Technical Papers. 33rd Annual Meeting. International Institute of Ammonia Refrigeration. March 27 30, 2011

Transcription

1 Technical Papers 33rd Annual Meeting International Institute of Ammonia Refrigeration March 27 30, Industrial Refrigeration Conference & Heavy Equipment Show Caribe Royale Orlando, Florida

2 ACKNOWLEDGEMENT The success of the 33rd Annual Meeting of the International Institute of Ammonia Refrigeration is due to the quality of the technical papers in this volume and the labor of its authors. IIAR expresses its deep appreciation to the authors, reviewers and editors for their contributions to the ammonia refrigeration industry. Board of Directors, International Institute of Ammonia Refrigeration ABOUT THIS VOLUME IIAR Technical Papers are subjected to rigorous technical peer review. The views expressed in the papers in this volume are those of the authors, not the International Institute of Ammonia Refrigeration. They are not official positions of the Institute and are not officially endorsed. International Institute of Ammonia Refrigeration 1001 North Fairfax Street Suite 503 Alexandria, VA (voice) (fax) Industrial Refrigeration Conference & Heavy Equipment Show Caribe Royale Orlando, Florida

3 Technical Paper #7 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems Mark Tomooka Mayekawa USA, Inc. Abstract Development and application of micro-channel heat exchangers show great application potential in refrigerated systems. Micro-channel heat exchangers allow for larger heat exchange surfaces in smaller packages. Tests show that compared to a round tube, plate fin condenser, a micro-channel air cooled condenser would be 14 times lighter, and would have 20% of the volume, 25% of the charge, and 60% of the pressure drop on the air-side. Applying micro-channel technology to ammonia refrigeration systems reduces system charge. Additional benefits are gained by using scroll compressors which allow for a smaller equipment foot print and lower weight. Energy savings are also realized due to lower fan horsepower required for the micro-channel condenser. IIAR

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5 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems Introduction Rapid technological development and implementation of refrigeration technology through the 20th century has allowed for the preservation of food, medical supplies and comfort air conditioning. Unfortunately, this technological boon consumes 15% of total energy worldwide [1] and created a trail of legislation aimed at limiting the environmental and health impacts of refrigeration technology. Increasing awareness of the environmental effects of refrigerants culminated in the Montreal Protocol (1987) and the call for the phase-out of ozone depleting refrigerants. A host of replacement refrigerants were developed for use as dropin replacements as well as for use in new construction. A decade later the Kyoto Protocol (1997) indicated that the use of these substitute refrigerants contributed to the greenhouse effect [2]. Thus, rekindling the refrigerant selection debate. The regulation of refrigerant usage was not limited to synthetic refrigerants saw the promulgation of the Process Safety Management Regulation (PSM) by the Office of Occupational Safety and Health (OSHA) that issued mandatory guidelines for facilities using ammonia as a refrigerant. Two years later, the Environmental Protection Agency (EPA) issued their regulatory guidelines called Process Safety Management. Federal concern for facilities that may contain chemicals used in terrorist attacks led to the formation of the Chemical Facilities Anti-Terrorism Standard (CFATS) in Several states have also instituted local regulations on ammonia as well. The inclusion of refrigerated facilities in California s Title 24 Regulation (2008), which is aimed at energy efficiency, signals the beginning of stricter guidelines on power consumption. Even in states that do not have explicit mandates on power consumption, energy efficiency is encouraged through the use of incentive programs for savings by design as well as retrofits. Technical Paper #7 IIAR

