Heat transfer composition for replacing R245fa for organic Rankine power generation system

Abstract

The invention discloses a heat transfer composition replacing R245fa for an organic Rankine power generation system, the composition is composed of a first component and a second component, the first component is trans-octafluoro-2-butene, and the second component is cis-1, 3, 3, 3-tetrafluoropropene. The ODP value of the heat transfer composition is 0, the GWP value is smaller than 2, the combustion grade does not exceed weak flammability, when the heat transfer composition is applied to an organic Rankine cycle power generation system, the output work of the system is larger than the output work when any single working medium is independently used, and irreversible heat loss in the heat exchange process of a heat exchanger can be reduced.

Description

Technical Field

[0001] The invention relates to the field of heat transfer compositions, and in particular to a heat transfer composition for replacing R245fa and used in an organic Rankine power generation system. Background Art

[0002] Organic Rankine Cycle (ORC) is a Rankine cycle that uses low-boiling-point organic matter as the working fluid. Its working principle is that the working fluid absorbs heat from the heat source to form steam with a certain pressure and temperature. The steam enters the expander to expand and do work, thereby driving the generator, and further condenses into liquid at the cold source end. Finally, it returns to the heat exchanger with the help of a working fluid pump, and the cycle continues.

[0003] As the "blood" of the system, the working fluid can directly affect the overall efficiency of the system. It is crucial for the development and application of ORC technology. The selection of working fluids should not only consider thermal performance, but also safety, stability and environmental friendliness. The working fluids currently used in ORC systems are mainly hydrofluorocarbons, hydrocarbons and hydrocarbon-containing olefins (HFOs). Hydrofluorocarbons mainly include R245fa, R123, etc., but they have the disadvantage of a high GWP value and will be restricted in production and use in the future. Hydrocarbon working fluids have excellent environmental performance, but they are generally flammable and have certain safety hazards that limit their application in ORC systems. Hydrocarbon-containing olefins have environmental friendliness and good thermodynamic properties and have received widespread attention. The most popular hydrocarbon-containing olefin working fluid on the market is R1233zd (E), which has excellent environmental performance and is the main alternative working fluid for HFCs such as R245fa. Summary of the invention

[0004] The purpose of the present invention is to provide a heat transfer composition for use in an organic Rankine power generation system instead of R245fa, so as to solve the problem of working fluids in the prior art that both environmental performance and system performance are not taken into consideration.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] The present invention provides a heat transfer composition for replacing 245fa for use in an organic Rankine power generation system. The composition consists of 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-tetrafluoropropene.

[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, in terms of mass percentage, the first component accounts for 1 to 99%, and the second component accounts for 1 to 99%.

[0012] Furthermore, in terms of mass percentage, the first component accounts for 1 to 70%, and the second component accounts for 30 to 99%.

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

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

[0015] Furthermore, in terms of 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 may also contain other impurities, such as hydrogen fluoride, water, carbon dioxide, etc., or impurities that are difficult to remove during the preparation of trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene.

[0017] The heat transfer composition of the present invention is a non-azeotropic composition, that is, within a certain temperature and pressure range, the components of the liquid phase and the gas phase are different.

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

[0019] The flammability rating of the heat transfer composition of the present invention is not higher than 2L, and the reference standard for the flammability rating is ASHRAE 34.

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

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

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

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

[0024] (1) The heat transfer composition provided by the present invention has excellent environmental performance and safety performance, an ODP value of 0, a GWP value of <2, and a combustion level not higher 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 the output power when any single working fluid is used alone.

[0026] (3) When the heat transfer composition provided by the present invention replaces R245fa, due to the existence of temperature glide, 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of an organic Rankine cycle power generation system, wherein 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 DESCRIPTION

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

[0029] The basic physical property parameters of the components involved in the present invention are shown in Table 1 below.

[0030] Table 1 Basic physical properties of substances

[0031]

[0032] The preparation process of the heat transfer composition of the embodiment of the present invention is as follows: according to the corresponding mass percentage, it is mixed in liquid form at normal temperature and pressure, and shaken evenly to form a uniform and stable non-azeotropic combination working fluid.

[0033] Embodiment 1:

[0034] The two components of trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene are physically mixed at a mass ratio of 99:1 in a liquid phase at room temperature and pressure to obtain an environmentally friendly combined working fluid.

[0035] Embodiment 2:

[0036] The two components of trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene are physically mixed at a mass ratio of 9:1 in a liquid phase at room temperature and pressure to obtain an environmentally friendly combined working fluid.

[0037] Embodiment 3:

[0038] The two components of trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene are physically mixed at a mass ratio of 8:2 in a liquid phase at room temperature and pressure to obtain an environmentally friendly combined working fluid.

[0039] Embodiment 4:

[0040] The two components of trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene are physically mixed at a mass ratio of 7:3 in a liquid phase at room temperature and pressure to obtain an environmentally friendly combined working fluid.

