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Energy Efficiency determination, classification & labelling of water chillers
 

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    Energy Efficiency determination, classification & labelling of water chillers Energy Efficiency determination, classification & labelling of water chillers Document Transcript

    • Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioning======================================================================= ANNUAL MEETING OF THE REGIONAL OZONE NETWORK FOR EUROPE & CENTRAL ASIA BELGRADE, SERBIA, 10-13 MAY 2011 Energy Efficiency Determination, Classification and Labelling for Water Chillers and Heat Pumps Dipl.-Ing. Slobodan Pejković Filter Frigo d.o.o. Serbia – 11050 Belgrade E-mail=filfrigo@EUnet.rsAbstractEnergy efficiency of water chillers and heat pumps is one of the most important disputable issues inthe field of HVAC&R. It is disputable due to the fact that neither domestic (Serbian) nor Europeanlegislation deals with the problem of energy saving with water chillers and heat pumps with more than12 kW cooling capacity, even though these units are known to be huge electricity consumers.By the implementation of the Directive 2002/96/EC on energy efficiency labelling and EN 14511standard in the European Union, a large step has been made in increasing energy efficiency of airconditioning units and heat pumps with cooling capacity equal to or lower than 12 kW. This Directivedoes not included equipment of higher cooling capacity, and therefore, in February 2005, EUROVENT(European Association of Air Handling and Refrigeration Equipment Manufacturers) made aclassification of such equipment in order to initiate the manufacture of more energy efficientequipment. The aim is to somehow slow down the increase of electricity demands, and thus reduceCO2 emission.As the implementation of the Kyoto Protocol is a priority issue in Europe and worldwide, the EuropeanUnion (EU) is planning to reduce CO2 emission by 8% in the period from 2008. to 2012. This is apowerful motive for improving energy efficiency of water chillers and heat pumps. Lower electricityconsumption means lower electricity generation demands, which results in reduction of CO2 emission.This paper deals with water chillers and heat pumps with electrically-driven cooling compressors, andexplains how this problem is considered in Europe and worldwide.Keywords: energy efficiency; coefficient of performance; water chiller; heat pump11. May 2011. Belgrade Page 1 
    • Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioning=======================================================================IntroductionChange of weather conditions caused by global warming has resulted in significant increase innumber of water chillers sold in Europe (Figure 1). Figure 1: Chillers sales evolution in EUThe figure shows that the biggest increase has been in the number of sold devices with air-cooledcondensers, which are also the biggest consumers of electricity in the cooling hardware.In order to limit increase in electricity consumption with increased number of sold devices, one had toinfluence increase of energy efficiency, which has been achieved by implementing Directive2002/96/EC for Devices of Cooling Capacity up to 12 kW. Figure 2: Evolution of energy efficiency levelFigure 2 shows that this evolution is especially prominent since 2004. for room air conditioners. Inthe European Union buyers choose devices with high energy efficiency.11. May 2011. Belgrade Page 2 
    • Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioning=======================================================================Determining and Defining Energy Efficiency Ratio (EER, COP, SEER, HSPF,IPLV, IEER, ESEER, ESCOP)There are several ways of expressing energy efficiency ratios which are defined differently in differentparts of the world.Let’s quote examples from U.S.A. In part 431, paragraph 92 e-CFR (Electronic Code of FederalRegulations) defines:COP – Coefficient of Performance is a ratio between the total cooling capacity and net absorbedpower of electricity consumer, expressed in the in identical units of measurement, and therefore thevalue is unitless.COP = Φh / ΦwWhere:Φh - total cooling capacity [Btu/h]Φw = 3.412 Pw - equivalent of absorbed power [Btu/h]Pw – absorbed power [W]EER – Energy Efficiency Ratio is a ratio between the total cooling capacity and net absorbed powerof electricity consumer, expressed in Btu/Wh.EER = Φh / PwWhere:Φh - total cooling capacity [Btu/h]Pw – absorbed power [W]Ratio between COP and EER is 3.412 and it represents a conversion ratio of Btu/h and W.The American COP and EER represent the same value, only expressed in different units. Besidesthat, they determine those ratios for cooling or for heating.For example COPcooling means ratio between total cooling capacity and net absorbed power, whileCOPheating