Patent Application
20190178544
The present invention relates to the field of refrigerants, refrigeration systems, and refrigeration system lubricants.
R-407C is an HFC refrigerant replacement for R-22, a HCFC refrigerant, in positive displacement systems such as new or existing residential and commercial air-conditioners and heat pumps. R-407C offers similar performance to R-22 and can be used to retrofit existing R-22 air-conditioning and refrigeration systems.
R-407C is a mixture of hydrofluorocarbons used as a refrigerant. It is a zeotropic blend of difluoromethane (R-32), pentafluoroethane (R-125), and 1,1,1,2-tetrafluoroethane (R-134a). R-32, R-125 and R-134a are present in the proportions 23%/25%/52% by weight (a ±2% tolerance is allowed for each of the components). R-407A is a mixture of 20% R32, 40% R125, and 40% R-134a, and is therefore R-407A is similar in many respects to R407C. Difluoromethane serves to provide the heat capacity, pentafluoroethane decreases flammability, tetrafluoroethane reduces pressure. R-22 is chlorodifluoromethane.
Most compressors require a lubricant to protect internal moving parts. The compressor manufacturer usually recommends the type of lubricant and proper viscosity that should be used to ensure acceptable operation and equipment durability. Recommendations are based on several criteria, which can include: lubricity; lubricant/refrigerant solubility; lubricant/refrigerant miscibility; compatibility with materials of construction; and thermal stability and compatibility with other lubricants. It is important to follow the manufacturer's recommendations for lubricants to be used with their equipment.
Lubricant return to the compressors is very important as well. One factor that affects this is the liquid-phase lubricant/refrigerant miscibility, particularly at evaporator temperatures. Miscibility is the ability of two liquids to mix and form a single liquid phase. Ideally, the lubricant-refrigerant pair have sufficient miscibility or mutual solubility to allow the lubricant to flow with the liquid refrigerant and return to the compressor in a single phase. Even if the lubricant/refrigerant pair are not miscible (two liquid phases form) in the evaporator, they may still have some degree of solubility. Solubility of refrigerant in lubricant lowers lubricant viscosity, which helps it flow through the evaporator and return to the compressor. This is why many refrigeration systems can operate properly, even though the lubricant and refrigerant are immiscible (yet partially soluble) at evaporation temperatures. Other factors, such as refrigerant vapor velocity and system geometry, play key roles in lubricant return. Overall, it is important to note that lubricant/refrigerant miscibility is helpful, but not necessarily essential for proper system operation.
In general, R-22 and mineral oil are miscible over most of the expected ranges of operating conditions for normal air conditioning and high to medium temperature operation. Miscibility is generally believed to aid lubricant return to the compressor. The miscibility of refrigerant and lubricant is determined by several factors: the relative amounts of refrigerant and lubricant present, the temperature, the chemical makeup of the lubricant and of the refrigerant, and the viscosity of the lubricant.
Therefore, it may be desirable in a retrofit of an existing system of this type to use a miscible lubricant, such as polyol ester lubricant, with R-407C refrigerant. In general, R-407C is miscible with polyol ester (POE) lubricant and immiscible with alkylbenzene and mineral oil lubricant.
Residual mineral oil or alkylbenzene left in a refrigeration system after a retrofit to any HFC refrigerant is performed is known to decrease the lubricant/refrigerant miscibility. This is one of the reasons why three oil changes are generally recommended when a system is being converted or retrofit to use HFC refrigerants and POE lubricants. Thus, a traditional recommendation is to replace all mineral oil or alkylbenzene lubricant with POE during a retrofit.
