Patent Application
20140190978
The present invention relates to devices, such as cold boxes, refrigerators, freezers and the like which are insulated and long-lasting.
Typical refrigerator appliance cabinets consist of an outer metal cabinet, an inner plastic liner and an insulating foam core, typically polyurethane foam, in the space between the metal cabinet and the liner. The foam insulation contains cells that are filed with the blowing agent that was used to form the polyurethane foam. In the past, completely halogenated methane, such as fluorotrichloromethane (CFC-11), was most commonly used as the blowing agent. More recently, more environmentally acceptable substitutes, such as HCFCs, including 2-fluoro-2,2-dichloroethane (HCFC-141b) and 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123), and HFCs, including HFC-245fa, have been used.
In general, it is not uncommon for some portion of the blowing agent used to form polyurethane foams to escape over time from the cells that contain them. As a result, the design of such devices must take into account the interrelationship that the blowing agent will have with the liner of the refrigerator, freezer and the like. For this reason, many of the blowing agents which have been used to form polyurethane foams can such as Freon (CFC-11) and Freon substitutes, such as 2-fluoro-2,2 dichloroethane and 2,2-dichloro-1,1,1-trifluoroethane, (HCFC 141b and HCFC 123, respectively), have been studied for their impact on liners and have been found to potentially cause liner blistering, catastrophic cracks, tiny cracks (crazing) and loss of impact properties (embrittlement), as well as stress whitening and/or dissolution. More recently used blowing agents such as HCFC 141b and HCFC 123 appear to have also exhibited a relatively high level of chemically aggressiveness toward many liner materials. The liner material can be formed from a large variety of materials. For example, U.S. Pat. No. 6,589,646, which is incorporated herein by reference, discloses a composite liner and discloses that the material from which the liner can be formed includes glass-clear polystyrene (GPPS), impact-modified polystyrene (HIPS), styrene 6, copolymers, such as styrene-butadiene block copolymers, ASA, SAN, ABS, polyolefins, such as polyethylene or polypropylene, acrylates and methacrylates, such as PMMA, polycarbonates (PCs), polyvinyl chloride (PVC), polyethylene terephthalate (PET) and mixtures of these.
To combat these problems, several solutions have been proposed. For example, WO 2010/103007 has proposed to use specialized rubber modified monovinylaromatic polymer compositions based on two of the most commonly used materials to form refrigerator liners, namely, ABS (acrylonitrile-butadiene-styrene) or HIPS (high impact polystyrene). Others have proposed forming the liner from multiple layers of different materials, see for example, U.S. Pat. No. 5,324,589. Still others have proposed to use certain additives to improve the resistance of the material to the blowing agents which have heretofore been used. See US 2011/016629 and WO2001148043 (PCT/US00/34362). Each of the patent documents referred to herein are incorporated herein by reference.
The present invention provides devices, such as cold boxes, refrigerators, freezers and the like which are insulated with foam and long-lasting. Preferably the device comprises: a cabinet or cabinet-like structure having an inner compartment for containing food, beverages and the like in a relatively cold condition; a liner which forms it at least a portion of the wall the inner compartment; and an insulating foam immediately adjacent to the liner or otherwise sufficiently adjacent to the liner such that the liner will be exposed to blowing agent degassing from the foam. Applicants have found that unexpected but highly desirable advantages can be achieved according to the preferred embodiments of the present invention wherein the foam is a closed cell foam, and more preferably a closed cell polyurethane foam, in which the blowing agent comprises in substantial part, and more preferably at least about 50% by weight, and even more preferably at least 75% by weight, of 1-chloro-3,3,3-trifluoropropene (1233zd). Applicants have found that foams blown with HFCO-1233zd, and preferably transHFCO-1233zd, provide a unique combination of highly desirable and beneficial blowing agent properties, such as low thermal conductivity, while at the same time being exceptionally benign with respect to the materials from which liners are made. As a result of this advantage, applicants have found that devices according to the present invention can be formed at relatively low cost but yet maintain high levels of reliability by forming the liners in relatively thin thicknesses. According to certain highly preferred embodiments, the liner is formed in part, and preferably in large part, from High Impact Polystyrene (HIPS), more preferably foodgrade HIPS, and even more preferably foodgrade HIPS, specially tailored for refrigeration products.
