JPS61138058A - Heat pump device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a heat pump device using a non-azeotropic mixed refrigerant as a working medium. The non-azeotropic mixed refrigerant used is a mixture of two or more media with different boiling points, and the gas and liquid phases have different compositions, so even when evaporated or condensed under a constant pressure, the It is a refrigerant that causes temperature changes during the phase change process. Conventionally, in a heat pump device using a non-azeotropic mixed refrigerant, in a cycle connected to a compressor, a condenser, an expansion mechanism, and an evaporator, the condenser and evaporator are connected to a fluid to be heated that serves as a heat source; It is being considered to reduce irreversible loss in the heat exchange process and increase efficiency by exchanging heat between the fluid to be cooled and the non-azeotropic mixed refrigerant in a counter-flow format. In implementing this, a large effect can be achieved by matching as much as possible the temperature rise of the heated fluid and the temperature drop due to the condensation process of the non-azeotropic mixed refrigerant, and the temperature drop of the cooled fluid and the temperature rise due to the evaporation process of the non-azeotropic mixed refrigerant. can be caused.

However, when such a non-azeotropic mixed refrigerant is used in a heat pump device, the refrigerant leaks from the device to the outside, and the refrigerant composition inside the device changes and becomes different from its initial state. This may reduce the effect of suppressing irreversible loss in the heat exchange process of evaporation and condensation as described above.

In what part of the equipment does the composition change due to this refrigerant leak occur?
It is difficult to quantitatively detect this because it changes depending on how much water is left in the refrigerant mixture.Also, even if you try to restore the refrigerant composition to the same as before the leak by replenishing it from outside, some of the elemental media that make up the mixed refrigerant There were extremely difficult technical problems, such as not knowing which medium and how much to inject into the patient's throat.

[Purpose of the invention]

This invention was devised in view of the above problems, and even if refrigerant leaks from the device, it is possible to quantitatively detect changes in the composition of the refrigerant due to the leakage, and to restore the composition to the same composition as before the leakage. A heat pump device that allows you to know the approximate amount of refrigerant to be injected when replenishing refrigerant from:
The purpose is to provide.

[Summary of the invention]

In order to achieve the above object, the present invention provides a method for detecting the temperature and pressure inside the heat pump device using a non-azeotropic mixed refrigerant and connecting a compressor, a condenser, an expansion mechanism, and an evaporator. This is a heat pump device configured to include a temperature detection section and a pressure detection section.

〔Effect of the invention〕

According to the configuration of the present invention, even if the refrigerant leaks from the device to the outside, a change in the composition of the refrigerant within the heat pump device can be detected. Further, by using the vapor-liquid equilibrium diagram of the non-azeotropic mixed refrigerant, it is possible to know the type of elemental medium required for replenishment and the approximate injection amount. This makes it possible to realize a heat pump device with extremely high maintainability and reliability.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIG.

FIG. 1 is a diagram showing a heat pump device according to an embodiment of the present invention. In FIG. 5, 1 is a compressor, 2 is a condenser, 3 is an expansion mechanism, and 4 is an evaporator. The non-azeotropic refrigerant mixture 5a compressed by the compressor 1 exchanges heat with the heated fluid 6 supplied to the outside as a high-temperature heat source in the condenser 2 in a counterflow manner, and is condensed in a high pressure state.

The liquefied non-azeotropic mixed refrigerant liquid 5b is depressurized by the expansion mechanism 3 and flows into the evaporator 4.Here, the refrigerant exchanges heat with a low-temperature heat source fluid 7 such as hot wastewater from a factory in a counterflow manner, and is in a low-pressure state. It is evaporated and supplied to the compressor 1.

The heat pump device, which is an embodiment of the present invention shown in FIG. This is where the detection unit 9 is installed. Accurate thermometers and pressure gauges are used to detect temperature and pressure. From these two detected values, it is possible to know the degree of change in the composition of the refrigerant in the device, the type of elemental refrigerant required for replenishment, and a guideline for the required injection amount, making it possible to realize a heat pump device with high maintainability and reliability. .

In order to determine the degree of change in refrigerant composition, first stop the device, leave it for a while, wait until the refrigerant in the device reaches an equilibrium state, and then measure the refrigerant temperature and pressure inside the device. An example of a method for evaluating the detected value is as follows. First, the detected temperature value to is converted to a saturated pressure Ps using the relationship diagram of the saturated pressure and temperature of the propellant as shown in Figure 2, and then the detected pressure value P' and its saturated pressure Pst are compared. Find the difference P' - Ps. The difference means a deviation from the initial state of the refrigerant composition, and the refrigerant may be replenished when the absolute value of the difference exceeds a preset value. Here, the relationship diagram between saturation pressure and temperature shown in Fig. 2 shows the internal volume of the heat pump device, mixed refrigerant f:, types of component refrigerants, initial mixing of refrigerants,
It is determined by the initial amount of light.

