Method for supplying pressurized refrigerant and pressurized refrigerant tank

Abstract

A method for filling tank 20 includes the steps of filling tank 20 with a predetermined amount of liquid refrigerant under pressure and supplying an inert gas to tank 20, wherein after the filling and supplying steps, the total pressure of the contents in tank 20 at ambient temperature is at least 95% of the equilibrium vapor pressure of liquid R-134a at ambient temperature. The total pressure of the contents in tank 20 can be in the range of 517.1 kPa to 792.9 kPa at a temperature of 21.1°C. The inert gas can be nitrogen, and the liquid refrigerant can be R-1234ze(E). The disclosed method can enable the use of a low environmental impact refrigerant as a substitute for an environmental impact refrigerant in relation to devices such as laser skin treatment devices 10 that were originally designed to use an environmental impact refrigerant.

Description

Technical Field

[0003] ,

[0001] [Cross - Reference to Related Applications] This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 63 / 462,792, filed on April 28, 2023, the disclosure of which is incorporated herein by reference in its entirety.

Background Art

[0002] Refrigerants have been used in many applications for many years. However, over time, environmental concerns have arisen regarding the environmental impact of using certain types of refrigerants, leading to restrictions on refrigerants with harmful side effects. For example, early refrigerants were chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs), which were found to cause significant damage to the ozone layer (i.e., they had high ozone depletion potential (ODP) levels), and thus such refrigerants began to be phased out in the mid - 1980s in conjunction with the signing of the Montreal Protocol. Instead of CFCs and HCFCs, hydrofluorocarbons (HFCs) were adopted because HFCs have a zero ODP and thus do not harm the ozone layer. However, HFCs are greenhouse gases with a high global warming potential (GWP). Thus, HFCs are now also considered undesirable. More recently, there has been a movement towards using low - environmental - impact refrigerants with lower GWP values. Government regulations have been adopted to limit the amount of refrigerants with high GWP that can be imported or exported. For example, the European Union and other jurisdictions have introduced regulations to limit the amount of refrigerants with a GWP value of 150 or more.

[0003] A newer class of "fourth-generation" refrigerants are hydrofluoroolefins (HFOs) with low GWP values. An early HFO was R-1234yf, which was jointly developed by DuPont and Honeywell and is marketed under the names Opteon YF (Chemours / DuPont) and Solstice YF (Honeywell). R-1234yf has a GWP value of 4.

[0004] One application of refrigerants is in laser-based tissue treatment devices. For example, non-invasive laser treatment devices have been developed in which high-intensity electromagnetic energy is delivered near or just below the surface of the skin, for example, to destroy tattoo ink in tattoo removal procedures or to damage hair follicles in hair removal procedures. However, the delivery of such high-intensity energy can cause thermal damage (burns) to the skin and the associated pain. One way to reduce the risk of burns during laser treatment procedures is to spray a refrigerant (also known as a chilling agent) onto the surface of the skin in the area to be treated. This technique cools the skin in the treatment area and thus reduces pain during the procedure. The refrigerant sprayed by such treatment devices is often supplied from a tank, such as a compressed gas cylinder, that is detachably connected to the laser treatment machine. The detachable tank can be easily replaced when the refrigerant level becomes low. The refrigerant is typically in liquid form, filled into a tank, and pressurized. During the laser treatment process, a pressurized coolant is discharged onto the patient's skin and rapidly evaporates, resulting in vapor that cools the skin to a temperature substantially lower than ambient room temperature.

[0005] A common refrigerant used in many laser treatment devices is R-134a (preferred IUPAC name: 1,1,1,2-tetrafluoroethane). R-134a has been beneficial for use in the field of laser treatment because it is classified as a Class A1 refrigerant in American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 34 and similarly in International Organization for Standardization (ISO) Standard 817, meaning it is non-toxic ("A" designation) and non-flammable ("1" designation), both of which are important considerations when the refrigerant is applied directly to human skin and near laser energy. However, R-134a is an HFC with a high GWP value of 1430. Therefore, R-134a has recently become subject to strict regulations and usage restrictions.

