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From: http://www.achrnews.com/articles/84847-the-case-for-using-carbon-dioxide-as-a-refrigerant
The Montreal Protocol regulations on gases that deplete the earth’s ozone layer have led to the phaseout of chlorofluorocarbons (CFCs) as refrigerants in industrialized countries. Moreover, hydrochlorofluorocarbons (HCFCs) are only an interim solution in industrialized countries until the year 2020. In fact, certain national regulations prescribe an even earlier phaseout date (for instance, by the end of the year 1999 for R-22 in Germany). Another environmental concern regarding these refrigerants is their behavior as greenhouse gases in the atmosphere. This also applies to the newly developed hydrofluorocarbons (HFCs). For this reason, these new HFC refrigerants are placed in a basket with five other gases covered by the Kyoto Protocol on greenhouse gases. This situation has led to increased use of the “old” refrigerants — ammonia and hydrocarbons. Although both are environmentally benign, they can exhibit a certain degree of local danger because of their flammability and/or toxicity. Therefore, carbon dioxide (CO2), an “old” refrigerant used in industrial and marine refrigeration, was proposed by the late Prof. Gustav Lorentzen in 1990 to be used as an alternative refrigerant, mainly because of its non-flammability. Ozone Depletion Potential As opposed to CFCs and HCFCs, ammonia, hydrocarbons, and CO2 all have an Ozone Depletion Potential (ODP) of zero and a negligible Global Warming Potential (GWP). As for HFCs, their ODP is zero. Their GWP ranges from a few hundred in the case of the flammable HFC-32 to several thousand in the case of the flammable HFC-143a and the non-flammable R-125. With respect to the safety of “old” refrigerants, only CO2 can compete with the non-flammable HFCs. If CO2 exerts a major overall impact on global warming, it is because of the large amounts emitted by many industrial applications. However, contrary to HFCs, its GWP is negligible when applied as a refrigerant. Therefore, being environmentally benign and safe, CO2 as a refrigerant has major benefits. The Carbon Dioxide Regerating Cycle The following question remains: Is CO2 also well suited for application in refrigeration, air conditioning, and heat pump systems? Here, because of its thermodynamic properties, CO2 differs from the other refrigerants mentioned. Its vapor pressure is much higher. Its critical temperature is around 31°C, because the heat discharge into the ambient atmosphere above this temperature is impossible through condensation, as happens in the normal vapor compression cycle. CO2 can only be used in the classic and very efficient refrigeration cycle when heat discharge temperatures are lower than the critical temperature (e.g., when used in the lower stage of a cascade system, with another refrigerant being used in the higher stage). For heat rejection at supercritical pressure, only gas cooling, not condensation, is possible. This leads to the cycle known as the trans-critical cycle. It was proposed by Lorentzen and his coworkers for automotive air conditioning and heat pump systems. This trans-critical cycle is not new. It has been well known since the last century as the Linde-Hampson process for air liquefaction, based on the Joule-Thomson effect. In this context, it shows a certain lack of efficiency. In classic refrigeration, air conditioning and heat pump applications, the principal energetic drawback of the trans-critical cycle with CO2 has to be taken into account. Therefore, it should only be applied where the environmental advantage is obvious and/or local safety is necessary, either of these measures compensating for the energetic drawback. Applications of Carbon Dioxide Refrigerant (direct effect) and CO2 emissions from energy supply to refrigerating systems (indirect effect) both contribute to greenhouse gas emissions expressed by using Total Equivalent Warming Impact (TEWI). Therefore, refrigeration systems with a high degree of emission are preferred application areas for CO2 as an alternative refrigerant, as long as the energy efficiency, defined as Coefficient of Performance (COP), can be kept at the same level. In the 1991 Technical Options Report of UNEP, automotive air conditioning was identified as the application with the largest refrigerant consumption worldwide and the highest direct effect on TEWI, expressed as a percentage. Therefore, Lorentzen and his coworkers first drew attention to the application for CO2 as a refrigerant. Out of necessity, they employed the trans-critical cycle because of higher outside air and heat discharge temperatures when running mobile air conditioning systems. But the entire transport sector can be a main application for CO2 as a refrigerant. Commercial refrigeration, including systems used in supermarkets, also has a rather large impact on TEWI due to the long refrigerant lines and the large