On 4 days, R744.com has reported from the 22nd International Congress of Refrigeration in Beijing. Check out here where the refrigerant CO2 was in the center of attention.
ICR 2007: Day 4
Welcome back for our final update from ICR 2007!
Just a few papers today on CO2 Technology, and interestingly a short course by Danfoss on CO2 Supermarket refrigeration, the poster session in the main hall area and a policy workshop in Heat Pump technology.
A packed room for the Danfoss short course. Not really a surprise!
10:30 AM Danfoss Short Course "CO2 in supermarkets"
Inderpal Saund, Food Retail Manager from Danfoss Australia, is giving a practical point of view presentation on Danfoss experience with CO2. Today there are 10 cascade CO2 installations in Australia, with 7 from Danfoss alone. At an early stage there were two failures due to dirt in the system. Apart from that, all compressors, piping, controllers, valves worked without problems. Also the servicing of CO2 systems is not complicated at all: once technicians start using CO2 they appreciate the easy installation. Key is to get the concept in the minds of technicians!
Regarding costs, Saund is definitely "pro-CO2": 100 kg of the refrigerant CO2 only cost around 99 Australian dollars, less than 60 euros. In addition, liquid lines in CO2 systems are much smaller: We are saving money on pipelines. This is a dramatic reduction. And the initial investment is only 5% higher than for conventional systems. So the next step for CO2 is already clear: transcritical systems. In Europe there are already 50 installations operating, of which 60% are equipped with Danfoss components. Now a test plant in Down Under is planned. This will be a real test for CO2 systems working in the high ambient temperatures of Australia! Danfoss plans first commercially available systems for 2007/08.
And why CO2? Saund is clear: "Our clients want a green image. They are tired of the negative image they now have!" CO2 is environmentally friendly, safe, cost-efficient. It saves 25% on energy costs in cold storage applications (real experience) and 15% in supermarkets (estimations). There are more than 250 various types running with the natural refrigerant.
Saund is asked for the safety of high pressure CO2 systems operating at up to 100 bar. He points out that there are complete control systems and safety measures to avoid accidents. There is no actual risk. It is more an "attitude issue" of the industry.
Now off to the Poster Session!
Lots of presenters and interested listeners in the same hall!
1:00 PM - Special Seminar "Heat Pump Development in different countries"
This special seminar, organized by the Swedish Energy Agency, gathers speakers from China, Germany and Sweden.
1:10 PM - Mr Xu Wei from the China Academy of Building Research (CABR) is giving a brief history overview of heat pumps, from the first research into ground source heat pumps in the 1980s to the year 2006, when the Chinese government decided to provide financial support for nation-wide heat pump pilot projects. He is speaking about the great potential of ground source heat pumps in China, existing laws promoting sustainable energy, and technical standards applicable to heat pumps.
1:40 PM - Sebastian Ott from Stiebel Eltron is representing Germany. He is replacing Dr. Rainer Jakobs from the Information Centre on Refrigeration and Heat Pumps (IZW), an organization providing objective information to German policymakers. After a short retrospective, he is showing the strongly rising popularity of heat pumps in Germany: while in 2005 only 8,000 units were sold, this figure had nearly quadrupled in 2007 (30,000).
Of the 17.5 million buildings in Germany, 14m are one- and two family houses. As most of them have to renew their fossil-fueled heating equipment in the next years, the market potential for domestic heat pump systems is high. Several German companies and research institutes have noticed the consumer trend towards sustainable heating and cooling, among them Stiebel and the University of Braunschweig. Both are currently investing in CO2 Technology for hot water heating. The key drivers for heat pump technology in Germany: an increased budget for energy-efficient equipment from the government, a commitment to reduce greenhouse gas emissions, and steadily rising energy prices.
2:30 PM - Last to speak is Mattias Tornell from the Swedish Energy Agency. Sweden is seeing a rising trend for sustainable heat pump technology as legal restrictions on HFCs promote the move towards natural refrigerants. In collaboration with universities, Swedish manufacturers are developing new compressor solutions and units of 25-40 kW suitable for multi-family houses and offices.