[0006] In relation to laser tissue treatment equipment, less environmentally hazardous alternative refrigerants have been considered for use in place of R-134a. For example, U.S. Patent No. 8,287,579 to Nimitz (hereinafter, "Nimitz"), the contents of which are incorporated herein by reference, discloses several possible refrigerants that may be used in that context. However, further improvements are desirable, particularly in achieving a solution that is as close as possible to a "drop-in" alternative, in which a pressurized tank containing the desired refrigerant can be easily connected to the laser treatment machine originally designed for use with different refrigerants. [Overview of the Initiative]

[0007] Some aspects of the present invention provide a method for filling a gas tank with a liquid refrigerant. One method preferably includes the steps of filling the tank with liquid refrigerant under pressure to a first filling state, and then supplying the tank with an inert gas to a second filling state. The order of the steps can be reversed, so that the inert gas is introduced into the tank before the liquid refrigerant. In the first filling state, the tank preferably contains liquid refrigerant below a predetermined limit, so that the contents inside are at a first pressure at ambient temperature. In the second filling state, the contents inside the tank preferably are at a second pressure, which is higher than the first pressure, when at the same ambient temperature as in the first filling state.

[0008] In some of the above embodiments of the present invention, the second pressure is preferably at least 95% of the equilibrium vapor pressure of liquid R-134a at the same ambient temperature. For example, if the ambient temperature is approximately 75 degrees Fahrenheit (23.9°C) and the equilibrium vapor pressure of liquid R-134a at that temperature is approximately 93 psia (641.2 kPa), the second pressure will be approximately 88 psia (606.7 kPa). Alternatively, if the ambient temperature is 70 degrees Fahrenheit (21.1°C) and the equilibrium vapor pressure of liquid R-134a at that temperature is 85.9 psia (592.3 kPa), the second pressure will be 81.6 psia (562.6 kPa). In other embodiments of the present invention, the second pressure can be in the range of 75 psia to 115 psia (517.1 kPa to 792.9 kPa) at ambient temperature. Furthermore, the ambient temperature can be 65°F to 75°F (18.33°C to 23.89°C). According to other embodiments of the present invention, the liquid refrigerant can be R-1234ze(E), and according to some embodiments of the present invention, the inert gas can be nitrogen.

[0009] Another method for filling a gas tank with a liquid refrigerant according to an aspect of the present invention comprises the steps of filling the tank with a predetermined amount of liquid refrigerant under pressure and supplying an inert gas to the tank, wherein, after the filling and supply steps, the total pressure of the contents in the tank at ambient temperature is at least 95% of the equilibrium vapor pressure of liquid R-134a at ambient temperature.

[0010] In some of the above embodiments of the present invention, the predetermined amount of liquid refrigerant can be less than or equal to a predetermined limit of liquid refrigerant in the tank, the predetermined limit being defined such that the volume of the liquid phase of the liquid refrigerant present in the tank is less than the total sealed volume of the tank at any temperature up to 131 degrees Fahrenheit (55°C). Thus, at ambient room temperature of 70 degrees Fahrenheit (21.1°C), the vapor space in the tank can occupy about 10 percent of the sealed volume of the tank when the predetermined amount of liquid refrigerant in the tank is equal to the predetermined limit of liquid refrigerant in the tank.

[0011] In some embodiments of the present invention, the filling step can be performed before the supply step. In at least some embodiments of the present invention, the inert gas can be nitrogen.

[0012] In at least some embodiments of the present invention, the liquid refrigerant may be R-1234ze(E). In some embodiments of the present invention, the liquid refrigerant may have a global warming potential (GWP) value of less than 150, and in further embodiments of the present invention, the liquid refrigerant may have a GWP value of less than 50 or less than 10. In other embodiments of the present invention, the liquid refrigerant may be classified as belonging to safety class A1 or class A2L according to ASHRAE 34 or ISO 817. In yet another embodiment of the present invention, the liquid refrigerant may have a boiling point of less than 0 degrees Fahrenheit (-17.78°C) at 1 atmosphere (101.325 kPa). In yet another embodiment of the present invention, the liquid refrigerant may have an equilibrium vapor pressure in the range of 60 psia to 90 psia (413.7 kPa to 620.5 kPa) at 70 degrees Fahrenheit (21.1°C).

[0013] In some embodiments of the present invention, after the filling and supply steps, the total pressure inside the tank at a temperature of 70 degrees Fahrenheit (21.1°C) is at least 81.6 psia (562.6 kPa). In other embodiments of the present invention, after those steps, the total pressure inside the tank at that temperature is less than 135 psia (930.8 kPa). In yet another embodiment of the present invention, after those steps, the total pressure inside the tank at that temperature is in the range of 82 psia to 115 psia (565.4 kPa to 792.9 kPa). In yet another embodiment of the present invention, after those steps, the total pressure inside the tank at that temperature is in the range of 85 psia to 105 psia (586.1 kPa to 724.0 kPa).

