RU2432531C2 - Cooler unit and procedure for circulation of cooling fluid medium in it - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: cooler unit consists of main compressor (190), of condenser (140) positioned downstream after main compressor (190) and communicated with it by fluid medium, of main expanding device (170) located downstream after condenser (140) and of evaporator (180) located downstream after main expanding device (170) and communicated with it by fluid medium. The cooler unit also consists of turbo-compressor unit (160) by fluid medium communicated with evaporator (180) and main compressor (190) and at least of one heat exchanger (150, 152) with hot branch (150c) by means of supplying line (145) connected upstream with condenser (140), while downstream - with main expanding device (170) by means of bypass line (149). The heat exchanger also has cold line (150f) connected upstream with expanding device (142, 144) arranged on branch (146) of line (145), while downstream - with turbine section (162) of turbo-compressor unit (160). Output of turbine section (162) is located downstream after evaporator (180). Invention also refers to the procedure for circulation of cooling fluid medium inside the above said unit.

EFFECT: raised efficiency of unit.

7 cl, 4 dwg

Description

FIELD OF THE INVENTION

The invention relates to a refrigeration device, in particular to industrial refrigeration units, as well as to domestic air conditioning systems and to a method for circulating a cooling fluid therein.

State of the art

Typically, a device for circulating a cooling fluid comprises a compressor for compressing gaseous refrigerant to increase its temperature and pressure; a condenser configured to condense the compressed gaseous refrigerant, followed by converting it to a liquid state and transferring heat to the external environment; an expansion unit, such as a capillary tube or an isentalpic butterfly valve, designed to lower the temperature and pressure of the refrigerant; and an evaporator that absorbs heat from the external medium, cooling it, and transfers this heat to the cooling fluid coming from the expansion unit with a low temperature and pressure, while the fluid changes from a liquid to a gaseous state.

In recent years, many attempts have been made to improve the performance of refrigeration units. Some of them came across technological obstacles that called into question their feasibility, while other attempts led to increased efficiency, but at the same time significantly complicated the installation. For example, a two-stage compression installation, where the presence of two independent compressors entails load balancing problems and complicates the management of the entire installation.

Disclosure of invention

The objective of the invention is to eliminate or at least reduce the above-mentioned disadvantages by creating a refrigeration device and a method for circulating a refrigerating fluid in it, in which the efficiency is increased.

The first object of the invention is a refrigeration device comprising a main compressor, a condenser located downstream of the main compressor and in fluid communication with it, a main expansion means located downstream of the condenser, and an evaporator located downstream of the main expansion means and in communication with him fluid, which according to the invention contains a turbocompressor unit installed between the evaporator and the main compressor, and at least one heat an exchanger having a hot branch connected upstream by means of a supply line with a condenser, and downstream by means of a discharge line with a main expansion means, and a cold branch connected upstream with an expansion means mounted on a branch of the supply line and from below flow - with the turbine section of the turbocompressor unit.

Another object of the invention is a method for circulating a cooling fluid in a device according to the invention, comprising

compressing the cooling fluid in the main compressor;

condensation of a fluid in a condenser located downstream of the main compressor and in fluid communication with it;

expansion of the fluid in a primary expansion means located downstream of the condenser;

evaporation of a fluid in an evaporator located downstream of the main expansion means and in fluid communication with it,

in which according to the invention

- between the condensation step and the expansion step, there is at least one step in which heat is exchanged inside at least one heat exchanger between the compressed cooling fluid flowing along the hot branch of the heat exchanger and the corresponding amount of compressed cooling fluid flow downstream of the heat exchanger, cooled inside the expansion means and flowing inside the cold branch of the heat exchanger; but

- between the main expansion step and the main compression step, there is a step in which the cooling fluid is pre-compressed inside the turbocompressor unit, the pre-compression step includes at least one step in which the extracted cooling fluid is expanded inside at least one turbine section of the turbocompressor unit environment leaving the cold branch of the heat exchanger.

Brief Description of the Drawings

Features and advantages of the invention will be more apparent from the following detailed description of a preferred non-limiting embodiment of the invention with reference to the accompanying drawings.

Figure 1 shows a known refrigeration device;

figure 2 is a diagram of "pressure - enthalpy" for the cooling fluid circulating inside the device shown in figure 1;

figure 3 - the device according to the invention;

figure 4 is a diagram of "pressure - enthalpy" for the cooling fluid circulating inside the device shown in figure 3.

In the accompanying drawings, identical or similar parts and components are denoted by the same reference numerals.