Next, when replenishing the refrigerant, a method for determining the type of elemental medium necessary for replenishment and the approximate injection amount will be explained using a non-azeotropic mixed refrigerant consisting of two components (A and B) as an example. FIG. 3 is a diagram showing the vapor-liquid equilibrium relationship of the mixed refrigerant at a constant temperature tmto K.

P on the vertical axis means pressure, and XA on the horizontal axis means the weight fraction of component A. FB at K where XA=O (B component only).

XA-1 (A component only) FA in K is the saturation pressure at the temperature to of the B component and A component, respectively, and in the figure A
In Figure 5, the saturation pressure is higher, which means it evaporates more easily.XA = Q; P = PB.

Two curves passing through the two points of XA=1; P=FA are drawn. The upper curve is called the liquidus line, and the lower curve is called the vapor line. In an equilibrium state, only liquid can exist in the mixed refrigerant in the region above the liquidus line, and only vapor can exist in the region below the vapor phase line. The region between both curves is the coexistence region of liquid and gas.

Now, in order to find out the approximate amount of refrigerant replenishment using this diagram, follow the steps below. From Figure 2, temperature t=t
Find the saturation pressure Ps in the initial state of the heat pump device at point o, and read the value of XA at the point where the horizontal line drawn at that pressure Ps intersects the liquidus line and the gaseous phase line in FIG. Intersection with liquidus line XA=XAL, intersection with gaseous line XA=
wXAv, and its value is the weight fraction (value in twto) of component A in the liquid phase and gas phase of the refrigerant in the heat pump device when the refrigerant is first filled, respectively. Read the XAO value at the point where the horizontal line drawn by the detected pressure value P' measured at tmto intersects the liquidus line and the gas phase line.The intersection with the liquidus line is XA=X
A II ', the intersection with the gas phase line is XA=XAv', the value of which indicates the weight fraction of the component in the liquid phase and gas phase of the refrigerant in the heat pump device at that time.

If P' (Ps as shown in the figure), then XA IJ'<
XA L.

XAY'< Conversely, if P")Ps, then XAL'>
XAL, XAv'>XAv, and contrary to the above case, it is necessary to additionally inject the element medium of B.

Now, the amount of additional injection is not strictly known because the amount of refrigerant leakage is unknown, but it is sufficient that the amount is smaller than ΔGA and ΔGB calculated by the following equations.

P' (When injecting element □ medium person in Ps, ΔGA=GB
(XAL-XAL')+Gv(XAv-Xhv'
)P') When injecting element medium B at Ps, ΔGB=GL
(XAL' -XAII)+GV (XAV' -XA
v) Here, GL and Gv are the weights of the liquid phase and gas phase (temperature t) when the heat pump device is first filled with refrigerant.
= value at to) and is a value calculated from the internal volume of the device, the initial mixing ratio of the refrigerant, and the initial light perspective.

However, since the above ΔGA and ΔGB are just upper limit values, the actual injection work requires ΔG.

It is necessary to inject a fraction of ΔGB of refrigerant while detecting the pressure and temperature inside the device. This work can be completed at the moment when the values of Ps and P' described above match.

As described in detail above, according to the present invention, even if the refrigerant leaks, the original refrigerant composition can be easily restored, making it possible to realize a highly reliable heat pump device. Note that the present invention can be used not only for heat pump devices but also for refrigerators.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a heat pump device according to an embodiment of the present invention, Fig. 2 is a diagram showing the relationship between saturation pressure and temperature of a non-azeotropic mixed refrigerant used in the heat pump device of the present invention, and Fig. 3 is a diagram showing isothermal vapor-liquid equilibrium of a non-azeotropic mixed refrigerant. 8...Temperature detection section, 9...Pressure detection section. Agent Patent attorney Kensuke Norichika (and 1 other person) Fig. 1 3 - Shoju Maki Otsu - Yoshiki 4 - Umenshun 7 - Low-passage source F -- All Gai To - Pressure Kan Misaki No. 2 Figure a 1 degree Figure 3

Claims (1)

[Scope of Claims] A heat pump device using a non-azeotropic mixed refrigerant and connecting a compressor, a condenser, an expansion mechanism, and an evaporator, comprising: a temperature detection unit for detecting temperature and pressure within the heat pump device. A heat pump device comprising: and a pressure detection section.