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In this issue
The latest developments in the use of CO2
as refrigerant
The interest in CO2 in the world is
very high at the moment. Although CO2
is generally regarded in a negative context, due to the greenhouse effect,
it is regarded in the heat pump and refrigeration world as a natural
refrigerant, i.e. one that it is naturally present in the environment.
After being “forgotten” for some 50-60 years, CO2
is nowadays the “hottest” refrigerant in scientific publications. In
addition, there is a large and growing industry in CO2
components and systems, from small applications to large systems.
In this issue, a number of applications such as water heaters, drink vending
machines, reversible air conditioners and heat pumps are presented in
topical articles.
We also include an article on the F-Gas Directive in this issue.
Heat Pump News
Eco-labelling of heat pumps
The discussion about the possible criteria for applying the EU eco-label
to various types of heat pump systems has reached an important stage,
with the EHPA circulating a set of proposals to members of the ad-hoc
working group set up by DG Environment. The various proposals are being
reviewed by DG Environ¬ment. If a consensus can be reached, then heat
pumps will become the first renewable energy system eligible for the EU
eco-label. This is an important stage in the evo¬lution of the market,
because it would be sensible for grants (where these are available) to
be given to sys¬tems which are awarded the eco-label.
Source: EUROPEAN HEAT PUMP NEWS ISSUE 7/2 August 2006
PETD – A new acronym to learn for everyone who wants to be cool
A new technology to defrost and de-ice refrigerators has been invented
by Professor Victor Petrenko of Dartmouth College. The technology, Pulse
Electro-Thermal De-icing (PETD) removes ice instantly by a short (less
than 1 sec) high-power electric pulse.
Read more and watch some really nice video clips at:
http://engineering.dartmouth.edu/
thayer/research/ice-engg.html
Source: RAC news, July, 2006
Heat pumps to be tested in practice
Fraunhofer-Institut für Solare
Energiesysteme ISE (Germany) is starting a four-year field test for heat
pumps. It plans to measure the performance of 140 heat pumps installed
in single-family houses.
In cooperation with seven heat
pump manufacturers and two utilities, the researchers will investigate
how efficient electric heat pumps can meet the heat requirements of low
energy houses.
Source: EHPN (http://ehpn.
fizkarlsruhe.de/en/aktuell/
kat1/akt218.html) |
Natural refrigerants fund
During the upcoming IIR conference, Ammonia Refrigeration Technology -
for Today and Tomorrow, an initiative for establishing a Natural
Refrigerants Fund will be launched.
The aim of this fund will be promotion and implementation of
technologies with natural refrigerants in developing countries and in
developed countries.
There are opposing views and many hot debates about the present and
future development in refrigeration and air conditioning regarding
refrigerants. However, a major barrier is proper information regarding
the use of natural refrigerants. This is particularly marked in
developing countries, where the penetration of HCFC and HFC technologies
is considerably greater.
Generally, the purpose of establishing the NRF is to:
- Promote the use of natural refrigerants (ozone-friendly and
climate-friendly technologies) through dissemination of information
- Organise workshops, give lectures (especially in developing countries)
- Provide financial and technical support to enable the use of new
technologies with natural refrigerants
- Arrange training courses (designing, maintenance, safety)
- Support demonstration projects aimed at the transfer of technologies
from developed countries
- Modernise existing ammonia refrigeration plants (especially in
developing countries)
- Support research and innovation in natural refrigerant technologies by
institutions and companies
- Integrate research activities, dissemination of results from research
to more stakeholders
- Organise public campaigns;
- Operate a web site to present all activities and news, case studies,
sponsors.
Source: Prof. Dr. Risto Ciconkov, Dipl. Ing. (mailto:ristoci@ukim.edu.mk)
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Topical Articles
Development of automatic drink vending machines
with CO2 refrigerant
Toshiaki Tsuchiya, Kouji Takiguchi, JAPAN.
The authors have developed a technology for applying carbon dioxide as
refrigerant to refrigera-ting system (unit) of vending machines of
cold(and hot) drinks in order to reduce green-house gas emissions and
power consumption. In the refrigeration system carbon dioxide becomes
supercritical at high ambient temperatures, resulting in lower operation
efficiency. The authors therefore optimized the refrigerating cycle by
employing two stage compressor, and developed a new fin-shaped
evaporator, thus increasing operation efficiency and reducing power
consumption by 9%. Moreover, the authors have confirmed that
simultaneous heating and cooling of cans and bottles with heat pump mode
can significantly reduce power consumption.
Measurement of the performance of an air/water heat pump using CO2
or R744 for the production of hot water for use in a hospital
Patrice Anstett, SWITZERLAND.
The main objective of this project is to explore the capacities of a 60
kW air/water heat pump using CO2 (or R744) as refrigerant for the
production of hot water at the Le Locle hospital (canton of Neuchâtel,
Switzerland). The goal is to produce hot water with a temperature of 60
° to 80 °C from cold water at a temperature of 10 °C. The project will
permit real-time measurement of the coefficient of performance of the
heat pump under differing conditions of use (e.g. changes in the
temperature of the cold water), as well as its verification over an
extended period of time in order to evaluate its performance under
changing seasonal conditions.
USE OF CO2 IN HEAT PUMP SYSTEMS – PRACTICAL EXPERIENCE WITH
TRANSCRITICAL SYSTEMS
C. S. Poulsen , DENMARK.
The use of CO2 as refrigerant in heat pump and refrigeration systems has
increased over the past few years in Denmark, especially in the Danish
commercial refrigeration market (e.g. in supermarkets). The Danish
environmental authorities have implemented a plan for phasing out HFC
refrigerants, and the plan has initiated a lot of activities within the
field of alternative refrigerants. An essential part of the work has
focused on the use of transcritical CO2 in heat pump systems.
