Heat transfer fluid for on-board refrigeration systems.

Abstract

Heat transfer fluid for on-board refrigeration systems. The invention relates to the use of R1234ZE gas as a refrigerant, particularly in equipment comprising an on-board refrigeration system. Figure for the abstract: no figure.

Description

Title of the invention: Heat transfer fluid for on-board refrigeration systems.

[0001] The present invention relates to equipment incorporating integrated refrigeration systems. It relates more particularly to the refrigerants used in such equipment. This equipment includes, in particular, refrigerators, freezers, ice machines and cold water dispensers, refrigerated display cases and cabinets. The refrigeration system is an integral part of the equipment and can be moved with it in a single transport.

[0002] The refrigeration system comprises a closed circuit in which a refrigerant circulates, the change of which from a liquid phase to a gaseous phase being used to produce the cooling used in the equipment. The refrigerant is generally a gas, that is to say, at normal temperature and pressure, it is in a gaseous form.

[0003] Among these gases, chlorofluorocarbons (CFCs) were used for a long time, but they have proven harmful to the ozone layer in the atmosphere. They are also potent greenhouse gases. For this reason, they were banned by the Montreal Protocol (1987). They were notably replaced by hydrofluorocarbons (HFCs). However, these gases are also potent greenhouse gases; the F-GAS regulation (No. 5172-014), which came into force on January 1, 2015, and concerns refrigerants, aims to progressively reduce the marketing of HFCs and to ban certain other fluids.

[0004] New fluids have therefore been proposed. They must have a low Global Warming Potential (GWP); the acronym GWP stands for Global Warming Potential. Thus, the GWP must be less than 150.

[0005] The gradual ban on gases with a GWP greater than 150 has led to the emergence on the market of gases with little impact on global warming and ozone depletion. These new-generation gases, which manufacturers of equipment using refrigerants have turned to, are generally proving dangerous, particularly due to their high flammability.

[0006] Currently, there is an international classification of refrigerants based on their flammability:

[0007] - Al: non-flammable fluids

[0008] - A2L: Slightly flammable fluids

[0009] - A2: Flammable fluids

[0010] - A3: Highly flammable and explosive fluids

[0011] The following gases are thus known:

[0012] - R455A: it is classified A2L and has a GWP of 146. It is therefore flammable and its PRG is close to the upper acceptable limit;

[0013] - R454C: it is classified A2L and has a GWP of 146. It is therefore flammable and its PRG is close to the upper acceptable limit;

[0014] - R1234YF: it is classified A2L and has a GWP of 4. It is therefore flammable. even though its particularly low GWP II is used for air conditioning in automobiles;

[0015] -R290 (Propane): It is classified A3. It is therefore particularly dangerous; it is used In most cases, this applies to all onboard equipment (including refrigerators, freezers, refrigerated display cases, ice machines, and cold water dispensers). Due to its hazardous nature, this gas is strictly limited in charge weight to a maximum of 150g per circuit, and, in accordance with regulations for establishments open to the public, the total weight of all charges combined cannot exceed 1.250 kg.

[0016] - R600A and R600 (isobutane): it is classified A3 and has a GWP of 4. Like the Propane is therefore very dangerous, even though its GWP is particularly low. It is used in domestic refrigeration, but also in installations with integrated compressors for small appliances in public buildings; it has the same disadvantages and limitations as propane (R290).

[0017] It is noted that R290, R600A and R600 are gases of fossil origin, that is to say, derived from the distillation of crude oil by purification of natural gases or separation of liquefied petroleum gases.

[0018] One object of the invention is to provide a heat transfer fluid that exhibits both low hazard and a low global warming potential (GWP), while being suitable for use in on-board refrigeration units, particularly for equipment used in homes or in public buildings. It should be noted that reference is made here to European Community regulations.

[0019] To solve this problem, and firstly, the invention proposes a method in which R1234ZE gas is used as a refrigerant. Advantageously, R1234ZE gas is used as a refrigerant in equipment designed to produce cold, comprising an integrated refrigeration system. This equipment may be from the following list:

[0020] - positive or negative cold storage cabinets

[0021] - ice machines;

[0022] - refrigerated display cases;

[0023] - refrigerated furniture;

[0024] - water fountains connected to a network, or not;

[0025] - variable capacity rapid cooling cells;

[0026] - mobile cold storage cabinets for maintaining temperature; and,

[0027] - small and medium power heat pumps, including heat pumps heat from professional dishwashers.

[0028] Secondly, the invention relates to equipment implementing a process according to the invention.

[0029] Several embodiments of the invention will be described below, by way of non-limiting examples.

[0030] The gas named HFO-1234ze (hereinafter R-1234ZE) is a hydrofluorolefin with the chemical formula:

[0031] trans-l,3,3,3-Tetrafluoroprop-l-ene

[0032] This gas is classified A2L and has a GWP of 7:1, according to data provided by the classification body. It is used for propulsion and injection, particularly for the injection of liquid-phase polyurethane. It is not used in commercial refrigeration.

[0033] After studying the thermodynamic properties of R1234ZE gas, it became clear to us that it can fulfill the function of a refrigerant gas, not derived from fossil products, with a GWP of less than 5, while avoiding classification A3 (explosive and highly flammable). Although classified A2L (slightly flammable), this gas has the particularity of being non-flammable (i.e., classified in category Al) up to an ambient temperature of 30.0 °C. This gas is therefore more advantageous than R290, R600A, and R600, mentioned previously, on all criteria.