The implementation of the invention

Figures 1 and 2 show a conventional type refrigeration device 10 for freezing food products and a p-h (pressure-enthalpy) diagram for a fluid circulating inside it, respectively. As shown in FIG. 1, device 10 comprises a compressor 12; a condenser 14 in fluid communication with the compressor 12; isoenthalic butterfly valve 16 in fluid communication with condenser 14; and an evaporator in fluid communication with a throttle valve 16 located upstream of it and with a compressor 12 located downstream of it.

A cooling fluid, such as freon, enters the compressor 12 in the form of superheated steam with a low temperature and pressure, for example -35 ° C and 1.33 bar (point 1 * in the diagram "p-h"), is compressed in the compressor and enters condenser 14 with high pressure and temperature, for example + 65 ° C and 16 bar (point 2 * in the diagram "p-h"). Inside the condenser 14, the fluid is cooled, passing from the state of superheated steam (point 2 *) to the liquid state (point 3 * in the "p-h" diagram) and releasing the amount of heat q _out into the environment. The cooling fluid leaving the condenser 14 in a liquid state expands by passing through an isentalpic throttle valve 16, and its pressure decreases, and heat exchange with the external medium does not occur (isentalpic transformation). The fluid leaving the throttle element (point 4 * in the p-h diagram) enters the evaporator, where it passes from the liquid state to the state of superheated steam (point 1 * in the p-h diagram), absorbing the amount of heat q _in from the external environment.

According to FIG. 3, which shows a preferred embodiment of the invention, the cooling fluid circulation device 100 comprises components of a conventional refrigeration device, namely a main condenser 140, a main expansion means, such as a main isoenthalic butterfly valve 170, an evaporator 180, and a main compressor 190 .

The aforementioned conventional device is supplemented with some components, conditionally enclosed inside a module, indicated by dashed lines in Fig. 3, which contains the first and second heat exchangers 150, 152, respectively, for example, plate or tubular, usually used in the field of refrigeration equipment, located in series between the condenser 140 and main throttle valve 170, and a turbocharger unit 160 located between the main compressor 190 and the evaporator 180 and having a compressor section 166, as well as first and second turbine sections 162, 164, in which the cooling fluid flows from the output of each coil 150, 152, respectively.

More specifically, the condenser 140 is connected via a supply line 145 to a higher temperature cooling fluid circuit, hereinafter referred to as a “hot branch” 150c of the first heat exchanger 150. A line 146 branches off from the supply line 145, which comprises a first expansion means, for example, a first throttle a valve 142 that leads to a lower temperature cooling fluid circuit, hereinafter referred to as a “cold branch” 150f of the first heat exchanger 150. The output of the hot branch 150c of the first heat exchanger 150 pos COROLLARY connecting line 147 is connected to the input circuit for refrigerating fluid at a higher temperature, referred to below as "hot branch" 152c of the second heat exchanger 152, and the outlet of the cold branch 150f of the first heat exchanger 150 is connected to the input of the first turbine portion 162 of the turbocompressor unit 160.

The line 147 connecting the first and second heat exchangers 150 and 152 to each other has a branch 148 provided with a second expansion means, for example a second throttle valve 144, which leads to a circuit for a cooling fluid with a lower temperature, hereinafter referred to as a "cold branch" 152f of the second heat exchanger 152. The output of the hot branch 152c of the second heat exchanger via the discharge line 149 is connected to the main throttle valve 170, and the output of the cold branch 152f is connected to the input of the second turbine section 164 of the turbocharger about block 160.

The output of the evaporator 180 is connected to the input of the compressor section 166 of the turbocompressor unit 160, the output of which is in fluid communication with the main compressor 190.

The following describes the principle of operation of the device corresponding to figure 3, with reference to the diagram "p-h" shown in figure 4 and related to the cooling fluid circulating through the device. In the particular example under consideration, a refrigeration device is used to quickly freeze food products. To this end, the temperature of the fluid circulating inside the device varies from T _min = -40 ° C to T _max = 63.7 ° C, and the selected cooling fluid is freon. It is clear that the refrigeration device according to the invention can have various applications, for example, it can be used for air conditioning in residential premises, so that depending on the intended use of the pressure and temperature of physical conditions 1-14, as well as the type of circulation inside the device the cooling fluid will change accordingly.

