A heat transfer composition for use in organic rankine power generation systems as an alternative to r245fa

Abstract

The application discloses a heat transfer composition for replacing R245fa and used in an organic Rankine power generation system, which is composed of a first component and a second component, wherein the first component is trans-octafluoro-2-butene, and the second component is cis-1,3,3,3-tetrafluoropropene. The heat transfer composition disclosed by the application has an ODP value of 0, a GWP value less than 2 and a combustion grade not more than weakly flammable. When the heat transfer composition is applied to an organic Rankine cycle power generation system, the output power of the system is greater than that when any single working medium is used alone, and the irreversible heat loss in the heat exchange process of a heat exchanger can be reduced.

Description

Technical Field

[0001] This invention relates to the field of heat transfer compositions, and more specifically to a heat transfer composition that can replace R245fa for use in organic Rankine power generation systems. Background Technology

[0002] The Organic Rankine Cycle (ORC) is a Rankine cycle that uses low-boiling-point organic compounds as the working fluid. Its working principle is that the working fluid absorbs heat from the heat source end, forming steam with a certain pressure and temperature. The steam enters the expander, expands and does work, thereby driving the generator. It is further condensed into liquid at the cold source end, and finally returns to the heat exchanger with the help of the working fluid pump, and the cycle continues indefinitely.

[0003] The working fluid, as the "blood" of a system, directly affects its overall efficiency and is crucial for the development and application of ORC technology. The selection of the working fluid must consider not only thermodynamic performance but also safety, stability, and environmental friendliness. Currently, the main working fluids used in ORC systems are hydrofluorocarbons (HFCs), hydrocarbons, and hydrocarbon-fluoroolefins (HFOs). HFCs mainly include R245fa and R123, but their high GWP (Gross Potentially Worn) value will likely lead to restrictions on their production and use in the future. Hydrocarbons offer excellent environmental performance, but their flammability poses certain safety hazards, limiting their application in ORC systems. Hydrofluoroolefins have attracted widespread attention due to their environmental friendliness and good thermodynamic properties. Currently, R1233zd(E) is a widely popular hydrocarbon-fluoroolefin working fluid on the market, offering excellent environmental performance and serving as a major alternative to HFCs such as R245fa. Summary of the Invention

[0004] The purpose of this invention is to provide a heat transfer composition that can replace R245fa for organic Rankine power generation systems, in order to solve the problem that the working fluid in the prior art does not take into account both environmental performance and system performance.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] This invention provides a heat transfer composition to replace 245fa for use in organic Rankine power generation systems, the composition comprising a first component and a second component.

[0007] The first component is trans-octafluoro-2-butene.

[0008] The second component is cis-1,3,3,3-tetrafluoropropylene.

[0009] The structural formula of trans-octafluoro-2-butene is shown in formula (1), and the structural formula of cis-1,3,3,3-tetrafluoropropene is shown in formula (2).

[0010]

[0011] Furthermore, by mass percentage, the first component accounts for 1-99%, and the second component accounts for 1-99%.

[0012] Furthermore, by mass percentage, the first component accounts for 1-70%, and the second component accounts for 30-99%.

[0013] Furthermore, by mass percentage, the first component accounts for 10-60%, and the second component accounts for 40-90%.

[0014] Furthermore, by mass percentage, the first component accounts for 30-50%, and the second component accounts for 50-70%.

[0015] Furthermore, by mass percentage, the first component accounts for 35% to 45%, and the second component accounts for 55% to 65%.

[0016] The heat transfer composition of the present invention also includes other impurities, such as hydrogen fluoride, moisture, carbon dioxide, etc., or impurities that are difficult to remove in the preparation of trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene.

[0017] The heat transfer composition described in this invention is a non-azeotropic composition, meaning that the liquid and gas phases have different compositions within a certain temperature and pressure range.

[0018] The heat transfer composition of the present invention has an ODP value of 0 and a GWP value of <2, with the GWP value being relative to CO2.

[0019] The heat transfer composition of the present invention has a combustion rating of no more than 2L, and the reference standard for combustion rating is ASHRAE 34.

[0020] The heat transfer composition of the present invention is applied to an organic Rankine cycle power generation system, wherein the system output power of the organic Rankine cycle power generation system is greater than the output power of using the first component alone or the output power of using the second component alone.

