Heat transfer method

Abstract

The invention relates to a heat transfer method using ternary compositions containing 2,3,3,3-tetrafluoropropene, 1,1-difluoroethane and difluoromethane, said compositions being especially interesting as a heat transfer fluid in compression refrigeration systems comprising exchangers operation in counterflow mode or in split flow mode with counterflow tendency.

Description

[0001] The present invention relates to the use of ternary compositions with 2,3,3,3-tetrafluoropropene as heat transfer fluids.

[0002] The problems posed by substances with ozone depleting potential (ODP) were discussed in Montreal, where a protocol was signed recommending the reduction of the production and use of chlorofluorocarbons (CFCs). This protocol was amended to impose a phase-out of CFCs and extend restrictions to other products, including hydrochlorofluorocarbons (HCFCs).

[0003] The refrigeration and air conditioning industry has invested heavily in replacing these refrigerant fluids, and this is why hydrofluorocarbons (HFCs) have been introduced to the market.

[0004] (Hydro)chlorofluorocarbons used as blowing agents or solvents have also been replaced by HFCs.

[0005] In the automotive industry, in the air conditioning systems of vehicles sold in many countries, chlorofluorocarbon refrigerant (CFC-12) has been replaced by hydrofluorocarbon refrigerant (1,1,1,2-tetrafluoroethane: HFC-134a), which is less harmful to the ozone layer. However, taking into account the targets set by the Kyoto Protocol, HFC-134a (GWP = 1300) has been considered to have a high warming potential. The contribution of a fluid to the greenhouse effect is quantified using the GWP (global warming potential) criterion, which reflects the warming potential, taking 1 as the reference value for carbon dioxide.

[0006] Carbon dioxide, which is non-toxic, non-flammable and has a very low GWP, has been proposed as a refrigerant fluid for air conditioning systems instead of HFC-134a. However, the use of carbon dioxide has many disadvantages, in particular related to the very high pressure at which it is used as a refrigerant fluid in existing devices and technologies.

[0007] Furthermore, a mixture of R-404A consisting of 44 wt% pentafluoroethane, 52 wt% trifluoroethane and 4 wt% HFC-134a is widely used as a refrigerant fluid in large areas (supermarkets) and in refrigerated transport. However, this mixture has a GWP of 3900. A mixture of R-407C consisting of 52 wt% HFC-134a, 25 wt% pentafluoroethane and 23 wt% difluoromethane is used as a heat transfer fluid in air conditioning units and heat pumps. However, this mixture has a GWP of 1800.

[0008] JP 4110388 describes the use of hydrofluoropropenes of formula C3HmFn, where m, n are an integer between 1 and 5 inclusive, and m + n = 6, as heat transfer fluids, and in particular tetrafluoropropene and trifluoropropene.

[0009] WO2004 / 037913 discloses the use of compositions comprising at least one fluoroalkene having three or four carbon atoms, in particular pentafluoropropene and tetrafluoropropene, preferably with a GWP of at most 150, as heat transfer fluids.

[0010] WO 2005 / 105947 discloses adding to tetrafluoropropene, preferably 1,3,3,3 tetrafluoropropene, at least one blowing agent such as difluoromethane, pentafluoroethane, tetrafluoroethane, difluoroethane, heptafluoropropane, hexafluoropropane, pentafluoropropane, pentafluorobutane, water and carbon dioxide.

[0011] WO 2006 / 094303 discloses an azeotropic composition comprising 7.4 wt% of 2,3,3,3-tetrafluoropropene (1234yf) and 92.6 wt% of difluoromethane (HFC-32). This document also discloses an azeotropic composition comprising 91 wt% of 2,3,3,3-tetrafluoropropene and 9 wt% of difluoroethane (HFC-152a).

[0012] US 2008 / 314073 describes a heat transfer system comprising a compressor, a condenser, a pressure reducing valve and an evaporator, and a closed-loop internal device for measuring the internal pressure of the system. A method for detecting leakage of a heat transfer composition, including for example fluoroolefins, in a closed-loop heat transfer system is further disclosed.

