JPS59102992A - Working fluid for rankine cycle - Google Patents

Abstract

PURPOSE:A novel working fluid for the Rankine cycle, consisting of dichlorotetrafluoroethane and difluoroethane, having improved energy conversion efficiency, heat exchange characteristics and thermal stability, and usable for the Rankine cycle. CONSTITUTION:A working fluid, consisting of a mixture of (A) preferably 90- 60wt% dichlorotetrafluoroethane with (B) preferably 10-40wt% difluoroethane, and usable for the Rankine cycle. EFFECT:A small amount of halogen is formed at high temperatures, and metallic materials in apparatuses are not easily corroded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention incorporates a new and previous fluid for Rankine cycles.

By heating and evaporating a liquid medium using thermal energy and expanding it once within one loaf of an expansion device, one mechanical energy is obtained, and then this medium is condensed and pressurized by a pump to form a liquid medium.The cycle is repeated. Water is almost the only working fluid that has traditionally been used as a working fluid for the Rankine cycle, which converts thermal energy into machine energy. Water as a working fluid has been used in steam engines for a long time. However, water has a high freezing point and a large vapor specific volume, which limits the scope of its use.Especially when using a low-temperature heat source, water has the disadvantage of increasing ij:2 and reducing efficiency. Because it freezes when used, there is a limit to how much wet ash can be used for toilet use.

Many organic products such as those that improve the drawbacks of water! Although lvr fluids have been proposed, many are flammable or 1. Due to Ilt erosivity, it is still 7
The ones that can be used with both feet are not the best.

However, among these, the one that has been put into practical use is trichlorofluoromethane (hereinafter referred to as Freon-11), but the working fluid for the Rankine cycle, which is made of Freon-11, has a low conversion efficiency from thermal energy to mechanical energy. In addition to having a female point, when the heating temperature is high, it decomposes and the thermodynamic properties of Freon-11 become qualitative, further reducing the energy conversion effect mentioned above. In addition, Freon-1
When 1 is decomposed by heating, halogen is liberated, and this liberated halogen causes corrosion of 11.

Because of the above-mentioned drawbacks, Freon-11 is not a working fluid that can be used with any heating source.

Therefore, the emergence of a ready-to-use fluid with high energy conversion efficiency and good heating stability is expected.

The inventors of the present invention have conducted various studies in response to such demands, and have found that, although all conventional IJ working fluids have been researched and used as single substances, they have been developed by mixing substances with different characteristics. It was discovered that a mixed system exhibits superior properties compared to a single substance.In particular, a mixture consisting of dichlorotetrafluoroethane (hereinafter referred to as Freon-114) and difluoroethane (hereinafter referred to as Freon-152) was used for the Rankine cycle. of? It was discovered that it had extremely excellent properties as an IJ fluid, and led to the completion of ``Fujitsu 1''1.

The mixed system of Freon-114 and Freon-152 of the present invention has the following characteristics as a pre-production fluid for Rankine cycle.

First, in the Rankine cycle using a mixed system of Freon-114 and Freon-152, the mechanical energy obtained from the heat source energy, that is, the energy exchange efficiency is -114 (dichlorotetrafluoroethane) has sufficiently better properties.

Second, high stability is required as a simple characteristic that a working fluid for a Rankine cycle should have.In this respect, the conventionally known HU-K Laflon 11 decomposes at high temperatures, so it cannot be used when the heat source temperature is high. On the other hand, Freon-114 and Freon-152 of the present invention do not decompose at room temperature and maintain high stability even in high temperature ranges, and this excellent mixture also exhibits the same stability as Ir11. have.

Furthermore, Freon-152 is flammable, but this January issue! The IFJ production fluid has reduced flammability due to the inclusion of Freon-114 as a component, and has no flammability when the composition has a large mixing ratio of 70-114.

In the present invention, Freon-114 and Freon-152 can be mixed in a wide range of mixing ratios, but in consideration of combustibility, it is preferable to use a mixing ratio in which Freon-152 is in a range of 40% or less.

Pressure of a mixture of Freon-114 and Freon-152 (mixing ratio 701 [acupuncture %/30 koi %])
It is an enthalpy diagram (P-HIFit diagram), and the points A, B, C, D, and h written in the diagram are the following diagrams 2 and 3 of the Rankine cycle applied in the example below, respectively. This corresponds to each state point of the Rankine cycle described in .

Figure 2 is a Rankine cycle system diagram for converting πζ energy into mechanic Nerky, and Figure 3 is a Freon-
The Rankine cycle using a mixture of Freon-114 and Freon-152 as the working fluid is shown on a temperature en)o diagram.

Note that the notation Jij (A-E) in FIG. 2 corresponds to each state point indicated by the symbol (A-E) in FIG.