[0021] Furthermore, the heat transfer composition is applied to an organic Rankine cycle power generation system, wherein the system output power of the organic Rankine cycle power generation system is ≥20% relative to the output power when using R245fa working fluid, further, ≥30%, even further, ≥35%, and even further, ≥40%.

[0022] The present invention also provides a method for preparing a heat transfer composition to replace R245fa for use in an organic Rankine cycle power generation system, the preparation method comprising the step of mixing the first component and the second component in a liquid phase state at room temperature and pressure according to corresponding mass percentages.

[0023] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0024] (1) The heat transfer composition provided by the present invention has excellent environmental and safety performance, with an ODP value of 0, a GWP value of <2, and a combustion rating of no more than 2L (weak flammability).

[0025] (2) When the heat transfer composition provided by the present invention is applied to an organic Rankine cycle power generation system, the output power of the system is greater than that of using any single working fluid alone.

[0026] (3) When the heat transfer composition provided by the present invention replaces R245fa, due to the existence of temperature slip, it can reduce the irreversible heat loss in the heat exchange process of the heat exchanger in the organic Rankine cycle power generation system and improve the power generation performance of the system. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of an organic Rankine cycle power generation system, where 1 is a heat exchanger, 2 is a superheater, 3 is an expander, 4 is a generator, 5 is a condenser, and 6 is a working fluid pump. Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments, but the invention is not limited to these specific embodiments. Those skilled in the art should recognize that the present invention covers all alternatives, improvements, and equivalents that may be included within the scope of the claims.

[0029] The basic physical properties of the components involved in this invention are shown in Table 1 below.

[0030] Table 1 Basic physical properties of substances

[0031]

[0032] The heat transfer composition of this invention is prepared as follows: the components are mixed in liquid form at room temperature and pressure according to the corresponding mass percentages, and shaken evenly to form a homogeneous and stable non-azeotropic working fluid.

[0033] Example 1:

[0034] An environmentally friendly combined working fluid was obtained by physically mixing trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene at a mass ratio of 99:1 in a liquid phase at room temperature and pressure.

[0035] Example 2:

[0036] An environmentally friendly combined working fluid was obtained by physically mixing trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene at a mass ratio of 9:1 in a liquid phase at room temperature and pressure.

[0037] Example 3:

[0038] An environmentally friendly combined working fluid was obtained by physically mixing trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene at a mass ratio of 8:2 in a liquid phase at room temperature and pressure.

[0039] Example 4:

[0040] An environmentally friendly combined working fluid was obtained by physically mixing trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene at a mass ratio of 7:3 in a liquid phase at room temperature and pressure.

[0041] Example 5:

[0042] An environmentally friendly combined working fluid was obtained by physically mixing trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene at a mass ratio of 6:4 in a liquid phase at room temperature and pressure.

[0043] Example 6:

[0044] An environmentally friendly combined working fluid is obtained by physically mixing trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene in a 5:5 mass ratio in a liquid phase at room temperature and pressure.

[0045] Example 7:

[0046] An environmentally friendly combined working fluid was obtained by physically mixing trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene at a mass ratio of 4:6 in a liquid phase at room temperature and pressure.

[0047] Example 8:

[0048] An environmentally friendly combined working fluid was obtained by physically mixing trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene at a mass ratio of 3:7 in a liquid phase at room temperature and pressure.

[0049] Example 9:

[0050] An environmentally friendly combined working fluid was obtained by physically mixing trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene at a mass ratio of 2:8 in a liquid phase at room temperature and pressure.

[0051] Example 10:

[0052] An environmentally friendly combined working fluid was obtained by physically mixing trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene at a mass ratio of 1:9 in a liquid phase at room temperature and pressure.

[0053] Example 11:

[0054] A composite working fluid was obtained by physically mixing trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene at a mass ratio of 1:99 in a liquid phase at room temperature and pressure.

[0055] Comparative Example 1:

[0056] 1,1,1,3,3-Pentafluoropropane (R245fa)

[0057] Comparative Example 2:

[0058] 1-Chloro-3,3,3-trifluoropropene (R1233zd(E))

[0059] Comparative Example 3:

[0060] trans-octafluoro-2-butene

[0061] Comparative Example 4:

[0062] cis-1,3,3,3-tetrafluoropropylene (R1234ze(Z))

[0063] Table 2 shows the performance of the organic Rankine cycle power generation system (net output power relative to Comparative Example 1) and the basic physical properties of the heat transfer compositions of Examples 1-11 and Comparative Examples 1-4 under the operating conditions of the organic Rankine cycle power generation system (i.e., heat source temperature: 130°C, flow rate: 100 L / min; cold source temperature: 5°C, flow rate: 800 L / min; working fluid pump outlet pressure: 25 bar; expander outlet pressure: 2 bar; liquid working fluid flow rate: 20 L / min).

