JPS5842224B2 - mixed refrigerant - Google Patents

Description

[Detailed description of the invention] The present invention relates to a mixed refrigerant for a refrigerator.

Refrigerators are used for various purposes, and depending on the purpose, it is often desirable to increase the capacity of the refrigerator in use.

Generally, in large refrigerators where the compressor is driven by a belt rather than an electric motor, it is possible to increase the compressor capacity by replacing the pulley and increasing the rotation speed of the compressor. Actions are often taken.

However, most small refrigerators these days use hermetic compressors in which the motor and compressor are integrated, and it is impossible to change the rotation speed.

It is also well known that the refrigeration capacity of refrigerators of the same size increases when a refrigerant with a lower boiling point is used, so different refrigerants such as Freon 12, Freon 22, and Freon 502 are used. Sometimes.

However, in this case, it has been difficult to implement this method with a hermetic compressor because the refrigerating capacity changes greatly and the required motor output varies.

As a result of research into replacement refrigerants that can increase the refrigerating capacity simply by replacing the refrigerant without modifying the refrigerator, the present inventors found that in a refrigerator that uses chlorodifluoromethane, or Freon 22, Freon 22 and 2 with propane
By using a mixed refrigerant, it is possible to increase the refrigeration capacity without significantly changing the required motor output, and furthermore, refrigerators using such a mixed refrigerant have better refrigeration characteristics than refrigerators using conventional refrigerants. The present inventors have discovered that the present invention has excellent characteristics in several respects, and have completed the present invention based on this new knowledge.

The present invention relates to a two-component mixed refrigerant characterized by a mixture of chlorodifluoromethane and propane. By appropriately selecting O
The refrigerating capacity and energy efficiency are higher than when using Freon 22 alone, and therefore, by using such a mixed refrigerant in place of Freon 22, it is possible to increase the refrigerating capacity without significantly changing the required motor output. It is something that

Next, as an example, a 5 horsepower water-cooled kneading machine (
The results of operating a closed type refrigerant filled with Freon 22 alone and a mixed refrigerant of Freon 22 and propane are shown below.

In this test, the amount of water fed to the condenser and evaporator was
The same refrigerator was operated by changing only the refrigerant.

Table 1 shows the operating conditions and refrigeration characteristics of the refrigerant in the above test.

Figures 1, 2, and 3 show the changes in the condensing side pressure, the refrigerating capacity of the refrigerator, and the effective energy ratio (EER) due to changes in the mixing ratio of propane to Freon 22 in the above test. .

As shown in these figures and tables, under the above test conditions, as the mixing ratio of propane increases, the pressure on the condensing side increases and the refrigerating capacity increases until the mixing ratio of propane reaches about 30% by weight.

Refrigeration capacity is affected by the amount of refrigerant circulation, its characteristics, and the performance of the evaporator and condenser, and since the size of the refrigerator's heat exchanger is constant, the rate of increase in refrigerating capacity is small.

Furthermore, it has been found that by mixing propane, the effective energy ratio becomes larger than when Freon 22 is used alone, and this is a major feature of the mixed refrigerant of the present invention.

Normally, when different types of refrigerants are mixed, the value of the energy effective ratio becomes an intermediate value between the values of each refrigerant alone.

However, since the mixed refrigerant of the present invention has higher compatibility with refrigerating machine oil and higher heat transfer coefficient than Freon 22 alone, the effective energy ratio can be significantly increased with a propane mixing ratio as small as about 2 weight φ. It gradually increases with the propane mixing ratio, reaching a maximum rate of increase of 7 parts.

The effect of simultaneously improving the refrigerating capacity and the effective energy ratio simply by replacing the refrigerant is of great benefit in terms of refrigerator operation.

However, since the heat exchangers of the refrigerators are the same and the margin ratio is small, this feature reaches a maximum when the propane mixing ratio is around 10% by weight, and the energy effective ratio gradually decreases at mixing ratios higher than that.

In other words, when the mixing ratio is about 20% by weight or less, the energy effective ratio is maintained at a relatively high value, but when the mixing ratio is about 30%
Near the weight range, the effective energy ratio is lower than in the case of Freon 22 alone.

Furthermore, for comparison, Table 3 shows the results of operation in the same manner as in the above example using a three-component mixed refrigerant consisting of Freon 22, Freon 115 (chloropentafluoroethane) and propane and having the composition shown in Table 2.

From the above test results, the three-component mixed refrigerant of Freon 22/Freon 115/propane has a lower EER and EER increase rate than the two-component system of Freon 22/propane of the present invention, and in such a system, the present invention It can be seen that the effect of increasing EER due to the mixing of propane as in the above is not recognized at all.

Next, since the mixed refrigerant of the present invention contains propane, it becomes a combustible gas depending on the content.

Figure 4 is the journal of the Japanese Society of Fire Science, “Fire” 22 [1] 55-60.
(1972) depicts the explosion range of a mixed gas of Freon-22 and propane, as determined by the U.S. Bureau of Mines standard method, and the vertical and horizontal axes indicate the air concentrations of Freon-22 and propane, respectively. , the shaded area is the explosion area.

Therefore, when the concentrations of both are within this range, the mixed gas is flammable, and outside this range, it will not burn.

The concentrations of Freon 22 and propane at the intersection point A on the tangent to this region drawn from the origin of the graph in Figure 4 have a capacity of approximately 18% and 3.2%, respectively;
If the mixing ratio of propane is calculated using only 2 and propane, it is about 8.3% by weight.

This shows that the mixed refrigerant of the present invention does not burn and is very safe as long as the propane mixing ratio is kept below 8.3 weight coefficient.

However, according to the definition of combustible gas under the High Pressure Gas Control Law as "a substance that burns in the air at a concentration of 1O weight φ or less", the composition of a mixed gas that does not become combustible and contains the largest amount of propane is shown in Figure 4. From the above calculation, point B is found (the concentrations of Freon 22 and propane are 7.8 volume and 2.2 volume, respectively), and the propane mixing ratio at this point is about 13 weight φ.

From the above facts, it is necessary to select the propane mixing ratio in the mixed refrigerant of the present application from the range of 2 to 20% by weight for the purpose of increasing the refrigeration characteristics, and if safety etc. are taken into account, It is preferable to select from a range of 15% by weight.

[Brief explanation of the drawing]

Figure 1 shows the change in condensing side pressure due to a change in the mixture ratio of Freon 22 and propane' in the mixed refrigerant, Figure 2 shows the change in refrigerating capacity due to the change in the mixture ratio, and Figure 3 shows the energy efficiency due to the change in the mixture ratio. Shows the change in ratio. Further, FIG. 4 shows an explosion area of a mixed gas of Freon 22 and propane.

Claims (1)

[Scope of Claims] 1 Consisting only of chlorodifluoromethane and propane, the mixing ratio of propane to chlorodifluoromethane is 2 to 20
Mixing between weight and weight 1. A mixed refrigerant characterized by: 2. The mixed refrigerant according to claim 1, wherein the mixing ratio of propane is in the range of 2 to 15 weight range.