Heat transfer fluid for on-board refrigeration systems

Abstract

The invention relates to the use of the R1234ZE gas as refrigerant, in particular in equipment comprising an on-board refrigeration system.

Description

[0001] Heat transfer fluid for on-board refrigeration systems.

[0002] DESCRIPTION

[0003] The present invention relates to equipment comprising on-board refrigeration systems. It relates more particularly to the refrigerants used in such equipment. Among these equipments, we know, in particular, refrigerators, freezers, ice machines and cold water fountains, display cases and refrigerated furniture. The refrigeration system is an integral part of the equipment and can be moved in one go with this equipment.

[0004] The refrigeration system consists of a closed circuit in which a refrigerant circulates, the transition from a liquid phase to a gaseous phase of which is used to produce cold used in the equipment. The refrigerant is generally a gas, that is to say that at normal temperature and pressure, it is in a gaseous form.

[0005] Among these gases, chlorofluorocarbons (CFCs) were used for a long time, and they have proven harmful to the ozone layer of the atmosphere. They are also powerful greenhouse gases. They were therefore banned by the Montreal Protocol (1987). They have been replaced by hydrofluorocarbons (HFCs). However, these gases are also powerful greenhouse gases; the F-GAS regulation (n°5172-014) which came into force on 01 / 01 / 2015 and relates to refrigerants aims to gradually reduce the marketing of HFCs and to ban certain other fluids.

[0006] New fluids have therefore been proposed. They must have a low Global Warming Potential (GWP); the acronym GWP corresponds to the acronym GWP, from the English (Global Warning Potential). Thus, the GWP must be less than 150.

[0007] REPLACEMENT SHEET (RULE 26) The gradual ban on gases with a GWP greater than 150 has thus seen the emergence on the market of gases with little impact on global warming and the reduction of the ozone layer. These new generation gases, which manufacturers of equipment using a refrigerant have turned to, are generally dangerous, particularly due to their high degree of flammability.

[0008] Currently there is an international classification of refrigerants based on their flammability:

[0009] - Al: non-flammable fluids

[0010] - A2L: slightly flammable fluids

[0011] - A2: flammable fluids

[0012] - A3: highly flammable and explosive fluids

[0013] We know the following gases:

[0014] - R455A: it is classified A2L and has a GWP of 146. It is therefore flammable and its GWP is close to the upper acceptable limit;

[0015] - R454C: it is classified A2L and has a GWP of 146. It is therefore flammable and its GWP is close to the upper acceptable limit;

[0016] - R1234YF: it is classified A2L and has a GWP of 4. It is therefore flammable, even if its particularly low GWP II is used for air conditioning in automobiles;

[0017] -R290 (Propane): it is classified A3. It is therefore particularly dangerous; it is used in most cases for all on-board equipment (including refrigerators, freezers, refrigerated glassware, ice machines and cold water fountains). Due to its dangerousness, this gas is very limited in charge weight to 150g maximum per circuit, and, in accordance with the regulations for establishments open to the public, all the charges added together cannot exceed a total weight of 1,250 kg.

[0018] SUBSTITUTION SHEET (RULE 26) - R600A and R600 (iso butane): it is classified A3 and has a GWP of 4. Like propane, it is therefore very dangerous, even if its GWP is particularly low. It is used in domestic refrigeration, but also on installations with an on-board unit for small appliances in establishments open to the public; it has the same disadvantages and constraints as propane (R290).

[0019] It should be noted that R290, R600A and R600 are gases of fossil origin, i.e. produced by the distillation of crude oil by purification of natural gas or separation of liquefied petroleum gas.

[0020] One aim of the invention is to propose a heat transfer fluid which presents both low hazard and low global warming potential (GWP), while being suitable for use in on-board refrigeration units, particularly for equipment for domestic use or in establishments open to the public. It should be noted that reference is made here to the regulations of the European Community.

[0021] 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 intended to produce cold comprising an on-board refrigeration system. This equipment may be in the following list:

[0022] - positive or negative cold cabinets

[0023] - ice machines;

[0024] - refrigerated display cases;

[0025] - refrigerated furniture;

[0026] - water fountains connected to a network, or not;

[0027] - rapid cooling cells of variable capacity;

[0028] - mobile cold temperature maintenance cabinets; and,

[0029] REPLACEMENT SHEET (RULE 26) - small and medium power heat pumps, including heat pumps for professional dishwashers.

[0030] Secondly, the invention relates to equipment implementing a method according to the invention.

[0031] Several embodiments of the invention will be described below, by way of non-limiting examples.

[0032] The gas named HFO-1234ze (hereinafter R-1234ZE) is a hydrofluorolefin with the chemical formula: trans- 1 ,3,3,3-Tetrafluoroprop- 1-ene

[0033] This gas is classified A2L and has a GWP of 7 / 1, according to the 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.

[0034] After studying the thermodynamic capabilities of R1234ZE gas, it appeared to us that it can fulfill the function of refrigerant gas, not derived from fossil products, with a GWP of less than 5 while avoiding the A3 classification (explosive and highly flammable). Although classified A2L (slightly flammable) this gas has the particularity of not being 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, previously mentioned, on all criteria.

[0035] R1234ZE is a pure gas. Tests in a 700-liter refrigerated cabinet and a 1400-liter refrigerated cabinet (HIBER M70TNN and M140 TNN cabinets) have shown that R1234ZE has good results, both in stability and refrigeration. These results are similar to those of R134A gas, also a

[0036] REPLACEMENT SHEET (RULE 26) pure gas, but now prohibited for all new equipment placed on the market since 1 er January 2022.