Emerson Climate Technologies (Copeland®) provided in 1995 & 2005 the following recommendations when conducting a changeover: “Copeland's only approved lubricants for use with R-407C are Polyol ester lubricants”; “Mineral oil lubricant, such as 3GS, cannot be used as the compressor lubricant. Copeland recommends the following lubricant choices: Polyol Ester (POE)”; “The mineral oil must be removed from the compressor crankcase. Hermetic compressors will have to be removed from the piping and the lubricant drained out through the suction stub. It is advisable to do an acid test on the lubricant removed”; “Those systems that have oil separators, oil reservoirs, oil floats and suction line accumulators must have the oil drained from them. If the liquid control device is going to be replaced, it is advisable that the suction line, liquid line, and evaporator coil be blown clean using properly regulated dry nitrogen”; “POEs are very hygroscopic. They will very quickly absorb moisture from the air once the container is opened. Once the lubricant is added to the compressor, the compressor should be quickly installed. Like an open container, an open compressor with POE will absorb moisture. Add the correct amount of lubricant, to the compressor. On systems using enhanced surfaces in the heat exchanger, excessive mineral oil can adversely effect the heat transfer due to logging. Therefore, it is desirable to have no more than one percent mineral oil in systems employing these types surfaces.” lvhvac.com/cope_bulletins/95-14.pdf.
Dupont (2004) advises that no more than 5% mineral oil remain in the refrigeration system after a changeover from R-22 to R-407C.
(www2.dupont.com/Refrigerants/en_US/assets/downloads/h70004_Suva407c_retrofit_guide.pdf)
Similarly, Tecumseh advised in 2009 (www.air-innovations.nl/web/pdf/GUIDELINES-FOR-UTILIZATION-OF-R407C.pdf):
Ennio Campagna et al., “The Use of R-407C: Applications and Guidelines”, makina.beun.edu.tr/eskisite/akademik_kadro/meyriboyun/mak723/The_Use_of_R-407C.pdf, states:
Similarly, Herronhill provides general guidelines to assist in the replacement of R22 condensing units with equivalent R407C units (2004, www.heronhill.co.uk/technical-information/40/converting-r22-systems-to-r407c), stating “Condensing units built and supplied by IMI Air Conditioning Ltd. (now Marstair Ltd) before 1999, for use with R22 will contain mineral oil. R407C units will contain polyolester oil (POE). Check the compressor label to confirm the type of oil in the system. For safe system operation it is essential to remove the mineral oil from the existing system, as R407C is not compatible with mineral oil. On completion of the change over the concentration of mineral oil remaining in the system should not exceed 5% of the total oil charge.
Sundaresan, S. G.; Pate, M. B.; Doerr, T. M.; and Ray, D. T., “A Comparison of the Effects of POE and Mineral Oil Lubricants on the In-Tube Evaporation of R-22, R-407C and R-410A” (1996). International Refrigeration and Air Conditioning Conference. Paper 322. docs.lib.purdue.edu/iracc/322, describe tests on the heat transfer efficiency of R-22, R-407C and R-410A on smooth and finned tubes, when neat, mixed with mineral oil, and when mixed with POE oil. POE-mineral oil mixtures were not tested. The heat transfer efficiency was higher for R-407C mixed with POE than with mineral oil.
Some more recent consideration of the choice or lubricant considers mixtures of lubricants, including mineral oil (MO) and polyol esters (POE). For example, The News, (Peter Powell, Dec. 3, 2012, www.achrnews.com/articles/print/121529-retrofit-round-up-plenty-of-options) states:
Therefore, there has been some evolution as to whether mineral oil can remain in the refrigeration system after a retrofit, with the permissible proportion of mineral oil increasing. In particular, National Refrigerants proposes a partial POE retrofit, with greater than 5% mineral oil remaining. However, the existing recommendations appear to require empirical testing for cases other than less than 5% mineral oil remaining.