represents a ratio between the produced heating effect of an heat pump and the netabsorbed power. The same applies also for EER.This method of presenting seems little confusing for users, and especially for those from Europe, whoplace different meaning on ratios with the same marks, COP and EER respectively.SEER, HSPF and IPLV have been defined in much clearer, and therefore also in more important way.SEER - Seasonal Energy Efficiency Ratio is used to define the average annual cooling efficiency ofan water chiller or heat pump system and represents a ratio between total cooling energy exchangedin the evaporator during the year – seasonal use of water chiller or heat pump in the cooling period,expressed in Btu, in relation to the total absorbed energy used in the same period, expressed in Wh.SEER is an average value of EERcooling during the year, at different external air temperatures, andtherefore in different device operating regimes. Bigger SEER value means device with higher energyefficiency. SEER value is always little bigger than EER, for some 0.5 to 1 Btu/Wh.11. May 2011. Belgrade Page 3 
    • Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioning=======================================================================The term SEER is generally applied to devices with cooling capacity less than 65000 Btu/h (19 kW).The most efficient cooling devices have value of SEER=13.HSPF - Heating Seasonal Performance Factor is used to signify the seasonal heating efficiency ofheat pumps and represents a ratio between heating energy exchanged in the condenser during theannual – seasonal use of heat pump in the heating period, expressed in Btu, in relation to the totalabsorbed energy used in the same period, expressed in Wh. HSPF is an average value of EERheatingduring the year at different external air temperatures, and therefore also in different device operatingregimes.The term HSPF is generally applied to heat pumps of cooling capacity up to 65000 Btu/h (19 kW). Themost efficient heat pumps have value of HSPF=10.IPLV - Integrated Partial Load ValueThe term IPLV is used to signify the cooling efficiency related to a typical (hypothetical) season ratherthan a single rated condition. The IPLV is calculated by determining the weighted average efficiencyat part-load capacities specified by an accepted standard. It is also important to note that IPLVs aretypically calculated using the same condensing temperature for each part-load condition and IPLVs donot include cycling or load/unload losses. The units of IPLV are not consistent in the literature;therefore, it is important to confirm which units are implied when the term IPLV is used. ASHRAEStandard 90.1 (using ARI reference standards) uses the term IPLV to report seasonal coolingefficiencies for both seasonal COPs (unitless) and seasonal EERs (Btu/Wh), depending on theequipment capacity category. The most chillers manufacturers report seasonal efficiencies for largechillers as IPLV using units of kW/ton (1 cooling ton=3.517 kW).IPLV = 1 / [kW/ton]Where: A = EER at 100% of load C = EER at 50% of load B = EER at 75% of load D = EER at 25% of loadThe term IPLV is generally applied to devices with cooling capacity exceeding 65000 Btu/h (19 kW).As of January 1, 2010 parametar IPLV was renamed from Integrated Partial Load Value to IntegratedEnergy Efficiency Ratio (IEER). IPLV will not longer be cited or referenced.IEER – How is determinedIEER is a weighted average of the unit’s efficiency at four load points - 100%, 75%, 50% and 25% offull cooling capacityIEER = 0.020 • A + 0.617 • B + 0.238 • C + 0.125 • DWhere: A = EER at 100% net capacity at AHRI standard rating conditions B = EER at 75% net capacity and reduced ambient (81.5ºF for air-cooled) C = EER at 50% net capacity and reduced ambient (68ºF for air-cooled) D = EER at 25% net capacity and reduced ambient (65ºF for air-cooled)11. May 2011. Belgrade Page 4 
    • Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioning=======================================================================In the same electronic code of U.S. Federal Regulations in part 431, paragraph 97 minimumcooling efficiency levels have been quoted for cooling devices and heat pumps of standard size,produced after January 1st, 1994 but before 30th September 2012. Manufacturers are thus obliged toachieve minimum energy efficiency levels, as quoted in Tables 1 and 2.That means that the legal regulations have eliminated from use cooling devices with low energyefficiency.Serbian legislation does not have such regulations.Table 1.          §431.97— Minimum Cooling Efficiency Levels Efficiency level1 Products Products Cooling Sub- manufactured manufactured Product Category capacity category until on and after October 29, October 29, 2003 2003 Split Air Cooled, <65,000 System SEER = 10.0 SEER = 10.0 3 Phase Btu/h Single SEER = 9.7 SEER = 9.7 Package Small Commercial Packaged Air <17,000 AC EER = 9.3 EER = 12.1 Conditioning and Water Cooled, Btu/h HP EER = 9.3 EER = 11.2 Heating Equipment Evaporatively ≥65,000 Cooled, and Water- Btu/h and AC EER = 10.5 EER = 11.5 Source <135,000 HP EER = 10.5 EER = 12.0 Btu/h ≥135,000 Btu/h and Air Cooled All EER = 8.5 EER = 8.5 Large Commercial <240,000 Packaged Air Btu/h Conditioning and ≥135,000 Heating Equipment Water-Cooled and Btu/h and Evaporatively All EER = 9.6 EER = 9.6 <240,000 Cooled Btu/h1 For equipment rated according to the ARI standards, all EER values must be rated at 95°F outdoor dry-bulbtemperature for air-cooled products and evaporatively cooled products and at 85°F entering water temperaturefor water-cooled products. For water-source heat pumps rated according to the ISO standard, EER must be ratedat 30°C (86°F) entering water temperature.     11. May 2011. Belgrade Page 5 
    • Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioning=======================================================================Table 2. §431.97—Minimum Heating Efficiency Levels Efficiency level1 Cooling Sub- Products Products Product Category manufactured manufactured capacity category until on and after October 29, 2003 October 29, 2003 Split Air <65,000 System HSPF = 6.8 HSPF = 6.8 Cooled, Btu/h Single HSPF = 6.6 HSPF = 6.6 3 Phase Small Package Commercial Split Packaged Air Water- <135,000 System COP = 3.8 COP = 4.2Conditioning and Source Btu/h and Single Heating Package Equipment ≥65,000 Air Btu/h and All COP = 3.0 COP = 3.0 Cooled <135,000 Btu/h Large Commercial ≥135,000 Split Packaged Air Air Btu/h and System COP = 2.9 COP = 2.9Conditioning and Cooled <240,000 and Single Heating Btu/h Package Equipment COP = 1.3 + (0.16 × COP = 1.3 + (0.16 × the applicable the applicable Packaged minimum cooling EER minimum cooling EER Terminal Heat All All All prescribed in Table 1— prescribed in Table 1— Pumps Minimum Cooling Minimum Cooling Efficiency Levels) Efficiency Levels).1 For units tested by ARI standards, all COP values must be rated at 47°F outdoor dry-bulb temperature for air-cooled products, and at 70°F entering water temperature for water-source heat pumps. For heat pumps tested bythe ISO Standard 13256–1, the COP values must be obtained at the rating point with 20°C (68°F) entering watertemperature.Table 3 quotes minimum energy efficiency levels that must be achieved in Hong Kong, according tothe „Code of Practice for Energy Efficiency of Air Conditioning Installations“ - 2007.Table 3. Minimum Cooling Efficiency Levels for Water Chillers                                                                        COPcooling  Capacity Range  < 500 500 to 1000 > 1000 [kW]  With scroll  4  4.5  5.2  Chillers    compressors  Water Cooled  With screw  4.6  4.6  5.5  compressors  With scroll 2.7  Chillers   compressors  Air Cooled  With screw 2.9  compressors  11. May 2011. Belgrade Page 6 
    • Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioning=======================================================================Table 4 shows data for EER, COP and IPLV, determined according to ARI standards for devicesmanufactured in the U.S.A.          Table 4. Technical Data for Water Chillers; Air Cooled  European Union Standards are clearer than the U.S. ones, but they didn’t cover devices withmore than 12 kW cooling capacity.According to the European Standard EN14511-1:2007 (D) EER and COP have been defined in thefollowing way:EER – Energy Efficiency Ratio (Cooling Efficiency Level) is a ratio between the total cooling capacityand absorbed power of electricity consumer (total power input), expressed in the in identical units ofmeasurement, and therefore the value is unitless.COP – Coefficient of Performance (Heating Efficiency Level) is a ratio between power of heatingexchanged in the condenser in relation to the absorbed power of electricity consumers, expressed inthe same measuring units Wat / Wat.When determining absorbed power all electricity consumers are taken into consideration, as follows:compressor drive engine, electrical panel, fans and pumps necessary for transport of fluids for heatexchange, which must overcome internal resistances during flow of fluids through the heatexchangers.Testing methods and procedures used for determining energy efficiency have been described in theEuropean standard EN14511-3:2007 (D).11. May 2011. Belgrade Page 7 
    • Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioning=======================================================================Standard conditions at which testing is performed for determining energy efficiency have beendescribed in the European standard EN14511-2:2007 (D).EUROVENT as European Committee of Air Handling and Refrigeration Equipment Manufacturersexists for more than 10 years and counts more than 180 manufacturers. In order to supportimplementation of the Energy Performance Building Directive (EPBD) which requires calculation ofbuilding energy performance and regular inspection of central air conditioners and chillers with morethan 12 kW cooling capacity, EUROVENT developed a European Seasonal Energy Efficiency Ratio -ESEER (Seasonal Cooling Efficiency Level), index based on ARI approach to determine theIntegrated Part Load Value.This index presents energy efficiency of water chillers in more realistic terms, because time periodduring the annual operating season in which the chiller works under full load is shorter. Therefore themanufacturers try to develop devices that would be more efficient during reduced load conditions.Chillers with the same cooling index EER, do not need to have the same ESEER. The chiller withbigger ESEER is more energy efficient.ESEER is a weighed formula enabling to take into account the variation of EER with the load rateand the variation of air or water inlet condenser temperature.ESEER = 0.03 • A + 0.33 • B + 0.41 • C + 0.23 • DWhere: A = EER at 100% of load C = EER at 50% of load B = EER at 75% of load D = EER at 25% of loadIn water chillers with air cooled condenser ratios are determined for different load at different airtemperatures when entering the condenser. For minimal load (25%) air temperature of 20ºC isadopted, and for maximum (100%) 35ºC temperature.In water chillers with water cooled condenser ratios are determined for different loads at differentwater temperatures when entering the condenser. For minimum load (25%) water temperature of18ºC is adopted, and for maximum (100%) 30ºC temperature.All those ratios for devices with more than 12 kW cooling capacity do not have the importance of»directive« or of a »standard« and their implementation is on voluntary basis.As there is no European or ISO standard for part load testing conditions, EUROVENT standard,6-C003-2006 has been amended including testing procedure for part load conditions.Table 5 shows data for EER and ESEER determined according to EUROVENT rules. Comparison ofdata from this table and data from Table 4 pertaining to U.S. devices is not purposeful, because theydo not pertain to the same working conditions.11. May 2011. Belgrade Page 8 
    • Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioning=======================================================================In the following conditions:(1) condenser air intake temperature 35°C; chilled water temperature 7°C; temperature differential at the evaporator 5 K.(2) condenser (evaporator) air intake temperature 7°C D.B. - 6°C W.B.-; water temperature 40/45°C.Table 5. Technical Data for Water Chillers; Air Cooled11. May 2011. Belgrade Page 9 
    • Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioning=======================================================================Table 6. Technical Data for Water Chillers; Freecooling Air Cooled      In the following conditions:(1) condenser air intake temperature 30°C; chilled water temperature 15/10°C - 30% ethylene glycol.(2) Water: 15/10°C – 30% ethylene glycol.Table 6 shows data for EER at a lower air temperature and higher water temperatures. Theseconditions are not good to compare different devices, but are realistic for water chillers with indirectfree cooling.11. May 2011. Belgrade Page 10 
    • Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioning======================================================================= Figure 3: EXAMPLE OF OUTPUT SOFWARE FOR THE ESTIMATION OF ENERGY SAVINGFigure 3 shows that large savings can be achieved with indirect free cooling in winter workingconditions.NEWS in Seasonal Energy EfficiencyEUROVENT is involved in a study for the development of the European Seasonal Coefficient ofPerformance – ESCOP (Seasonal Heating Efficiency Level).Some AC engineer proposes a new index of the seasonal energy efficiency for chillers, CSE (ChillerSeasonal Efficiency). This index has an advantage in that it is adaptable to multiple-chiller systems bysetting six rating points to consider the difference in the EER due to the entering condenser watertemperature as well as the part load.Using the CSE index, the advantage of a chiller with variable-speed turbo compressors is presented.Rooftop manufacturers asked the European Committee for Standardization to consider free cooling inthe calculation of the seasonal efficiencies in order to represent the energy savings such a systembrings along.VDMA (Verband Deutscher Maschinen und Anlagenbau - German Engineering Federation) wasfounded the working group “Energy Efficiency of Refrigerating Systems”. This working group is anintegration of industry, science, craft, user, associations and politics.The working group developed basic principles for energy efficient components and systems inrefrigerating technology and prepares recommendations for politics and legislationThe working group “Energy Efficiency of Refrigerating Systems” developed a model offering a simpleevaluation of the refrigerating load and published it in a “VDMA-Einheitsblatt”. They introduced newcoefficients. One of them is - Efficiency of use of cold η ETA(Qo).EHPA - European Heat Pump Association with its EHPA Norms & Standards Committee considersthat COP does not exist in real-life. Ecodesign establishes the Efficiency Factor η (ETA).It is expected that the results of these activities will be after the year 2012.11. May 2011. Belgrade Page 11 
    • Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioning=======================================================================Classification of Water Chillers according to Cooling Efficiency Level (in Europe)EUROVENT established classification for full load Energy Efficiency Ratio of each type of waterchillers; see Table 7.Table 7. Chillers Energy Classification in Cooling Mode Class EER Air Cooled Water Cooled Remote Condenser A EER ≥ 3.1 EER ≥ 5.05 EER ≥ 3.55 B 2.9 ≤ EER < 3.1 4.65 ≤ EER < 5.05 3.4 ≤ EER < 3.55 C 2.7 ≤ EER < 2.9 4.25 ≤ EER < 4.65 3.25 ≤ EER < 3.4 D 2.5 ≤ EER < 2.7 3.85 ≤ EER < 4.25 3.1 ≤ EER < 3.25 E 2.3 ≤ EER < 2.5 3.45 ≤ EER < 3.85 2.95 ≤ EER < 3.1 F 2.1 ≤ EER < 2.3 3.05 ≤ EER < 3.45 2.8 ≤ EER < 2.95 G < 2.1 < 3.05 < 2.8Table 7 presents values of EER for chillers with different types of condensers and for differentclasses. The basic goal of such classification is to eliminate from use chillers of class G, and tostimulate sales of top class ones.All those ratios for chillers with more than 12 kW cooling capacity do not have the importance of»directive« or of a »standard« and their implementation is on voluntary basis.Labelling of Water Chillers according to Cooling Efficiency Level (in Europe)At present, the Energy Labelling Directive is restricted to household appliances. Indeed, the label ismandatory only for Room Air Conditioners with capacity equal to or lower than 12 kW.By applying Directive 2002/96/EC on labelling of devices according to Energy Efficiency, a greatmove has been made in increasing energy efficiency of air-conditioning devices and heat pumps withcapacity equal to or lower than 12 kW.This Directive prescribes mandatory labelling of energy efficiency class of a device. Method oflabelling in the form of defined size sticker with data about energy efficiency class from A to G,enables the buyer to influence the energy saving himself, during selection and purchase of the device.This method of labelling is not defined by standards or regulations for water chillers and heat pumpswith more than 12 kW cooling capacity.11. May 2011. Belgrade Page 12 
    • Roundtable on climate & ozone-friendly technologies in refrigeration & air-conditioning ======================================================================= Conclusion The Energy Performance Building Directive (EPBD) requires calculation of building energy performance and regular inspection of central air conditioners and chillers with more than 12 kW cooling capacity. However, these measures only address the efficiency of the end-use equipment as determined under standard conditions at full load and will not realize many of the potential energy savings which are related to operating conditions at part load. To be really effective, energy efficiency options have to be defined not on the basis of nominal operating conditions but on a variety of part load conditions, which better reflect the central air conditioners operating modes that occur in real use. Development of the European Seasonal Coefficient of Performance – ESCOP (Seasonal Heating Efficiency Level) must be finish. Take in to account free cooling in the calculation of the seasonal efficiencies in order to represent the energy savings such a system brings along. Consider the advantage of a multiple-chiller systems with variable-speed turbo compressors in the calculation of the energy savings. As the implementation of the Kyoto Protocol is a priority issue in Europe and worldwide, the European Union is planning to reduce CO2 emission by 8% in the period from 2008. to 2012. This is a powerful motive for improving energy efficiency of water chillers and heat pumps. Lower electricity consumption means lower electricity generation demands, which results in reduction of CO2 emission. Literature: 1. EN standard 14511: 2007 (D) 2. ARI standard 340/360 – 2007 3. IIR bulletin No. 2001 – 5 4. Energy Labeling Directive, 2002/96/EC and EN 14511 Standard for Room Air Conditioners, Yamina Saheb, Andre Pierrot, Sulejman Bećirspahić 5. Effect of the Certification on Chillers Energy Efficiency, Yamina Saheb, Sulejman Bećirspahić, Jerome Simon 6. Air-conditioning, air handling and refrigeration equipment: European-wide certification, standards and European directives on energy efficiency, Sandrine Marinhas, Sylvain Courtey, Mohamed Ouhemmou, E. Melquiond and G. Robertsson Eurovent certification Company, France  11. May 2011. Belgrade Page 13