6 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida The cumulative effect of the environmental and regulatory constraints focused the priorities of refrigeration on [1]: 1. Improving system efficiency 2. Reducing refrigerant charge 3. Reducing the physical size of the equipment 4. Developing solutions to these problems cost effectively The ability to respond to these priorities will determine future success. Ammonia has many favorable characteristics that make it the refrigerant of choice for high efficiency systems, thus addressing issue 1 above. However, these systems are typically used for food refrigeration, cold storage warehousing, and process cooling, but seldom are considered in applications where small charge and equipment size are a factor [3]. Additionally, since ammonia refrigeration components are typically industrial grade, cost prevents wider use in commercial and chiller applications. Micro-channel heat exchangers (MCHX) and hermetic compressors are examples of technology that can make ammonia refrigeration more attractive in applications typically dominated by synthetic refrigerants. These technologies retain their high efficiency characteristics and ally them with creative solutions that have prevented more widespread use. It also has the advantage of directly responding to the challenges facing refrigeration as outlined above. Micro-channel Heat Exchangers Traditional heat exchangers for use in refrigeration applications are typically round tube plate fin (RTPF). RTPF heat exchangers have a continuous fin sheet that has holes which the tubes pass through [4]. The diameter of the tubes is comparatively large: larger than 1/8 inch (3mm) [1]. MCHX are constructed of flat tubes that contain rectangular passages of small hydraulic diameter (generally less than 1/8 4 IIAR 2011 Technical Paper #7

7 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems inch {3mm}) 1. Folded louvered fins are used on the air side of the heat exchanger [Figure 1]. Examples of other microchannel geometry are shown in Figure 2. MCHX have gained wide acceptance in the mobile and residential air conditioning sectors, but only recently has attracted the attention for use in larger, stationary applications [4]. MCHX application in mobile and residential air conditioning along with much research has shown that MCHX have many benefits in the areas of heat transfer coefficient and physical size [1]. All of this research was directed toward synthetic refrigerants and applications. Hrnjak and Litch compared the use of ammonia MCHX against plate type condensers as a method of charge reduction and also found favorable heat transfer to volume, mass and surface area ratios [5]. Based on the results of this paper an air-cooled chiller package was tested with the standard RTPF condenser and compared to the performance of a MCHX. MCHX Ammonia Chiller Package Testing Baseline Test Model The original chiller was an air-cooled, semi-hermetic ammonia compressor [Figure 3], chiller unit with a nominal capacity of 10 tons of refrigeration (TR)(35kW). A picture of the test unit can be seen in Figure 4. Discharge temperature control was achieved through liquid injection. A pulse type expansion valve controlled the discharge temperature at 185 F (85 C). Oil circulation was achieved through differential pressure. Miscible oil was used so that similar operating characteristics to synthetic refrigerants could be attained. Properties of this oil are listed in Table 1. The condensers used in baseline testing were RTPF type mounted on both sides of the chiller. Two fans draw air through the condensers and variable frequency drives Technical Paper #7 IIAR

8 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida control the fan motors. Proper oil circulation is maintained by using the fan motors to keep a minimum pressure differential between suction and discharge of the system. The chiller evaporator is a plate-type heat exchanger that uses a 51% ethyl glycol mixture on the secondary side. Electric heaters supply load to the glycol for testing. Main liquid supply to the heat exchanger is a pulse type expansion device set to 5K superheat at the evaporator exit. Condensers Important dimensions for the baseline RTPF condensers are given in Table 2. The MCHX used for the comparison test was designed with the following methodology: 1. Obtain the same or lower condensing pressure as the original RTPF condenser. 2. The MCHX must have the same face area 2 and equal or lower air side pressure drop at the same face velocity. 3. Significantly reduce the overall size of the condenser Two micro-channel (MC) condenser configurations were used in the tests 1. A dual stack configuration that has two heat exchangers connected in series on each side of the unit. This configuration was used to test the effect of condenser thickness on performance. See Table 3 for dimensions. 2. A single condenser configuration that only has one heat exchanger on each side of the unit. For these tests, the second condenser was not removed from the unit for testing. The second slab was removed from the refrigeration loop, but not physically removed from the system. See Table 4 for dimensions. Figures 5 and 6 show the general arrangement for the condensers on the test unit. Table 5 is a summary of the physical comparison of the RTPF and MC condensers. 6 IIAR 2011 Technical Paper #7