In addition, applicants have found that preferred embodiments of the present invention comprise a liner material, and in particular a preferred HIPS-based liner material, having an average thickness of not greater than about 5 mm, more preferably not greater than about 4 mm, and even more preferably in certain embodiments not greater than 3 mm. In certain highly preferred embodiments, the liner has an average thickness of not greater than about 2 mm, more preferably not greater than about 1.5 mm, more preferably not greater than about 1 mm, and even more preferably in certain embodiments not greater than 0.75 mm. In certain preferred embodiments, the liner has an average thickness of about 0.5 mm, which is generally considered to be the minimum thickness permitted according to certain commercial standards. While it is certainly possible to form liners having thicknesses greater than those indicated herein, and to thereby improve the reliability and longevity of the refrigerant cabinet by minimizing the impact of the chemical aggressiveness of the blowing agent, such a solution has significant and undesirable downsides in terms of the cost of the product as well as potentially creating difficulties in forming the product into the desired shape of the inner wall of the cabinet, which sometimes can have intricate corners and indentations. Accordingly, the present invention has the highly desirable yet unexpected advantage of providing a refrigerator cabinet which is at once low-cost, economical, thermally efficient, reliable and long-lasting.
Thus, according to certain preferred embodiments highly cost effective liners are used in the refrigerator which is insulated with a foam containing a highly thermally efficient halogenated olefin blowing agent, and in, particular HFCO-1233zd, while maintaining durability of the liner and avoidance of stress cracking or other deleterious effects.
Accordingly, an object of one embodiment of the inventions is the provision of an thermal insulating device for keeping foodstuffs cool, cold or frozen in which the foam is a closed-cell foam having a halogenated olefin contained in at least a portion of the cells, and more preferably 1-chloro-3,3,3-trifluoropropene (1233zd), and a liner comprised of HIPS material, and even more preferably a liner formed from foodgrade HIPS and having a thickness of not greater than 2.0 mm.
It is an object of certain embodiments of the present invention to provide a refrigeration appliance liner to be fabricated from a thermoformable, plastic sheet material which retains a high level of toughness (impact properties) and strength (tensile properties), even at low temperatures (at 5° F. or less).
In one aspect, the present invention relates to a device for containing item(s) or fluid(s) and maintaining for at least an extended period of time (eg, at least 1 hour) a temperature inside said container either below or above ambient temperature. Preferably the devices of the present invention include (a) a container or compartment, preferably having an opening that is either open or closable by a door, hatch, sliding cover or the like, for holding an item(s) or fluid(s), and preferably food and/or beverage items, to be maintained in a cooled or heated condition, and most preferably in a cooled condition, relative to the ambient temperature, said container having an inner liner which corresponds at least in part to the interior shape of the compartment or container; and (b) thermal insulation comprising a polymeric material having closed cells therein wherein said cells are formed from and/or contain blowing agent comprising, and preferably comprising in major proportion by weight, a haloalkene according to Formula IA:
In certain preferred embodiments, the device further includes a heat transfer system for adding and/or removing heat from the compartment or container by use of a is heat transfer fluid. In certain of said preferred embodiments, the heat transfer fluid comprises a haloalkene Formula IB:
While not limited thereto, the container or compartment for holding an item(s) or fluid(s) of the present invention include refrigerators, freezers, vending machines, reach-in coolers, transport refrigeration units, and water heater heat pumps.
