JPS5856528Y2 - Refrigeration equipment - Google Patents

Description

[Detailed description of the invention] This invention is a heat recovery type air conditioner in which a water-to-air heat exchanger and an air-to-air heat exchanger, which serve as the heat source, are connected in parallel and can be switched using a switching mechanism. Regarding a suitable refrigeration system, in detail, during heating operation in winter, the air-to-air heat exchanger that is inactive acts as a refrigerant reservoir, causing a gas shortage in the refrigerant system and causing unstable refrigeration operation. The present invention relates to a structure of a refrigeration system that can reliably prevent this from occurring.

A heat exchanger for air and a heat exchanger for water are connected in parallel to a refrigerant circuit, and hot water heated by an auxiliary heat source such as solar heat is used as heat source water during heating operation in winter. A refrigeration system that uses a heat exchanger for heat absorption as a heat exchanger while keeping the heat exchanger for air inactive is a heat recovery type air conditioner that uses a cold/hot water circuit. It is widely adopted.

However, during heating operation, the heat source water is heated to about 20°C by the radiant heat from the sun, but the outside temperature is 0°C.
When the temperature is as low as 0.degree. C., the refrigerant gradually flows into the air-to-air heat exchanger that is inactive due to the leakage phenomenon of the solenoid valve, and this inflowing refrigerant is cooled by the outside air.

In this case, the pressure inside the air-side heat exchanger is lower than the evaporation pressure inside the water-side heat exchanger, so the refrigerant accumulates and the air-side heat exchanger becomes a liquid reservoir. As a result, the amount of refrigerant circulated within the system decreases, resulting in an undesirable situation where the system runs out of gas.

Needless to say, if such a situation occurs, the refrigerating capacity will drop to the magnetic limit, and the oil return will also become poor, causing problems such as burnout of the compressor.

Therefore, in the past, a large receiver was inserted in the refrigerant circuit, and the amount of refrigerant charged was set in advance in anticipation of the shortage at the time of design. Although the lack of operation can be prevented, the large amount of refrigerant charged not only increases equipment costs, but also causes other problems such as liquid returning to the compressor.

The present invention was developed in order to provide a new refrigeration system that can deal with the conventional problems mentioned above and fundamentally eliminate these defects. and a heat exchanger for water are connected in parallel and configured to be switchable by a switching mechanism, so that when the temperature of the heat source water flowing to the heat exchanger for water is high, the heat exchanger for water is connected in parallel. Switching the exchanger so that the air heat exchanger is activated when the temperature is low.
On the other hand, a liquid return prevention device such as an accumulator is installed in the suction gas pipe to prevent low pressure or pressure from falling below a specified value during heating operation when the water heat exchanger operates as an evaporator. At this time, the low pressure or temperature detector is used to operate the air-to-air heat exchanger for a predetermined period of time, and the liquid refrigerant accumulated in the heat exchanger is sucked into the liquid return prevention device. It is characterized by

The features of the present invention will be described in detail below with reference to the accompanying drawings.

1 and 2 are circuit diagrams of heat recovery type air conditioners according to embodiments of the device of the present invention. First, the device shown in FIG. 1 will be explained. The refrigeration circuit includes a compressor 1. Four-way switching valve for frost switching 2. Water heat exchanger 3 (hereinafter referred to as water coil 3), liquid receiver 4. Reciprocating check valve (shuttle valve)5. A pressure reducing expansion valve 6° 7, an air heat exchanger 8 (hereinafter referred to as air coil 8) serving as a heat source, a water heat exchanger 9 (hereinafter referred to as water coil 9), and a defrost expansion valve 10. ．． Accumulator 1 as liquid return prevention device
1 and four electromagnetic valves 12, 13, 14.15 as component devices, and the cold/hot water circuit has a water fan coil 1 installed in the area to be air-conditioned.
7. Koonong Tower 18. Heat storage tank 19. Cold heat storage tank 2
0. Solar collector 21. Each of the pumps 22 to 25 has pumps 22 to 25 as component devices.

The circuit configuration of the refrigeration circuit is as follows.

That is, the discharge port of the compressor 1 can be selectively connected to the inlet of the water coil 3 or the outlet of the air coil 8 by switching the four-way switching valve 2, and the inlet of the compressor 1 can be connected to the inlet of the water coil 3 or the outlet of the air coil 8. It can be selectively connected to the outlet of the air coil 8 or the inlet of the water coil 3 through the outlet of the water coil 3 and the inlet of the air coil 8. The ports are connected to each other.