[0037] We will now describe in more detail the test steps carried out. Each test is carried out in the workshop. In the example described below, it concerns the 700 litre nominal 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.

[0038] Step 1:

[0039] - Recovery of the original refrigerant gas (here R134A), and removal of the original compressor.

[0040] Step 2:

[0041] Installation of a compressor of the same power, suitable for use with R1234ZE gas. This compressor is in A2L configuration, meaning it is configured to operate with a slightly flammable refrigerant gas. This ensures that the cabinet remains compliant with the requirements for use with R1234ZE gas in a public building.

[0042] Step 3:

[0043] Absolute vacuuming of the refrigeration circuit for 24 hours in order to detect any leaks.

[0044] Step 4:

[0045] After checking that there are no leaks, inject R1234ZE gas into the circuit with the same value, i.e. the same weight of gas as for R134A, i.e. a charge of 285g.

[0046] SUBSTITUTION SHEET (RULE 26) Step 5:

[0047] A first test is carried out with a capillary expansion; two turns were added to the capillary expansion system in order to validate the temperature reduction time of the cabinet.

[0048] A second test was carried out by replacing the capillary expansion system with a pressure reducer.

[0049] Step 6 - Initial Descent Duration Test:

[0050] With the ambient temperature outside the cabinet being 35 degrees Celsius, the initial drop from this temperature of +35°C to +2°C took 24 minutes. This time is 5 minutes less than with the original R134A gas.

[0051] Step 7 - Door opening test:

[0052] During a test simulating door openings for filling with food, normal temperature increases were observed, ranging from +2°C to +8°C instantaneously. The products entering the cabinet were at 3°C. The time taken to return to the set point was 8 minutes, which is 1 minute less than with R134A. Ambient temperatures remained below 30°C, temperatures for which R1234ZE is classified. In the context of this test, the use of a compressor in A2L configuration is therefore superfluous.

[0053] Step 8: Analysis of the test results.

[0054] This test demonstrates that R1234ZE gas has the thermodynamic qualities necessary for producing cold. These thermodynamic capacities are very close to those of a fossil-based gas, without the drawbacks. In particular, R1234ZE gas, given its low hazard, and even its total absence of hazard at ambient temperatures, does not require the complex, long and costly intervention and repair procedures

[0055] REPLACEMENT SHEET (RULE 26) maintenance on the refrigeration system, in particular to replace the compressor.

[0056] The same results are obtained in the first test, with the capillary expansion system and in the second test, with the expander

[0057] All tests carried out on equipment using an on-board unit have shown us, both ecologically and in terms of safety, a result at least equivalent to R290 (Propane), without its drawbacks. In particular, fossil gases are limited in charge volumes per circuit to a maximum of 150g and to 1,250kg for all charges added together in a building open to the public, regardless of the size of the building. Given its very low GWP, R1234ZE gas is not subject to these limitations.

[0058] Although surprisingly R1234Ze gas has never been used as a refrigerant to replace propane (R290), it is just as efficient and does not have the disadvantages relating to safety and the greenhouse effect.

[0059] The use of R1234ZE gas, particularly in equipment with an on-board refrigeration system, particularly for domestic equipment or equipment usable in establishments open to the public.

[0060] It therefore appears that the scope of use of R1234ZE gas includes in particular use as a refrigerant for:

[0061] - positive and negative cold cabinets

[0062] - ice machines;

[0063] - refrigerated display cases;

[0064] - refrigerated furniture;

[0065] - water fountains connected to a network, or not;

[0066] REPLACEMENT SHEET (RULE 26) - rapid cooling cells of variable capacity;

[0067] - mobile cold temperature maintenance cabinets;

[0068] - small and medium power heat pumps, including heat pumps for professional dishwashers; and,

[0069] - remote groups for cold rooms and temperature-controlled premises.

[0070] More generally, the scope of use of R1234ZE gas extends to all equipment intended to produce cold with an on-board refrigeration system.

[0071] Of course, the invention is not limited to the examples just described. On the contrary, the invention is defined by the claims which follow.

[0072] It will indeed appear to those skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to them.

[0073] SUBSTITUTION SHEET (RULE 26)

Claims

CLAIMS 1. Process for producing cold, characterized in that R1234ZE gas is used as refrigerant.

2. Method according to claim 1, characterized in that the R1234ZE gas is used as a refrigerant in equipment intended to produce cold comprising an on-board refrigeration system.

3. Method according to claim 2, characterized in that the material is included in the following list: - cold cabinets - ice machines; - refrigerated display cases; - refrigerated furniture; - water fountains connected to a network, or not; - rapid cooling cells of variable capacity; - mobile cold temperature maintenance cabinets; and, - small and medium power heat pumps, including heat pumps for professional dishwashers.

4. Equipment for producing cold, characterized in that it uses R1234ZE gas as refrigerant.

5. Equipment according to claim 4, characterized in that it comprises an on-board refrigeration system.

6. Material according to claim 5, characterized in that it is included in the following list: - cold cabinets - ice machines; - refrigerated display cases; refrigerated furniture; - water fountains connected to a network, or not; - rapid cooling cells of variable capacity; - mobile cold temperature maintenance cabinets; and, - small and medium power heat pumps, including heat pumps for professional dishwashers.