In certain embodiments, the haloalkene according to Formula IA is selected from the group consisting of 1,1,1,4,4,4-hexafluoro-2-butene (1336), 1-chloro-3,3,3-trifluoropropene (1233zd), 1,3,3,3-tetrafluoropropene (1234ze), and combinations thereof. In further aspects, 1,1,1,4,4,4-hexafluoro-2-butene (1336) is provided as the cis isomer; 1-chloro-3,3,3-trifluoropropene (1233zd) is provided as the trans isomer; and/or 1,3,3,3-tetrafluoropropene (1234ze) is provided as the trans isomer. Applicants have found, however, that highly advantageous but unexpected results can be achieved, particularly with respect to thermal insulating quality and the durability and longevity of the device, by selecting from among these compounds monochloro, trifluoropropenes for use as a component of the blowing agent, and preferably as a component which comprises at least about 50% by weight, and even more preferably at least about 75 weight percent of the blowing agent. Even more preferably, the monochloro, trifluoropropene comprises, in preferred embodiments comprises at east about 75% by weight, and even more preferably in certain embodiments consists essentially of, trans 1-chloro-3,3,3-trifluoropropene (transHFCO-1233zd)).
Additional embodiments and advantages to the invention will be readily apparent to one of skill in the art based on the disclosure provided herein.
Applicants have come to appreciate that the judicious selection of the materials to be used for the heat transfer fluid and as the blowing agent in container-type heat transfer systems, particularly in relatively small systems such as domestic refrigerators and freezers, vending machines, reach-in coolers, transport refrigeration units, water heater heat pumps and the like, can provide such systems with highly advantageous energy performance while at the same time providing such systems that have extraordinarily low environmental impact and are durable and long-lasting.
One aspect of the present invention provides systems, devices and methods for containing item(s) or fluid(s) at a temperature either below or above the ambient temperature, preferably for an extended period of time (such as at least several hours or days). Such systems, devices, and methods include (a) a container or compartment for holding an item(s) or fluid(s) to be maintained in a cooled or heated condition relative to the ambient; (b) thermal insulation disposed with respect to said container or compartment so as to inhibit the flow of heat into and/or out of the compartment, said insulation comprising a polymeric material having closed cells therein wherein said cells are formed from and/or contain a haloalkene according to Formula IA:
As used herein the terms container and compartment are used in the broad sense and are not limited to containers that fully enclose or surround the items or fluid being contained. Thus, for example, containers that have relatively permanent openings, such as would be the case in reach-in coolers and refrigerators, are encompassed within the meaning of this term.
In certain preferred embodiments the compound of Formula IA comprises, and preferably comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of one or more compounds selected from 1,1,1,4,4,4-hexafluoro-2-butene (1336), 1-chloro-3,3,3-trifluoropropene (1233zd), and 1,3,3,3-tetrafluoropropene (1234ze). In certain highly preferred aspects of such embodiments, the 1-chloro-3,3,3-trifluoropropene (1233zd) is trans-1-chloro-3,3,3-trifluoropropene (1233zd(E)), the 1,3,3,3-tetrafluoropropene (1234ze) is trans-1,3,3,3-tetrafluoropropene (1234ze(E)), and the 1,1,1,4,4,4-hexafluoro-2-butene (1336) is cis-1,1,1,4,4,4-hexafluoro-2-butene (1336(Z)).
In certain preferred embodiments, including particularly and preferably the embodiments in which the compound of Formula 1A comprises, and preferably comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of one or more compounds selected from 1,1,1,4,4,4-hexafluoro-2-butene (1336), 1-chloro-3,3,3-trifluoropropene (1233zd), and 1,3,3,3-tetrafluoropropene (1234ze), and the compound of Formula IB comprises, and preferably comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of one or more compounds selected from 1-chloro-3,3,3-trifluoropropene (1233zd) (preferably trans-1233zd), 2,3,3,3-tetrafluoropropene (1234yf) and 1,3,3,3-tetrafluoropropene (1234ze) (preferably trans-1234ze). In certain of such embodiments, the 1-chloro-3,3,3-trifluoropropene (1233zd) is trans1-chloro-3,3,3-trifluoropropene (1233zd(E)), the 1,3,3,3-tetrafluoropropene (1234ze) is trans1,3,3,3-tetrafluoropropene (1234ze(E)), and the 1,1,1,4,4,4-hexafluoro-2-butene (1336) is cis 1,1,1,4,4,4-hexafluoro-2-butene (1336(Z)).