[0014] A further method for filling a gas tank with a liquid refrigerant according to an aspect of the present invention preferably includes filling the tank with a predetermined amount of R-1234ze(E) to bring it to a first filled state and achieving a first pressure at the first filled state and ambient temperature. The method also preferably includes supplying gaseous nitrogen to the tank to bring it to a second filled state and achieving a second pressure in the tank at ambient temperature, the second pressure being in the range of 75 psia to 115 psia (517.1 kPa to 792.9 kPa) and higher than the first pressure. In at least some embodiments of this method, a predetermined amount of R-1234ze(E) is less than or equal to a predetermined limit of R-1234ze(E) in the tank, and that predetermined limit of R-1234ze(E) in the tank is defined such that the volume of the liquid phase of R-1234ze(E) present in the tank is less than the total sealed volume of the tank at any temperature up to 131 degrees Fahrenheit (55 degrees Fahrenheit), including 131 degrees Fahrenheit (55 degrees Fahrenheit).

[0015] A further method for filling a gas tank with a liquid refrigerant according to an aspect of the present invention preferably includes the steps of filling the tank with a predetermined amount of liquid refrigerant under pressure and supplying an inert gas to the tank, so that, after the filling and supply steps, when the temperature is 70 degrees Fahrenheit (21.1°C), the total pressure of the contents in the tank is in the range of 75 psia to 115 psia (517.1 kPa to 792.9 kPa). In at least some aspects of this method, the liquid refrigerant may be R-1234ze(E), and according to at least some aspects of this method, the inert gas may be nitrogen. In at least some other aspects of this method, the predetermined amount of liquid refrigerant may be less than or equal to a predetermined limit of liquid refrigerant in the tank, the predetermined limit being defined such that the volume of the liquid phase of the liquid refrigerant present in the tank is less than the total sealed volume of the tank at any temperature up to 131 degrees Fahrenheit (55°C).

[0016] Another aspect of the present invention includes a filled refrigerant tank containing a liquid refrigerant and an inert gas disposed within the tank as described above. The contents of the tank are preferably pressurized to a pressure in the range of 75 psia to 115 psia (517.1 kPa to 792.9 kPa) when the temperature is 70 degrees Fahrenheit (21.1°C). The tank is preferably equipped with a nozzle that can supply and discharge the contents into and out of the tank. Furthermore, the nozzle is preferably configured to be detachably connected to the refrigerant supply connection of a laser treatment device for skin. The liquid refrigerant disposed within the tank is preferably R-1234ze(E), and the inert gas disposed within the tank can be nitrogen.

[0017] A filled refrigerant tank according to an aspect of the present invention contains liquid R-1234ze(E) and an inert gas, which are placed inside the tank and pressurized to a pressure in the range of 75 psia to 115 psia (517.1 kPa to 792.9 kPa) when the temperature is 70 degrees Fahrenheit (21.1°C). The tank preferably includes a nozzle that can supply and discharge contents into and from the tank. Furthermore, the nozzle is preferably configured to be detachably connected to the refrigerant supply connection of a laser treatment apparatus for skin tissue. In at least some aspects of the present invention, the inert gas placed inside the tank may be nitrogen. In some other aspects of the present invention, the sealed volume of the tank may consist essentially of liquid R-1234ze(E) and an inert gas.

[0018] A filled refrigerant tank according to another aspect of the present invention contains liquid R-1234ze(E) and an inert gas, which are placed inside the tank and pressurized to a pressure that is at least 95% of the equilibrium vapor pressure of liquid R-134a when at a temperature of 70 degrees Fahrenheit (21.1°C). The tank preferably includes a nozzle that can supply and discharge contents into and from the tank. Furthermore, the nozzle is preferably configured to be detachably connected to the refrigerant supply connection of a laser treatment apparatus for skin tissue. In at least some aspects of the present invention, the inert gas placed inside the tank may be nitrogen. In some other aspects of the present invention, the sealed volume of the tank may consist essentially of liquid R-1234ze(E) and an inert gas.

