JPH05231732A - Air cycle type air conditioner - Google Patents

Abstract

PURPOSE:To prevent operating medium temperature from being abnormally lowered after expansion thereof in an air conditioner which employs air as the operating medium. CONSTITUTION:Medium temperatures at an inlet and an outlet of an expander 102 are detected, and based thereupon the medium temperature at the inlet of the expander 102 is controlled. For expander inlet temperature control means, there may be provided drawing means 161 parallely to a condenser 103 or there may be altered the flow rate of a cooling medium acting on the condenser 103.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an open type air cycle type air conditioner using air as a working medium, and more particularly to prevention of abnormal decrease in air temperature after expansion.

[0002]

2. Description of the Related Art FIG. 5 is a schematic view showing an example of a conventional open air cycle type air conditioner using air as a working medium, and FIGS. 6 and 7 are views showing a concrete structure of an improved example thereof. is there. In these figures, 6 and 39 are engines, 7 and 41 are exhaust turbines, 8 is a centrifugal compressor, and 9 and 2
0 is the space to be cooled, 10 and 22 are centrifugal compressors, and 11 and 30
Is a heat exchanger, 12 and 25 are expansion turbines, 13 is an outside air introduction fan, 21 is an inlet duct of a centrifugal compressor, 23 is also an inlet, 28 is also an outlet, 26 is an outlet of an expansion turbine, and 29 is an outlet. Inlet, 27 is also an exhaust duct, 24 is a main shaft, 31 is a drive shaft, 32 is an electric motor, 33 is an output shaft, 34 is a speed increaser, 35 and 43 are cooling fans, 36
Is a belt transmission device, 40 is an exhaust pipe, and 42 is an exhaust bypass mechanism.

First, the working gas circulation system shown in FIG. 5 is a so-called bootstrap type, which drives the exhaust turbine 7 using the velocity energy of the exhaust gas of the engine 6, and is of the centrifugal type coaxial with this. The air in the space 9 to be cooled is compressed by the compressor 8. The air compressed by the centrifugal compressor 8 is further compressed by another centrifugal compressor 10 to have a higher pressure, is guided to the heat exchanger 11, and is cooled.
Then, after being expanded by the expansion turbine 11 and having its temperature lowered, it is guided to the space 9 to be cooled. Outside air is introduced into the space to be cooled 9 by the outside air introduction fan 13 for temperature adjustment.

Such an air-cooling system is expensive because it requires two sets of exhaust turbo supercharging systems which have been developed as supercharging systems for automobiles. Therefore, in order to realize this at low cost, as shown in FIG. 6 and FIG. 7, the main shaft 24 of the set of exhaust turbocharger is accelerated by the electric motor 32 using the speed increaser 34, or Alternatively, there is a device that is directly connected to the exhaust turbine 41 and is driven at high speed to achieve the intended purpose.

[0005]

When the cooling capacity of the heat exchangers 11 and 30 is constant and the temperature of the space 9 to be cooled decreases,
The inlet temperature of the expansion turbines 12 and 25 decreases. Since the temperature drop amount ΔT in the expansion turbine is determined by the turbine efficiency, the temperature drop of the air at the expansion turbine outlet becomes excessive. To prevent this, it is necessary to keep the temperature at the inlet of the expansion turbine constant.

Even when the centrifugal compressor 8 constantly sucks the atmosphere outside the space to be cooled 9, if the atmospheric temperature changes when the cooling capacity of the heat exchangers 11 and 30 is constant, the expansion turbine 12 and
The inlet temperature of 22 drops and the same as above occurs.

[0007]

In order to solve the above-mentioned conventional problems, the present invention provides an air cycle type air which uses air as a working medium and is provided with a compressor, an expander and a cooler for cooling the compressed air. In the harmony machine, means for detecting the medium temperature at the inlet or outlet of the expander, means for adjusting the medium temperature at the inlet of the expander, and the medium temperature adjusting means based on the output of the medium temperature detecting means. The operation amount is calculated and output,
An air cycle type air conditioner comprising: a control means for keeping the medium temperature at the outlet of the expander at a predetermined value;
An air cycle type air conditioner characterized in that the medium temperature adjusting means comprises a throttle means connected in parallel with the cooler between an outlet of the compressor and an inlet of the expander; and the medium. The present invention proposes an air cycle type air conditioner characterized in that the temperature adjusting means is a circulation amount variable pump means for forcibly circulating the cooling medium acting on the cooler.

[0008]

In the present invention, the medium temperature at the inlet of the expander is adjusted based on the temperature at the inlet or outlet of the expander. Therefore, even if the intake air temperature of the compressor changes, the inlet temperature and outlet of the expander The temperature can be kept constant, and the condensed water in the gas-liquid separator can be prevented from freezing, and the temperature of the air used for cooling can be prevented from abnormally decreasing. The present invention also provides
As the medium temperature adjusting means, a throttle means is provided in parallel with the cooler or the flow rate of the cooling medium acting on the cooler is changed, so that the temperature of the working medium can be adjusted by a simple means.