In certain preferred embodiments, the compound of Formula 1A comprises, and preferably comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of one or more compounds selected from 1,1,1,4,4,4-hexafluoro-2-butene (1336), and 1-chloro-3,3,3-trifluoropropene (1233zd), and the compound of Formula IB comprises, and preferably comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of one or more compounds selected from 2,3,3,3-tetrafluoropropene (1234yf) and 1,3,3,3-tetrafluoropropene (1234ze) (preferably trans-1234ze).
In certain preferred embodiments, the compound of Formula 1A comprises, and preferably comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of one or more compounds selected from 1,1,1,4,4,4-hexafluoro-2-butene (1336) and 1-chloro-3,3,3-trifluoropropene (1233zd), and the compound of Formula IB comprises, and preferably comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of 1,3,3,3-tetrafluoropropene (1234ze), and even more preferably trans-1234ze.
In certain preferred embodiments, the compound of Formula 1A comprises, and preferably comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of 1,1,1,4,4,4-hexafluoro-2-butene (1336) (preferably cis-1336) and the compound of Formula IB comprises, and preferably comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of 1,3,3,3-tetrafluoropropene (1234ze), and even more preferably trans-1234ze.
In certain preferred embodiments, the compound of Formula 1A comprises, and preferably comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of one or more compounds selected from 1,1,1,4,4,4-hexafluoro-2-butene (1336) (preferably cis-1336) and the compound of Formula IB comprises, and preferably comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of and 1-chloro-3,3,3-trifluoropropene (1233zd) (preferably trans-1233zd).
In certain preferred embodiments, the compound of Formula 1A comprises, and preferably comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of one or more compounds selected from 1-chloro-3,3,3-trifluoropropene (1233zd) (preferably trans-1233zd) and the compound of Formula IB comprises, and preferably comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of and 1,3,3,3-tetrafluoropropene (1234ze), and even more preferably trans-1234ze.
In certain preferred embodiments, the compound of Formula 1A comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of 1-chloro-3,3,3-trifluoropropene (1233zd) (preferably transHFCO-1233zd), and the compound of Formula IB comprises, and preferably comprises at least about 50% by weight, and more preferably comprises at least about 70% by weight, and even more preferably consists essentially of 2,3,3,3-tetrafluoropropene (1234yf).
For the purposes of illustration, reference is now made to
Applicants have found that in highly preferred embodiments, including and preferably those in which the blowing agent is transHFCO-1233zd and the liner comprises HIPS, the liner of the present invention has a thickness of not greater than about 10 mm, more preferably not greater than about 5 mm, more preferably not greater than about 4 mm, and even more preferably in certain embodiments not greater than 3 mm, or the other preferred thicknesses described herein. As mentioned herein, while it is contemplated that the preferred liner may be formed at least in part from material selected from glass-clear polystyrene (GPPS), impact-modified polystyrene (HIPS), styrene 6, copolymers, such as styrene-butadiene block copolymers, ASA, SAN, ABS, polyolefins, such as polyethylene or polypropylene, acrylates and methacrylates, such as PMMA, polycarbonates (PCs), polyvinyl chloride (PVC), polyethylene terephthalate (PET) and mixtures, combinations, laminates and layers of these, in certain highly preferred embodiments the liner is formed from food grade High impact Polystyrene (HIPS), and even more preferably such material such material which is specially tailored for refrigeration products. One example of such a food grade produce is the HIPS sold under the trade designation “Polystyrol 2710” by BASF and “Edistir RR740E” by Polimeri Europa. In preferred embodiments the liner is formed from materials having a Melt Flow Rate index of 4 g/10 min. Preferably the HIPS is considered by those skilled in the art to be Extrusion and Thermoforming grade.