See, U.S. Pat. Nos. 2,834,748; 2,846,458; 2,889,379; 2,917,480; 2,931,840; 2,970,988; 3,085,918; 3,384,828; 3,723,318; 3,884,828; 4,138,855; 4,198,313; 4,272,960; 4,465,786; 4,482,465; 4,788,352; 4,798,818; 4,810,403; 4,941,986; 4,944,890; 5,026,497; 5,053,155; 5,080,823; 5,108,637; 5,182,040; 5,227,245; 5,304,320; 5,318,716; 5,360,566; 5,370,812; 5,387,357; 5,417,871; 5,425,890; 5,458,798; 5,616,275; 5,622,644; 5,624,596; 5,626,790; 5,648,017; 5,672,293; 5,685,163; 5,714,083; 5,785,883; 5,788,886; 5,811,603; 5,968,406; 6,025,532; 6,106,740; 6,111,150; 6,117,356; 6,235,951; 6,258,292; 6,316,681; 6,374,629; 6,426,019; 6,516,837; 6,526,764; 6,589,355; 6,604,368; 6,606,868; 6,629,419; 6,673,976; 6,783,691; 6,858,571; 6,991,743; 7,238,299; 7,279,451; 7,341,984; 7,442,321; 7,465,698; 7,524,805; 7,629,306; 7,767,638; 7,825,081; 7,829,748; 7,833,433; 7,846,355; 7,862,742; 7,972,528; 8,008,244; 8,053,404; 8,101,672; 8,148,317; 8,444,874; 8,465,664; 8,551,354; 8,557,136; U.S. Published Patent Application Nos. 20020046568; 20030042463; 20040089839; 20040119047; 20040127383; 20040256594; 20050233923; 20050233931; 20050233932; 20050245421; 20050247905; 20060019857; 20060025322; 20060043331; 20060058560; 20060243944; 20060243945; 20070007488; 20070010592; 20070069175; 20070108403; 20070210275; 20070210276; 20070290163; 20070290177; 20080069177; 20080075673; 20080099190; 20080121837; 20080171652; 20080230738; 20080308763; 20080314073; 20090041677; 20090053695; 20090120619; 20090158771; 20090224199; 20090242828; 20090253820; 20090278076; 20090285764; 20090302285; 20090305876; 20100025619; 20100044619; 20100048961; 20100075046; 20100122545; 20100127209; 20100200798; 20110162410; 20110226983; 20110289748; 20120138846; 20120187331; 20120312048; 20130075063; 20130119299; 20130126776; 20130126777; 20130126778; CN101864276; CN95117074; DE4116274; EP0398147; EP0430169; EP0509673; EP0539952; EP0565265; EP0582451; EP0608164; EP0659862; EP0720639; EP0779352; EP0974571; EP1167894; EP1193305; EP1716216; EP1832640; EP1985680; EP2036943; EP2149592; EP2246649; EP2249104; GB2007000746; GB2435747; GB2440258; JP4110388; RU2073058; WO1998050331; WO2004037752; WO2004037913; WO2005042663; WO2005083028; WO2005103190; WO2005103191; WO2005103192; WO2005105947; WO2005108522; WO2005108523; WO2006094303; WO2007002625; WO2007035697; WO2007053697; WO2007099350; WO2007109748; WO2008027555; WO2008065011; WO2008076272; WO2008121776; WO2008121783; WO2008121785; WO2009047535; WO2009114397; WO2009134957; WO2009151669; WO2010000993; WO2010000994; WO2010002020; WO2010002023; WO2010056695; WO2010059677; WO2010065005; WO2010075046; WO2010088320; WO2010119265; WO2011019350; each of which is expressly incorporated herein by reference in its entirety.
The present invention provides a premixed HFC refrigerant and compatible POE lubricant, e.g., in a transport container. The amount of lubricant is selected to an amount between about 5% to 20% by weight of the refrigerant. Preferably, the amount is 8% by weight.
The amount of POE should be at least 10% of the total lubricant amount, with about 20% POE by weight of refrigerant representing the amount of POE in the absence of mineral oil.
The mixture is preferably provided in a transport container, typically DOT approved, such as a DOT-39 container.
The refrigerant-lubricant mixture is charged into the refrigeration system after recovery of the R-22 from the system, without special efforts to remove the mineral oil lubricant. Assuming that the residual mineral oil is 8-24% of the charge, and the mixed refrigerant includes 8% POE, the resulting mixture is about 25-50% of the total lubricant, and the resulting mixed lubricant is 16-32% of refrigerant charge. Therefore, the present technology provides a compromise amount of lubricant that is sufficient to provide a charge to a range of refrigeration systems to be retrofitted, without having to remove mineral oil already in the system, measure the amount of oil removed or infer the total amount, measure an amount of POE to be added to the system based on the actual amount of R-407C added to the system, or measuring mineral oil/POE ratios.