[0019] In accordance with the above embodiments, the present invention can enable a low-environmental-impact refrigerant to be an acceptable "drop-in" replacement for an environmentally-impact refrigerant in a laser skin treatment apparatus that was originally designed to use an environmentally-impact refrigerant to cool the patient's skin during laser treatment procedures. Advantageously, the present invention can minimize, or even avoid, the need to reprogram the laser treatment apparatus and / or the need for the user to operate the apparatus in a different manner, while achieving such a result. It is also desirable that the present invention minimize or eliminate the additional time (or possible errors) that the apparatus may inherently require when handling the alternative refrigerant, so that the apparatus can operate with the alternative refrigerant despite the alternative refrigerant having different properties than the original refrigerant. For example, the present invention can preferably increase the pressure of the alternative refrigerant to at least approximately the same pressure as the original refrigerant at the same ambient temperature. It is desirable that the present invention achieve this result without adversely affecting the properties of the alternative refrigerant and without exceeding the maximum allowable volume of the tank filled with the refrigerant. [Brief explanation of the drawing]

[0020] [Figure 1] This is a perspective view showing a cylindrical tank connected to a laser treatment device. [Figure 2A] This is a cross-sectional view of a cylindrical tank for containing a refrigerant. [Figure 2B] Figure 2A is an enlarged cross-sectional view of the valve for the tank. [Figure 3A] This is a perspective view showing a cylindrical tank connected to a device for filling the tank with refrigerant. [Figure 3B] This is a magnified view focusing on the tank located in Figure 3A. [Modes for carrying out the invention]

[0021] Note that in this specification, the units "psia" and "psig" are referenced. Psia is a value representing "absolute pressure" in pounds per square inch, which is a measure of pressure relative to a perfect vacuum. On the other hand, psig is "gauge pressure" and means the pressure in pounds per square inch relative to atmospheric pressure. Gauge pressure is generally indicated by a pressure gauge, but it is not universal in the sense that it varies based on changes in atmospheric pressure, and atmospheric pressure also varies based on conditions such as altitude. Any value given in psia in this specification can be converted to psig by subtracting the local atmospheric pressure, which is approximately 14.7 psi at sea level. Conversely, any value given in psig in this specification can be converted to psia by adding the local atmospheric pressure.

[0022] Among the considerations in selecting a desirable alternative refrigerant for a tissue treatment device are low GWP values, especially because the refrigerant evaporates into the atmosphere after being sprayed onto the patient's skin. Other desirable characteristics include a boiling point as close as possible to that of the refrigerant being replaced. For example, if R-134a is the refrigerant being replaced, it is ideal for the alternative refrigerant to have a boiling point relatively close to -15.34 degrees Fahrenheit (-26.3 °C) at 1 atmosphere (101.325 kPa). Other considerations include low flammability (especially in relation to laser applications) and low toxicity (especially in applications where the refrigerant is sprayed directly onto a person's skin).

[0023] Other considerations in achieving an ideal "drop-in" replacement include ensuring that the characteristics of the alternative refrigerant when it is discharged are similar to those of the refrigerant being replaced when it was discharged. For example, having a similar discharge pressure is important, so that when the cooling gas is ejected from the nozzle and contacts the patient's skin, it maintains substantially the same effect. Another consideration is to minimize (or eliminate) the need to reprogram the laser treatment device that discharges the refrigerant. Such reprogramming involves a logistics burden in ensuring that all currently operating devices are updated, and also requires a significant amount of cost.

[0024] The following embodiments relate to embodiments of the present invention related to an exemplary laser treatment device commercially available from Candela Corporation, Marlborough, Massachusetts (hereinafter, "Candela"), and illustrate the principles of the present invention. Candela markets laser treatment devices under product names such as "Gentle Pro Series", "Vbeam™ Perfecta", and "Vbeam™ Prima" (hereinafter referred to as "Candela devices"). Such products include a handpiece that an operator positions near the target area so that laser pulses can be applied to the target area of the patient's skin. Such products can also be designed for use with cryogenic cooling by providing a nozzle on the handpiece so that a pulse of refrigerant can be directed towards the target area in conjunction with the laser pulse. The refrigerant is supplied from a standardized tank of pressurized liquid refrigerant that is connected to the device and can be replaced as needed.

[0025] FIG. 1 shows a cylindrical tank 20 of liquid refrigerant connected to a laser treatment device 10. Specifically, the upper portion 12 of the laser treatment device 10 includes an opening 14 in which the tank 20 can be disposed. The device 10 includes a tank receiving opening 14 disposed behind a display 16 (e.g., an LCD screen) disposed towards the front of the device 10. Although not shown in FIG. 1, the tank 20 includes an outlet through which the refrigerant is supplied. The outlet is disposed downwardly and is removably connected at that location to a refrigerant supply connection (not shown) disposed within the device 10.

[0026] Figure 2A shows a refrigerant storage tank 20 positioned in the same vertical configuration as when connected to the treatment device 10 in the manner shown in Figure 1. When initially filled, the tank 20 contains liquid refrigerant 40 filled to a certain level, generally less than 100% of the tank 20's sealed volume 22. This filling level can be the maximum filling level of a given refrigerant at ambient temperature, as will be further described below. Figure 2A shows a typical top line 42 of the liquid refrigerant, and above it, near the upper end 24 of the tank 20, is a vapor space 44 (also known as the "headspace") containing gaseous gas. At the other lower end 26 of the tank 20 is an opening 28 where a valve 30 can be positioned to completely seal the tank 20.