Applicants have come to appreciate that the present systems and devices, including household refrigerators and the like, have a number of attributes for refrigerants and blowing agents that can, if the right combination of materials can be identified, potentially produce excellent and unexpected advantage over previously used materials. These attributes include:
good environmental properties, with preferred materials exhibiting zero ozone depletion potential (ODP), and low global warming potential (GWP);
low order of toxicity;
high performance, specifically with respect to efficiency and capacity for refrigerant gases;
thermal performance for blowing agents;
non-flammable, or low flammability risk characteristics;
relatively low cost;
durability, including particularly resistance to liner degradation.
Illustrated in Table 1, certain preferred systems utilize transHFCO-1233zd (which is sometimes also referred to herein as “1233ZD”) as a blowing agent which exhibits physical properties similar to 245fa. It would be noted that the global warming potential (GWP) of 1233ZD is more than two orders of magnitude lower than that of currently utilized HFCs, and more than one order of magnitude lower than the present language in the EU F-Gas Regulation, and within the rationale of the EU WEEE Directive pertaining to household refrigerator/freezers, with a GWP less than 15.
Preferred forms of the present invention utilize the preferred blowing agents in the various polyurethane (PUR) applications, including appliance foams. PUR foam properties of lambda (k-factor), compressive strength, and dimensional stability derived from characterization of hand mix foams or foam panels prepared by means of a high pressure foam machine have evidenced efficacy of the present systems in comparison to systems using 245fa foams. Furthermore, applicants have come to appreciate that until a commercial refrigerator product has been manufactured under industrial conditions, and assessed for energy performance and ancillary performance in other aspects, for example, liner compatibility, adhesion to liner and metal cabinet and doors, freeze stability, and other quality aspects, the full value and performance of the system will not be fully understood.
The following non-limiting examples serve to illustrate the invention.
A scale trial, utilizing 1233zd blowing agent, in a commercially available polyurethane system, in a commercially in available 710 liter (25 ft3) household refrigerator freezer with a food grade and Extrusion and Thermoforming grade HIPS liner having a thickness of 10 mm was undertaken. These thirty two refrigerator cabinets, with associated door sets, were foamed to investigate:
The baseline comparison for these low climate change impact refrigerators is the same commercial household refrigerator/freezer product utilizing 245fa blowing agent and 134a refrigerant. It should be noted that:
(1) polyurethane formulation: 1233ZD was equal molar substituted for 245fa. (2) No other modifications were made to the PUR system. (3) 134a sealed side loop: No modifications were made. (4) 1234yf sealed loop: minor modifications were made to the capillary tube diameter and length.
A. Polyurethane Foam Formulation
The polyurethane formulation was a commercially available, and currently utilized, 245fa appliance formulation, supplied by a major PUR systems house, with 1233ZD equal molar substituted for 245fa. The foaming process conditions, including machine temperatures and pressure were identical to the conditions for the 245fa baseline cabinets and doors. The polyurethane formulation and process parameters are illustrated in Table 2. Those familiar with refrigerator factories and scale will observe the scale of foam through put is consistent to scale found in North American world-scale factories, and is consistent with the size refrigerators manufactured in this test.
1233ZD processed very similarly to 245fa, and no modifications were made to the PUR foaming equipment or process, effectively, conventional existing PUR equipment, existing in the factory, accommodated 1233ZD.