Therefore, the present technologies vastly simplify the process for retrofitting, while achieving good results. Indeed, preliminary tests show that the efficiency of an R-22 air conditioning system is improved after the retrofitting, a surprising result given that the system itself is optimized for R-22 and mineral oil.
The container may be, for example, a 10, 15, 20, 30, 40, 50, 96, 123 pound or larger container. The amount of lubricant may be, for example, 0.8, 1.2, 1.6, 2.4, 3.2, 4, 8, or 10 pounds (8% lubricant). Bulk quantities may also be provided.
The amount of POE may be varied, for example, and may be about 5%, 6%, 7%, 7.5%, 8%, 9%, 10%, 12%, 12.5%, 15%, or the like. The precision of measurement may be, for example. ±0.1%, ±0.2%, ±0.25%, ±0.3%, ±0.5%, ±0.75%, ±1%, or ±2%. Preferably, the precision is within ±0.5%.
The container may be a DOT 3, 3A, 3AA, 3AL, 3B, 3BN, 3E, 4B, 4BA, 4B240ET, 4BW, 4E, 39, steel drum, for example: DOT-3AL1800; DOT 4D; DOT-3; DOT-39; DOT-3A; DOT-3A1000; DOT-3A1200; DOT-3A150; DOT-3A1800; DOT-3A2000; DOT-3A225; DOT-3A240; DOT-3A2400; DOT-3A300; DOT-3A400; DOT-3A480; DOT-3A480X; DOT-3AA; DOT-3AA1000; DOT-3AA1200; DOT-3AA150; DOT-3AA1800; DOT-3AA2000; DOT-3AA225; DOT-3AA240; DOT-3AA2400; DOT-3AA300; DOT-3AA400; DOT-3AA480; DOT-3AAX1800; DOT-3AAX2000; DOT-3AAX2200; DOT-3AAX2400; DOT-3AL; DOT-3AL1000; DOT-3AL150; DOT-3AL1800; DOT-3AL2000; DOT-3AL225; DOT-3AL240; DOT-3AL2400; DOT-3AL400; DOT-3AL480; DOT-3AX1800; DOT-3AX2000; DOT-3AX2200; DOT-3AX2400; DOT-3B; DOT-3B150; DOT-3B1800; DOT-3B225; DOT-3B240; DOT-3B300; DOT-3B400; DOT-3BN400; DOT-3BN480; DOT-3E1800; DOT-3HT; DOT-3HT2000; DOT-3T1800; DOT-3T2000; DOT-3T2200; DOT-3T2400; DOT-4A; DOT-4AA480; DOT-4B; DOT-4B150; DOT-4B150; DOT-4B225; DOT-4B240; DOT-4B240ET; DOT-4B300; DOT-4B400; DOT-4B480; DOT-4BA; DOT-4BA225; DOT-4BA240; DOT-4BA300; DOT-4BA400; DOT-4BW; DOT-4BW225; DOT-4BW240; DOT-4BW300; DOT-4BW400; DOT-4BW480; DOT-4DA; DOT-4DS; DOT-4E225; DOT-4E240; DOT-4L; DOT-AAX2400; and ICC-3E1800.
The preferred embodiment encompasses R-407C. However, the method is more generally directed to a retrofitting of systems employing a range of refrigerants that generally require mineral oil, alkane or alkylbenzene lubricants (CFC, PCC, HCC, HCFC, CFO, HCFO), with refrigerants that generally require polymeric or oxygenated lubricants, e.g., POE, PVE (HFC, PFO) (CFC=Chlorofluorocarbon, CFO=Chlorofluoroolefin, HCFC=Hydrochlorofluorocarbon, HCFO=Hydrochlorofluoroolefin, HFC=Hydrofluorocarbon, HFO=Hydrofluoroolefin, PCC=Perchlorocarbon). See Table 1, en.wikipedia.org/wiki/List_of_refrigerants.
