JPH04236062A - Air conditioner - Google Patents

Abstract

PURPOSE:To produce an air conditioner in which, in the prevention of condensation on a radiant panel during cooling, simplicity of mechanical constitution and capability of economization in energy are introduced. CONSTITUTION:In an air conditioner 1 provided with a refrigeration cycle and having a radiant panel 8 for absorbing radiant heat from the indoor space connected to the refrigeration cycle in parallel with the indoor heat exchanger 6 in the refrigeration cycle, an expansion valve 9 which can be opened and closed is provided on the refrigerant-delivery side of the radiant panel 8. An expansion valve-controlling device 12 calculates the dew point Tad of the air near the radiant panel 8 on the basis of the indoor temperature Ta and humidity Rh both detected by a humidity sensor 10 provided near the radiant panel 8, and controls the opening of the expansion valve 9 according to a difference between the dew point Tad calculated as above and the surface temperature Tps of the radiant panel 8 detected by a temperature sensor 11. Therefore the evaporative temperature or the evaporative pressure of the refrigerant inside the radiant panel 8 can be controlled.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an air conditioner that utilizes heat transfer by radiation in addition to forced convection, and particularly relates to an air conditioner with a simple configuration for preventing dew condensation on a radiant panel during cooling operation. .

0002

[Prior Art] In recent years, the above-mentioned air conditioners have been required to provide more comfort than ever before, such as low noise, uniform room temperature, elimination of discomfort caused by air blowing, and sanitization. There is. Therefore, the use of radiant panels with the ability to emit infrared rays for heating and cooling systems is attracting attention as a means of increasing comfort. According to the above-mentioned radiant panel, unlike an indoor evaporator, there is no need for air flow to generate forced convection, so no noise is generated and there is no discomfort when the wind hits the body. In addition, since the infrared rays from the radiant panel pass through the air and act directly on objects, there is a heat transfer effect even if the indoor temperature has not yet reached the set value.If the indoor air temperature is the same, the radiant panel The temperature of the indoor air maintained by the forced convection can be set low for heating and high for cooling, for example. Note that even during cooling, low-energy infrared rays are emitted from the radiant panel, but at that time, the energy of the infrared rays from the object is higher, so the canceling amount of each infrared ray is absorbed by the radiant panel.

FIG. 4 shows an example of an air conditioner that utilizes heat transfer by forced convection and radiation as described above. In the figure, the air conditioner 1b has an outdoor refrigeration cycle 4 in which a refrigerant as a heat medium flows through a circulation path made up of refrigerant pipes 7.
0, and an indoor brine cycle 41 in which brine as a heat medium flows through a circulation path formed by a brine pipe 27. In the outdoor refrigeration cycle 40, the high-temperature, high-pressure refrigerant discharged from the compressor 2 exchanges heat with the outside air from the outdoor fan 18 when passing through the outdoor heat exchanger 3 and radiates heat, thereby condensing and liquefying the refrigerant. Then, after being further reduced in pressure by the expansion valve 28 and becoming a low-pressure gas-liquid two-phase state,
It passes through a refrigerant/brine heat exchanger 29 that exchanges heat with the brine cycle 41, and at this time absorbs heat from the brine. Therefore, the refrigerant is evaporated and turned into low-temperature, low-pressure vapor, and then returned to the compressor 2, and the cycle is repeated. On the other hand, the above brine cycle 4
1, when the brine discharged from the circulation pump 31 passes through the refrigerant/brine heat exchanger 29, it radiates heat to the refrigerant on the refrigeration cycle 40 side and is cooled. Here, a part of the cooled brine is guided to the indoor heat exchanger 6 (in the direction of arrow D), and the rest is guided to the three-way mixing valve 30 for controlling the temperature of the radiant panel 8 (arrow C). direction). The three-way mixing valve 30 supplies brine from the refrigerant/brine heat exchanger 29 and the brine pipe 27 of the radiant panel 8.
circulation pump 32 for circulating the radiant panel.
Mix with the brine (arrow F) sent by
The temperature of the brine (arrow E) flowing into the radiant panel 8 is controlled to a temperature that does not cause dew condensation on the surface of the radiant panel 8. The radiant panel 8 cools the room by absorbing radiant heat from the outside. Then, a portion of the brine heated by the absorbed radiant heat returns to the circulation pump 31, and the above-described cycle is repeated. In the air conditioner 1b, the dew point of the indoor air and the surface temperature of the radiant panel 8 are measured, and the three-way mixing valve 30 is controlled so that the temperature of the radiant panel 8 does not fall below the dew point of the indoor air. In this way, if brine with no phase change is used as a heat medium for the radiant panel 8, the radiant panel 8 can be easily heated.
surface temperature can be controlled. In this way, the air conditioner 1b utilizes forced convection by the indoor heat exchanger 6 and radiation by the radiant panel 8, and can achieve comfortable indoor cooling.