[0027] As shown in Figure 2B, the opening 28 at the lower end 26 of the tank 20 may have threads 29 for securing to threads 31 on the valve 30. To form a fluid-tight seal, an O-ring 32 may also be provided at the interface between the valve 30 and the periphery of the opening 28. The valve 30 can be operated by pushing down the valve stem 34 to open a fluid communication through the valve in order to discharge the refrigerant 40 and / or fill the tank 20. The valve 30 and stem 34 may be of a standardized design configured to work with the refrigerant supply connection in the laser treatment apparatus 10 so that the valve stem 34 is pushed down when the valve 30 of the tank 20 is fully and properly seated against its connection. As similarly shown in Figure 2B, the valve 30 may be equipped with a standard pressure relief device 36 for safety, which may operate by including, for example, a burst disc configured to rupture at a predetermined excess pressure so that gas in the tank 20 can be discharged through an associated passage 38 communicating with the pressure relief device 36.

[0028] The Candela apparatus identified above was designed to be used with a tank filled with liquid R-134a, as shown in Figure 2A. In this context, “filled” does not mean that such a tank 20 is completely filled with liquid, but rather that the tank is “maximum filled” so that a certain minimum vapor space is provided within the tank for safety reasons (and as required by law) in which the refrigerant exists in a gaseous state. The amount of vapor space as a percentage of the tank’s sealed volume when the tank is maximum filled will vary depending on the contents of the tank and the temperature of those contents. One way to describe the maximum filled requirement is that the liquid phase of the refrigerant does not fill the entire sealed volume of the tank at any temperature up to 131 degrees Fahrenheit (55°C), including 131 degrees Fahrenheit (55°C). Thus, at temperatures closer to ambient room temperature (e.g., 70 degrees Fahrenheit (21.1°C)), the vapor space may occupy, for example, about 10 percent of the tank’s sealed volume when the tank is maximum filled. When filled in this manner with R-134a, the pressure of the tank contents is at an equilibrium vapor pressure of approximately 85.9 psia (592.3 kPa) at its ambient temperature. However, Candela devices are designed to discharge the refrigerant at approximately 115 psig to 120 psig (approximately 130 psia to 135 psia), and such devices are equipped with an internal heater configured to heat the connected tank until the pressure of its contents reaches its design pressure. Thus, once the pressurized tank, fully filled with liquid R-134a, is heated to that pressure, the refrigerant is discharged at its originally intended design values ​​in terms of characteristics such as mass flow rate and cooling effect. A preferred alternative refrigerant to R-134a in the above applications is R-1234ze(E) (preferred IUPAC name: trans-1,3,3,3-tetrafluoropropane-1-ene), which was developed by Honeywell and sold under the brand name SOLSTICE. This refrigerant is a low-environmental-impact HFO with a very low GWP value. Depending on the source, R-1234ze(E) shows different GWP values, some stating it as less than 10, while others say it's less than 1.R-1234ze(E) is classified by ASHRAE and ISO as a safety class A2L refrigerant. Again, "A" indicates non-toxicity, and "2L" indicates low flammability. This is a higher flammability designation than refrigerants considered non-flammable ("1" designation), but refrigerants with a "2L" designation are considered to have low flammability because their burning rate is less than 10 cm / s. R-1234ze(E) has a boiling point of -2.11 degrees Fahrenheit (-18.95°C) at 1 atmosphere (101.325 kPa).