[0041] Embodiment 5:

[0042] The two components of trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene are physically mixed at a mass ratio of 6:4 in a liquid phase at room temperature and pressure to obtain an environmentally friendly combined working fluid.

[0043] Embodiment 6:

[0044] The two components of trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene are physically mixed at a mass ratio of 5:5 at normal temperature and pressure in a liquid phase to obtain an environmentally friendly combined working fluid.

[0045] Embodiment 7:

[0046] The two components of trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene are physically mixed at a mass ratio of 4:6 in a liquid phase at normal temperature and pressure to obtain an environmentally friendly combined working fluid.

[0047] Embodiment 8:

[0048] The two components of trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene are physically mixed at a mass ratio of 3:7 in a liquid phase at room temperature and pressure to obtain an environmentally friendly combined working fluid.

[0049] Embodiment 9:

[0050] The two components of trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene are physically mixed at a mass ratio of 2:8 in a liquid phase at room temperature and pressure to obtain an environmentally friendly combined working fluid.

[0051] Embodiment 10:

[0052] The two components of trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene are physically mixed at a mass ratio of 1:9 in a liquid phase at room temperature and pressure to obtain an environmentally friendly combined working fluid.

[0053] Embodiment 11:

[0054] The two components of trans-octafluoro-2-butene and cis-1,3,3,3-tetrafluoropropylene are physically mixed at a mass ratio of 1:99 at normal temperature and pressure in a liquid phase to obtain an environmentally friendly combined working fluid.

[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-tetrafluoropropene (R1234ze(Z))

[0063] 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), the performance of the organic Rankine cycle system (relative to the net output work of the system of Comparative Example 1) when using the heat transfer compositions of Examples 1-11 and Comparative Examples 1-4 and the basic physical properties of the heat transfer compositions of Examples 1-11 and Comparative Examples 1-4 are shown in Table 2.

[0064] Table 2 Comparison of performance indicators

[0065] Heat transfer composition GWP Flammability level 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 Embodiment 11 ＜1 Weakly 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 Weakly 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 output work of the system of Example 7 is increased by 40% compared with that of Comparative Example 1 and by 102% compared with that of Comparative Example 2, and the system performance is greatly improved. The net output work of the systems of Examples 5 to 10 is better than the net output work of the systems of the single working fluids of their components, among which the net output work of the system of Example 7 is increased by 35% compared with that of Comparative Example 3 and by 9% compared with that of 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] In terms of flammability, Example 11 has weak flammability, and the combustion levels of other examples are all non-flammable. The influence of the weak flammability of R1234ze(Z) on its application is eliminated by mixing the working fluids.

[0069] In summary, the heat transfer composition provided by the present invention not only has the environmental protection 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 achieve the replacement of R245fa and R1233zd (E).

Claims

1. A heat transfer composition for replacing R245fa for an organic Rankine power generation system, characterized in that: The composition consists of a first component and a second component. The first component is trans-octafluoro-2-butene, The second component is cis-1,3,3,3-tetrafluoropropene.

2. The heat transfer composition for replacing R245fa for an organic Rankine power generation system according to claim 1, characterized in that: In terms of mass percentage, the first component accounts for 10-60%, and the second component accounts for 40-90%.

3. The heat transfer composition for replacing R245fa for an organic Rankine power generation system according to claim 2, characterized in that: In terms of mass percentage, the first component accounts for 30-50%, and the second component accounts for 50-70%.

4. The heat transfer composition for replacing R245fa for an organic Rankine power generation system according to claim 3, characterized in that: In terms of mass percentage, the first component accounts for 35% to 45%, and the second component accounts for 55% to 65%.

5. The heat transfer composition for replacing R245fa for an organic Rankine power generation system according to any one of claims 2 to 4, characterized in that: The output work of the organic Rankine power generation system using the heat transfer composition is greater than the output work of using the first component alone or the output work of using the second component alone.

6. The heat transfer composition for replacing R245fa for an organic Rankine power generation system according to any one of claims 2 to 4, characterized in that: The output power of the organic Rankine power generation system using the heat transfer composition is ≥30% relative to the output power when using R245fa as a working fluid.

7. The heat transfer composition for replacing R245fa for an organic Rankine power generation system according to claim 6, characterized in that: The output power of the organic Rankine power generation system using the heat transfer composition is ≥35% relative to the output power when using R245fa as a working fluid.

8. The heat transfer composition for replacing R245fa for an organic Rankine power generation system according to any one of claims 1 to 4, characterized in that: The heat transfer composition is a non-azeotropic composition.

9. The heat transfer composition for replacing R245fa for an organic Rankine power generation system according to any one of claims 1 to 4, characterized in that: The heat transfer composition has an ODP value of 0 and a GWP value of <2.

10. The heat transfer composition for replacing R245fa for an organic Rankine power generation system according to any one of claims 1 to 4, characterized in that: The heat transfer composition has a combustion rating of no more than weakly flammable.

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