0004

However, the conventional air conditioner 1b required two cycles, the refrigeration cycle 40 and the brine cycle 41, and therefore had a complicated configuration. Furthermore, as mentioned above, one of the features of air conditioning using radiation is that it can save energy. However, the coefficient of performance (hereinafter referred to as COP (=cooling capacity/required power)) that evaluates the energy saving performance of the air conditioner 1b is inferior to that of a general air conditioner that uses only a refrigeration cycle and performs cooling by forced convection. There are many. This is because the above-mentioned forced convection air conditioner using only the refrigeration cycle is a so-called direct expansion type in which the refrigerant is directly evaporated in the indoor heat exchanger, whereas in the above air conditioner 1b, the refrigerant and brine are directly evaporated. Since heat is exchanged via the refrigerant/brine heat exchanger 29,
The temperature difference between the indoor air and the refrigerant after heat exchange becomes large. As a result, the evaporation pressure of the refrigerant decreases, resulting in a small COP. Furthermore, the air conditioner 1b must use at least one circulation pump for the brine cycle 41, and compared to an air conditioner using only the refrigerant cycle, the COP is reduced by the power consumption of the circulation pump.
was getting smaller.

[0005] Therefore, in order to realize a system that uses only the above-mentioned refrigeration cycle and employs the above-mentioned direct expansion type indoor heat exchanger to prevent dew condensation on the above-mentioned radiant panel 8, for example, two compressors are prepared, and one of them is One of the compressors is used to compress the refrigerant supplied to the indoor heat exchanger, and the remaining one is used to compress the refrigerant sent to the radiant panel 8. By changing the capacity of this compressor, the surface temperature of the radiant panel 8 can be adjusted. There are ways to control this. However, with such a method, it is difficult to control each compressor and, in addition, the manufacturing cost increases, so it is not practical and has not been put to practical use.

[0006] Accordingly, an object of the present invention is to provide an air conditioner that has a simple configuration and can save energy in preventing dew condensation on a radiant panel during cooling operation.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the main means adopted by the present invention is to install a compressor, a condenser, a first expansion valve, and an evaporator in this order. A radiant panel that absorbs radiant heat from the outside is connected to the refrigeration cycle in parallel with the evaporator to form a refrigeration cycle. In air conditioners,
a second expansion valve that is openable and closable on the heat medium outlet side of the radiant panel; a dew point detection means for detecting the dew point of the air in the vicinity of the radiant panel; and a dew point detected by the dew point detection means and the The air conditioner is configured to include an expansion valve control means for controlling the opening degree of the second expansion valve according to the difference in temperature of the radiant panel.

[0008]