[0029] However, in relation to devices such as the Candela system identified above, there are several unexpected challenges in implementing R-1234ze(E) as a refrigerant. For example, as explained above, if the tank is filled to the same pressure as a tank fully filled with R-134a, the minimum allowable vapor space in the tank will be exceeded because R-1234ze(E) has a lower equilibrium vapor pressure than R-134a within the typical ambient room temperature range. That is, at a temperature of 70 degrees Fahrenheit (21.1°C), the equilibrium vapor pressure of R-1234ze(E) is approximately 63.2 psia (436 kPa), which is lower than R-134a's 85.9 psia (592.3 kPa) at the same temperature. As described above, the Candela system is configured to heat the refrigerant tank until the pressure of its contents rises to a preset discharge pressure. Therefore, in principle, a tank fully filled with R-1234ze(E) (having the minimum vapor space required for safety and / or by law) will be heated by the Candela device until the pressurized refrigerant reaches a preset discharge pressure, even though the pressure in such a filled tank will start at a lower pressure than that of a tank filled with R-134a. Nevertheless, unexpected problems can arise, one of which is that it takes longer for the pressure in the R-1234ze(E) tank to reach the preset pressure. This may mean that fewer treatment procedures can be performed within a given time due to the additional time required for the device to reach an operational state, which may correlate with a decrease in the profit derived from the procedure and can therefore be important to businesses using laser treatment devices. Furthermore, the additional heating of the alternative refrigerant to reach the preset temperature will result in the refrigerant being heated to a higher temperature than R-134a, which may negatively affect the cooling effect of the discharged refrigerant compared to the original calibrated effect when using R-134a. Another issue is that if the additional heating time is too long or the temperature reaches too high, it can cause a programmed malfunction in the device, potentially preventing it from functioning properly.Fixing the problem may require updating the programming of all currently operating equipment, which would lead to the aforementioned logistical and cost burdens.

[0030] Based on current research and testing of alternative solutions to the above problems, a solution has been developed that avoids, and even improves upon, at least some of such problems. Specifically, the present invention includes a process for increasing the pressure of R-1234ze(E) refrigerant contained in a tank without sacrificing the minimum vapor space in the tank. The process includes filling the tank with nearly the maximum amount of liquid R-1234ze(E) (while maintaining the minimum vapor space). Then, an inert gas is added to the tank to increase the pressure to a higher target pressure. The inert gas is preferably nitrogen, but other inert gases can also be used. However, air and pure oxygen should be avoided because the presence of oxygen can toxicly increase flammability. Figures 3A and 3B show a tank 20 connected to a filling device 50, the filling device 50 having a connection 52 to a valve 30 located at the lower end 26 of the tank 20. The connection portion 52 can be configured to push down the valve stem 34, similar to the connection portion in the laser treatment apparatus 10 mentioned above, thereby allowing gas (i.e., liquid refrigerant and gaseous inert gas) to be supplied to the tank 20.

[0031] As explained above, the higher target pressure levels achieved by increasing the pressure with an inert gas can be approximately the same as the pressure of a fully filled R-134a tank at the same temperature. In another example, the target pressure can be even higher, thereby reducing the heating time when used in Candela equipment (and other laser treatment equipment), and thus benefiting the company that owns such equipment. Such a target pressure should be below the preset discharge pressure, as the equipment may be configured only to heat the refrigerant to raise the pressure to the discharge pressure rather than cooling the refrigerant to reduce the pressure. Furthermore, considering the possibility of fluctuations in the room temperature in which the equipment is located during operation, the target pressure should be well below the preset discharge pressure so that the pressure in the tank remains below its discharge pressure at a variety of reasonably expected room temperatures. In addition, it may be desirable to further limit the target pressure to avoid causing pre-programmed malfunctions of the equipment, such as programming that could cause errors and / or prevent the heating process from proceeding if the initial (preheating) pressure is higher than some setpoints. Therefore, one desirable range for the target pressure (at an ambient temperature of 70 degrees Fahrenheit (21.1°C)) is 75 psia to 115 psia (517.1 kPa to 792.9 kPa). Other ranges are also desirable.For example, the internal pressure range at ambient temperature is 80 psia~115 psia (551.6 kPa~792.9 kPa), 80 psia~110 psia (551.6 kPa~758.4 kPa), 85 psia~110 psia (586.1 kPa~758.4 kPa), 90 psia~110 psia (620.6 kPa~758.4 kPa), 95 psia~110 psia (655.0 kPa~758.4 kPa), 100 psia~110 psia (689.5 kPa~758. The ranges can be 4kPa, 85psia-105psia (586.1kPa-724.0kPa), 90psia-105psia (620.6kPa-724.0kPa), 95psia-105psia (655.0kPa-724.0kPa), 90psia-100psia (620.6kPa-689.5kPa), 95psia-100psia (655.0kPa-689.5kPa), and 82psia-115psia (565.4kPa-792.9kPa). In other examples, the range of internal pressure can be "approximately" one of these ranges specified above, where "approximately" means that the specified lower and / or specified upper limits can vary by up to 1psia (6.9kPa).