Additionally, characterization of the 1233ZD versus 245fa foamed cabinets and doors suggest no differences:
Minimum fill weights were nearly identical—within one quarter of one percent (0.25%)
Over pack conditions (lambda/k-factor assessment) were identical at 10%
Density (10% over pack)
Cabinets: 34.9 kg/m3 (2.18 lbs/ft3)
Doors: 34.1 kg/m3 (2.13 lbs/ft3)
B. Lambda (k-Factor) Performance
Foam samples from various locations in the fresh food compartment and freezer compartment were assessed for lambda (k-factor) performance. PUR foam thermal conductivity can, and will vary throughout the refrigerator/freezer due to foam flow characteristics and associated density variation.
C. Compressive Strength Performance
Polyurethane foam in refrigerator freezers provides, firstly insulation performance, however, also provide structural strength for the appliance. Appliance PUR foams typically exhibit compressive strength greater than 100 kPa (15 psi) at 10% deflection. Samples were taken from varying locations in the fresh food and freezer compartments to assess compressive strength, and are shown in Table 4.
D. Dimensional Stability Performance
Dimensional stability of the PUR foam is important as a quality measure. Changes in foam dimensions (volume) when subjected to temperature variation impacts the external metal case, the internal liner, and should the volume change due to temperature difference be extreme, impacts the adhesion characteristics to the metal case and liner. Refrigerator/freezer appliances, particularly in the freezer section, are subjected to wide temperature difference between the compartment interior and ambient room temperature in the home. PUR foam samples from various locations in the fresh food and freezer compartments were assessed for volume change at temperature extremes over 1 day and 7 day interval, and exhibited less than 1% average volume change, and the results are shown in Table 5.
E. Plastic Liner (HIPS) Compatibility
Four refrigerator/freezers with doors were thermal cycled in a cold room chamber for five consecutive days as follows:
F. DOE Energy Assessment
The U.S. Department of Energy (DOE) established, in July 2001, a standard (DOE Standard) for the maximum energy consumption of household refrigerators. In simplified terms (reader is referred to Federal Register 10CFR 430 for more detail) the standard allows a maximum energy usage by refrigerator internal volume, adjusted for various accessories, such as though the door water and ice dispensers. In addition, the DOE provides for the Energy Star label for refrigerators, refrigerator/freezers, and freezers, which, as of March 2008 is DOE Standard minus 20% energy consumption. Further, presently the DOE is in the process of establishing, for promulgation in 2014, a revised and presumably more stringent energy standard for household refrigerators, refrigerator/freezers, and freezers.
All the lambda (k-factor) assessments aside, meeting the DOE Energy Standard determines whether a refrigerator meets the energy requirements to be sold in the U.S. The refrigerator/freezers manufactured in this trial not only met the DOE Standard, not only met the DOE Energy Star label, but exceeded the Energy Star label requirements by an average of 7.6%, effectively DOE Standard minus 27.6%. Five refrigerator/freezers utilizing 1233ZD blowing agent/134a refrigerant were assessed by the DOE Energy Star test method. Five refrigerators/freezers utilizing 245fa blowing agent/134a refrigerant was the baseline comparison, that on average, exceeded DOE Energy Star label by 6.0%. Effectively, the 1233ZD refrigerator/freezers showed an energy reduction of 1.6% from the baseline, with the results (normalized) illustrated in
G. Discussion—Household Refrigerator Energy Performance Utilizing 1233ZD Blowing Agent
Commercially manufactured 710 liter (25 ft3) household refrigerator/freezers with 1233ZD, equal molar substituted for 245fa, in a commercially available 245fa appliance PUR formulation, exceeded the DOE Energy Star performance criteria, and, exceeded the 245fa baseline performance.
1233ZD, in all ancillary assessment related to a household refrigerator/freezer, met or exceeded all requirements, that is liner compatibility, compressive strength, dimensional stability, and freeze stability.
Example 1A is repeated except that the liner used has a thickness of 5 mm. All results are equivalent, including liner compatibility after the five-day thermal cycling program.
Example 1A is repeated except that the liner used has a thickness of 4 mm. All results are equivalent, including liner compatibility after the five-day thermal cycling program.