Now off to the ICR 2007 Banquet dinner and awards ceremony...
Goodbye fellow R744 experts. We hope that you have enjoyed our Blog from ICR 2007, feel free to send us any comments on info@R744.com
--image1-- ICR 2007: Day 3
Welcome back for Day 3 of our ICR 2007 Blog!
Today there will be around 20 papers covering various CO2 issues, namely ejectors, micro-fin tubes and cascade systems.
09:30 AM: Natural Working Fluids and Application I
Ono Takashi from the Fukuoka University, is talking to us about pressure drop characteristics of pure CO2 and CO2-oil mixtures in evaporators with horizontal smooth and micro-fin tubes. As he expects CO2 heat pumps (Eco Cute) to be widely used in the coming years, the research on the pressure drop of CO2 is a priority, especially for micro-fin tubes. His conclusions: For pure CO2, the pressure drops of the micro-fin tube is 20-70% higher than those predicted with the homogeneous model. In the case of CO2-oil mixtures, the pressure drops increase with the increase in the oil circulation ratio for the smooth tube.
10:00 AM "Flow boiling of natural refrigerants in horizontal microchannels" is the topic of a presentation by A.S. Pamitran from the Chonnam National University, South Korea. He underlines that two-phase pressure drops of refrigerants in minichannels has been a research subject for several decades, but that there are only a few studies on natural refrigerants. His study is proving the significant effect of mass flux, tube diameter, saturation temperature, and refrigerant properties on the pressure drop. The experimental results were compared to existing prediction models and seeing their insufficiency, a new pressure drop prediction method was developed based on the experimental results.
His conclusion: The pressure drop of R744 is much lower than that of R-290. The pressure drop is higher for a smaller inner tube diameter, lower saturation temperature, and for higher mass and heat fluxes. Pamitran hopes that his findings will contribute to the design of heat exchangers with minichannels.
After a short coffee break to discuss technical details, back to the packed room again! CO2 seems to be popular here in Beijing. People are standing along the wall. Most faces in the room are from Asia.
10:45 AM - Dong-Won Han from the Korean Institute of Science and Technology is talking about the performance of gas coolers for CO2 heat pump systems using a two stage compressor. His study suggested various performance simulation results for a given design of gas cooler. It was part of a project to develop CO2 cooling and heating systems sponsored by the Korean Ministry of Commerce, Industry and Energy.
11:00 AM - Dongho Park from the Sogang University is presenting another project sponsored by the Korean government to promote CO2 technology. This time we are told about the evaporating heat transfer and pressure drop characteristics of CO2 in multi-channel micro tubes for hot water heat pumps.
11:15 AM - Mr. Aittomake from the Tampere University in Finland has set his focus on the optimum configuration of a cooling coil working with carbon dioxide. CO2 has already a strong status in a wide range of applications, among them air cooling. New types of air cooling coils, including micro-channel designs, have been examined and developed. Aittomakes study set up a simple model of the coil to evaluate the refrigerant-side and air-side heat transfer resistances.
To be continued after lunch!
Welcome back to part II of the Natural Working Fluids and Application Session.
1:30 PM - The keynote speech this afternoon is delivered by Klaus Martin from the Virtual Vehicle Competence Center Graz (vif). His presentation focuses on one of the most important component in refrigeration systems on the expansion device. Especially for the refrigerant CO2 it is of major importance as the expansion valve can significantly vary the cooling capacity and efficiency of the system. vif has developed simulation models to predict the mass flow through expansion devices and deliver valuable results regarding their control strategy on the efficiency of the refrigerant cycle.
Martin concludes: The influence of the type of expansion device on the behaviour of the refrigerant cycle has to be studied more in detail now, using the simulation models developed by vif.
2:45 PM Lixin Cheng from the Ecole Polytechnique Federal de Lausanne (EPFL), Switzerland, is talking about the prediction of flow boiling heat transfer of CO2. The EPFL has developed an updated flow pattern model to provide more accurate heat transfer predictions for flow boiling of CO2. The project was financially supported by Valeo Engine Cooling in France.