9 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems Test Conditions Table 6 contains the test conditions for the unit. A range of conditions for condenser face velocity and evaporative temperature were gathered to determine the performance difference between the RTPF and MC condenser. For all test runs, the inlet temperature was controlled at 95 F (35 C). Suction superheat is consistent through all tests (5K), and the temperature difference across the evaporator is 5K as well. Test Facility Testing was conducted at Creative Thermal Solutions (CTS) in Urbana, Illinois. The entire unit was placed in a test cell. The test cell can regulate the face velocity over the condensers by using a variable speed blower. It also maintains the ambient air condition at a consistent 95 F (35 C). Air mixture louvers combine outside air with recycled discharge air to regulate temperature. In the event that ambient air conditions are below the desired test parameter, a supplemental heater is used to warm the inlet air. A 51% ethylene glycol brine loop was used as a cooling load for the chiller. Heating load was supplied by a manually controlled electric heater. A PID controller varies pump speed to maintain a 5K temperature difference between the inlet and outlet of the evaporator. Test Results System Capacity Figure 7 shows a plot of system capacity versus condenser face velocity. Only the experiment extremes of 23 F ( 5 C) and 4 F ( 20 C) are provided for graph Technical Paper #7 IIAR

10 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida simplicity. The evaporator capacity of the RTPF and MC condenser equipped systems tracked closely to each other. System COP A plot of COP comparison between the single and dual slab MC condensers and the RTPF condenser is shown in Figure 8. The RTPF condenser out performs the single slab MC condenser. This is because of a slight mismatch in condenser size between the RTPF and MC condensers as previously noted in footnote 2. The dual slab MC condenser does show higher system COP than the RTPF condenser. Examining Table 5 shows that even the dual slab MC condenser has favorable physical characteristics compared to the RTPF condenser. Unit Charge An additional benefit of using a MCHX is the smaller internal volume of the condenser. This allows the charge to be smaller than that of a RTPF condenser. The MC condenser has 25% of the refrigerant charge of the RTPF condenser. The condenser charge is a fractional percentage of the total system charge and therefore did not significantly reduce the overall system charge. Testing did show that there were significant savings in system charge by manipulating the amount of charge in the high pressure receiver. Table 7 shows a summary of the system charge of the unit. Refrigerant side pressure drop Figure 9 shows the relationship between the RTPF condenser and the two MC condensers. Both MCHX have a larger pressure drop than the RTPF. The values shown in Figure 8 are an average of the pressure drops across the four face velocities. It is expected that the refrigerant side pressure drop of a MCHX will be larger than a RTPF. This is an area where optimization of MCHX design can decrease the refrigerant side pressure drop. 8 IIAR 2011 Technical Paper #7

11 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems Air side pressure drop A comparison of air side pressure drop for the different heat exchangers is presented in Figure 10. The graph shows that the single slab MC condenser has significantly lower pressure drop than the RTPF. Therefore, it would be possible to reduce fan horsepower, or the same fans can be used for greater air flow. Either option would increase system efficiency. Heat Transfer Coefficient Figure 11 is a plot of the heat transfer coefficient (U) for the different heat exchangers. The U values are averaged over the four evaporating temperatures. The graph shows a significant improvement in heat transfer of the MC condenser over the RTPF condenser. In many cases, the heat transfer coefficient is more than twice that of the RTPF. The dual slab condenser has a lower heat transfer coefficient than the single slab due to the flow arrangement and large size. Summary Overall, compared to an air cooled RTPF condenser, the MCHX condenser offers the following significant advantages: 1. Condenser weight reduced 14 times, or 7% of baseline weight 2. Interior tube volume reduced 5 times, or 20% of baseline 3. Condenser charge reduced 4 times, or 25% of baseline 4. Airside pressure drop reduced to 60% of baseline 5. Equivalent cooling capacity with minimal reduction of COP in a significantly smaller package Technical Paper #7 IIAR