[0009]

1 is a schematic diagram showing a first embodiment of the present invention. In this figure, 101 is a compressor, 102 is an expander, 103 is a cooler, 104 is means for detecting the medium temperature at the outlet or inlet of the expander 102, 105 is arithmetic control means, 106 is medium temperature adjusting means, 107 Is drive means, 1
Reference numeral 08 is an intake passage, 109 is an air supply passage, 110 is a filter, and 111 is a gas-liquid separator. The compressor 101 is driven by the driving unit 107, and sucks air as a working medium filtered by the filter 110 from the suction passage 108 and compresses it. The cooler 103 cools the air compressed by the compressor 101 and having a high temperature. The cooled air expands in the expander 102 almost adiabatically. At this time, the air has a constant temperature drop ΔT determined by the inlet / outlet pressure ratio of the compressor 101, that is, the outlet / inlet pressure ratio of the expander 102.
This temperature-decreased air is used for cooling after the condensed water is separated by the gas-liquid separator 111 in the air supply passage 109.

At this time, when the intake air temperature of the compressor 101 changes, if the cooling capacity of the cooler 103 is constant,
The inlet temperature of the expander 102 changes, and the temperature of the air at the outlet of the expander 102 falls below the freezing point temperature. Then, problems such as freezing of condensed water in the gas-liquid separator 111 and abnormal decrease in temperature of air used for cooling occur. Therefore, in this embodiment, the medium temperature detecting means 104 detects the medium temperature at the outlet or the inlet of the expander 102, and the arithmetic control means 105 compares it with the set temperature value to calculate the manipulated variable. Then, by controlling the medium temperature adjusting means 106, the expander 1
Keep the inlet temperature of 02 constant. In this way, the outlet temperature of the expander 102 can be kept constant.

The medium temperature adjusting means 106 of this embodiment is specifically a throttle means 161 which is connected in parallel to the cooler 103 which connects the outlet of the compressor 101 and the inlet of the expander 102. The expansion means 161 changes the amount of the medium gas discharged from the compressor 101 bypassing the cooler 103, and maintains the expander inlet temperature of the compressed gas at a predetermined temperature.

The operation of this embodiment will be described in more detail. now,
The symbols for each physical quantity are defined as follows.

[0013]

[Equation 1]

Then, the compressor 101 and the expander 10
2, the state change of the working gas circulating through the cooler 103
4 is shown. That is, the inlet state of the compressor 101 (P
₁, T ₁) Gas is pressure P₂Adiabatic compression up to pressure loss
If the loss is ignored, the cooler 103 causes an equal pressure P₂(P₂=
P₃) Under temperature T₃Expander 102 after being cooled to
At pressure P_Four(= P₁) Adiabatic expansion to
It is discharged to the road. At this time the temperature T₂, T_FourIn between
The relationship shown by is established.

[0015]

[Equation 2]

The pressure ratio P ₁ / P ₂ and the expander efficiency η _t are
Since each is determined by the operating conditions and the expander, and the constant pressure specific heat C _p is determined by the type of gas, the temperature drop ΔT in the expander is determined by the pressure ratio P ₄ / P ₃ (= P ₁ / P ₂ ). Therefore, in order to keep the outlet temperature T ₄ of the expander constant, the inlet temperature T ₃ of the expander may be kept constant. The calculation of the amount of temperature drop is as follows.

[0017]

[Equation 3]

Next, the outlet of the compressor 101 and the expander 102
Means 1 connected in parallel to the cooler 103 connecting the inlets of the
06 causes the gas discharged from the compressor 101 to bypass the cooler 103 according to the opening degree. If the bypass rate is X and the outlet of the cooler 103 is subscript 3, the following equations (5) and (6) are established.

[0019]

[Equation 4]

From the above equation (6), the temperature T ₃ of the gas at the outlet of the cooler 103 at the bypass rate X is obtained, and from the equation (5), the temperature of the gas at the outlet of the cooler 103 is T ₃ ′. Time,
The bypass rate X required for heating to the predetermined temperature T ₃ is obtained. Due to the relationship in which these two equations (5) and (6) are connected, the inlet temperature of the expander 102 is maintained at a predetermined temperature or higher. At this time, the following equations (7) and (8) are established, and most power is recovered by connecting the shafts of the compressor 101 and the expander 102. If the compressor 101 and the expander 102 are coaxial, the loss power is only friction loss and η _{mt ≈1} .

[0021]

[Equation 5]

Next, FIG. 2 is a schematic diagram showing a second embodiment of the present invention. In this figure, 201 is a compressor, 202 is an expander, 203 is a cooler, 204 is means for detecting the medium temperature at the outlet or inlet of the expander 202, 205 is arithmetic control means, 206 is medium temperature adjusting means, and 207. Is a driving means, 208 is an intake passage, 209 is an air supply passage, 210 is a filter, and 211 is a gas-liquid separator.