In addition, the outlet of the water coil 3 and the inlet of the air coil 8 are
Expansion valve for frosting 10. Receiver 4. Solenoid valve 12.
The liquid receiver 4 and the accumulator 11 are connected to each other by a piping via an expansion valve 6, and a solenoid valve 13. Expansion valve7. The air coil 8 and the water coil 9 are connected in parallel via a water coil 9 and a solenoid valve 15 so as to be switchable by the switching mechanism A.

Note that the liquid receiver 4 and the outflow port of the shuttle valve 5 are directly connected by piping.

In the case of normal heat recovery operation, the refrigeration circuit having the circuit configuration described above repeats the flow of refrigerant as shown by the solid line arrow in Fig. 1, and hot water is supplied to the water coil 3, which acts as a condenser, and water, which acts as an evaporator. Each of the coils 9 can obtain cold water, and if necessary, the solenoid valves 12 to 1 as the switching mechanism A can be used.
By combining the opening and closing operations of 5, it is possible to switch to the air coil 8 instead of the water coil 9.

On the other hand, the cold/hot water circuit performs a heating operation in which hot water obtained from the water coil 3 is sent to the water fan coil 17 and cold water obtained from the water coil 9 is transferred to both heat storage tanks 19 by a combination of opening and closing operations of the on-off valves 26 to 31. .20 to the water fan coil 17,
In addition, the circuit is capable of switching between cooling operation and sending the hot water obtained by the water coil 3 to the cooling tower 18, and further stores the hot water obtained by the solar collector 21 in the thermal storage tank 19. The circuit is designed to enable heat storage operation.

This refrigeration system is equipped with a detector 16 for detecting low pressure in the suction gas pipe connected to the suction port of the compressor 1, and a cold water thermostat 32 is installed at the cold water side inlet of the water coil 9.
During the heating operation by the water coil 9, the low pressure is set to a predetermined value (2,
6kg/cm2G) or less, the output of the detector 16 automatically switches from water coil 9 operation to air coil 8 operation, and when the chilled water temperature drops to a level where there is a risk of freezing (inlet water temperature 12 degrees Celsius), the chilled water thermostat is activated. Similarly, automatic switching is performed by the output of 32, and the control circuit for this automatic switching will be explained with reference to FIG.

R8 is an operation switch, and the cooling and heating side notches energize the compressor motor 1 and energize the solenoid of the four-way switching valve 2, while the cooling notch energizes the solenoids of the solenoid valves 13 and 15 to open and close them. Also, the heating notch has a solenoid valve 12.14.
The excitation can be opened by switching between the set consisting of the solenoid valves 13 and 15 and the set consisting of the solenoid valves 13 and 15.

The compressor motor 1 is connected in parallel with a circuit in which a defrost thermometer (DT), which closes when frost forms, and an auxiliary relay X are connected in series, and a normally closed contact of the auxiliary relay are connected in series.

The solenoid of electromagnetic on-off valve 12.14 closes either the circuit consisting of the normally closed contact of auxiliary relay X or the circuit consisting of the normally closed contact of the timer (TM) and the normally closed contact of auxiliary relay X in series. The solenoids of the electrode on-off valves 13 and 15 are energized during heating by
It is energized during cooling, and is energized when the normally closed contact of the auxiliary relay X and the normally closed contact of the timer (TM) are both closed during heating.

The timer (TM) is for setting the operating time of the air coil 8 to a predetermined time, and is used when the detector 16 is closed, that is, when the low pressure force reaches a predetermined value (2.6 kg/c
This is a time-limited relay that returns after issuing a command signal for a predetermined period of time, for example, 5 to 10 minutes, after an abnormality occurs when the voltage has become low compared to m2G). It is formed into a circuit that operates to open the valve by excitation.

Note that this timer (TM) is provided in association with a low temperature closing contact of the cold water thermostat 32.

Next, to explain the operating mode of the refrigeration system having the above configuration, during cooling operation, the operation switch (R5) is set to the cooling notch, and at the same time, the on-off valves 26, 27, 30.31 are opened, and the on-off valves 28, 29 are opened. and pump 22.2.
By energizing 3.25, the compressor 1 is energized, the four-way switching valve 2 is energized to the cooling operation side, and the electromagnetic on-off valve 13.15 is energized.
is energized to open the valve, the refrigerant flows in the direction indicated by the solid line arrow in Figure 1, and the water coil 3 becomes a condenser and the water coil 9 becomes an evaporator, and the hot water obtained in the water coil 3 is sent to the cooling tower. 18 radiates the heat outdoors, while the cold water obtained from the water coil 9 circulates to the water fan coil 17 while using the hot heat storage tank 19 and the cold heat storage tank 20 as intermediate compensators.
Cooling operation is performed using chilled water.