[0013] Document FR2182956 discloses a cross counterflow heat exchanger comprising a central tube provided with a flange at each end thereof and a number of smaller diameter tubes spirally wrapped around the central tube and terminating in inlet openings or a channel in the flanges.

[0014] FR 2256381 discloses a heat transfer device comprising a compressor, a condenser and an evaporator connected in a closed circuit in which a heat transfer fluid circulates. The document describes that the device further comprises a heat exchanger and a throttle valve arranged in series in the part of the circuit located between the condenser and the evaporator.

[0015] A heat exchanger is a device that allows thermal energy to be transferred from one fluid to another without mixing. The heat flow passes through a heat exchange surface that separates the fluids. This method is most often used to cool or heat a liquid or gas that cannot be cooled or heated directly.

[0016] In pressurized systems, heat exchange between the refrigerant and the heat sources takes place via heat transfer fluids. These heat transfer fluids are in a gaseous state (air in an air conditioning unit and in direct expansion cooling), a liquid state (water in domestic heat pumps, water-glycol solution) or are two-phase.

[0017] There are different modes of transfer: - two fluids are directed parallel and flow in the same direction: co-current (antimodectorial) mode; - two fluids are oriented parallel but flow in opposite directions: countercurrent (methodical) mode; - two fluids are positioned perpendicularly: cross-flow mode. Cross-flow can be co-current or counter-current; One of the two fluids is recycled in a larger conduit, through which the other fluid flows. This configuration is similar to a co-current exchanger for half its length, and a counter-current exchanger for the other half: a "pinhead" type of configuration.

[0018] The Applicant has now found that ternary compositions comprising 2,3,3,3-tetrafluoropropene, 1,1-difluoroethane and difluoromethane are of particular interest as heat transfer fluids in pressurized cooling systems with heat exchangers operating in countercurrent or cross-flow mode with a countercurrent tendency.

[0019] Thus, these compositions can be used as a heat transfer fluid in heat pumps, optionally reversible, in an air conditioning unit, in an industrial air conditioning unit (paper, server room), in a portable home air conditioning unit, in home refrigeration and freezing units, for low and medium temperature cooling and for cooling refrigerated vehicles using pressurized systems with exchangers operating in countercurrent mode or in crossflow mode with a countercurrent tendency.

[0020] These compositions have both zero ODP and a GWP lower than existing heat transfer fluids such as R-404A or R-407C.Furthermore, their efficiencies (COP: coefficient of performance, defined as the ratio of the useful power delivered by a system to the power absorbed or consumed by that system; and CAP: volumetric efficiency (kJ / m3)) are higher than those of heat transfer fluids such as R-404A or R-407C.

[0021] The compositions used as heat transfer fluid in the present invention have a critical temperature higher than 93°C (the critical temperature of R-404A is 72°C). These compositions can be used in heat pumps to supply heat up to a temperature of up to 65°C, but also up to a temperature higher than 90°C (the temperature range in which R-404A cannot be used).

[0022] The compositions used as the heat transfer fluid in the present invention have lower condenser pressures than R-404A pressures, as well as lower compression ratios. These compositions can be used with the same compression technology as R-404A. The compositions used as the heat transfer fluid in the present invention have a lower saturated vapor density than the saturated vapor density of R-404A. The volumetric efficiencies provided by these compositions are equivalent to or higher than the volumetric efficiency of R-404A (between 97 and 110%). Due to these properties, these compositions operate with smaller piping diameters and therefore with less pressure loss in the vapor lines, which increases plant efficiency.

[0023] The subject of the present invention is therefore the use of ternary compositions comprising 2,3,3,3-tetrafluoropropene, 1,1-difluoroethane and difluoromethane, which are of particular interest as heat transfer fluid in pressurized cooling installations with exchangers operating in countercurrent mode or in cross-flow mode with a countercurrent tendency. Preferably, the compositions used in the present invention comprise essentially from 20 to 80% by weight of 2,3,3,3-tetrafluoropropene and from 15 to 40% by weight of difluoromethane, and from 5 to 40% by weight of 1,1-difluoroethane.