A cooling fluid, usually freon, with a temperature of T ₅ = 35 ° C and a pressure of p ₅ = 16.1 bar (point 5 in the "p-h" diagram), namely in the liquid / vapor equilibrium state, flows from the condenser 140. A portion of the cooling fluid flowing out of the condenser 140, hereinafter referred to as the first outlet portion s1, is supplied from line 145 via a branch 146 to the first isoanthalic throttle valve 142, where it is cooled to a temperature between the maximum temperature (T _max = 35 ° C) and minimum temperature (T _min = -35 ° C) of the cycle, preferred up to temperature Т ₉ = 7 ° С (point 9 in the diagram “p-h”, p ₉ = 7.48 bar), then the first outlet part s1 enters the cold branch 150f of the first heat exchanger 150, and the remaining part 1-s1 is cooled the fluid enters directly into the hot branch 150c of the heat exchanger 150 at a temperature of T ₅ and a pressure of p ₅ .

Inside the first heat exchanger 150, a part of the cooling fluid located in the hot branch 150c transfers the heat of the part of the cooling fluid located in the cold branch 150f, cooling from T ₅ = 35 ° C to a temperature of T ₆ = 12 ° C, and entering the unheated zone liquid in the p-h diagram (point 6; p ₆ = 16.1 bar), and the part of the cooling fluid located in the cold branch 150f absorbs heat from the part of the cooling fluid located in the hot branch 150c, heating from T ₉ = 7 ° C to a temperature of T ₁₀ = 12 ° C and entering the zone of superheated steam in the diagram "p-h" (point 10; p ₁₀ = 7.48 bar).

After the first downstream heat exchanger 150, a second amount of cooling fluid is discharged, so that part s2 of the unheated liquid leaving the hot branch 150c passes through the second isoenthalic throttle valve 144, where it is additionally cooled from temperature T ₆ = 12 ° C to temperature T ₁₂ = -17 ° C (point 12 in the diagram “p-h”; p ₁₂ = 3.38 bar), and then enters the cold branch 152f of the second heat exchanger 152, and the remaining part 1-s1-s2 of the cooling fluid leaving the heat exchanger 150 enters the hot branch 152c of the second heat exchanger 152 at a temperature of T ₆ and a pressure of p ₆ .

Inside the second heat exchanger 152, part of the cooling fluid located in the hot branch 152c gives off the heat of the part of the cooling fluid located in the cold branch 152f, cooling from T ₆ = 12 ° C to a temperature of T ₇ = -12 ° C and moving further left to the diagram shown in figure 4, in the zone of underheated liquid (point 7 in the diagram "p-h"; p ₇ = 16.1 bar), and part of the cooling fluid located in the cold branch 152f absorbs heat from the part of the cooling fluid medium located in the hot branch 152s, heating from T ₁₂ = -17 ° C to a temperature of T ₁₃ = - 12 ° С and entering the superheated steam zone of the “p-h" diagram (point 13; p ₁₃ = 3.38 bar).

Each of the outlet parts s1, s2 of the cooling fluid leaving the heat exchangers 150 and 152 in the form of a cooling fluid in a superheated steam state is respectively introduced into the first and second turbine section 162 and 164 of the turbocompressor unit 160. Inside the first turbine section 162, a cooling fluid the medium expands, passing from the state with pressure p ₁₀ = 7.48 bar (T ₁₀ = 12 ° C) to the state with pressure p ₁₁ = 2.03 bar (T ₁₁ = -25 ° C). Similarly, inside the second turbine section 164, the cooling fluid expands, passing from a state with pressure p ₁₃ = 3.38 bar (T ₁₃ = -12 ° C) to a state with pressure p ₁₄ = 2.3 bar (T ₁₄ = -25 , 6 ° C).

Part 1-s1-s2 of the cooling fluid leaving the hot branch 152c of the second heat exchanger 152 (point 7 in the "p-h" diagram) enters the main throttle valve 170, cooling from T ₇ = -12 ° C to a temperature of T ₈ = -40 ° C (point 8 in the diagram “p-h”; p ₈ = 1.33 bar), and then enters the evaporator 180, where it passes from the state of liquid + steam to the state of superheated steam (point 1 in the diagram “p -h "), absorbing the amount of heat Q _in from the external environment. The cooling fluid in the state of superheated steam leaving the evaporator 180 enters the compressor section 166 of the turbocompressor unit 160.

A compressor 166 driven by turbines 162 and 164 that convert the kinetic energy of the extracted coolant fluid s1 and s2 in superheated steam supplied by the first and second heat exchangers 150 and 152 into mechanical energy pre-compresses the coolant supplied by the evaporator 180 (point 3 on the diagram "p-h"; T ₃ = -22.1 ° C, p ₃ = 2.03 bar) before it enters the main compressor 190.