refrigerant charges. Cascade systems with CO2 as the low-temperature refrigerant in a classic vapor compression cycle, or CO2 as secondary refrigerant, are possibilities enabling reduction of greenhouse gas emissions of refrigerants without the disadvantage of higher energy consumption. The third largest quantity of refrigerant emission per system is shown by the unit air conditioning and heat pump systems. In the heat-pump application, unit systems and chillers offer good perspectives for CO2 as a refrigerant, thanks to use of the trans-critical cycle. The heat rejected on the high-temperature side is used for space heating or hot water production. Since the trans-critical cycle also shows a temperature glide in the gas cooler, the temperature profiles of the refrigerant and the secondary fluid can be advantageously adapted in order to minimize heat-transfer loss and hence improve energy efficiency. Good results can be achieved only with similar and rather large temperature intervals on both sides, so the preferred application should be hot air or water production. Advantages of Carbon Dioxide In the trans-critical cycle, gas cooler pressure and temperature are not linked as in the sub-critical two-phase region. Since the high-side pressure greatly affects — via the pressure ratio — compressor work and efficiency, high temperatures can be achieved with reasonable compressor power. Therefore, the application of CO2 in heat pumps (e.g., for hot water at 90°C) can be an excellent goal. The high vapor pressure leads not only to a low-pressure ratio with the advantage of high compressor efficiency, but also to high heat transfer coefficients and low relative pressure losses. Thus, despite the lack of efficiency of the theoretical trans-critical cycle, the CO2 supercritical refrigeration cycle may still compete with the vapor compression cycle using other refrigerants. A further advantage related to the use of CO2 is its higher volumetric capacity due to its high working pressures enabling small equipment components and small-diameter lines to be used. Also, the fact that one is not forced to recover, reclaim, or recycle the CO2 refrigerant means that CO2 appears to be very attractive in certain applications where the infrastructure is poor or too expensive, as in developing countries. Drawbacks of Carbon Dioxide The main drawback of carbon dioxide as a refrigerant is its inherent high working pressure. This pressure is much higher than that of the other natural and synthetic refrigerants mentioned. On one hand, this means that for CO2 cycles, components must be redesigned. Since CO2 offers a much higher volumetric capacity, the problem of the higher working pressure can be overcome by optimal design involving smaller, stronger components. Nevertheless, newly designed components have to be produced and can only be manufactured at reasonable prices if mass-produced in sufficient numbers. This can be a big hurdle to surmount before CO2 technology is introduced in refrigeration, air conditioning, and heat pump systems. If, for instance, the automotive and transport industries decided to move to this technology, other fields would benefit from mass-produced low-price components. CONCLUSION CO2 technology is very attractive as it is environmentally benign and safe, but needs a breakthrough enabling mass production of the necessary components in order to be cost-competitive compared with conventional refrigeration, air conditioning, and heat pump technology. Extensive research and developmental work on CO2 technology has been performed internationally over the past nine years. This has especially been the case within two large European Community projects: the EC RACE Project for the development of CO2 automotive air conditioning systems and the EC COHEPS Project for CO2 heat pumps. These projects have shown that CO2 technology can compete with common technology in automotive and transport air conditioning. It works as well as in heat pumps providing high temperatures for hydronic systems and for the production of hot water at temperatures of up to 90°C. It also works well for industrial drying processes. However, it should also be mentioned that there are some applications in which the nature of the less efficient trans-critical cycle cannot be compensated for by taking advantage of the particular operating conditions of the system. In conclusion, CO2 technology can meet the environmental and safety requirements of today’s challenges for refrigeration, air conditioning and heat pump systems, but only in suitable applications where the advantages outweigh the drawbacks of this technology. Billiard is director of the International Institute of Refrigeration, located in Paris, France. For more information, visit www.iifiir.org (website). Daikin Industries, Ltd. Announces Expansion and Consolidation of Goodman Operations in Houston10/13/2015 Original link: http://www.businesswire.com/news/home/20150106006864/en/Daikin-Industries-Ltd.-Announces-Expansion-Consolidation-Goodman#.Vh2LVnpViko