[0024] Preferably, the compositions used comprise essentially from 20 to 70% by weight 2,3,3,3-tetrafluoropropene and from 20 to 40% by weight of difluoromethane and from 10 to 40% by weight of difluoroethane.

[0025] Particularly preferred compositions generally contain from 35 to 70% by weight 2,3,3,3-tetrafluoropropene, from 20 to 25% by weight of difluoromethane, and from 10 to 40% by weight of 1,1-difluoroethane.

[0026] The compositions used in the present invention may be stabilized. The stabilizing agent constitutes at most 5% by weight of the total composition. Stabilizers that may be mentioned include, in particular, nitromethane, ascorbic acid, terephthalic acid, azoles such as tolutriazole or benzotriazole, phenolic compounds such as tocopherol, hydroquinone, t-butylhydroquinone, 2,6-di-tert-butyl-4-methylphenol, epoxy compounds (alkylated, optionally fluorinated or perfluorinated or alkenylated, or aromatic) such as n-butyl glycidyl ether, hexanediol diglycidyl ether, allyl glycidyl ether, butylphenylglycidyl ether, phosphites, phosphates, phosphonates, thiols and lactones. Another object of the present invention relates to a heat transfer method using ternary compositions comprising 2,3,3,3-tetrafluoropropene, 1,1-difluoroethane and difluoromethane, which are of particular interest as heat transfer fluid in pressurized cooling installations with exchangers operating in countercurrent mode or in cross-flow mode with a countercurrent tendency.

[0029] The method of the present invention can be used in the presence of lubricants such as mineral oil, alkylbenzene, polyalkylene glycol and polyvinyl ether.

[0030] The compositions used in the present invention are suitable for replacing R-404A in refrigeration and / or R-407C in air conditioning and heat pump equipment in existing installations. EXPERIMENTAL PART Computational Tools

[0031] The RK-Soave equation is used to calculate density, enthalpy, entropy, and liquid-vapor equilibrium data for mixtures. Use of this equation requires knowledge of the properties of the pure components used in the given mixtures, as well as the interaction coefficients for each binary system.

[0032] The data required for each pure ingredient are: Boiling point, critical temperature and pressure, pressure-temperature curve from boiling point to critical temperature, density of saturated liquid and saturated vapor as a function of temperature. HFC-32, HFC-152a:

[0033] Data for these products is published in ASHRAE Handbook 2005, Chapter 20, and is also available in Refrop (software developed by NIST for calculating the properties of refrigerant fluids). HFO-1234yf:

[0034] The temperature-pressure curve data for HFO-1234yf are measured using a static method. The critical temperature and pressure are measured using a C80 calorimeter sold by Setaram. The saturation density as a function of temperature is measured using a vibrating tube densimeter technology developed by the Ecole Mines de Paris laboratories. Binary Mixture Interaction Coefficient

[0035] The RK-Soave equation uses binary mixture interaction coefficients to represent the behavior of products in mixtures. These coefficients are calculated from experimental data on liquid-vapor equilibrium.

[0036] The technique used to measure the liquid-vapor equilibrium is the analytical static cell method. The equilibrium cell has a sapphire tube and is equipped with two electromagnetic ROLSITM sampling devices. It is immersed in a cryothermal bath (HUBER HS40). To accelerate the achievement of equilibrium, magnetic stirring with a variable speed rotating magnetic field drive is used. Sample analysis is performed by gas-phase chromatography (HP5890 series II) using a catharometer (TCD). HFC-32 / HFO-1234yf, HFC-152a / HFO-1234yf:

[0037] Liquid-vapor equilibrium measurements for the two-component system HFC-32 / HFO1234yf were carried out for the following isotherms: -10°C, 30°C and 70°C. Liquid-vapor equilibrium measurements for the two-component system HFC-152a / HFO-1234yf were carried out for the following isotherms: 10°C HFC-32 / HFO-152a:

[0038] Liquid-vapor equilibrium data for the HFC152a / HFC-32 binary system are available from Refprop. Two isotherms (-20°C and 20°C) and two isobars (1 bar and 25 bar) were used to calculate the interaction factors for this binary system. Compression system

[0039] A compression system equipped with a counterflow evaporator and condenser, a screw compressor and a pressure reducer is considered.

