnergiMidt in Denmark
has supplemented the traditional glycol based free
cooling system with a pumped CO 2
system for the server
cooling. The installation encompasses a cascade CO 2
system
with propane compressors. The benefits of phase
transition and an increased heat transfer coefficient are
utilized and the temperature limit is raised, lowering the
annual energy consumption. To further reduce operating
costs the heat is recovered from the server room
and the canteen refrigeration system by the use of heat
pumps. Calculations show a significant reduction in the
energy consumption.
Private Residential Housing: Refrigerators,
hot water & air-conditioning
HC: Across the world there are over 600 million hydrocarbon
domestic refrigerators – around 36% of the global
market for new domestic refrigerators and freezers today,
and estimated to rise to up to 75% by 2020 (TEAP
2010). The refrigerant R600a (isobutane) is widely used
in fridges and freezers in Europe, Japan, China, which are
also available in South America, Canada and Mexico, and
are expected to enter the U.S. now that legislative approval
has been granted. Portable air conditioning based
on propane has been on the European market since
1985. Australian companies have also been producing a
variety of HC-based split-air conditioners for both home
and office use. 2011 saw the launch of the first Chinese
produced hydrocarbon (R290) room air conditioner
mainly for export – an important milestone given that
90% of the world’s small air conditioners are manufactured
here. All models meet high European safety standards.
They conform to the international safety standard
IEC 60335-2-40 and are certified by the German Association
for Electrical, Electronic & Information Technologies
(VDE), one of Europe’s largest technical and scientific associations.
Moreover, the final product has been certified
by global leader in independent testing TÜV. In China 18
of the 32 air conditioning production lines will be converted
to R290 as part of the country’s HCFC Phase-out
Management Plan (HPMP). First projects in India are currently
under way to build domestic production lines for
HC A/C systems. Overall, HC low charge packaged solutions
(less than 1 kg) are expected to see increased use,
from a market share of below 1% today.
In light of the Greenfreeze triumph in domestic fridges,
the increasing investment in R290 air conditioning systems
could pave the way for a similar HC success in small
charge applications like room ACs. Other potential applications
for HCs include residential heat pump dryers.
CO 2
: Carbon dioxide has been extensively used as a refrigerant
in domestic hot water heat pumps in Japan,
where they were introduced as “Eco Cute” in 2001. The
market for CO 2
heat pump water heaters has rapidly expanded
with models now available in Europe for space
and water heating. Over 2 million residential models can
now be found in family homes. Tumble dryers using CO 2
heat pumps are also being researched. Residential airconditioning
using CO 2
is under investigation but still
faces energy efficiency challenges.
In addition Norway and Austria have seen the development
and testing of brine-to-water CO 2
heat pump prototypes
for domestic hot water-only operation and for
combined space heating and hot water production, under
the IEA Heat Pump Programme’s collaborative project
on “economical heating and cooling systems for low
energy houses”. Both projects have delivered promising
results with high COP values. Prior to this a Norwegian
research study also indicated that in low energy and passive
houses, where Domestic Hot Water (DHW) heating
accounts for 50-85% of the total annual heating demand,
an integrated CO 2
heat pump system will outperform the
most energy efficient HFC units on the market.
District Heating & Cooling
NH 3
: Although not yet widely used, ammonia chillers
and heat pumps can provide residential and commercial
heating and cooling requirements from a central plant
via a water piping network. For example, in Drammen
in Norway, the background heat from seawater is being
harnessed by a single screw ammonia heat pump to provide
hot water for the local district heating network. In
the US, Montgomery College in Rockville Maryland has
used an ammonia district cooling plant since 1994. The
Roche Welwyn Garden City, UK site also has a centralised
water chilling plant that uses ammonia as the refrigerant.
HC: In Denmark isobutane heat pumps installed in the
new central cooling plant of Aarhus University Hospital
Skejby supply cooling water to the entire hospital via a
new distribution network.
CO 2
: A large scale 100% renewable energy project in
Denmark incorporates a CO 2
heat pump into a largescale
district heating system. The 1.5 MW (thermal) CO 2
driven heat pump “moves” energy to the energy storage
heat pit, providing the whole system with greater flexibility
in energy output.
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