This pre-compression step provides significant benefits. First, since mechanical energy is generated by the diverted parts s1 and s2, which expand in turbines 162 and 164, the use of an external energy source is not required. Secondly, the turbocompressor unit 160 compresses the cooling fluid by performing the L _TC operation (FIG. 4) when the fluid is in the maximum specific volume state, so that the main compressor 190 does not perform this part of the work, which, due to its structural characteristics, reduces it efficiency and, in particular, its processed mass flow rate, with the resulting reduction in electrical energy supplying the compressor itself. In addition, the turbocompressor unit 160 is fluidly coupled or dynamically coupled to the main compressor 190 and can independently adapt to different loading conditions without external control. Finally, it is important to mention the fact that cooling of the cooling fluid in the heat exchangers 150 and 152 causes an increase in the performance of the evaporator 180, despite the fact that after the taps s1 and s2 there is a simultaneous decrease in the flow of coolant into the evaporator 180.

The cooling fluid pre-compressed in the turbocompressor unit 160 enters the main compressor 190, where it is compressed to a pressure of p ₄ = 16.1 bar (point 4 in the diagram “p-h”; T ₄ = 63.7), and then fed to the input of the capacitor 140.

It has been found that in the device for circulating the cooling fluid according to the invention, in particular with the precompression step performed by the turbocompressor unit, it is possible to achieve the COP coefficient of cooling, defined as the ratio between the heat Q taken from the source of lower temperature and constituting the “quantity cold ”, and the work L spent on the operation of the device for circulating the cooling fluid. Moreover, the refrigeration coefficient of the device according to the invention is greater than the refrigeration coefficient of traditional devices shown in figures 1 and 2.

In particular, taking the pressure of the outlet parts s1 and s2, respectively, p ₉ = 7.48 bar and p ₁₂ = 3.38 bar, the minimum temperature difference in the heat exchangers is 150 and 152 ΔT _min = 5 ° C, the efficiency of the first and second turbine sections 162 and 164 η _T = 0.85, the efficiency of the compressor section 166 η _C = 0.80 and the efficiency of the main compressor 190 η _CP = 0.75, the values of pressure p, temperature T and enthalpy h were obtained for physical states 1-14 in the diagram "p-h" according to figure 4, are shown in Table 1:

Table 1 Physical state p [bar] T [° C] h [kJ / kg] one 1.33 -35 347.6 2 2.03 -twenty 358.1 3 2.03 -22.1 356.6 four 16.1 63.7 415.0 5 16.1 35 254.8 6 16.1 12 217.5 7 16.1 -12 183.4 8 1.33 -40 183.4 9 7.48 7 254.8 10 7.48 12 376.7 eleven 2.03 -25 354.3 12 3.38 -17 217.5 13 3.38 -12 362.5 fourteen 2.03 -25.6 353.8

The COR refrigeration coefficient is defined as the ratio of the heat Q taken from the source of lower temperature, which is the created “amount of cold”, to the work L spent on the operation of the device for circulating the cooling fluid. In particular, the refrigeration coefficient is determined by the ratio of the heat Q _in taken from the external medium by the evaporator 180 to the work L _CP performed by the main compressor 190, namely:

Q _in = (1-s1-s2) × (h1-h7)

L _CP = h4-h2.

From which, based on the values shown in Table 1, we obtain the following:

The following Table 2 shows typical values of pressure, temperature and enthalpy of the cooling fluid circulating in a conventional refrigeration device of the type shown in figures 1 and 2.

table 2 Physical state p [bar] T [° C] h [kJ / kg] one 1.33 -35 347.6 2 16.1 65.3 416.9 3 16.1 35 254.8 four 1.33 -40 254.8

This gives q _in = (h1-h4) and L _CP = h2-h1, from which, based on the values given in Table 2, we obtain the following:

The gain Δ as a percentage of the use of a new refrigeration device compared to a traditional type refrigeration device is

From the above description it is seen that the refrigeration device according to the invention, due to the presence of a turbocompressor unit 160 and, as a result, pre-compression of the cooling fluid circulating inside the device, upstream of the main compressor 190 allows to obtain an increase in productivity of approximately 30%, and all this increase does not require additional energy supply, but uses the mechanical energy of one or more turbine sections 162, 164 of the turbocompressor unit 160, which obtained by expanding one or more parts s1, s2 of cooling fluid discharged downstream of the condenser 140.