This presentation concentrates on four projects concerning the use of
CO2 as refrigerant in small, medium-sized and large heat pump systems:
• CO2 used in domestic hot water heat pumps
• CO2 used in heat pumps for commercial applications
• CO2 used in HVAC systems (air conditioning and heat pump systems)
• CO2 used in large heat pump systems for district heating.
It also presents project results obtained through a combination of
traditional R&D projects and field test measurements. Finally, the
discussion considers the future of CO2 in refrigeration and heat pump
systems.
PERFORMANCE TEST OF A CARBON DIOXIDE HEAT PUMP FOR COMBINED DOMESTIC
HOT WATER AND FLOOR HEATING
Eiji Hihara, Hirofumi Ida, JAPAN.
Japanese companies were the first to succeed in the commercialisation of
a heat pump for domestic hot water heating, in which carbon dioxide is
used as a refrigerant. As shown in Figure 1, sales of heat pumps have
been steadily rising. In recent years, several types of multi-functional
heat pumps that provide hot water, floor heating, or bathroom heating
have been introduced on the Japanese market. However, no method for
testing these multi-functional heat pumps has yet been established. It
is difficult to decide a suitable test standard for these heat pumps in
a reasonable and easy manner because of the diversities in their use by
family members and household structures. In order to establish a new
standard for measuring annual energy consumption of multi-functional
heat pumps, they were subjected to several tests for combined domestic
hot water and floor heating. This research was carried out as part of
Annex 28 of the IEA Heat Pump Program.
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BRINE-TO-WATER CO2 HEAT PUMP SYSTEMS FOR HEATING AND COOLING OF
NON-RESIDENTIAL BUILDINGS Jørn Stene, NORWAY.
Carbon dioxide (CO2) has been identified as an interesting working fluid
in brine-to-water heat pumps for heating and cooling of non-residential
buildings. Connecting such a heat pump in series with a hydronic
radiator and ventilation heater system provides a relatively low return
temperature in the system, and thus favourable oper¬ating conditions for
a CO2 heat pump. Preheating and re-heating of domestic hot water will
lead to a further increase in the COP of the CO2 heat pump system.
Computer simulations have demon-strated that a CO2 heat pump system in
non-residential buildings can achieve the same or higher seasonal
performance factor (SPF) than heat pumps using convent-ional working
fluids, as long as the heat distribution system is designed for a low
return temperature. The operational time of the ventilation system will
have a major impact on the SPF of the CO2 heat pump, since the return
temperature in the heat distribution system is con-siderably lower when
the ventila-tion system is in operation.
Technology and Market Develop-ment of CO2 Heat Pump Water Heaters
(ECO CUTE) in Japan
Katsumi Hashimoto, JAPAN.
In Japan, numerous heat pump water heaters for the residential sector
have been developed in recent years, and are growing rapidly in
popularity. Of these water heaters, the ECO CUTE*1 variety using CO2 as
a refrigerant is attracting attention for its ability to save energy and
reduce greenhouse gas emissions. ECO CUTE technology was developed
commercially in collaboration between TEPCO, Denso and CRIEPI in 2001.
Several other manufacturers have also joined the market, and a
government support program has been introduced with a target to increase
total ECO CUTE installation to 5.2 million by 2010.
*1:"ECO CUTE" is a name used by electric power companies and water
heater manufacturers, and refers only to heat pump water heaters using
CO2 as a refrigerant.
F-gas Regulation is now published
Lars Nordell, SWEDEN.
14 July 2006 saw publication of the new EU F-gas Regulation in the
Official Journal of the European Union: 20 days later it came into force.
This new EU Regulation governs requirements for the use of greenhouse
gases. For the European refrigeration and heat pump industry, it means
requirements for the use of all the HFC refrigerants, such as R134a,
R407C and R410A as just a few examples.
At the same time, the EU Directive for the Use of Greenhouse Gases in
Air Conditioning in Motor Vehicles – the MAC-Directive – was adopted.
See table “EU regulation for HFC products in Europe”.
This article will focus on the F- gas Regulation.
DEVELOPMENT OF REVERSIBLE RESIDENTIAL AIR CONDITIONERS
AND HEAT PUMPS USING CO2 AS WORKING FLUID
Jakobsen, A., Skiple, T., Nekså, P., Wachenfeldt, B., Stene, J.,
Skaugen, G., NORWAY.
Since 1997, SINTEF Energy Research and The Norwegian University of
Science and Technology (NTNU) have been investigating and developing
reversible residential air conditioners and heat pumps (RAC split-type
units) using carbon dioxide (CO2) as their working fluid. A
third-generation prototype CO2 RAC split-type unit has recently been
constructed and extensively tested in heating and cooling modes. The
test results have been used for calculating the seasonal heating and
cooling performance (SPF) for two different climates; Greece (Athens)
and Norway (Oslo). The results have been compared with manu¬facturer's
data with verified rating points for the most energy-efficient Japanese
R410A split-type unit available on the market.
In both the heating mode and the cooling mode, the calculated SPF for
the CO2 and R410A units in the Oslo climate were more or less identical.
However, in the cooling mode in the Athens climate, the SPF of the CO2
unit was about 17 % lower than that of the R410A unit. Further
development and optimi¬zation of the CO2 unit, e.g. by utilizing
microchannel heat exchanger technology, increasing the isentropic
efficiency of the compressor and/or using an ejector or expander for
expansion work recovery, will be necessary before the CO2 unit will be
able to match or outperform the market-leading R410A unit in terms of
energy efficiency. However, since the CO2 unit already matches many of
the better R410A units on the market, CO2 must be regarded as a
promising working fluid in reversible air-conditioning and heat pump
units for residential use.
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