HOUSTON--(BUSINESS WIRE)--Daikin Industries, Ltd., the world’s largest manufacturer of heating, cooling and refrigerant products, announced today that its board members have approved an expansion plan for its Goodman operations in the United States. “Total employment in the Houston area will increase to approximately 4000 employees.” Over the next several years, Daikin will be building a new state-of-the art business campus that consolidates the current manufacturing and logistics footprints to a location outside of Houston, TX, in an area near U.S. 290 and approximately three miles west of Texas State Highway 99. The new campus is currently projected to be operational mid-2016. This commitment of approximately $417 million represents the largest single investment since the founding of the Goodman organization over 40 years ago. The construction is planned to commence in the coming months. The new facility, when finished, will include one of the largest and most technologically advanced HVAC (Heating, Ventilating, and Air Conditioning) manufacturing facilities in the country. The consolidated campus will enable Daikin to manufacture in one location the full range of energy-efficient ducted residential and light commercial products as well as various ductless products that are currently imported from other inter-company business units located outside North America. In fact, the facility will manufacture both ducted and ductless HVAC products, which is a first for Daikin. Ducted heating and cooling systems are considered the standard in the United States. Ductless systems are installed extensively around the world. Ductless systems have gained rapid acceptance in the North American marketplace and have become one of the fastest growing HVAC market segments. Texas and Tennessee operations that will be relocated to the new business campus include engineering, logistics, procurement, manufacturing, and marketing. Manufacturing operations at this new campus will consist of residential and commercial heating and cooling systems marketed primarily under the Daikin, Goodman® and Amana® brand names. “The new business campus will provide many outstanding benefits to our customers,” stated Mr. Takeshi Ebisu, President and CEO of Goodman Manufacturing Company, L.P. “The operational efficiencies we achieve will be reflected in the superb quality of our high-efficiency, energy-saving heating and cooling systems. We are excited about the outstanding value that this move will bring to our current and future customers. As the leading global HVAC manufacturer, Daikin expressed a strong, long-term commitment to its customers in North America by constructing this new business campus.” “Our successful growth has fueled the need for additional manufacturing capacity. The new campus will allow us to dramatically increase our production efficiencies and enable us to continue to serve our customers better than ever before from the leading market position that we hold today, ” said Sam Bikman, SVP Global Supply Chain for Goodman. “The integration of our engineering, procurement, logistics, manufacturing and marketing functions at the same location will facilitate and expedite our ability to respond proactively to customer needs.” This consolidation directly reflects Daikin’s global commitment to local, in-country, manufacturing. This philosophy is a driving force throughout the organization and is central to the consistent growth that has led to Daikin being the leading global manufacturer in the HVAC industry. “Our employees in the United States embrace a philosophy of American Pride,” added Ebisu. “This is because employees are the driving force and a core value that allows us to continue as a leader in the market. Building the new campus is an exciting opportunity that will help us create synergies by bringing together our valuable employees and giving them what we believe will be the best facilities and work environment in the HVAC industry. “Our selection of Houston as the location for our new campus was a result of careful analysis and business considerations. We know that Houston is one of the best cities in the United States for this type of expansion program. It offers an outstanding combination that includes the ability to provide an educated workforce, economic growth, and a favorable year-long climate necessary for manufacturing and operational excellence”, continued Ebisu. Houston is well known as the energy capital of the United States. Soon it will be recognized as the energy-savings capital with regard to the production of high-efficiency heating and cooling systems for residential, commercial and industrial applications. Employment at the new campus will increase as a result of expanded product manufacturing and the consolidation of facilities located in Texas and Tennessee. “Our goal is to treat our current employees fairly and