[0034] R1234ZE is a pure gas. Tests in a 700-liter and a 1400-liter refrigerated cabinet (HIBER M70TNN and M140 TNN cabinets) demonstrated that R1234ZE performs well in terms of both stability and refrigeration. These results are similar to those of R134A, also a pure gas, but now banned for all new equipment placed on the market since January 1, 2022.

[0035] We will now describe in more detail the test steps carried out. Each test is performed in the workshop. In the example described below, this concerns the 700-liter nominal capacity cabinet (HIBER M70TNN cabinet). The results of the tests with R1234ZE gas are compared with identical tests carried out on the same cabinet in its original configuration, prior to its modification and adaptation for the use of R1234ZE gas. The refrigerant originally used in the cabinet is R134A.

[0036] Step 1:

[0037] - Recovery of the original refrigerant gas (here R134A), and removal of the compressor of origin.

[0038] Step 2:

[0039] Installation of a compressor of the same power, adapted for use with R1234ZE gas. This compressor is in A2L configuration, that is to say that it is configured to operate with a slightly flammable refrigerant gas. Thus, the cabinet remains compliant with the requirements for use with R1234ZE gas in a public building.

[0040] Step 3:

[0041] Absolute vacuuming of the refrigeration circuit for 24 hours in order to detect any possible leaks.

[0042] Step 4:

[0043] After verifying that there is no leak, R1234ZE gas is injected into the circuit with the same value, i.e. the same weight of gas as for R134A, i.e. a charge of 285g.

[0044] Step 5:

[0045] A first test is carried out with a capillary expansion; two turns have been added to the capillary expansion system in order to validate the temperature drop time of the cabinet.

[0046] A second test was carried out by replacing the capillary relaxation system with a pressure regulator.

[0047] Step 6 - test of the initial descent time:

[0048] With an ambient temperature outside the cabinet of 35 degrees Celsius, the initial temperature drop from +35°C to +2°C took 24 minutes. This is 5 minutes shorter than with the original R134A gas.

[0049] Step 7 - Door opening test:

[0050] During a test simulating door openings for food refills, normal temperature increases were observed, ranging from +2°C to +8°C instantaneously. The products entering the cabinet were at 3°C. The time to return to the setpoint was 8 minutes, which is 1 minute less than with R134A. Ambient temperatures remained below 30°C, which is the temperature range for which R1234ZE is rated. Therefore, in the context of this test, the use of a compressor in an A2L configuration is redundant.

[0051] Step 8: Analysis of the test results.

[0052] This test demonstrates that R1234ZE gas possesses the thermodynamic qualities necessary for producing cold. These thermodynamic capacities are very close to those of a fossil-based gas, without its drawbacks. In particular, given its low hazard level, and even its complete absence of hazard at ambient temperatures, R1234ZE gas does not require complex, lengthy, and costly intervention and maintenance procedures on the refrigeration system, especially for replacing the compressor.

[0053] The same results are obtained in the first test, with the detent system capillary tube and in the second test, with the pressure regulator

[0054] All tests carried out on equipment using an on-board unit have shown us, from both an environmental and safety standpoint, a result at least equivalent to R290 (Propane), without its drawbacks. In particular, fossil fuel gases are limited in charge volume per circuit to a maximum of 150g and to 1.250kg of total charge in a public establishment, regardless of the size of that establishment. Given its very low GWP, R1234ZE gas is not subject to these limitations.

[0055] Although very surprisingly R1234Ze gas has never been used as a refrigerant to replace propane (R290), it performs just as well and does not have the disadvantages relating to safety and greenhouse effect.

[0056] The use of R1234ZE gas, particularly in equipment with an on-board refrigeration system, especially for domestic equipment or equipment usable in establishments open to the public.

[0057] It therefore appears that the field of application of R1234ZE gas includes, in particular, its use as a refrigerant for:

[0058] - positive and negative cold storage cabinets

[0059] - ice machines;

[0060] - refrigerated display cases;

[0061] - refrigerated furniture;

[0062] - water fountains connected to a network, or not;

[0063] - variable capacity rapid cooling cells;

[0064] - mobile cold storage cabinets for maintaining temperature;

[0065] - small and medium power heat pumps, including heat pumps heat from professional dishwashers; and,

[0066] - remote groups for cold rooms and temperature-controlled premises.

[0067] More generally, the field of use of the R1234ZE gas extends to all equipment intended to produce cold having an on-board refrigeration system.

[0068] Of course, the invention is not limited to the examples just described. On the contrary, the invention is defined by the following claims.

[0069] It will indeed appear to the person skilled in the art that various modifications can be made to the embodiments described above, in the light of the teaching which has just been disclosed to him.

Claims

Demands

1. A method for producing cold, characterized in that R1234ZE gas is used as the refrigerant in equipment for producing cold comprising an integrated refrigeration system, among: - cold storage cabinets; - ice machines; - refrigerated display cases; - refrigerated furniture; - water fountains connected to a network, or not; - variable capacity rapid cooling cells; - mobile refrigerated storage cabinets; and, - small and medium power heat pumps, including heat pumps for professional dishwashers.

2. Equipment for producing cold, characterized in that it uses R1234ZE gas as a refrigerant fluid which includes an on-board refrigeration system and which is included in the following list: - cold cabinets - ice machines; - refrigerated display cases; - refrigerated furniture; - water fountains connected to a network, or not; - variable capacity rapid cooling cells; - mobile refrigerated storage cabinets; and, - small and medium power heat pumps, including heat pumps for professional dishwashers.