[Operation] In the air conditioner according to the present invention, the heat medium sent out by the compressor and passed through the condenser is reduced in pressure by the first expansion valve and used for cooling the evaporator and the radiant panel. The radiant panel absorbs radiant heat from the outside. A second expansion valve is provided on the heat medium outlet side of the radiation panel so as to be openable and closable. Therefore, the dew point detection means detects the dew point of the air near the radiant panel. Subsequently, the expansion valve control means controls the opening degree of the second expansion valve according to the difference between the dew point detected by the dew point detection means and the temperature of the radiant panel. That is, the expansion valve control means is
When the temperature of the radiant panel is close to or below the dew point, the degree of opening of the second expansion valve is reduced. As a result, the heat medium flowing through the radiant panel becomes difficult to flow, and the temperature of the radiant panel increases to exceed the dew point.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples embodying the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention. It should be noted that the following examples are examples of embodying the present invention, and are not intended to limit the technical scope of the present invention. Here, FIG. 1 is a block configuration diagram showing a control system of an air conditioner according to an embodiment of the present invention, FIG. 2 is a flowchart showing a processing procedure for cooling operation by the air conditioner, and FIG. 3 is a block diagram showing a control system of an air conditioner according to an embodiment of the present invention. FIG. 2 is a block configuration diagram showing an air conditioner for heating and cooling according to an embodiment of the present invention. However, the same reference numerals are used for elements common to those of the conventional air conditioner 1b shown in FIG. 4.

As shown in FIG. 1, the air conditioner 1 according to this embodiment includes a compressor 2, an outdoor heat exchanger 3, an expansion valve 4 for the indoor heat exchanger (first expansion valve), and an indoor heat exchanger. A refrigeration cycle is provided in which the vessels 6 are connected by a refrigerant pipe 7 through which refrigerant flows to form a circulation path. Further, a fan 18 for blowing outdoor air to the outdoor heat exchanger 3 is installed in this heat exchanger, and a fan 18 for blowing indoor air to the indoor heat exchanger 19 is installed in the heat exchanger.
9 is installed in this heat exchanger. Further, a radiant panel 8 that absorbs radiant heat from the room is provided in the refrigerant pipe 7 of the refrigeration cycle in parallel with the indoor heat exchanger 6. An expansion valve 5 (first expansion valve) for adjusting the cooling load of the radiation panel 8 is provided on the refrigerant inlet side of the radiation panel 8.
An expansion valve 9 (second expansion valve) for adjusting the evaporation temperature of the refrigerant evaporated in the radiation panel 8 is provided on the refrigerant outlet side.
is provided. Each of the expansion valves 4, 5, and 9 described above can be opened and closed with respect to the refrigerant pipe line, and the opening degree of the valve can be adjusted, and a stepping motor with excellent controllability is used as the drive source for each valve. There is.

[0011]The indoor heat exchanger 6 has a refrigerant inlet temperature Thexi and a refrigerant outlet temperature T on the refrigerant inlet and outlet sides.
Temperature sensors 14 and 15 for detecting hexo are provided, respectively. Furthermore, temperature sensors 16 and 17 are provided on the refrigerant inlet and outlet sides of the radiation panel 8, respectively, to detect the refrigerant inlet temperature Tpi and the refrigerant outlet temperature Tpo, and the panel itself has a temperature sensor 16 and 17 for detecting the refrigerant inlet temperature Tpi and refrigerant outlet temperature Tpo. A sensor 11 is provided. Further, a humidity sensor 10 is provided near the radiant panel 8 to detect the air temperature Ta and humidity Rh in the vicinity of the radiant panel 8. Furthermore, this air conditioner 1 controls the opening degree of the expansion valve 4 according to the temperature difference between the refrigerant inlet temperature Thexi and the refrigerant outlet temperature Thexo of the indoor heat exchanger 6, and adjusts the refrigerant inlet temperature Tpi of the radiation panel 8. The opening degree of the expansion valve 5 is controlled according to the temperature difference between the temperature and the refrigerant outlet temperature Tpo, and the radiant panel 8 is
an expansion valve control device 12 (expansion valve control means) that calculates the dew point Tad of the air in the vicinity of and controls the opening degree of the expansion valve 9 according to the difference between this dew point Tad and the surface temperature Tps of the radiant panel 8; We are prepared. That is, the humidity sensor 10 and the expansion valve control device 12 constitute a dew point detection means for detecting the dew point of the air near the radiant panel 8.