Example 1A is repeated except that the liner used has a thickness of 3 mm. All results are equivalent, including liner compatibility after the five-day thermal cycling program.
Example 1A is repeated except that the liner used has a thickness of 2 mm. All results are equivalent, including liner compatibility after the five-day thermal cycling program.
Example 1A is repeated except that the liner used has a thickness of 1 mm. All results are equivalent, including liner compatibility after the five-day thermal cycling program.
Example 1A is repeated except that the liner used has a thickness of 0.5 mm. All results are equivalent, including liner compatibility after the five-day thermal cycling program.
1234yf was the low GWP refrigerant gas chosen for this work due the very close proximity of boiling point and pressure-temperature curve—compared to 134a. This is shown on
Further to characterization of refrigerant working fluids suitability is thermal stability with compressor lubricants under extreme conditions of temperature and moisture (water) contamination. 1234yf and a typical appliance compressor oil—ISO 10 (Proeco 10S) were evaluated utilizing ASHRAE Standard 97 test method. Under extreme conditions of high moisture (1000 ppm); high temperatures (200° C.); and two week duration, visual examination of the sealed tubes (containing 1234yf/lubricant) exhibited no change in the appearance. Analysis of the oil yielded very low acidity values (TAN values ranging from 0.07 to 0.44); and, GC analysis and molecular weight analysis of the refrigerants indicated no change in the purity. Thus concluding that 1234yf is stable, used in conjunction with typical lubricants for these applications.
Simulations utilizing a semi-theoretical model: Cycle-11 UA (Domanski and McLinden 1992) confirmed 1234yf as a near drop-in replacement to 134a in this refrigerator/freezer application. Table 6 illustrates the simulation comparison of 1234yf to 134a.
A. Expansion Devices
Mass flow differences shown in Table 6, suggest modifications in capillary tubes. An analysis of capillary tubes was performed utilizing ASHRAE RP 948 model, which is based on Buckinghan Pi dimensionless number. This model accounts for both thermodynamic and transport properties of the refrigerant.
Simulations were performed for design conditions of −23° C. evaporation temperature, 0° C. superheat at the evaporator outlet, and 32.2° C. compressor inlet temperature. The condensing temperature was 55° C. with 5° C. sub-cooling at the condenser outlet. Previous system simulations determined the ‘target’ mass flow, allowing 1234yf to equal 134a capacity. Table 7 illustrates simulations for the drop-in assessment, and for modified capillary tube diameter assessment, while maintaining the same characteristic overall length. The 134a baseline calculations are a capillary tube: 0.66 mm diameter; 2.7 m length; of which 1.622 m is in contact with the suction line.
Five 1233ZD PUR foamed (710 liter/25 ft3) refrigerator/freezers were built up for energy performance utilizing 1234yf replacement for 134a. Minor modifications to the capillary tube diameter and length were made prior to foaming the refrigerator/freezer with 1233ZD PUR foam. These low GWP refrigerators are in assessment at this writing.
B. Discussion: Household Refrigerator Energy Performance utilizing 1234yf 1234yf, as a potential 134a replacement, exhibits significant promise as equal in energy efficiency performance, low GWP refrigerant fluid, with minor (sic low manufacturing cost) modifications in a NA style household refrigerator/freezer. Further, 1234yf utilization significantly mitigates the risk associated with utilization of highly flammable hydrocarbon refrigerants, such as R-600a.
1233ZD is a non-flammable liquid by ASTM E-681 test methods, and exhibits no flashpoint or vapor flame limits. In transportation, storage, and in factory use as a blowing agent, 1233ZD has no limitations on hazards classification.