In the present embodiment, the medium temperature adjusting means 2
06 is the cooling air 203 which is the cooling medium of the cooler 203
a or cooling water, forced circulation amount variable type pump means 231
Is. The circulation amount variable pump unit 231 is operated by changing the operating frequency according to the output of the arithmetic control unit 205. Then, the circulation amount of the cooling medium is changed, the cooling capacity of the cooler 203 is changed, and the cooler outlet temperature (= expander inlet temperature) of the compressed gas is maintained at a predetermined temperature.

This operation will be described in more detail. Cooler 20
A variable circulation type port that forcibly circulates the cooling medium that acts on
The pump means 231 changes the Ga in the formula (6) above.
can do. As a result, cooling corresponding to X = 0
Characteristics of the container 203 f (G₀, Ga) becomes variable and T
₂Due to changes in₃′ Changes to T₃′ + Δ
T ₃′ = T₃= Const, the expander 20 is controlled.
The inlet temperature of 2 can be kept above a certain level.

Next, FIG. 3 is a schematic view showing a third embodiment of the present invention. In this figure, 301 is a compressor, 302 is an expander, 303 is a cooler, 304 is means for detecting the medium temperature at the outlet or inlet of the expander 302, 305 is arithmetic control means, 306 is medium temperature adjusting means, 307. Is a drive means, 308 is an intake passage, 309 is an air supply passage, 310 is a filter, and 311 is a gas-liquid separator. In this embodiment, the medium temperature adjusting means 306 is the pump means 3 with a constant discharge amount.
31 and bypass means 332, and this bypass means 332 changes the amount of the cooling medium passing through the cooler 303 according to the output of the arithmetic control means 305, and changes the cooling capacity of the cooler 303. .. In this way
The outlet temperature (= expander inlet temperature) of the compressed gas cooler 303 can be maintained at a predetermined temperature.

[0026]

According to the present invention, it is possible to prevent the temperature drop of the fluid at the outlet of the expander from becoming excessively large, and to prevent problems due to freezing of condensed water in the gas-liquid separator and to prevent ice in the air supply passage. Problems such as melting and collecting water in the passage and adhering foreign matter to the wet passage can be eliminated.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing a third embodiment of the present invention.

FIG. 4 is a diagram showing a state of a working gas during a cycle.

FIG. 5 is a schematic view showing an example of a conventional open type air cycle type air conditioner using air as a working medium.

6 is a diagram showing a specific structure of an improved example of FIG.

FIG. 7 is a diagram showing a specific structure of another improvement example of FIG.

[Explanation of symbols]

6,39 Engine 7,41 Exhaust turbine 8,10,22 Centrifugal compressor 9,20 Cooled space 11,30 Heat exchanger 12,25 Expansion turbine 13 Outside air introduction fan 21 Centrifugal compressor suction duct 23 Centrifugal compressor suction Port 28 Centrifugal compressor outlet port 26 Expansion turbine outlet port 29 Expansion turbine inlet port 27 Expansion turbine exhaust duct 24 Main shaft 31 Drive shaft 32 Electric motor 33 Output shaft 34 Speed increaser 35,43 Cooling fan 36 Belt transmission device 40 Exhaust pipe 42 Exhaust bypass mechanism 101, 201, 301 Compressor 102, 202, 302 Expander 103, 203, 303 Cooler 203a, 303a Cooling medium 104, 204, 304 Expander outlet or inlet medium temperature detecting means 105, 205 , 305 arithmetic control means 106, 206, 306 medium Degree adjusting means 107, 207, 307 Driving means 108, 208, 308 Intake passage 109, 209, 309 Air supply passage 110, 210, 310 Filter 111, 211, 311 Gas-liquid separator 161 Throttling means 231, 331 Cooling medium pumping means 332 Cooling medium bypass means

Claims (3)

[Claims] 1. A means for detecting a medium temperature at an inlet or an outlet of an expander in an air cycle type air conditioner comprising air as a working medium and comprising a compressor, an expander and a cooler for cooling the compressed air. And a means for adjusting the medium temperature at the inlet of the expander, and a calculation output of the operation amount of the medium temperature adjusting means based on the output of the medium temperature detecting means, and the medium temperature at the outlet of the expander to a predetermined value. An air-cycle type air conditioner comprising: 2. The medium temperature adjusting means comprises a throttle means connected in parallel with the cooler between an outlet of the compressor and an inlet of the expander.
Air cycle type air conditioner described. 3. The air cycle type air conditioner according to claim 1, wherein the medium temperature adjusting means comprises a circulation amount variable type pump means for forcibly circulating the cooling medium acting on the cooler.