[0032] By utilizing the above method, the pressure in the tank containing R-1234ze(E) can be increased to the desired target pressure without affecting the refrigerant's properties, thanks to the use of an inert gas. Furthermore, when the tank is positioned vertically within the apparatus (as shown in Figure 2A), gaseous nitrogen is located in the vapor space 44 near the upper end 24 of the tank 20, while the liquid R-1234ze(E) refrigerant is located below the upper surface line 42 and, due to gravity, comes into contact with the valve 30. Therefore, during refrigerant discharge, the inert gas remains in the vapor space 44 near the upper end 24 of the tank 20, while only the R-1234ze(E) refrigerant is discharged.

[0033] The method described above involved adding liquid refrigerant to the tank before adding a gaseous inert gas such as nitrogen, but this method can also include performing those steps in reverse order. For example, if it is known in advance how much refrigerant needs to be added to fully fill the tank and how much inert gas needs to be added to raise the pressure in the tank to a target pressure, then such amounts of liquid refrigerant and inert gas can be added in reverse order.

[0034] The embodiments of the present invention described above can be carried out in various possible variations, each of which is intended to be encompassed by an independent aspect of the present invention. For example, a different refrigerant can be used as a substitute refrigerant, and the pressure of the substitute refrigerant can be increased using the methodology described above by adding an inert gas (e.g., nitrogen) to the tank until the substitute refrigerant reaches a target pressure that is at least approximately the same (e.g., 95%) as the pressure of the refrigerant being substituted (e.g., the equilibrium vapor pressure of R-134a). Such a target pressure is also preferably lower than a preset discharge pressure (at a reasonably wide range of expected room temperatures) of the apparatus to which the tank is connected, and / or lower than a preset pressure that could cause failure of the apparatus (at such a reasonably wide range of expected room temperatures).

[0035] Other possible refrigerants that can be used as alternative refrigerants as described above include refrigerants classified by ASHRAE and ISO as safety class A1 and / or class A2L refrigerants. Preferably, the selected alternative refrigerant has a relatively low GWP value. For example, the selected alternative refrigerant may have a GWP value of less than 150. More preferably, such an alternative refrigerant may have a GWP value of less than 50. Even more preferably, such an alternative refrigerant may have a GWP value of less than 10. As a further example, other HFO refrigerants can be selected. In yet another example, any of the refrigerants specified in the Nimitz patent can be used.

[0036] Another embodiment of the present invention disclosed herein is a filled refrigerant tank containing an alternative refrigerant to R-134a and an inert gas. Both the alternative refrigerant and the inert gas placed in the tank can be pressurized to a pressure that is at least 95% of the equilibrium vapor pressure of liquid R-134a at ambient temperature. For example, at an ambient temperature of 70 degrees Fahrenheit (21.1°C), the equilibrium vapor pressure of liquid R-134a is 85.9 psia (592.3 kPa), and therefore 95% of that pressure is 81.6 psia (562.6 kPa). In another embodiment, both the alternative refrigerant and the inert gas placed in the tank can be pressurized to a pressure in the range of 75 psia to 115 psia (517.1 kPa to 792.9 kPa) at a temperature of 70 degrees Fahrenheit (21.1°C). As described above, the inert gas used in the filled refrigerant tank can be nitrogen.

[0037] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the present invention. Therefore, it should be understood that numerous modifications can be made to the exemplary embodiments, and that other configurations can be devised without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method for filling a tank, The steps include filling a tank with a predetermined amount of liquid refrigerant under pressure, The steps include supplying an inert gas to the tank, Includes, A method wherein, after the filling step and the supply step, the total pressure in the tank at ambient temperature is at least 95% of the equilibrium vapor pressure of the liquid R-134a at ambient temperature.

2. The method according to claim 1, wherein the liquid refrigerant is R-1234ze(E).

3. The method according to claim 1, wherein the inert gas is nitrogen.

4. The method according to claim 1, wherein the filling step is performed before the supply step.

5. The method according to claim 1, wherein the predetermined amount of the liquid refrigerant is less than or equal to a predetermined limit of the liquid refrigerant in the tank, and the predetermined limit is defined such that the volume of the liquid phase of the liquid refrigerant present in the tank is less than the total sealed volume of the tank at any temperature up to 131 degrees Fahrenheit (55 degrees Fahrenheit), including 131 degrees Fahrenheit (55 degrees Fahrenheit).

6. The method according to claim 1, wherein the liquid refrigerant has a GWP (Global Warming Potential) value of less than 150.

7. The method according to claim 6, wherein the liquid refrigerant has a GWP value of less than 50.

8. The method according to claim 6, wherein the liquid refrigerant has a GWP value of less than 10.

9. The method according to claim 1, wherein the liquid refrigerant is classified as belonging to safety class A1 or class A2L according to ASHRAE 34 or ISO 817.