12 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida Discussion Micro-channel Heat Exchanger The results above demonstrate the viability of expanding MCHX use outside of mobile and small refrigeration applications. The specific charge is competitive with similar HFC equipment (Table 8), and studies, such as those conducted by Hrnjak and Litch [5], suggest that much lower specific charges are possible. MCHX are superior to RTPF heat exchangers in the area of size, weight, cost and charge. They allow a refrigeration unit to be more compact while delivering comparable performance to RTPF heat exchangers. These characteristics address the future concerns of lower refrigerant charge systems and smaller package size. Lower air side pressure drop can also lead to lower fan horsepower or greater system capacity. Semi-Hermetic Ammonia Compressor The use of a semi-hermetic compressor allows an ammonia system to have similar operating and maintenance characteristics to a HFC system. Both systems use miscible refrigeration oil eliminating the added risk of oil draining in a traditional, non-miscible, ammonia system. Use of a semi-hermetic compressor also eliminates shaft seal maintenance that requires highly trained technicians for service and replacement. It also eliminates a large potential for refrigerant leaks. Compressor specifications are given in Table 9. Interior permanent magnet (IPM) motors are used to reduce the motor size and to help increase efficiency. This type of motor has a permanent magnet inserted into the rotor. Since the motor does not require excitation power like typical motors, there is an increase in efficiency [10]. Aluminum windings are necessary due to ammonia s corrosive attack on copper. 10 IIAR 2011 Technical Paper #7

13 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems Application Potential Many recent papers highlight the opportunity for ammonia as an alternative refrigerant in commercial systems, noticeably Pearson (2003) [7], Hrnjak and Litch (2001) [8], and Hinde and Zha (2009) [6]. These papers identify the possibility of expanding ammonia s use and current examples of installations, but also recognize its limited appeal due to several significant obstacles. Use of efficiency improving and space saving technology such as MCHX helps reduce charge which is an important factor for wider commercial use as cited in the above papers. Further appeal comes from implementing technology that commercial refrigeration users are already familiar with, such as semi-hermetic scroll compressors. Conclusion Comparison of a MCHX and a RTPF heat exchanger were conducted, and the results show that application of MCHX in air-cooled applications significantly improve system design. Couple MCHX with technology such as semi-hermetic compressors, and the use of ammonia refrigeration in traditionally synthetic refrigerant applications becomes possible. This is an important step to addressing the four hurdles outlined in the introduction and to continue the advancement of ammonia as the natural refrigerant choice. Application of ammonia as a refrigerant improves system COP over synthetic refrigerants [3]. MCHX and semi-hermetic compressors allow for smaller equipment size and reduce equipment charge. Technical Paper #7 IIAR

14 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida Footnotes: 1 It should be noted that these figures are not firmly set. There are various schemes for determining what is or is not a micro-channel. These discussions can be found elsewhere and are outside the scope of this paper. 2 This experiment had several phases of testing. The current results are for Phase II, however the MCHX was designed for the original chiller in Phase I. This accounts for the discrepancy in the face areas of the two condensers. This also impacts total air flow over the condenser during testing. Special Thanks: Special thanks goes to Creative Thermal Solutions in Champaign, Illinois, for their cooperation and work in testing the equipment. Their expertise and knowledge was invaluable to this process and would not be possible without them. 12 IIAR 2011 Technical Paper #7

15 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems References Kandlikar, Satish G.(2007) A Roadmap for Implementing Minichannels in Refrigeration and Air-Conditioning Systems Current Status and Future Directions, Heat Transfer Engineering, 28: 12, F. Poggi, H. Macchi-Tejeda, D. Leducq, A. Bontemps, Refrigerant charge in refrigerating systems and strategies of charge reduction, International Journal of Refrigeration, Volume 31, Issue 3, May 2008, Pages A Pearson, Refrigeration with ammonia, International Journal of Refrigeration, Volume 31, Issue 4, Refrigeration with Ammonia and Hydrocarbons, June 2008, Pages D Westphalen, K Roth, J Brodrick, Microchannel Heat Exchangers, ASHRAE Journal, Volume 45, No 12, December 2003, Pgs P Hrnjak, A Litch, Microchannel heat exchangers for charge minimization in aircooled ammonia condensers and chillers, Internation Journal of Refrigeration, volume 31, 2008 pgs D Hinde, S Zha, Natural Refrigerant Applications in North American Supermarkets, Proceedings of IIAR National Conference, 2009, pgs 1-24 A Pearson, Low-Charge Ammonia Plants: Why Bother?, Proceedings of IIAR National Conference, 2003, pgs P Hrnjak, A Litch, Charge Reduction in Ammonia Chiller Using Air Cooled Condensers with Aluminum microchannel tubes, Proceedings of IIAR National Conference, 2001, Pgs Technical Paper #7 IIAR

