JP5250519B2 - Cooling system - Google Patents

Description

  The present invention relates to a cooling device, and more particularly to a cooling device that can be used by switching between cooling using the evaporation heat of a medium and cooling using sensible heat.

  In general, a cooling device that cools an indoor space or the like employs a heat pump system that uses evaporation heat of a medium.

  In this type of cooling device, a gas-phase refrigerant compressed to a high temperature and high pressure by a compressor radiates heat by an outdoor heat exchanger to form a liquid phase refrigerant, depressurizes by a decompression device, and then cools the indoor air by an indoor heat exchanger. Heat exchanges and evaporates to become a gas phase refrigerant and returns to the compressor.

  On the other hand, the indoor air heat-exchanged by the indoor heat exchanger is cooled and circulated through the room and cooled by the indoor fan.

  However, in the conventional cooling device, not only when the outside air temperature is higher than the room temperature such as in the daytime in summer, but also when the outside temperature is lower than the room temperature such as at night in summer, the refrigerant is cooled by compressing the refrigerant with the compressor. Therefore, power consumption increases and lacks energy saving.

  In addition, a cooling system for a housing is proposed in which a heat pump type forced circulation refrigerant circuit is used for the main cooling device and a natural circulation refrigerant circuit using a heat pipe is installed in an auxiliary cooling device installed separately from the main cooling device. (For example, refer to Patent Document 1).

  However, since the cooling system described in Patent Document 1 is provided with the main cooling device and the auxiliary cooling device separately, the structure becomes complicated and expensive. Further, since the auxiliary cooling device circulates the refrigerant in the natural circulation refrigerant circuit using the refrigerant weight difference, it is necessary to install the natural circulation refrigerant circuit in an upright manner, and a large installation space is required.

JP 2002-277002 A

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a cooling device that can save energy, has a simple structure, is inexpensive, and can save space.

  In order to achieve the above-described object, a cooling device according to the present invention includes a compressor having a variable rotation speed, a four-way valve, an indoor heat exchanger, a decompression unit that can be controlled in a throttled state and a fully open state, and an outdoor heat exchanger. When the outdoor temperature is higher than the room temperature, the gas phase medium compressed into a high temperature and high pressure by the compressor and flowing into the outdoor heat exchanger through the four-way valve is provided with a medium circulation cycle formed by pipe connection. The outdoor heat exchanger radiates heat to the outside air to become a liquid phase refrigerant, is depressurized by the decompression means in the throttle state, evaporates in the indoor heat exchanger, cools the indoor air, and the outdoor temperature is lower than the indoor temperature In this case, the compressor is operated at a lower speed than when the gas-phase refrigerant is compressed, so that the liquid phase medium cooled by the outdoor air is transferred to the indoor heat exchanger via the four-way valve, and the indoor air is cooled. It is characterized by.

  According to the cooling device of the present invention, it is possible to provide a cooling device that can save energy, has a simple structure, is inexpensive, and can save space.

The conceptual diagram of the medium circulation cycle used for one Embodiment of the cooling device which concerns on this invention. The conceptual diagram of one Embodiment (cooling using evaporative heat) of the cooling device which concerns on this invention. The conceptual diagram of one Embodiment (cooling using sensible heat) of the cooling device which concerns on this invention.

  An embodiment of a cooling device according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the cooling device 1 according to the present embodiment includes a medium circulation cycle 2 and includes a control device (not shown) that controls the operation of the medium circulation cycle 2.

  The medium circulation cycle 2 is used by switching between cooling using evaporative heat (heat pump operation) and cooling using sensible heat of the medium. The compressor 3, the four-way valve 4, the indoor heat exchanger 7, the decompression means 6, and the outdoor heat are used. The exchanger 5 is sequentially connected by piping.

  The compressor 3 is, for example, a reciprocating type, and is controlled by an inverter device so that the rotation speed is variable. The variable speed range is switched between the evaporative heat utilization cooling operation of the medium operated on the high speed side and the sensible heat utilization cooling operation of the medium operated on the low speed side.

  The outdoor heat exchanger 5 is installed outdoors and includes an outdoor fan 5a, and the indoor heat exchanger 7 is installed indoors and includes an indoor fan 7a.