On the other hand, in the case of heating operation, the operation switch (R3) is set to the heating notch, and the on-off valves 28 and 29 are opened at the same time.

By closing the on-off valves 26, 27, 30.31 and energizing the pumps 22, 23, 24, the refrigeration circuit is operated so that the compressor 1 is energized and the four-way switching valve 2 is switched to the heating operation side (cooling and cooling). similar).

In this state, if the low pressure is above a predetermined value and the temperature of the cold water in the water coil 9 is high enough not to activate the thermostat 32, the electromagnetic on-off valves 13.15 are energized to open, so the refrigerant flows in the same way as during cooling. The hot water flowing in the direction indicated by the solid line arrow in FIG. The cold water is sent to the cold heat storage tank 20.

In this way, the heating operation using hot water is stopped, but the low-temperature cold water in the cold storage tank 20 absorbs solar heat in the solar collector 21 and rises in temperature, and then returns to the hot storage tank 19, so a heat recovery operation using solar heat is started. is possible.

While such heating operation continues, if the cooling capacity of the water coil 9 is greater than the heat exchange capacity of the solar collector 21, the temperature of the water sent to the heat source side water coil 9 will decrease. , there is a risk that it will eventually freeze, but the cold water thermometer 3
2 is closed, the contacts of the timer (TM) are switched to demagnetize and close the electromagnetic on-off valve 13.15, while the electromagnetic on-off valve 12.14 is energized and opened.
M) continues as long as the contact of the cold water thermostat 32 is closed regardless of the set time limit.

In this way, the water coil 9 is separated from the refrigeration circuit, and the air coil 8 acts as an evaporator in its place, so that efficient heating operation using outside air as a heat source is performed, and furthermore, freezing of the cold water is prevented. Ru.

During heating operation using this air heat source, if frost forms on the air coil 8, defrost I/thermo (
When the contact of DT) is closed, the four-way switching valve 2 is switched to the frost operation side, and the electromagnetic on-off valves 12 and 14 are forcibly energized and opened, so the high-pressure refrigerant flows to the air coil 8 and defrosts. After that, it is condensed and liquefied and passed through the liquid receiver 4 to the expansion valve 1.
After reaching 0, the pressure is reduced by this, and then evaporated by the water coil 3
It passes through the accumulator 11 and returns to the compressor 1, where a defrost cycle is performed.

When the tea frost is completed, the tea frost thermo (DT)
), the refrigeration cycle is switched to a heating cycle, and when the heat source water temperature is high, the water coil 9 is automatically switched to the heating operation, and when it is low, the air coil 8 is automatically switched to the heating operation, which acts as an evaporator.

In the refrigeration system of the present invention that operates as described above, when the water coil 9 is in operation and the air coil 8 is inactive due to the heat source water being in a high temperature state, at the beginning As mentioned in , there is a slight refrigerant leak from the closed solenoid valves 12 and 14, and the refrigerant gradually flows into the stopped air coil 8, where it is cooled by the outside air and stored. .

As a result, the amount of refrigerant circulated within the refrigerant circulation system decreases, resulting in power-out operation, which causes various adverse effects on the refrigeration system.

When such a situation occurs, the refrigeration system detects the lack of gas as a low pressure drop (2.6 kg/cm2G) using the detector 16, and by closing the contact of the detector 16, the timer is activated. (TM) is activated, solenoid valve 12.14
is demagnetized and closed, and the solenoid valves 13 and 15 are energized and opened, so that the operation of the water coil 9 is stopped and the operation of the air coil 8 is switched.

Therefore, the liquid refrigerant accumulated in the air coil 8 is drawn out by the compressor 1 and sent to the accumulator 11, while the refrigerant flow path of the air coil 8 is filled with gas with less liquid.

The time required for the liquid refrigerant to be completely expelled outside the air coil 8 in this way is approximately 5 to 10 minutes at most, so if the operating time of the timer (TM) is set to a time that suits this, it is possible to After the set time has elapsed, the timer (TM) operation is restored, so the solenoid valves 12 and 14 are demagnetized and closed, and the solenoid valves 13 and 15 are energized and opened, and the operation of the water coil 9 is switched again. , return to heating operation using heat source water.