It is therefore an object to provide a transportable container for charging a refrigerant system, having a charging port, containing a polyol ester (POE) lubricant and a compatible HFC refrigerant in a predetermined proportion. The proportion may be at least 2%, 3%, or 5% by weight and less than 25%, 20%, or 15% by weight, and preferably 8% by weight.
It is another object to provide a composition for retrofitting an R-22 refrigeration system, comprising POE and R-407C. The POE may be present at between 2-25%, 3-20%, 5-15%, or preferably 8% by weight, with the balance substantially R-407C.
It is a further object to provide a method for retrofitting a refrigeration system from R-22 refrigerant to R-407C refrigerant, comprising evacuating the R-22 refrigerant from the refrigeration system while maintaining at least 25% of the lubricant, wherein the lubricant is not POE, and adding a premixture of POE mixed in R-407C to charge the refrigeration system. The POE may be present at between 2-25%, 3-20%, 5-15%, or preferably 8% by weight, with the balance substantially R-407C.
It is a still further object to provide a retrofit kit for an R-22 refrigeration system, comprising a DOT-approved transport container for R-407C containing a mixture of R-407C and POE, and at least one replacement seal compatible with R-407C. The POE may be present at between 2-25%, 3-20%, 5-15%, or preferably 8% by weight, with the balance substantially R-407C.
It is a still further object to provide a method for retrofitting a hermetically sealed refrigeration system from an HCFC refrigerant compatible with a mineral oil or alkyl benzene lubricant to a HFC refrigerant compatible with polyol ester lubricant, comprising: providing a transport container containing the HFC refrigerant mixed with polyol ester lubricant; withdrawing the HCFC from within the refrigeration system through a charge-discharge port, leaving at least a portion of the mineral oil or alkyl benzene lubricant; and charging the refrigeration system from the transport container with the HFC mixed with the polyol ester lubricant. The polyol ester lubricant may be present at between 2-25%, 3-20%, 5-15%, or preferably 8% by weight, with the balance substantially HFC.
Another object is to provide a method for retrofitting a system from an HCFC refrigerant compatible with a mineral oil or alkyl benzene lubricant to an HFC refrigerant compatible with a polyol ester lubricant, comprising: evacuating the HCFC from the system, leaving at least a portion of the mineral oil or alkyl benzene lubricant; and charging the refrigeration system with an HFC refrigerant mixed with a polyol ester lubricant in a predetermined ratio of 5-15% by weight.
A kit is provided for retrofitting an HCFC refrigeration system having residual mineral oil lubricant, comprising: a transport container, containing an HFC refrigerant mixed polyol ester lubricant. A kit is also provided for retrofitting an R-22 refrigeration system having residual mineral oil lubricant, comprising: a U.S. Department of Transportation certified transport container; and R-407C mixed with polyol ester lubricant. The polyol ester lubricant may be present at between 2-25%, 3-20%, 5-15%, or preferably 8% by weight. The mineral oil or alkyl benzene lubricant may be a mineral oil lubricant.
The HCFC to be replaced may comprise R-22, R-401A, R-409A, R-401B, R-409B, R-402A, R-402B, R-403B, R-408A, R-502, and/or mixtures of HCFCs, for example as provided in Table 1.
The HFC may comprise R-134a, R-404A, R-407A, R-407C, R-407F, R-410A, R-417A, R-417B, R-422A, R-422B, R-422C, R-422D, R-424A, R-427A, R-428A, R-434A, R-438A, R-442A, and R-507A, or for example, other blends of difluoromethane (R-32), pentafluoroethane (R-125), and 1,1,1,2-tetrafluoroethane (R-134a). Other HFCs or HFC blends, or HFC/HC blends, for example as provided in Table 1, may also be employed. The HFC may be a zeotropic blend.
The refrigeration system after recharging may have a concentration of about 15-32% mixed lubricant, or a concentration of about 20-25% mixed lubricant, or a concentration of about 15-25% mixed lubricant, by weight.
The transport container may be U.S. Department of Transportation compliant, e.g., DOT-39.
The metrics recited herein are intended to be interpreted according to common understanding and usage among those skilled in the art of refrigerant manufacture, distribution, and refrigeration system maintenance.