As described above, the air conditioner 1 of this embodiment is equipped with one system of refrigeration cycle using only refrigerant, and its operation will be explained below. The high-temperature, high-pressure refrigerant discharged from the compressor 2 exchanges heat with outside air in the outdoor heat exchanger 3 and is condensed and liquefied. Then, the refrigerant that has flowed out of the outdoor heat exchanger 3 is branched toward the indoor heat exchanger 6 and the radiant panel 8, respectively, and the expansion valve 4 (arrow A).
It reaches the expansion valve 5 (arrow B). Therefore, the refrigerant guided to the expansion valve 4 is depressurized by the expansion valve 4 and becomes a low temperature, low pressure gas-liquid two-phase state, and then exchanges heat with the indoor air in the indoor heat exchanger 6 to evaporate and vaporize at a low temperature. It becomes low pressure steam. At this time, the indoor air is cooled and dehumidified and returned to the room to cool the room. On the other hand, the refrigerant guided to the expansion valve 5 is depressurized by the expansion valve 5 and becomes a low-temperature, low-pressure gas-liquid.
After reaching a phase state, it exchanges heat with the radiant panel 8 and evaporates, turning into low-temperature, low-pressure steam. At this time, the refrigerant evaporation temperature of the radiation panel 8 is determined by the expansion valve control device 12.
The opening degree of the panel is adjusted to prevent condensation from forming on the surface of the panel. The radiant panel 8 cooled by the refrigerant absorbs radiant heat from the room and performs radiant cooling. Then, the refrigerant vapor from the expansion valve 9 joins with the refrigerant vapor from the indoor heat exchanger 6 mentioned above and returns to the compressor 2.
The cycle repeats.

Subsequently, each expansion valve 4 of the air conditioner 1
, 5, and 9 will be explained below using the flowchart shown in FIG. In addition, S1 in FIG.
S2, . . . indicate operation steps of the above processing procedure. In addition, the above processing procedure is implemented as a program in the expansion valve control device 1.
2 is stored in advance in a memory (not shown). First, the expansion valve control device 12 initializes the opening degrees of all the expansion valves 4, 5, and 9. For example, the expansion valves 4, 5,
9 is once fully closed (S1), and then set to an appropriate, for example, intermediate opening degree for each expansion valve (S2). Temperature data Thexi, T necessary for controlling each expansion valve detected by each temperature sensor 10, 11, 14 to 17, respectively.
hexo, Tpi, Tpo, Tps, Ta and Rh (→
Tad) is input to the expansion valve control device 12 (S3). Subsequently, the expansion valve control device 12 determines whether cooling operation using the radiation panel 8 is possible (S4). Note that in order to prevent dew condensation on the surface of the radiant panel 8, the surface temperature Tps of the surface must be higher than the dew point Tad of the indoor air. Measurement accuracy is taken into account. That is, when the surface temperature Tps is higher than the dew point Tad of indoor air by 2°C or more (S4, YES), cooling operation using the radiant panel 8 is performed, and when it is lower than the dew point Tad+2°C (S4, YES).
, NO) The expansion valves 5 and 9 are fully closed (S5), and the indoor heat exchanger 6 is operated to promote dehumidification of the indoor air (
Steps S16 to S18 (to be described later): The operation of the radiant panel 8 is stopped until the conditions of step S4 are satisfied.

On the other hand, when cooling the radiant panel 8, it is determined whether or not the expansion valves 5 and 9 are at appropriate opening degrees (S6). If not (NO), the appropriate opening degrees are set for each in step S7, and then the routine returns to detecting the temperature data again (S3). In normal room air conditioners, the degree of superheating of the evaporator (evaporator refrigerant outlet temperature -
The expansion valve on the inlet side of the evaporator is controlled according to the evaporator refrigerant inlet temperature), and the indoor heat exchanger 6 and radiant panel 8 of this air conditioner 1 are also controlled in the same way. However, in the cooling operation, first, the expansion valve 5, which adjusts the degree of superheating of the radiation panel 8, is controlled. The expansion valve control device 12 is S3
The refrigerant inlet temperature Tpi of the radiant panel 8 detected at
, the current degree of superheating (Tpo - Tpi) of the radiant panel 8 is calculated based on the refrigerant outlet temperature Tpo, and when this degree of superheating is larger than the preset allowable degree of superheating (5 to 2 degrees Celsius) (S
8, YES) Increase the opening degree of the expansion valve 5 (S9),
When the calculated degree of superheat is smaller than the allowable degree of superheat (S10, YES), the opening degree of the expansion valve 5 is decreased (S10, YES).
11), and when the calculated degree of superheat is within the range of the allowable degree of superheat (NO in S8, NO in S10), the expansion valve 5 is held at the opening degree at that time.