Therefore, running out of gas is prevented, and efficient heating operation continues.

Furthermore, the liquid refrigerant that has flowed out of the air coil 8 once flows into the accumulator 11, so that the liquid refrigerant is transferred to the compressor 1.
Therefore, the phenomenon of liquid return is reliably prevented, and there is no problem of damage to the compressor 1.

The detector 16 may be one that detects temperature rather than low pressure, and the sensor 16 may be mounted on the water coil 9 so that it can detect the evaporation pressure or temperature of the water coil 9 instead of the suction pipe. It's good.

Further, as the switching mechanism A, two three-way valves may be used instead of the four electromagnetic valves 12 to 15.

Next, Fig. 2 shows a heat recovery type air conditioner according to another example of the device of the present invention. The structural explanation of each part will be omitted since they are numbered the same as the corresponding equipment, but while the device shown in Figure 1 uses the same refrigeration cycle for cooling and heating operations, this The embodiment device forms a reversible cycle with cooling and heating for the refrigeration system, while the water coil 3 and water fan coil 17 can be connected to a simple system with wood pipes on the forward and backward sides. .

Further, the four-way switching valve 2 switches between cooling and defrosting operation and heating operation, and the expansion valve 1
0 is for functioning during heating, and is mechanically different from the device shown in FIG. 1 in these points.

Although the electric circuit related to the device shown in the second figure is not shown,
By only making slight changes to the circuit shown in Figure 3, automatic switching operation control between the water coil 9 and air coil 8 and gas-starvation operation prevention control can be performed depending on the temperature of the heat source water flowing through the water coil 9. This can be done in the same way as the device shown in the first figure.

As is clear from the above explanation, the present invention has a structure in which the heat exchanger 8 for air and the heat exchanger 9 for water, which are the heat source side, are connected in parallel and can be switched by the switching mechanism A. When the temperature of the heat source water flowing into the water heat exchanger 9 is high, the water heat exchanger 9 is operated, and when the temperature is low, the air heat exchanger 8 is operated. On the other hand, a liquid return prevention device 11 such as an accumulator is installed in the suction gas pipe to prevent low pressure or temperature from falling below a predetermined value during heating operation when the water heat exchanger 9 operates as an evaporator. Detector 1 that detects the low pressure or temperature when the temperature drops to
6, the heat exchanger 8 for air is operated only for a predetermined time, and the liquid refrigerant stored in the heat exchanger 8 for air is sucked into the liquid storage device 11. It is possible to extend the operating limits of the refrigeration system by expanding the usage period of the refrigeration system, and to obtain a system with high safety and high utilization efficiency.

Furthermore, the detector 16 automatically switches from the heat source water operation mode to the outside air operation mode for a predetermined period of time, and refrigeration operation that prevents the amount of refrigerant circulating in the refrigerant system from drastically decreasing is enforced. There is no operational state at all, and stable operation is possible.

In addition, since the amount of refrigerant charged is as small as possible, liquid return is less likely to occur, and by providing a liquid return prevention device on the suction side line of the compressor 1, there is no liquid back and the compressor 1 is completely protected. The present invention is a refrigeration system with great practical value, and is particularly suitable for implementation in a heat recovery type air conditioner.

[Brief explanation of the drawing]

1 and 2 are refrigerant/cold/hot water piping system diagrams of a heat recovery type refrigeration system according to each embodiment of the device of the present invention, and FIG. 3 is a developed diagram of the main part electric circuit shown in FIG. 1. 8...Air heat exchanger, 9...Water heat exchanger, 11...Liquid K+') prevention device, 16... ...Detector, A...Switching mechanism.

Claims (1)

[Scope of utility model registration request] The heat exchanger 8 for air and the heat exchanger 9 for water, which are the heat source side, are connected in parallel and are configured to be switchable by a switching mechanism A, so that the heat source flows to the heat exchanger 9 for water. The heat exchanger 9 for water is activated when the water temperature is high, and the heat exchanger 8 for air is activated when the water temperature is low. A detector is disposed inside the interior and detects the low pressure or temperature when the low pressure or temperature drops below a predetermined value during heating operation in which the water-to-water heat exchanger 9 operates as an evaporator. 16, the air heat exchanger 8 is operated only for a predetermined period of time to cause the liquid refrigerant accumulated in the heat exchanger 8 to be sucked into the liquid return prevention device 11.