Although the invention has been described with reference to a preferred embodiment, those skilled in the art will understand that numerous modifications and changes can be made to it that fall within the scope of the appended claims. For example, instead of two heat exchangers and a turbocompressor unit with two turbines, one heat exchanger and a turbocompressor unit with one turbine can be used. In this particular case, the heat exchanger will have a hot branch connecting the condenser and the main throttle valve, and a cold branch in fluid communication with the inlet of the turbine section of the turbocharger. In addition, instead of a turbocompressor unit having several turbine sections, there may be several turbocompressors, each of which has one turbine section.

Claims (7)

1. A refrigeration device comprising a main compressor (190), a condenser (140) located downstream of the main compressor (190) and in fluid communication with it, a main expansion means (170) located downstream of the condenser (140), and an evaporator (180) located downstream of the main expansion means (170) and in fluid communication with it, characterized in that it comprises a turbocompressor unit (160) in fluid communication with the evaporator (180) and the main compressor (190) and at least one heat a box (150, 152) having a hot branch (150 s) connected upstream by means of a supply line (145) with a capacitor (140), and downstream by a discharge line (149) with a main expansion means (170), and a cold branch (150f) connected upstream with expansion means (142, 144) mounted on a branch (146) of line (145), and downstream to a turbine section (162) of the turbocompressor unit (160), wherein the outlet of the turbine section (162) is located downstream of the evaporator (180). 2. The device according to claim 1, characterized in that at least one heat exchanger (150, 152) is a tube bundle heat exchanger. 3. The device according to claim 1, characterized in that at least one heat exchanger (150, 152) is a plate-type heat exchanger. 4. The device according to claim 1, characterized in that the expansion means (142, 144) is an isentalpic butterfly valve. 5. The device according to any one of claims 1 to 4, characterized in that it comprises first and second heat exchangers (150, 152) located in series between the condenser (140) and the main expansion means (170), and the turbocompressor unit (160) contains the first and a second turbine section (162, 164), the second heat exchanger (152) having a hot branch (152 s) in fluid communication through a connecting line (147) with a hot branch (150 s) of the first heat exchanger, and a cold branch (152f) connected upstream with expansion means (144) mounted on the bore occurrence (148) of the line (147) and the bottom flow - a second turbine portion (166) of the turbocompressor unit (160). 6. A method of circulating a cooling fluid, comprising the steps of:
- carry out the compression of the cooling fluid in the main compressor (190);
- condensing the fluid in a condenser (140) located downstream of the main compressor (190) and in fluid communication with it;
- expand the fluid in the main expansion means (170) located downstream of the condenser (140);
- evaporate the fluid in the evaporator (180), located downstream after the main expansion means (180) and communicated with it through the fluid;
characterized in that
- between the condensation step and the expansion step, there is at least one step in which heat is exchanged inside at least one heat exchanger (150, 152) between the compressed cooling fluid circulating inside the hot branch (150c, 152c) of the heat exchanger (150, 152) and the corresponding amount (s1, s2) of compressed cooling fluid flow downstream of the heat exchanger cooled inside the expansion means (142, 144) and flowing inside the cold branch (150f, 152f) of the heat exchanger (150, 152); but
- between the main expansion step and the main compression step, the cooling fluid is pre-compressed inside the turbocompressor unit (160), the pre-compression step includes at least one step in which the inside of the at least one turbine section (162, 166) of the turbocompressor unit is expanded the withdrawn amount (s1, s2) of cooling fluid leaving the cold branch (150f, 152f) of the heat exchanger (150, 152), while the fluid is released from the turbine section (162, 166) downstream from the vapor of Tell (180). 7. The method according to claim 6, characterized in that it comprises after at least one heat exchange step carried out between the condensation step and the expansion step:
- the second stage, in which heat is exchanged in a second heat exchanger (150) located in series with at least one heat exchanger (150), between the cooling fluid leaving the hot branch (150c) of at least one heat exchanger (150) and circulating inside the hot branch (152c) of the second heat exchanger (152), and the corresponding amount (s2) of cooling fluid diverted downstream of the heat exchanger (152), cooled in the expansion means (144) and circulated in the cold branch;
moreover, the pre-compression stage between the main expansion stage and the main compression stage is supplied with energy by expanding in the first and second turbine sections (162, 164) of the turbocompressor unit (160) the allocated parts of the cooling fluid from each heat exchanger (150, 152).

Images