Next, control of the expansion valve 9 for adjusting the refrigerant evaporation temperature of the radiant panel 8 is executed. In this case as well, the temperature/humidity distribution of the indoor temperature or the measurement accuracy of each temperature sensor is considered, and when the surface temperature Tps of the radiant panel 8 is 5°C or more higher than the dew point Tad of the indoor air (S12, YES).
, since no dew condensation occurs on the surface of the radiation panel 8,
The opening degree of the expansion valve 9 is increased (S13), and the refrigerant evaporation temperature is lowered. Conversely, the surface temperature Tps is the dew point Ta.
When the temperature is lower than d+3°C (S14, YES), the opening degree of the expansion valve 9 is reduced to prevent dew condensation from forming on the surface of the panel (S15). As a result, the above-mentioned radiant panel 8
It becomes difficult for the refrigerant to flow on the exit side of the radiant panel 8, and the evaporation temperature of the refrigerant in the radiation panel 8 increases. In this case as well, the temperature difference between the surface temperature Tps and the dew point Tad is within a predetermined temperature range (5 to 5
3° C.), operation continues with the opening degree of the expansion valve 9 at that time. Subsequently, the expansion valve control device 12
controls the expansion valve 4. Like the expansion valve 5, this expansion valve 4 also has a superheat degree (Thexo-Th) of the indoor heat exchanger 6.
exi). As for the degree of superheating of this indoor heat exchanger 6, a predetermined temperature range (5 to 3°C) related to the degree of superheating is set in advance as in the case of the above-mentioned radiant panel 8, and when the degree of superheating exceeds 5°C, (S16, YES
), the opening degree of the expansion valve 4 is increased (S17), thereby increasing the cooling load of the indoor heat exchanger 6. On the other hand, when the degree of superheat is below the temperature range (S18, Y
ES) The opening degree of the expansion valve 4 is reduced.

As mentioned above, the air conditioner 1 of this embodiment
According to the invention, the degree of superheating of the refrigerant in the radiant panel 8 is adjusted by the expansion valve 5 on the refrigerant inlet side of the radiant panel 8, and the refrigerant evaporation temperature (pressure) in the radiant panel 8 is adjusted by the expansion valve 9 on the refrigerant outlet side. be able to. Therefore, there is no need to use a brine cycle as in the conventional case, and cooling using forced convection and radiation can be performed only by the refrigeration cycle without causing dew condensation on the radiation panel 8. Therefore, the configuration of the air conditioner is simpler than in the past, and manufacturing costs can be reduced. In addition, this air conditioner 1 has good thermal efficiency because there is no need to interpose the refrigerant/brine heat exchanger 29 between the brine cycle 41 and the refrigeration cycle 40 (both shown in FIG. 4) as in the conventional case. In addition, since the power required to drive the circulation pumps 31 and 32 for brine is not required, the CO of the refrigeration cycle is reduced.
P is improved and energy saving can be achieved.

