JP4335115B2 - Air refrigerant refrigeration system - Google Patents

Description

  The present invention relates to an air refrigerant refrigeration apparatus that forms a refrigeration cycle using air as a refrigerant.

There is known an air refrigerant refrigeration apparatus that forms a refrigeration cycle using air as a refrigerant instead of chlorofluorocarbon or ammonia (for example, Patent Document 1). In the air refrigerant refrigeration apparatus such as Patent Document 1, the low temperature air supplied to the cooled part is circulated and used, and at that time, the cold air of the return air from the cooled part is given to the air before entering the expander. Air-to-air heat exchangers were used for heat recovery. In this heat recovery heat exchanger, in order to minimize the pressure loss, a plate type heat exchanger is used as described in Patent Document 2, for example.
Japanese Patent No. 2715054 International Publication WO96 / 11367

  When using a plate-type air-to-air heat exchanger as a heat exchanger for heat recovery in the above-described air refrigerant refrigeration system, in addition to high cost, air drift in the chamber is unavoidable. For this reason, it is difficult to achieve the performance as designed, and the position of the air inlet / outlet is fixed. Therefore, the layout design of the entire system is restricted by the position and direction of connection with the parts in the system. The problem of getting harder came along. In addition, there is a problem that it is not possible to realize control with high heat exchange efficiency that follows fluctuations in the flow rate and temperature of the return air.

In order to solve this problem, according to the present invention, air that has passed through an air compressor, an air cooler, and an air expander is supplied to a cooled portion, and return air from the cooled portion is supplied to the air compressor. In the circulating air refrigerant refrigeration system, an air-to-liquid heat exchanger is disposed in the air path between the air cooler and the air expander, and the air path between the cooled portion and the air compressor is also air. An air refrigerant refrigeration system characterized in that a heat medium circulation path in which a heat medium liquid is circulated between two heat exchangers and a heat medium circulation path is arranged so that the amount of heat medium circulation can be controlled. provide.

As described above, in Patent Documents 1 and 2, the air that has passed through the air compressor, the air cooler, and the air expander is supplied to the cooled portion, and the return air from the cooled portion is circulated to the air compressor. It is also known that an air-to-air heat exchanger is used to apply the cold heat of the return air from the cooled part to the air before entering the expander. . The present invention adopts a heat medium circulation type heat exchange method in place of the air-to-air heat exchanger used in this conventional apparatus , and can control the amount of heat medium circulation. There are features.

  A configuration example of the air refrigerant refrigeration apparatus of the present invention adopting this heat medium circulation type heat exchange system is shown in FIG. In the apparatus of FIG. 1, the first air compressor 1, the first air cooler 2, the second air compressor 3, the second air cooler 4, and the air-to-liquid heat exchanger 5 (third An air cooler), an air expander 6, and a collector 7 (snow removal / defroster) are arranged, and the air that has passed through these is sent to a portion to be cooled 8 (for example, a freezer warehouse). The return air from the cooled part 8 is circulated to the first air compressor 1 via an air-to-liquid heat exchanger 9 (heater).

  In the illustrated apparatus, the air compressor is divided into first and second air compressors 1 and 3, and a first air cooler 2 is interposed between them. The second air compressor 3 and the expander 6 are coaxial air compression / expansion devices that are integrally combined with a common power source. The values of pressure and temperature shown in the figure are as follows. When air is supplied to the cooled part 8, low-temperature air with a pressure of 0.1 Mpa and a temperature of −55 ° C. is produced, and the air returning from the cooled part 8 has a pressure of 0. The pressure and temperature between each apparatus in case of the air of 1 Mpa and temperature-30 degreeC are illustrated. Each of the first cooler 2 and the second cooler 3 uses an air-to-water heat exchanger, and the cooling water is passed from the outside so that the air discharged from the compressor is required. Cool to temperature.

  In the present invention, an air-to-liquid heat exchanger 5 (which functions as a third cooler) is disposed in an air path before leaving the second cooler 4 and entering the expander 6. On the other hand, an air-to-liquid heat exchanger 9 (which functions as a heater) is also arranged in the air path before the return air that has exited the cooled portion 8 enters the first compressor 1. Both of these air-to-liquid heat exchangers 5 and 9 use fin tube type heat exchangers, and both tube sides are formed in a circulation path with a pump 10 interposed therebetween, and brine is used as a heat medium in this circulation path. Circulate. The pump 10 is configured to be capable of controlling the number of revolutions by an inverter, or to control the circulation amount of the heat medium by interposing a control valve capable of opening degree control in the circulation path.

  Alternatively, shell and tube heat exchangers can be used as the air-to-liquid heat exchangers 5 and 9. Also in this case, the tube sides are connected to each other to form a heat medium circulation path, the heat medium (brine) is forcibly circulated by the pump 10, and the amount of circulation is controlled by the pump rotation speed control by the inverter or the opening degree control by the control valve. Do by.

  In any case, with this configuration, the high-pressure and high-temperature air before leaving the compressor and entering the expander and the low-pressure and low-temperature air before entering the compressor from the cooled part are heated via the heat medium. It will be exchanged, and optimal heat exchange can be performed by controlling the circulation amount of the heat medium. In other words, by controlling the amount of circulating heat medium, the temperature, pressure, and flow rate of the air in the system fluctuate even if there is a change in the exchange of heat with the outside in the cooled part or the operating conditions change. It can be avoided as much as possible.