3:30 PM Armin Hafner from SINTEF is giving two presentations in a row on the design, parametric, and experimental investigation of a R744 ejector. The ejector was developed by SINTEF to improve the compressor efficiency at high ambient temperatures for AC systems.
Based on the theoretical analysis of the component, SINTEF has conducted first tests with the ejector prototype. The results have shown that the entrainment of two-phase flow can be done without problems; a good trade-off will be a CO2 vapour fraction of the evaporator outlet close to the saturated line. Thus, the first results look very promising, but clearly there is still room for improvement.
ICR 2007: Day 2
Welcome back on Day 2 of ICR2007!
This afternoon there are three separate technical sessions dealing with the refrigerant CO2 in different applications, such as industrial freezers, supermarkets, bottle coolers, or cascade systems. Plus a special event by Daikin that will cover several topics including CO2 heat pumps. Unfortunately, it is impossible to attend all presentations. We have to focus on a few.
1:00 PM CO2 and Natural Refrigerants Thermodynamic Systems Session.
First to talk is Havard Rekstad from the Norwegian University of Science and Technology - on a prototype 40 kW cooling capacity CO2 liquid chiller, to be used in fishing boats. Both the water chiller and the gascooler are totally new designs adapted to CO2. The semi-hermetic compressor was designed by Mycom.
Experiments were conducted at various cooling water temperatures and at steady state and cool-down situations. Rekstad concludes: The CO2 liquid chiller worked stable and well. This technology is definitely promising and there is still room for performance improvements through better evaporators and heat exchangers.
1:20 PM - Xianyang Zeng from the Tianjin University, China, is talking to us about a CO2 rolling piston expander and how replacing the throttle valve with this expander is one of the best ways to improve the efficiency of CO2 transcritical cycle. From the P-V diagram of the CO2 expander he shows that three different processes can occur in an expander: over-, normal-, and under-expansion. Operating near the designed rotational speed, the efficiency, recovery work and COP of the expander is optimal, experiments have shown.
2:15 PM - Tobias Sienel - Carrier Europe - is presenting medium and low temperature CO2 DX systems for supermarkets in Europe. HFCs have become subject to many legal restrictions now and natural refrigerants are favoured by the concerned public and the refrigeration industry. Carrier is thus focusing on ecologically-safe CO2 solutions.
Sienel explains: A positive market feedback from the CO2 LT systems led to the design of the MT systems. Installed in large European supermarkets, the CO2 systems used 10% less energy than R404a DX systems, and even 20% less than indirect systems.
And answering to a question about the costs of combined CO2 MT/LT systems: Currently, they are 30% more expensive (i.e. similar to indirect systems). Carrier knows that this will not be competitive across the whole of Europe. But: Our goal is to get the cost down to the same price as R404a systems. Come back to us in two years!
2:50 PM - Brian Rees from McAlpine Hussmann Ltd is presenting a paper on the comparison of a liquid overfeed, a cascade CO2 system with R404a as a primary refrigerant, and a R404a baseline system. As a key message is emerging: At high temperature ration conditions, the cascade CO2 system is roughly 5% more efficient than a R404a direct expansion system, and the liquid overfeed CO2 system at least as efficient as the R404a baseline system. This has been proved through 11 month daily monitoring of two real world supermarkets.
4:30 PM - Jun Yang from the Shanghai Jiaotong University is giving a presentation about a combined CO2 compressor-expander. He is clear that the most effective way to improve the efficiency of a transcritical CO2 cycle is to replace the throttling valve with an expander. In his prototype a two-stage rolling piston type compressor is taking the compression part, and a two-cylinder rolling piston expander the expansion part. Further research is needed, however, to improve this combined component.
4:50 PM - B. Liu from the Xi'an Jiaotong University is speaking about the development of free piston expanders for transcritical CO2 refrigeration cycles. The experimental results show: A double acting free piston expander can work more steadily in a much wider range of pressure difference than a single acting type. Liu is clear that further work is needed to improve the prototypes and investigate expanders in transcritical CO2 cycles.
ICR 2007: Day 1
Good afternoon dear CO2 Community!