10. The method according to claim 1, wherein the liquid refrigerant has a boiling point of less than 0 degrees Fahrenheit (-17.78°C) at 1 atmosphere (101.325 kPa).

11. The method according to claim 1, wherein the liquid refrigerant has an equilibrium vapor pressure in the range of 60 psia to 90 psia (413.7 kPa to 620.5 kPa) at 70 degrees Fahrenheit (21.1°C).

12. The method according to claim 1, wherein, after the filling step and the supply step, the total pressure in the tank at a temperature of 70 degrees Fahrenheit (21.1°C) is at least 81.6 psia (562.6 kPa).

13. The method according to claim 12, wherein, after the filling step and the supply step, the total pressure in the tank at a temperature of 70 degrees Fahrenheit (21.1°C) is less than 135 psia (930.8 kPa).

14. The method according to claim 13, wherein, after the filling step and the supply step, the total pressure in the tank at a temperature of 70 degrees Fahrenheit (21.1°C) is in the range of 82 psi to 115 psi (565.4 kPa to 792.9 kPa).

15. A method for filling a tank, A predetermined amount of R-1234ze(E) is filled into the tank to achieve a first filling state, and a first pressure is achieved in the first filling state and at the ambient temperature. By supplying gaseous nitrogen to the tank to achieve a second filled state, and by achieving a second pressure inside the tank at the ambient temperature, Includes, The method wherein the second pressure is in the range of 75 psia to 115 psia (517.1 kPa to 792.9 kPa) and is higher than the first pressure.

16. The method according to claim 15, wherein the predetermined amount of R-1234ze(E) is less than or equal to a predetermined limit of R-1234ze(E) in the tank, and the predetermined limit of R-1234ze(E) in the tank is defined such that the volume of the liquid phase of R-1234ze(E) present in the tank is less than the total sealed volume of the tank at any temperature up to 131 degrees Fahrenheit (55 degrees Fahrenheit), including 131 degrees Fahrenheit (55 degrees Fahrenheit).

17. A method for filling a tank, The steps include filling a tank with a predetermined amount of liquid refrigerant under pressure, The steps include supplying an inert gas to the tank, Includes, A method wherein, after the filling step and the supply step, when the temperature is 70 degrees Fahrenheit (21.1°C), the total pressure in the tank is in the range of 75 psia to 115 psia (517.1 kPa to 792.9 kPa).

18. The method according to claim 17, wherein the liquid refrigerant is R-1234ze(E).

19. The method according to claim 17, wherein the inert gas is nitrogen.

20. The method according to claim 17, wherein the predetermined amount of the liquid refrigerant is less than or equal to a predetermined limit of the liquid refrigerant in the tank, and the predetermined limit is defined such that the volume of the liquid phase of the liquid refrigerant present in the tank is less than the total sealed volume of the tank at any temperature up to 131 degrees Fahrenheit (55 degrees Fahrenheit), including 131 degrees Fahrenheit (55 degrees Fahrenheit).

21. A filled refrigerant tank, A tank having a side wall defining a sealed volume, having a nozzle capable of supplying contents to the sealed volume and discharging contents from the sealed volume, wherein the nozzle is configured to be detachably connected to the refrigerant supply connection of a laser treatment device for skin tissue, and The following are arranged in the tank and, when at a temperature of 70 degrees Fahrenheit (21.1°C), pressurized to a pressure in the range of 75 psia to 115 psia (517.1 kPa to 792.9 kPa): liquid R-1234ze(E) and an inert gas, A filled refrigerant tank equipped with [a specific feature / feature].

22. The refrigerant tank according to claim 21, wherein the inert gas is nitrogen.

23. The refrigerant tank according to claim 21, wherein the sealed volume of the tank essentially consists of liquid R-1234ze(E) and the inert gas.

24. A filled refrigerant tank, A tank having a side wall defining a sealed volume, having a nozzle capable of supplying contents to the sealed volume and discharging contents from the sealed volume, wherein the nozzle is configured to be detachably connected to the refrigerant supply connection of a laser treatment device for skin tissue, and The following are placed inside the tank and, when at a temperature of 70 degrees Fahrenheit (21.1°C), pressurized to a pressure that is at least 95% of the equilibrium vapor pressure of liquid R-134a, containing liquid R-1234ze(E) and an inert gas, A filled refrigerant tank equipped with [a specific feature / feature].

25. The refrigerant tank according to claim 24, wherein the inert gas is nitrogen.

26. The refrigerant tank according to claim 24, wherein the sealed volume of the tank essentially consists of liquid R-1234ze(E) and the inert gas.

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