The working fluid heated by the steam generator (4) evaporates and becomes steam at high temperature and 6 pressures. This state of eclipse is shown in Figure 3 (L).
), ■), and (4). During this time, the liquid working fluid is heated and its temperature rises, and d8 begins to rise, and the entire amount is vaporized. This working fluid vapor then enters the expansion device (1) and undergoes adiabatic expansion to lower its temperature and pressure and perform the work shown in (2)-03) in FIG. ; Expansion device (1)
The working fluid that performs work inside and becomes low temperature and low pressure then enters the condenser @(2) and is condensed and liquefied as shown at ([4)-(C)] in Fig. 3. This liquefied working fluid is pumped (
3), the pressure is increased and the steam generator fM(4)
.

, and the cycle as described above is repeated. Note that in Figure 3, point (a) indicates the state of hot water when the hot water that is the heat source enters the Rankine cycle steam generator, and point (b)
) fd indicates the state of the hot water when it leaves the steam generator, and the arrow on the l line drawn from point (a) to point (1)) indicates the direction of flow of hot water. . Also, point (d),
(e) shows the state of the cooling water in the condenser, and (d) shows the state of the cooling water in the condenser.
The state of the cooling water at the outlet of the mJ machine is shown, from point (d) to point (e
) indicates the direction of the flow of cooling water.

As the lung expansion device used in the above-mentioned Rankine cycle, a rotary or reciprocating positive displacement cannon or a turbine expander can be used. Those of the same type can also be used, and as the condensing device, those of the type used in refrigeration equipment can be used. As the bonder, a pressurized liquid pump for the post-I solvent, which is generally used for chemical solutions (α), can be used.

Next, the present invention will be explained with reference to Examples, Comparative Examples, and 51 various trial samples. The blending ratio of each component is expressed in weight %.

Examples 1 to 4 and Comparative Example 1 According to the Rankine cycle shown in FIGS. 1 to 3 above, mixtures of Freon-114 and Freon-152 of the present invention at various mixing ratios and Freon-114 were used as working fluids in the same apparatus. This cycle was run by: The operating conditions are shown in Figure 3 (the hot water temperature at point aJ is set at two levels, 110°C and 140°C, and the cooling water temperature shown at points (d) and (e) is set at 25°C and 32°C, respectively. ℃, we calculated the output characteristics when generating electricity using mechanical energy obtained from 1500 t/hour of thermal energy of ntJ hot water, and obtained the results shown in Table 1.The evaporation temperature of this cycle is the maximum output. The condensation temperature is 35°C.

Table 1 Hot water 16.1 degrees 110℃ Thread (water d; ^J,, It 140℃ From the results of the first person, the mixture of Freon-114 and 70-152 The improvement in the output characteristics due to the thread is remarkable, and the inclusion of waste in the output is particularly observed in the set Ml where the mixture ratio of Freon-152 is 10% or more.Furthermore, the mixed system of Freon-114 and Freon-152 It has been found that the steam M heat degree at the turbine outlet is small and the cycle efficiency is improved when the steam temperature is increased. Therefore, a mixing ratio of 1 Asahi H in terms of combustibility and power output is preferable.

Next, Freon-114 and Freon-11 alone and unexploded 1
Freon-114/Freon-152 (and 1-total ratio 70/
The working fluid of 30) was sealed in a glass shield tube together with scissors and lubricating oil, and heated at 150°C for 100°C.
After heating for 4 minutes, the halogen concentration of the Hp working fluid in the shield tube and the power of decomposition products were measured using a gas chromatograph. The results are shown in Table 2.

As shown in Table 2, Freon-11 and 70-114
11 (, respectively) Compared to the German NtlJ working fluid, the mixed thread of Freon-114 and Freon-152 of the present invention produces less halogen ions at 6 temperatures, and the decomposition products fr detected by gas chromatography analysis: A little fx.

In the case of the Freon-114/Freon-152 mixed system, the small amount of halogen produced at sub-temperatures means that it is less likely to corrode the metal materials of the equipment, and it is said that there are almost no decomposition products. This means that during use, the increase in decomposition products will prevent narrowing of the thermodynamic properties and decrease in efficiency as a working fluid for Rankine cycle.

As mentioned above, incomplete 4 Freon-114 and Freon-1
The mixed system with 52 is superior to conventional Freon-11, Freon-114, etc. in terms of energy conversion efficiency, IL conversion characteristics, and thermal stability, and has excellent Rankine cycle operation. Can be used as a fluid.

[Brief explanation of drawings]

Figure 1 is a pressure Keren-Kurvy diagram of the 7on-114/Freon-152 mixture M, which is a non-exploding Rankine cycle fluid, and Figure 2 is a Rankine cycle I) h system 1'
l, M'y 3 The figure shows Freon-114/Freon-15
FIG. 2 is a temperature-entropy diagram showing a Rankine cycle using a two-mixing system as a UJ working fluid. (That's all), 7 pa. Representative J'11 Patent Attorney Hide Saegusa 2. :,'ヂFigure 2A ヱ1'ヅ3

Claims (1)

[Claims] ■ A working fluid for Rankine cycle consisting of dichlorotetrafluoroethane and difluoroethane. ■ Dichlorotetrafluoroethane is 90-60% by weight
The working fluid for Rankine cycle according to claim 1, wherein the amount of difluoroethane is 1θ to 40% by volume.