Today R744.com is reporting back to you about the latest CO2 discussions at the ICR2007. There will be three more daily updates covering a range of CO2 issues, coming from Beijing this week. We are located at the International Convention Center, right next to the Beijing Olympic stadium (see photo).
You may have noticed that we are trying a new 'Blog style' reporting. This is a first for R744.com and keeps within our tradition of continuously innovating. So please bear with us as we get this reporting refined. Any comments or suggestions are welcome! Our intention is to do this type of reporting for other major CO2 conferences, workshops and seminars over the coming months. We believe that this is a great way to share with the wider CO2 Community what is going on at these key events. We will add photos, presentations, abstracts and videos whenever possible.
ICR2007. So what is it?
This is the 22nd International Congress of Refrigeration. It happens every four years (last time in Washington, next time in Prague) and brings together hundreds of refrigeration experts to discuss about the latest developments in Components, Systems and Refrigerants, across various application areas. This year it is Beijing, bringing together 1,200 experts (700 from China alone), to present over 500 different papers. CO2 is present too with over 60 papers from across the world.
There are 5 days to this event including this weekend. Day 1 is today and started this morning with a general introduction to the challenges the refrigeration industry faces today. In the afternoon, SINTEF gave a paper on R744 LCCP MAC. Tomorrow, over 20 CO2 Papers will be presented together with a technical session by Daikin on CO2 Heat Pump Technology.
10:30 AM - Plenary Session.
Rajendra Shende (UNEP) is speaking to us this morning about the challenges the refrigeration industry faces over the coming years. He is highlighting the fact that global greenhouse gas emissions have risen by 25% between 1990 and 2004. That this is projected to increase by 90% by 2030. Shende is showing some slides of natural disasters, yet his message is still one of hope. He is arguing that environmental and economic issues are on the same side of the game. The successful Montreal Protocol is a perfect example of this: industry has seized this opportunity to innovate and offer new products that have helped solve the ozone problem. Indeed, over the last 20 years the refrigeration industry has undergone 7-8 technological revolutions in order to adapt to the new reality. Industry had always been ahead of policy deadlines (see photo) yet without the policy thrust or push industry would not have adapted so quickly. And most importantly: The initial cost of change to new technologies has always been overestimated. So if industry met the Montreal Protocol deadlines, so too can it adapt to the new reality or opportunities of the Kyoto Protocol.
Finally, Shende is mentioning the "Refrigerants, Naturally!" campaign as a model to follow for the future, highlighting the fact that Coca-Cola will have 1,000 CO2 vending machines here next year for the Olympics. But there is more: CO2 has also a huge potential in car air conditioning. China and India can benefit from these important changes, too!
11:30 AM - Plenary Session.
Robert Wilkins - Chair of the Air-Conditioning and Refrigeration Institute (ARI) and President of Danfoss North America - is speaking about providing technology for the future. Products from the air-conditioning and refrigeration industry are the most efficient ever. But still there are many challenges the industry is facing, not least the increasing energy constraints in terms of demand and resources. They will have an impact on the products and technologies we use.
Wilkinson is sure: We will see CO2 being used as a refrigerant in several applications. ARI is supporting its wide-spread use by sponsoring research in two-phase ejector expansion devices for CO2 systems. Together with ASHRAE, the organisation is looking at Zero Net Energy Buildings by 2030 at fair market value. This is the way forward!
5:00 PM - Energy/Environment Assessment and System Control Session.
Armin Hafner from SINTEF is presenting its paper on the "Global Environmental & Economic Benefits of Introducing R744 in Mobile Air Conditioning". His main message: R744 is not only more efficient in cool countries but also in the hot climate of New Delhi, Bombai, Shanghai and Beijing. The key figure is 40: CO2 air conditioning will save up to 40% fuel and emit 40% less greenhouse gas emissions compared to HFC-134a.
And what about the costs of R744 systems? Available as a low-cost and high-class option, CO2 MAC is definitely a global solution suitable for any kind of vehicle. Not to forget the low-cost servicing of CO2 systems.
To sum up: The only CO2-related paper in this session has sparked the highest interest from the audience with Mr Hafner getting a lot of questions. Of course also about the VDA decision to choose CO2, and the U.S. EPA policy