  The heat exchange capacity of the outdoor heat exchanger 5 is set to be larger than the heat exchange capacity of the indoor heat exchanger 7.

  An outdoor temperature sensor S1 is provided in the vicinity of the suction port of the outdoor unit 8 in which the outdoor blower 5a is accommodated. An indoor temperature sensor s2 is provided in the vicinity of the suction port of the indoor unit 9 in which the indoor blower 7a is housed, and the decompression means 6 can control the throttle amount in the throttle state and fully open, and is composed of, for example, an electronic expansion valve. The opening degree of the valve can be adjusted by the stepping motor.

  The decompression means 6 may be constituted by a capillary tube instead of the electronic expansion valve and a bypass circuit provided in parallel with the capillary tube and provided with a closing valve. In the case of an electronic expansion valve, the flow resistance is set to almost disappear when the valve is fully opened. Further, when a bypass circuit having a shut-off valve is provided, piping is designed so that there is almost no flow resistance in the flowable direction of the check valve.

  Further, the cooling device 1 controls the compressor 3, the four-way valve 4 and the pressure reducing means 6 by a control device having a temperature sensor and a timer, and switches the medium from evaporative heat use cooling to sensible heat use cooling and vice versa. Is done. Switching from cooling using evaporative heat to cooling using sensible heat is performed after a predetermined time has elapsed from when the outdoor temperature detected by the outdoor temperature sensor S1 is lower than the indoor temperature detected by the indoor temperature sensor S2, for example, It is preferable to carry out after 30 minutes. When this condition is not satisfied, for example, when the outdoor temperature detected by the outdoor temperature sensor S1 is higher than the indoor temperature detected by the indoor temperature sensor S2, evaporative heat cooling using the medium is performed.

  Next, operation | movement of the cooling device of this embodiment is demonstrated.

  As shown in FIGS. 1 and 2, when the outside air temperature is, for example, 35 ° C. and higher than the indoor temperature of 27 ° C., such as in the daytime in summer, the medium is cooled by using evaporative heat.

  The gas phase medium (refrigerant) compressed to a high temperature and high pressure by the compressor 3 flows into the outdoor heat exchanger 5 through the four-way valve 4 and exchanges heat with the outdoor air to be radiated and cooled to become a liquid phase. .

  The medium in the liquid phase is decompressed by the decompression means 6 in a state where the opening degree is reduced, evaporated in the indoor heat exchanger 7 to cool the indoor air, and the medium in the gas phase is the outdoor heat exchanger. The heat is dissipated in 5 and cooled, and then returns to the compressor 3 through the four-way valve 4. In order to perform the compression operation, the rotation speed of the compressor is set to a high speed, and is controlled to, for example, 20 rps or more.

  The indoor air cooled by the indoor heat exchanger 7 circulates in the room by the action of the indoor blower 7a and cools the room. In addition, as shown in FIG. 2, it is also possible to eliminate the indoor blower 7a and perform cooling by natural convection or radiant heat.

  On the other hand, in the outdoor heat exchanger 5, heat exchange is performed between the outside air and the gas phase medium by blowing air from the outdoor blower 7a. Also in the outdoor heat exchanger 5, the indoor blower 5a may be eliminated as shown in FIG. 2, and heat exchange between the outside air and the refrigerant may be performed by natural convection or radiant heat. When the blowers 7a and 5a are eliminated, the heat exchange amount in the respective heat exchangers is reduced and the cooling capacity is reduced, but the power for driving the blowers can be reduced, resulting in energy saving.

  In addition, when the outside air temperature is higher than the room temperature and the house is exposed to direct sunlight and the cooling load is large, the compressor 3 is rotated at a high speed to increase the capacity of the medium using evaporative heat for cooling. Increase the circulation rate of the medium. In such a case, power consumption also increases.

  In contrast, as shown in FIGS. 1 and 3, when the outside air temperature is, for example, 20 ° C. and lower than the indoor temperature of 27 ° C., such as at night in summer, the sensible heat cooling of the medium is performed.