The present invention is applicable not only to an air conditioner 1 that performs only cooling operation as in the above embodiment, but also to an air conditioner 1a that performs switching between cooling and heating operations as shown in FIG. 3, for example. It is also possible to apply In addition to the configuration of the air conditioner 1 of the previous embodiment, the air conditioner 1a has a four-way valve 24 that mutually switches the refrigerant path on the discharge side and the suction side of the compressor 2 in order to switch between cooling and heating operations. , a radiant panel 20 that performs indoor radiant heating by passing a high-temperature refrigerant during heating operation, and the radiant panel 20
An expansion valve 25 is mainly provided to reduce the pressure of the refrigerant flowing out of the refrigerant, partially vaporize it, and send it to the outdoor heat exchanger 3. The heating radiant panel 20 is provided in parallel with the expansion valve 4 on the refrigerant inlet side of the indoor heat exchanger 6 in a route that bypasses the expansion valve 4. In addition, three check valves 21, 22, 23 are provided to regulate the flow of refrigerant in a predetermined direction during each operation.
The refrigerant pipes are arranged between the radiant panel 20 and the expansion valve 4, between the expansion valve 9 and the four-way valve 24, and between the expansion valve 25 and the outdoor heat exchanger 3, respectively. In the air conditioner 1a, during the cooling operation, the four-way valve 24 is driven, and the ports A to B and ports C to D are driven.
are each set to allow refrigerant to flow through them. As a result, the air conditioner 1a allows the refrigerant to flow in the directions of the solid arrows, as in the air conditioner 1 of the previous embodiment.
To efficiently cool a room without forming dew condensation on a cooling radiation panel 8. On the other hand, during heating operation, the four-way valve 24 is switched, and ports a to d and ports b to c are set to be able to flow, respectively. Therefore, the refrigerant sent out by the compressor 2 flows as shown by the arrow shown by the broken line, and for example, the high temperature refrigerant passes through the indoor heat exchanger 6.
The air then passes through a radiant panel 20 to heat the room, is depressurized by an expansion valve 25, is further vaporized by receiving heat from the outside air in an outdoor heat exchanger 3, and returns to the compressor 2.

[0018]

[Effect of the invention] According to the present invention, the compressor, the condenser, the first
The expansion valve and the evaporator are connected in this order through a pipe through which a heat medium flows for transferring heat to form a refrigeration cycle, and a radiant panel that absorbs radiant heat from the outside is connected to the evaporator. In an air conditioner connected to the refrigeration cycle in parallel, a second expansion valve is provided on the heat medium outlet side of the radiant panel so as to be openable and closable, and a dew point for detecting the dew point of the air in the vicinity of the radiant panel is provided. It is characterized by comprising: a detection means; and an expansion valve control means for controlling the opening degree of the second expansion valve according to the difference between the dew point detected by the dew point detection means and the temperature of the radiant panel. An air conditioner is provided. Thereby, in order to prevent dew condensation on the radiant panel during cooling operation, it is possible to employ a refrigeration cycle with a simple configuration in which one type of heat medium flows. Therefore, unlike in the case where a refrigeration cycle is configured using two or more types of heat carriers, the power required for the circulation means for circulating the remaining heat carrier is not required. As a result, the air conditioner described above can save energy.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram showing a control system of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure for cooling operation by the air conditioner.

FIG. 3 is a block configuration diagram showing an air conditioner for heating and cooling according to another embodiment of the present invention.

FIG. 4 is a block configuration diagram showing a conventional air conditioner as an example of the background of the present invention.

[Explanation of symbols]

1, 1a, 1b...Air conditioner 2...Compressor 3
...Outdoor heat exchanger 4...Expansion valve (first expansion valve) 5...Expansion valve (first expansion valve) 6...Indoor heat exchanger 7...Refrigerant pipe
8... Radiation panel 9... Expansion valve (second expansion valve) 10...
Humidity sensor 11...Temperature sensor
12...Expansion valve control device 30...Three-way mixing valve

Claims (1)

[Claims] [Claim 1] A refrigeration cycle is constructed by connecting a compressor, a condenser, a first expansion valve, and an evaporator in this order via a pipe through which a heat medium for transferring heat flows, and also connects the compressor, condenser, first expansion valve, and evaporator to the outside. In an air conditioner comprising a radiant panel connected to the refrigeration cycle in parallel with the evaporator, the second expansion valve is provided on the heat medium outlet side of the radiant panel so as to be openable and closable; a dew point detection means for detecting the dew point of air near the radiant panel; and an expansion control for controlling the opening degree of the second expansion valve according to the difference between the dew point detected by the dew point detection means and the temperature of the radiant panel. An air conditioner characterized by comprising a valve control means.