16 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida K Kawamura, et al, Design Considerations for a NH 3 System Utilizing CO 2 as a seconday refrigerant in Tokyo Japan, Proceedings of IIAR National Conference, 2008, pgs 1-14 N Mugabi, Semi-Hermetic Ammonia Compressor Packages, Ammonia Refrigeration Technoligy, IIR Conference Ohrid, Macedonia 2009 Consulted works, not specifically cited: S.M. Miner, An Appraisal of Ammonia as an Alternative Refrigerant in Light of the CFC and GWP Situation, Proceedings of IIAR National Conference, 1992, pgs B Palm, Refrigeration Systems With a Minimum Charge of Refrigerant, Applied Thermal Engineering Vol 27, 2007, pgs J McMullan, Refrigeration and the Environment Issues and Strategies for the Future, International Journal of Refrigeration, vol 25, 2002, pg P Fairchild and V Baxter, Ammonia Usage in Vapor Compression for Refrigeration and Air-Conditioning in the United States, Proceedings of the IEA Annex 22 Workshop on: Compression Systems with Natural Working Fluids Applications Experience and Developments, 1995 N Mugabi, J Boone, K Kawamura, Refrigerant Charge Reduction in Ammonia Refrigeration Systems, 1st IIR International Workshop on Refrigerant Charge Reduction, 2009 A Pearson, Ammonia s Future, ASHRAE Journal, Feb 2008, pgs IIAR 2011 Technical Paper #7

17 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems Figure 1. Microchannel and Conventional Heat Exchanger Example [4] Technical Paper #7 IIAR

18 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida Figure 2. Examples of Other Microchannel Geometry [1] 16 IIAR 2011 Technical Paper #7

19 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems Figure 3. Semi Hermetic Ammonia Compressor Technical Paper #7 IIAR

20 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida Figure 4. Test Unit 18 IIAR 2011 Technical Paper #7

21 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems Figure 5. Dual Slab MC Arrangement Technical Paper #7 IIAR

22 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida Figure 6. Single Slab MC Arrangement 20 IIAR 2011 Technical Paper #7

23 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems Figure 7. Evaporator Capacity vs Condenser Face Velocity Evaporator Capacity (TR) RTPF 23 F Dual Slab MC 23 F Single Slab 23 F RTPF -4 F Dual Slab MC -4 F Single Slab MC -4 F Condenser Air Inlet Velocity (ft/s) Technical Paper #7 IIAR

24 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida Figure 8. System COP vs Condenser Face Velocity COP (-) RTPF 23 F Dual Slab MC 23 F Single Slab 23 F RTPF -4 F Dual Slab MC -4 F Single Slab MC -4 F Condenser Air Inlet Velocity (ft/s) 22 IIAR 2011 Technical Paper #7

25 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems Figure 9. Refrigerant Side Pressure Drop Refrigerant Pressure Drop (psi) RTPF Dual Slab MC Single Slab MC Mass flow (lb/min) Technical Paper #7 IIAR

26 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida Figure 10. Air Side Pressure Drop Air Side Pressure Drop (in/h2o) RTPF Dual Slab MC Single Slab MC Condenser Air Inlet Face Velocity (ft/s) 24 IIAR 2011 Technical Paper #7

27 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems Figure 11. Heat Transfer Coefficient Comparison Average Heat Transf Coeff (W/m^2 C) RTPF Average Dual Slab MC Average Single Slab MC Average Face Velocity (m/s) Technical Paper #7 IIAR

28 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida Figure 12. Internal Permanent Magnet Motor Schematic 26 IIAR 2011 Technical Paper #7