[0040] The system operates with an overheating of the order of 15°C and an undercooling of the order of 5°C. A minimum temperature difference of 5°C between the secondary fluid and the coolant fluid is taken into account.

[0041] The isentropic efficiency of compressors depends on the compression ratio. This efficiency is calculated according to the following equation:

[0042] For a screw compressor, the constants a, b, c, d and e of equation (1) for isentropic efficiency are calculated from typical data published in the "Handbook of air conditioning and refrigeration", page 11.52. The % CAP is the percentage ratio of the volumetric efficiency delivered by each product to the capacity of R-404A.

[0043] The coefficient of performance (COP) is defined as the ratio of the useful power delivered by a system to the power absorbed or consumed by that system.

[0044] The Lorenz coefficient of performance (Lorenz COP) is a reference coefficient of performance. It depends on temperature and is used to compare the COP of different fluids.

[0045] The Lorenz coefficient of efficiency is defined as follows:

[0046] (Temperatures T are given in degrees Kelvin)

[0047] Lorenz's COP for an air conditioning and refrigeration unit:

[0048] Lorenz's COP in case of heating:

[0049] For each composition, the Lorenz cycle efficiency coefficient is calculated as a function of the corresponding temperatures.

[0050] % COP / Lorenz COP is the ratio of the system COP to the COP of the corresponding Lorenz cycle. Results for heating mode

[0051] In heating mode, the pressurized system operates between an evaporator inlet refrigerant temperature of -5°C and a condenser inlet refrigerant temperature of 50°C. The system delivers heat up to 45°C.

[0052] The performance of the compositions of the invention under heating operating conditions is given in Table 1. The values ​​for the components (HFO-1234yf, HFC-32, HFC152a) for each composition are given in weight percent. Table 1

Claims

1. Patent claims 1. Use of a ternary composition of 2,3,3,3-tetrafluoropropene, 1,1-difluoroethane and difluoromethane as a heat transfer fluid in pressurized cooling systems with exchangers operating in countercurrent mode or in cross-flow mode with a countercurrent tendency.

2. Use according to claim 1, characterized in that the ternary composition comprises essentially from 20 to 80% by weight of 2,3,3,3-tetrafluoropropene and from 15 to 40% by weight of difluoromethane, and from 5 to 40% by weight of difluoroethane.

3. Use according to claim 1, characterized in that the ternary composition comprises essentially from 20 to 70% by weight of 2,3,3,3-tetrafluoropropene and from 20 to 40% by weight of difluoromethane, and from 10 to 40% by weight of difluoroethane.

4. Use according to claim 1, characterized in that the composition comprises essentially from 35 to 70% by weight of 2,3,3,3-tetrafluoropropene and from 20 to 25% by weight of difluoromethane, and from 10 to 40% by weight of difluoroethane.

5. Use according to any one of claims 1 to 4, characterized in that the composition is stabilized.

6. A heat transfer method comprising using ternary compositions comprising 2,3,3,3-tetrafluoropropene, 1,1-difluoroethane and difluoromethane as a heat transfer fluid in pressurized cooling installations with exchangers operating in a countercurrent mode or in a cross-flow mode with a countercurrent tendency.

7. The method of claim 6, wherein the composition comprises essentially from 15 to 70% by weight of 2,3,3,3-tetrafluoropropene and from 20 to 25% by weight of difluoromethane, and from 10 to 40% by weight of difluoroethane.

8. The method according to claim 6 or 7, characterized in that it is carried out in the presence of a lubricant. Authorized person: Arkema France Representative: Iwona Sierzputowska, M.Sc., Eng., Patent Attorney