equitably when the transfer of manufacturing operations begins,” said Kari Durham, senior vice president human resources. “Total employment in the Houston area will increase to approximately 4000 employees.” Goodman Sales and Distribution operations, Quietflex Manufacturing Company, L.P. (a leading manufacturer of flexible duct and fiberglass products), Daikin Marine Container, and other Daikin operations are not impacted by the consolidation. About Daikin Industries, Ltd. Daikin Industries, Ltd., headquartered in Osaka, Japan, is the world’s largest manufacturer of heating, cooling and refrigerant products in the world. As a Global Fortune 1000 company with over 50,000 employees worldwide, the company engages in the development, manufacture, sales and aftermarket support of heating, ventilation, air conditioning and refrigeration equipment, refrigerants and other chemicals. The company recently celebrated its 90th anniversary. The company also has manufacturing operations in 18 countries and a sales presence in more than 90 countries. For additional information, please visit www.daikin.com. About Daikin North America Daikin North America LLC (DNA) is a subsidiary of Daikin Industries, Ltd. DNA and its affiliates manufacture heating and cooling systems for residential, commercial and industrial use and are sold via a select group of independent HVAC contractors. For additional information, visit www.daikincomfort.com. About Goodman A member of the DAIKIN group, Houston-based Goodman Global Group, Inc. is a leading manufacturer of heating, ventilation and air conditioning products for residential and light commercial use. Goodman's products are predominantly sold through company-operated and independent distribution networks, with more than 1000 total distribution points throughout North America. Goodman factories are ISO 14001:2004 accredited, an international certification that recognizes manufacturing processes and policies that are sustainable. For more information, visit www.goodmanmfg.com. Amana® is a registered trademark of Maytag Corporation or its related companies and is used under license. All rights reserved. Pressure Transducer from: http://www.sensorsmag.com/sensors/pressure/fundamentals-pressure-sensor-technology-846 Types of Pressure Measurements Absolute pressure is measured relative to a perfect vacuum. An example is atmospheric pressure. A common unit of measure is pounds per square inch absolute (psia). Differential pressure is the difference in pressure between two points of measurement. This is commonly measured in units of pounds per square inch differential (psid). Gauge pressure is measured relative to ambient pressure. Blood pressure is one example. Common measurement units are pressure per square inch gauge (psig). Intake manifold vacuum in an automobile engine is an example of a vacuum gauge measurement (vacuum is negative gauge pressure). Pressure Units Pressure is force per unit area and historically a great variety of units have been used, depending on their suitability for the application. For example, blood pressure is usually measured in mmHg because mercury manometers were used originally. Atmospheric pressure is usually expressed in in.Hg for the same reason. Other units used for atmospheric pressure are bar and atm. The following conversion factors should help in dealing with the various units: 1 psi = 51.714 mmHg = 2.0359 in.Hg = 27.680 in.H2O = 6.8946 kPa 1 bar = 14.504 psi 1 atm. = 14.696 psi Pressure Sensing Pressure is sensed by mechanical elements such as plates, shells, and tubes that are designed and constructed to deflect when pressure is applied. This is the basic mechanism converting pressure to physical movement. Next, this movement must be transduced to obtain an electrical or other output. Finally, signal conditioning may be needed, depending on the type of sensor and the application. Pressure Sensor Technologies Potentiometric Pressure Sensors; Inductive Pressure Sensors; Capacitive Pressure Sensors; Piezoelectric Pressure Sensors; Strain Gauge Pressure Sensors; Piezoresistive Integrated Semiconductor. A piezoelectric sensor is a device that uses the piezoelectric effect, to measure changes in pressure, acceleration, temperature, strain, or force by converting them to an electrical charge (electric potential). Coriolis Mass Flowmeter Technology from http://www.flowmeters.com/coriolis-mass-technology How Coriolis Mass Flowmeters Work Coriolis mass flowmeters measure the force resulting from the acceleration caused by mass moving toward (or away from) a center of rotation. This effect can be experienced when riding a merry-go-round, where moving toward the center will cause a person to have to “lean into” the rotation so as to maintain balance. As related to flowmeters, the effect can be demonstrated by flowing water in a loop of flexible hose that is “swung” back and forth in front of the body with both hands. Because the water is flowing toward and away