29 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems Table 1. Properties of PAG Oil Density (15 C/59 F) 1014 kg/m 3 (63.3 lb/ft 3 ) Color (ASTM) L0.5 Flash Point 236 C (457 F) Kinematic Viscosity: 40 C (104 F) 100 C (212 F) 47 cst 10.6 cst Viscosity Index 223 Pour Point 40 C ( 40 F) Total Acid Number (TAN) 0.01 mgk0h/g Table 2. RTPF Heat Exchanger Physical Properties. This is the total a single condenser. Two are equipped per unit. Physical Property Value Face Area m ft 2 Depth 88 mm 3.46 in Air Side Volume m ft 3 Weight 140 kg lbs Refrigerant Side Volume m ft 3 Air Side Heat Transfer Area m ft 2 Refrigerant Heat Transfer Area 3.76 m ft 3 Technical Paper #7 IIAR

30 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida Table 3: Dual Slab MC Condenser Physical Properties. This is the total for a dual condenser. Two dual units are equipped per unit. Physical Property Value Face Area m ft 2 Depth 40 mm 1.57 in Air Side Volume 0.75 m ft 3 Weight 19.4 kg lbs Refrigerant Side Volume.004 m ft 3 Air Side Heat Transfer Area m ft 2 Refrigerant Heat Transfer Area 5.47 m ft 3 Table 4: Single Slab MC Condenser Physical Properties. This is the total for a single condenser. Two dual units are equipped per unit. Physical Property Value Face Area m ft 2 Depth 20 mm in Air Side Volume m ft 3 Weight 9.7 kg 21.4 lbs Refrigerant Side Volume.002 m ft 3 Air Side Heat Transfer Area m ft 2 Refrigerant Heat Transfer Area 2.73 m ft 3 28 IIAR 2011 Technical Paper #7

31 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems Table 5: Comparison of RTPF and MC Condensers Physical Property Dual Slab vs RTPF Single Slab vs RTPF Face Area 87.6 % 87.6 % Depth 45.5 % 22.7 % Air Side Volume 39.8 % 49.9 % Weight 13.9 % 6.9 % Refrigerant Side Volume 55.3 % 27.6 % Air Side Heat Transfer Area 70.6 % 35.3 % Refrigerant Heat Transfer Area % 72.7% Table 6. Test Conditions Condenser Air Side Inlet Temperature Face Velocity C / F (m/s) / (ft/s) 35 / / / 95 2 / / / / / 7.9 Evaporator C / F 5 / / / 5 20 / 4 5 / / / 5 20 / 4 5 / / / 5 20 / 4 5 / / / 5 20 / 4 Technical Paper #7 IIAR

32 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida Table 7. System Charge Information Condenser Charge [kg / lb] Note RTPF 5.44 / 12.0 Original Design Dual Slab MC 5.44 / 12.0 Original Design Dual Slab MC 2.90 / 6.39 Modified System Single Slab MC 2.50 / 5.51 Modified System Table 8. Specific Charge Comparisons System Type Specific Charge (kg/kw) / (lb/tr) Ref Type Chilling w/secondary refrigerant 0.8 / 6.2 [2] HFC Experimental Ammonia MC Chiller / [5] NH3 Ammonia RTPF Chiller / 1.23 [ 2] NH3 Ammonia /CO 2 Brine Freezer 0.06 / 0.47 [9] NH 3 /CO 2 Current Test Unit.071 / 0.55 NH3 30 IIAR 2011 Technical Paper #7

33 Application of Micro-channel Heat Exchangers to Compact Ammonia Systems Table 9. Scroll Compressor Specifications Item Value Units Casing Design pressure 392 / 2.7 Psia / MPa Design temp. 248 / 120 ºF / ºC Operation Cond. Temp. 86~ 131 / 30 ~ 55 ºF / ºC range Eva. Temp. -31 ~ 50 / -35 ~ 10 ºF / ºC Cond. Pressure 170 ~ 335 / 1.17 ~ 2.31 Psia / MPa (A) Eva. Pressure 13.5 ~ 90 / ~ 0.62 Psia / MPa (A) Rotational speed 1800 ~ 3600 rpm Model 2 (low and high temp.) Motor Type IPM Nominal/Max. power (15/20) / (11/15) HP/ kw Oil / motor cooling Liquid injection Oil supply Oil pump Weight 220 / 100 Lb / kg Technical Paper #7 IIAR

34 2011 IIAR Industrial Refrigeration Conference & Heavy Equipment Show, Orlando, Florida Notes: 32 IIAR 2011 Technical Paper #7