As shown in the schematic representation in
A test was conducted of a residential air conditioning unit to determine the results of retrofitting an R-22 system with R-407C. In the test, the R-22 system, which was design and manufactured optimally for R-22, and used a mineral oil lubricant, was retrofitted with R-407C.
Instead of removing all of the mineral oil in the system, and replacing it with a defined amount of POE oil, which is required for R-407C, the R-22 was removed, and the residual mineral oil allowed to remain.
The evacuated system was recharged with a premixed quantity of R-407C with 8% by weight POE oil. Since R-407C is charged in the liquid phase, all of the oil, and most of the R-407C was transferred to the system from a transport container, e.g., DOT-39. The final POE concentration is estimated at 10-15% of the total oil in the system.
Prior to retrofitting, system was run for 13 hours over two days with the R-22 to collect the baseline data. The R-22 was then evacuated, and charged with R-407C to about 85% of the R-22 charge. The retrofitted refrigeration system with R-407C was then run for 91 hours.
The operating temperatures for R-22 (>86F and <86F) and R-407C (<86F) were not the same, so performance measurements are not directly comparable, but the results support a conclusion that the R-407C does not degrade system efficiency performance.
Therefore, despite the various unknowns, including the amount of mineral oil remaining in the system, migration characteristics of the mixed lubricants around the system, the impact of the various lubricant phases on compressor lubrication, the operation of the system with R-407C was improved over the R-22 implementation.
See: www.honeywell-refrigerants.com/india/?document=guide-to-retrofitting-ac-systems-from-r-22-to-r-422d-or-r-407c&download=1;
www.honeywell.com/sites/servlet/com.merx.npoint.servlets.DocumentServlet?docid=DB0284B 88-942E-BOAS-4028-CAFB85BB40AB, which are expressly incorporated herein by reference.
See:
www2.dupont.com/Refrigerants/en_US/assets/downloads/h70004_Suva407C_retrofit_guide.pdf, which is expressly incorporated herein by reference.
See: opi.emersonclimate.com/CP1D/GRAPHICS/Types/AEB/95-14.pdf, which is expressly incorporated herein by reference.
See: www.refrigerants.com/pdf/Nat-R407Broch.pdf, which is expressly incorporated herein by reference.
See: neilorme.com/Tecumseh%20Guidelines%20R407c.shtml, which is expressly incorporated herein by reference.
See: www.bristolcompressors.com/files/1313/5464/2815/application_bulletin_124.pdf, which is expressly incorporated herein by reference.
See: americas.forane.com/export/sites/forane-americas/.content/medias/downloads/literature/forane-technical-digest.pdf, which is expressly incorporated herein by reference.
Although the present system and/or approach has been described with respect to at least one illustrative example, many variations and modifications will become apparent to those skilled in the art upon reading the specification. It is therefore the intention that the appended claims be interpreted as broadly as possible in view of the related art to include all such variations and modifications.
The present application is a Continuation of U.S. patent application Ser. No. 15/255,826, filed Sep. 2, 2016, now U.S. Pat. No. 10,094,603, issued Oct. 9, 2018, which is a Continuation of U.S. patent application Ser. No. 14/877,609, filed Oct. 7, 2015, now U.S. Pat. No. 9,435,575, issued Sep. 6, 2016, which is a Continuation of Ser. No. 14/744,776, filed Jun. 19, 2015, now pending, which each claim benefit of priority from U.S. Provisional Patent Application No. 62/032,129, filed Aug. 1, 2014 and from U.S. Provisional Patent Application No. 62/017,530, filed Jun. 26, 2014, the entirety of which are expressly incorporated herein by reference. This application is related to PCT/US15/37689, filed Jun. 25, 2015.
| Number | Date | Country | |
|---|---|---|---|
| 62032129 | Aug 2014 | US | |
| 62017530 | Jun 2014 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15255826 | Sep 2016 | US |
| Child | 16153642 | US | |
| Parent | 14877609 | Oct 2015 | US |
| Child | 15255826 | US | |
| Parent | 14744776 | Jun 2015 | US |
| Child | 14877609 | US |