  For example, the compressor 3 is operated at a low speed (for example, about 5 to 15 rps) which is not used by the control device and the inverter device at the time of gas phase refrigerant compression as described above, and the compressor 3 almost compresses the refrigerant. The liquid phase medium that functions as a pump that is not performed and is cooled below the room temperature by the outdoor air is conveyed to the indoor heat exchanger 7 via the four-way valve 4. The liquid phase medium cooled with the outdoor air cools the room air by exchanging heat with the room air, and returns to the compressor 3 through the decompression means 6 and the four-way valve 4 in the open state.

  In the sensible heat cooling of the medium, heat exchange may be promoted by operating the blowers 7a and 5a as in the refrigeration cycle shown in FIG. 1, and energy saving can be achieved by eliminating the blower as shown in FIG. Space may be saved.

  Thus, when the outside air temperature is lower than the room temperature and the cooling load is small, the cooling capacity is small because the sensible heat of the medium is used, but the compressor only carries the liquid phase medium by low speed operation, Power consumption can be greatly reduced.

  Switching between the evaporative heat utilization cooling and the sensible heat utilization cooling is performed after a predetermined time has elapsed since the outdoor temperature detected by the outdoor temperature sensor has become lower than the indoor temperature detected by the indoor temperature sensor. Thereby, since cooling using sensible heat with a small cooling capacity is performed after the cooling load is reduced, the cooling is reliably performed (cooling).

  In addition, unlike the case where outside air is taken in by opening a window, the use of sensible heat makes it safe for crime prevention and avoids the influence of external noise.

  Furthermore, since an expensive compressor is used in two ways, a compressor and a pump, the cost is lower than when using each separately.

  In addition, since the heat exchange capacity of the outdoor heat exchanger is set to be larger than the heat exchange capacity of the indoor heat exchanger, the temperature difference between the outside air temperature and the liquid phase medium is smaller than that during evaporative heat cooling. However, it is possible to balance the heat dissipation in the outdoor heat exchanger and the heat absorption in the indoor heat exchanger.

  In this embodiment, the example of cooling a room in a house has been described. However, the present invention can also be applied to cooling a building or a warehouse.

  According to the cooling device of this embodiment, energy saving can be achieved, and a cooling device that has a simple structure, is inexpensive, and can save space is realized.

  DESCRIPTION OF SYMBOLS 1 ... Cooling device, 2 ... Medium circulation cycle, 3 ... Compressor, 4 ... Four-way valve, 5 ... Outdoor heat exchanger, 5a ... Outdoor fan, 6 ... Decompression means, 7 ... Indoor heat exchanger, 7a ... Indoor fan, 8 ... outdoor unit, 9 ... indoor unit.

Claims (3)

A compressor having a variable rotation speed, a four-way valve, an indoor heat exchanger, a decompression means that can be controlled to a throttled state and a fully opened state, and a medium circulation cycle in which an outdoor heat exchanger is sequentially connected by piping,
If the outdoor temperature is higher than the indoor temperature,
The gas phase medium compressed to a high temperature and high pressure by the compressor and flowing into the outdoor heat exchanger via the four-way valve radiates heat to the outside air by the outdoor heat exchanger to become a liquid phase refrigerant, and is in a throttle state. The pressure is reduced by the pressure reducing means, evaporated by the indoor heat exchanger to cool the indoor air,
If the outdoor temperature is lower than the indoor temperature,
The compressor is operated at a speed lower than that at the time of gas phase refrigerant compression, thereby transporting the liquid phase medium cooled by outdoor air to the indoor heat exchanger via the four-way valve, thereby cooling the indoor air. And cooling device. Switching from the operation when the outdoor temperature is higher than the indoor temperature to the operation when the outdoor temperature is lower than the indoor temperature is such that the outdoor temperature detected by the outdoor temperature sensor is lower than the indoor temperature detected by the indoor temperature sensor. The cooling apparatus according to claim 1, wherein the cooling apparatus is performed after a predetermined time has elapsed. The cooling device according to claim 1, wherein a heat exchange capacity of the outdoor heat exchanger is set to be larger than a heat exchange capacity of the indoor heat exchanger.

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