  Examples of this heat medium circulation rate control are shown in FIGS. FIG. 2 shows an example in which the rotation speed of the pump 10 is controlled by inverter control. In this case, temperature sensors T1 and T2 are installed in the vicinity of the air inlet / outlet of the heat exchanger 5, and temperature sensors T3 and T4 are also installed in the vicinity of the air inlet / outlet of the heat exchanger 9, and these detected values are input to the control panel 11. Send. The control panel 11 issues a command to the inverter 12 to perform feedback control so that the values detected by these temperature sensors are within the set value range. In place of the temperature sensors T1, T2, T3, and T4, pressure sensors P1, P2, P3, and P4 that detect the pressure of air may be installed to perform the same control. Although not shown, a flow meter is installed in each air passage of the heat exchangers 5 and 9 to detect the air flow rate in these air passages, and this value is input to the control panel 11 to input the heat medium circulation amount. It can also be used to control It is also possible to install a flow meter 13 in the heat medium circulation path and perform control so that the detected flow rate becomes a predetermined value.

  FIG. 3 shows an example in which the heat medium circulation amount is controlled by opening control of the control valve 14 interposed in the heat medium circulation path instead of the inverter control. The opening degree of the control valve 14 is automatically adjusted according to a command from the control panel 11, but detection signals such as a temperature sensor, a pressure sensor or an air volume sensor transmitted to the control panel 11 are the same as in the case of FIG. Can be detected.

  FIG. 4 shows an example in which a bypass passage 15 is provided instead of the inverter control method, and the amount of the heat medium flowing through the bypass passage 15 is controlled by opening control of the control valves 16 and 17. The opening degree of each control valve 16 and 17 is automatically adjusted by a command from the control panel 11. Detection signals from the temperature sensor, pressure sensor, air flow sensor, etc. transmitted to the control panel 11 can be detected in the same manner as in FIG.

  In any case, the heat exchange amount and the heat exchange efficiency can be calculated from the input values of each sensor, and the flow rate of the heat medium can be controlled so as to maximize the heat exchange efficiency. For example, in control using a temperature sensor, the value of (T4-T3) / (T1-T2) is calculated from the values detected by each sensor (this value corresponds to the heat exchange efficiency), and this value is the highest. The amount of circulation of the heat medium is controlled so that The same applies when a pressure sensor is used.

  Thus, according to the present invention, in the air refrigerant type refrigeration apparatus that forms a refrigeration cycle using air as a refrigerant, return air (low-temperature low-pressure air) from the cooled part and (high-temperature high-pressure air) before entering the expander When heat is exchanged, an air-to-liquid heat exchanger is installed in both air passages so that the liquid heat medium circulates between the two and the heat medium circulation rate can be controlled. Even if there are fluctuations in temperature, pressure, flow rate, etc., in addition to being able to exchange heat so that the heat exchange efficiency is maximized, the following advantageous effects can be obtained compared to the cases of Patent Documents 1 and 2. .

(1) By dividing the heat exchanger into two, the layout of the system is free and the equipment configuration is compact.
(2) Compared to air-to-air heat exchangers, the flow rate and temperature distribution are less biased when the liquid heat medium passes through the air-to-liquid heat exchangers 5 and 9, so the air side Also, the temperature distribution in the region can be reduced and the heat exchange efficiency can be increased.
(3) In an air-to-air heat exchanger, the dew point rises in the high-pressure side of the air exchanger, so moisture in the air tends to condense (especially in air where the temperature is lower than the average temperature if the air temperature distribution is large). Moisture tends to condense), which can become ice and block the system or reduce the heat exchange efficiency. However, when circulating the liquid heat medium, the temperature distribution is less , Freezing is unlikely to occur.

It is an apparatus arrangement | positioning systematic diagram which shows the example of the air refrigerant type refrigeration apparatus according to this invention. It is a figure which shows the example of control of the heat medium circulation amount in two air-to-liquid heat exchangers used with this invention apparatus. It is a figure which shows the other example of a heating-medium circulation amount in the two air versus liquid heat exchangers used with this invention apparatus. It is a figure which shows the further another example of control of the heat medium circulation amount in the two air versus liquid heat exchangers used by this invention apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st air compressor 2 1st cooler 3 2nd air compressor 4 2nd cooler 5 Air-liquid heat exchanger (3rd cooler)
6 Expander 7 Collector 8 Cooled part 9 Air-to-liquid heat exchanger (heater)
10 Pump
11 Control panel
12 Inverter controller
13 Flow meter
14 Control valve
15 Bypass
16 Control valve
17 Control valve

Claims (2)

In an air refrigerant refrigeration system for supplying air that has passed through an air compressor, an air cooler, and an air expander to a cooled part and circulating return air from the cooled part to the air compressor, the air cooler An air-to-liquid heat exchanger is placed in the air path between the air expander and the air expander, and an air-to-liquid heat exchanger is also placed in the air path between the cooled part and the air compressor. An air refrigerant refrigeration apparatus, characterized in that a heat medium circulation path through which a heat medium liquid circulates is formed so that the amount of heat medium circulation can be controlled .   A pump capable of controlling the number of revolutions is arranged in the heat medium circuit, or a control valve capable of controlling the opening degree is installed in the heat medium circuit, and the pump is controlled according to the air temperature or pressure passing through both heat exchangers. The air refrigerant type refrigeration apparatus according to claim 1, which controls the rotational speed or the opening degree of the control valve.

Images