from the hands, opposite forces are generated and cause the hose to twist. They represent about 21% of all flowmeters sold. In a Coriolis mass flowmeter, the “swinging” is generated by vibrating the tube(s) in which the fluid flows. The amount of twist is proportional to the mass flow rate of fluid passing through the tube(s). Sensors and a Coriolis mass flowmeter transmitter are used to measure the twist and generate a linear flow signal. Plusses and Minuses This technology has high accuracy, can handle sanitary applications, is approved for custody transfer and is highly reliable and low maintenance. Mass flow is more important than volume for fluids intended for the production of energy. These include petroleum liquids and natural gas both compressed and liquefied. The cost is high, especially for line sizes above four inches. Pressure drop can be a consideration for “U” shaped tube designs and high viscosity fluids. Thermocouple
When two wires composed of dissimilar metals are joined at both ends and one of the ends is heated, there is a continuous current which flows in the thermoelectric circuit. Thomas Seebeck made this discovery in 1821. All dissimilar metals exhibit this effect. For small changes in temperature the Seebeck voltage is linearly proportional to temperature: ∆eAB = α∆T where α, the Seebeck coefficient, is the constant of proportionality. Manual download![]()
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Energy Star (USA) Equipment: Room Air Conditioners Criteria: At least 15% more energy efficient than the minimum federal government standards. Equipment: Air-Source Heat Pumps Specification: >= 8.2 HSPF/ >=14.5 SEER/ >=12 EER* for split systems >= 8.0 HSPF/ >=14 SEER/ >=11 EER* for single package equipment including gas/electric package units Equipment: Central Air Conditioners Specification: >=14.5 SEER/ >=12 EER* for split systems >=14 SEER/ >=11 EER* for single package equipment including gas/electric package units (*Energy Efficiency Ratio) Air-Source Heat Pump (ASHP): An air-source unitary heat pump model consists of one or more factory-made assemblies which normally include an indoor conditioning coil(s), compressor(s), and outdoor coil(s), including means to provide a heating function. ASHPs shall provide the function of air heating with controlled temperature, and may include the functions of air-cooling, air-circulation, air-cleaning, dehumidifying or humidifying. Central Air Conditioner: A central air conditioner model consists of one or more factory-made assemblies which normally include an evaporator or cooling coil(s), compressor(s), and condenser(s). Central air conditioners provide the function of air-cooling, and may include the functions of air-circulation, air-cleaning, dehumidifying or humidifying. Heating Seasonal Performance Factor (HSPF): This is a measure of a heat pump's energy efficiency over one heating season. It represents the total heating output of a heat pump (including supplementary electric heat) during the normal heating season (in Btu) as compared to the total electricity consumed (in watt-hours) during the same period. HSPF is based on tests performed in accordance with AHRI 210/240 (formerly ARI Standard 210/240). Seasonal Energy Efficiency Ratio (SEER): This is a measure of equipment energy efficiency over the cooling season. It represents the total cooling of a central air conditioner or heat pump (in Btu) during the normal cooling season as compared to the total electric energy input (in watt-hours) consumed during the same period. SEER is based on tests performed in accordance with AHRI 210/240 (formerly ARI Standard 210/240). Energy Efficiency Ratio (EER): This is a measure of the instantaneous energy efficiency of cooling equipment. EER is the steady-state rate of heat energy removal (e.g., cooling capacity) by the equipment in Btuh divided by the steady-state rate of energy input to the equipment in watts. This ratio is expressed in Btuh per watt (Btuh/watt). EER is based on tests performed in accordance with AHRI 210/240 (formerly ARI Standard 210/240). DownloadEuropean Union energy labelAir conditioners For air conditioners, the directive applies only to units under 12 kW. On every label, you will find: 1. the model, 2. the energy efficiency category from A to G, 3. the annual energy consumption (full load at 500 hr per year) 4. the cooling output at full load in kW 5. the energy efficiency ratio in cooling mode at full load 6. the appliance type (cooling only, cooling/heating) 7. the cooling mode (air- or water-cooled) 8. the noise rating in dB (where applicable) For air conditioners with heating capability, you will also find: 1. the heat output at full load in kW 2. the heating mode energy efficiency category downloadDownload |
Jingwei ZhuPh.D. candidate in the Department of Mechanical Science and Engineering at the University of Illinois at Urbana-Champaign. Categories
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