[0064] Table 2 Comparison of various performance indicators

[0065] heat transfer composition GWP Flammability rating Relative net output power Example 1 ＜2 1 1.01 Example 2 ＜1.9 1 1.11 Example 3 ＜1.8 1 1.19 Example 4 ＜1.7 1 1.27 Example 5 ＜1.6 1 1.34 Example 6 ＜1.5 1 1.39 Example 7 ＜1.4 1 1.40 Example 8 ＜1.3 1 1.37 Example 9 ＜1.2 1 1.35 Example 10 ＜1.1 1 1.31 Example 11 ＜1 Slightly flammable 1.03 Comparative Example 1 962 1 1 Comparative Example 2 7 1 0.69 Comparative Example 3 1.97 1 1.04 Comparative Example 4 ＜1 Slightly flammable 1.28

[0066] In terms of system performance, the system performance of all embodiments of the present invention is significantly better than that of R245fa and R1233zd(E). The net system output power of Embodiment 7 is increased by 40% compared with Comparative Example 1 and by 102% compared with Comparative Example 2, resulting in a significant improvement in system performance. The net system output power of Embodiments 5 to 10 is better than that of their respective component single working fluids, with the net system output power of Embodiment 7 being increased by 35% compared with Comparative Example 3 and by 9% compared with Comparative Example 4.

[0067] In terms of environmental performance, the environmental performance (GWP) of all embodiments of the present invention is significantly better than that of Comparative Example 1 and Comparative Example 2.

[0068] Regarding flammability, Example 11 has weak flammability, while the other examples are all non-flammable. The influence of the weak flammability of R1234ze(Z) on its application is eliminated by mixing the working fluid.

[0069] In summary, the heat transfer composition provided by this invention not only has the environmentally friendly characteristics of low GWP and zero ODP, but also has excellent safety performance. The power generation performance of the organic Rankine cycle system is not only significantly better than that of R245fa and R1233zd(E), but also better than the system performance of any of its components, and can replace R245fa and R1233zd(E).

Claims

1. A heat transfer composition for use in an organic Rankine power generation system as an alternative to R245fa, characterized in that: The composition consists of a first component which is trans-octafluoro-2-butene and a second component which is cis-1,3,3,3-tetrafluoropropene; The first component accounts for 10-60% and the second component accounts for 40-90% by mass percentage.

2. The heat transfer composition of claim 1 which is a replacement for R245fa for use in an organic Rankine power generation system. The first component accounts for 30-50% and the second component accounts for 50-70% by mass percentage.

3. The heat transfer composition of claim 2 which is an alternative to R245fa for use in organic Rankine power generation systems, characterized by: The first component accounts for 35-45% and the second component accounts for 55-65% by mass percentage.

4. Heat transfer composition for use in an organic Rankine power generation system as an alternative to R245fa according to any of claims 1 to 3, characterized in that: The output power of an organic Rankine power system using the heat transfer composition is greater than the output power of using the first component alone or the output power of using the second component alone.

5. The heat transfer composition of any of claims 1-3 as an alternative to R245fa for use in an organic Rankine power generation system characterized by: The output power of an organic Rankine power system using the heat transfer composition is ≥30% relative to the output power when using R245fa working medium.

6. The heat transfer composition of claim 5 which is an alternative to R245fa for use in organic Rankine power generation systems. The output power of an organic Rankine power system using the heat transfer composition is ≥35% relative to the output power when using R245fa working medium.

7. A heat transfer composition for use in an organic Rankine power generation system which is an alternative to R245fa according to any one of claims 1-3, characterized in that: The heat transfer composition is a non-azeotropic composition.

8. The heat transfer composition of any of claims 1-3 as an alternative to R245fa for use in an organic Rankine power generation system characterized by: The heat transfer composition has an ODP value of 0 and a GWP value <2.

9. A heat transfer composition for use in an organic Rankine power generation system which is an alternative to R245fa according to any one of claims 1-3, characterized in that: The heat transfer composition has a combustion rating of no more than weakly flammable.

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