1234yf is a flammable gas. However, the flammability characterization, and associated risk in use, of 1234yf is significantly different from highly flammable hydrocarbon refrigerants, for example R-600a (isobutane). The significance centers in: the minimum ignition energy (very high for 1234yf/very low for R-600a); the heat of combustion (low for 1234yf/high for R-600a); and burning velocity, or flame speed (very slow for 1234yf/very high for R-600a). ASHRAE characterization of flammability: 134a=A1; R-600a=A3; while 1234yf=A2L (A2 category of flammability, however, very low in that category). The significant differences in flammability measures between 1234yf and R-600a are shown in Table 9.
In preferred embodiments, the present invention a North American design platform refrigerator [eg., 710 liter (25 ft3)], for a highly energy efficient household refrigerator/freezer utilizing ultra low global warming potential (GWP less than 15) materials, in the manner of blowing agent for the polyurethane foam insulation and refrigerant working fluid inclusive. Unlike hydrocarbon blowing agent and refrigerant gases, 1233ZD and 1234yf achieve comparable energy performance to existing HFC materials without significant design or hardware modifications.
The heat transfer and blowing agent compositions used in the present systems and methods may include other components for the purpose of enhancing or providing certain functionality to the composition, or in some cases to reduce the cost of the composition. For example, the present compositions may include co-refrigerants, lubricants, stabilizers, metal passivators, corrosion inhibitors, flammability suppressants, and other compounds and/or components, and the presence of all such compounds and components is within the broad scope of the invention.
In certain preferred embodiments, the refrigerant compositions according to the present invention, especially those used in vapor compression systems, include a lubricant, generally in amounts of from about 30 to about 50 percent by weight of the composition, and in some case potentially in amount greater than about 50 percent and other cases in amounts as low as about 5 percent. Furthermore, the present compositions may also include a compatibilizer, such as propane, for the purpose of aiding compatibility and/or solubility of the lubricant. Such compatibilizers, including propane, butanes and pentanes, are preferably present in amounts of from about 0.5 to about 5 percent by weight of the composition. Combinations of surfactants and solubilizing agents may also be added to the present compositions to aid oil solubility, as disclosed by U.S. Pat. No. 6,516,837, the disclosure of which is incorporated by reference. Commonly used refrigeration lubricants such as Polyol Esters (POEs) and Poly Alkylene Glycols (PAGs), PAG oils, silicone oil, mineral oil, alkyl benzenes (ABs) and poly(alpha-olefin) (PAO) that are used in refrigeration machinery with hydrofluorocarbon (HFC) refrigerants may be used with the refrigerant compositions of the present invention. Commercially available mineral oils include Witco LP 250 (registered trademark) from Witco, Zerol 300 (registered trademark) from Shrieve Chemical, Sunisco 3GS from Witco, and Calumet R015 from Calumet. Commercially available alkyl benzene lubricants include Zerol 150 (registered trademark). Commercially available esters include neopentyl glycol dipelargonate, which is available as Emery 2917 (registered trademark) and Hatcol 2370 (registered trademark). Other useful esters include phosphate esters, dibasic acid esters, and fluoroesters. In some cases, hydrocarbon based oils are have sufficient solubility with the refrigerant that is comprised of an iodocarbon, the combination of the iodocarbon and the hydrocarbon oil might more stable than other types of lubricant. Such combination may therefore be advantageous. Preferred lubricants include polyalkylene glycols and esters. Polyalkylene glycols are highly preferred in certain embodiments because they are currently in use in particular applications such as mobile air-conditioning. Of course, different mixtures of different types of lubricants may be used.
This application claims the priority benefit of U.S. Provisional Patent Application Ser. No. 61/788,293, filed Mar. 15, 2013, the contents of which are incorporated by reference herein in its entirety. This application is also a continuation-in-part of U.S. patent application Ser. No. 13/191,141 filed on Jul. 26, 2011 (now pending), which is based on and claims the priority benefit of U.S. Provisional Patent Application Ser. No. 61/368,249 filed Jul. 27, 2010, the contents of each of which are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61788293 | Mar 2013 | US | |
| 61368249 | Jul 2010 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13191141 | Jul 2011 | US |
| Child | 14209406 | US |
