JP6036939B1 - Operation method of refrigeration equipment - Google Patents

Abstract

[PROBLEMS] To operate a refrigeration system capable of improving the efficiency and output (capacity) of a refrigerant cycle without impairing the stability of the refrigeration cycle when the vapor compression refrigeration cycle is used as a heat pump using hot water for heating feed water. Provide a method. In a refrigeration apparatus constituting a vapor compression refrigeration cycle, a condenser 4 is a hot water generator, and is connected to a refrigerant pipe between the liquid receiver 5 and an expansion valve 7 from the liquid receiver 5. A supercooler 6 that exchanges sensible heat between the refrigerant condensate and the heat medium is installed, a first heat medium pipe 16 that allows the heat medium to flow into the subcooler 6, and the heat medium to the condenser 4. A step of providing a second heat medium pipe 18 to be sent and a third heat medium pipe for allowing the heat medium to flow out of the condenser 4 as hot water, whereby the temperature of the heat medium flowing through the second heat medium pipe 18 is adjusted. A method of operating a refrigeration apparatus, wherein sensible heat exchange and latent heat exchange on the refrigerant side are separated without adjustment, and latent heat exchange by the condenser 4 is performed after sensible heat exchange by the subcooler 6. . [Selection] Figure 1

Description

  The present invention relates to a method for operating a refrigeration apparatus, and more particularly, operation of a refrigeration apparatus capable of improving the efficiency and output (capacity) of a refrigeration cycle when a vapor compression refrigeration cycle is used as a heat pump for heating feed water. Regarding the method.

Conventionally, a refrigeration apparatus that constitutes a vapor compression refrigeration cycle in which a compressor, a condenser, a liquid receiver, an expansion mechanism, and an evaporator are sequentially connected in this order by a refrigerant pipe has been widely used.
In such a refrigeration cycle, the receiver is usually installed on the downstream side of the condenser of the refrigerator, and is used as a container that absorbs fluctuations in the amount of refrigerant in the evaporator due to load fluctuations.
For example, in the case of using as a heat pump, especially in a condenser, when the feed water flowing into the condenser is heated and discharged as warm water or steam by the latent heat of condensation of the refrigerant, the hot water temperature is It's going to happen.
On the other hand, the feed water inlet temperature is affected by the situation on the feed water supply side, and when the difference from the condensation temperature of the condenser is large (the refrigerant inlet temperature is the compressor discharge temperature, it is 10 to 10 There are cases where the temperature is higher than 20 ° C). For example, when the temperature is lower than 10K, there are the following technical problems to achieve the required temperature and flow rate of hot water or steam.

In other words, the temperature on the refrigerant outlet side does not sufficiently approach the temperature on the water supply side, and is discharged from the condenser in a supercooled state of about 1 to 5K, so it is not possible to fully utilize the heating (heat radiation) enthalpy difference on the refrigerant side It is.
In this case, for example, even if a plurality of condensers are installed in series on the upstream side of the liquid receiver, the refrigerant temperature is kept constant in the latent heat exchange. Although the exchange area has only increased, the effect of lowering the condensation temperature can be expected, but the heating on the refrigerant side (heat dissipation) contributes little to the expansion of the enthalpy difference, so the required temperature and required flow rate of hot water or steam are achieved. For this purpose, the refrigerant circulation amount must be increased by increasing the size of the heat pump device itself, which may be difficult to install in a limited installation space.

  On the other hand, the liquid receiver and the heat exchanger are integrated, the water supply pipe of the heat exchanger is arranged in the liquid receiver, and the portion of the water supply pipe exposed from the refrigerant liquid surface and the gas refrigerant in the liquid receiver If the sensible heat exchange is performed between the liquid refrigerant and the portion of the water supply pipe that is immersed in the refrigerant liquid, the sensible heat exchange and the latent heat exchange are performed between the refrigerant and the water supply. It is possible to perform heat exchange, but the ratio of sensible heat exchange and latent heat exchange fluctuates because the liquid level in the receiver rises and falls according to the operating condition of the refrigeration cycle. However, the stability of the refrigeration cycle is impaired.

In this regard, in Patent Document 1, as a heat pump type steam generation method, there is a technique in which a steam generator that is a condenser is installed on the upstream side of the receiver and a supercooler is installed on the downstream side of the receiver. It is disclosed.
More specifically, a compressor, a steam generator, a refrigerant receiver, a first heat exchanger, an expansion valve, a refrigerant circuit through which a refrigerant flows through a heat recovery device, and a steam generator through the first heat exchanger Is provided with a water supply pipe to which makeup water is supplied, and after the makeup water is warmed in the first heat exchanger by sensible heat of refrigerant supercooling, it is fed into the steam generator and the refrigerant is condensed in the steam generator. In a heat pump steam generation method configured to generate steam by latent heat, liquid refrigerant close to saturation immediately after being condensed by the steam generator is stored in a liquid receiver in a state where the liquid level is provided, and the refrigerant The liquid refrigerant stored in the liquid receiver is supplied to the first heat exchanger, and the makeup water is heated to near the saturation temperature using only the supercooled sensible heat of the liquid refrigerant in the first heat exchanger. And is supplied into the steam generator.

  According to this method, since the liquid refrigerant stored with the liquid level in the refrigerant receiver is supplied to the first heat exchanger, only the liquid refrigerant is caused to flow in the first heat exchanger, The refrigerant gas does not flow. Accordingly, in the first heat exchanger, only the supercooled sensible heat of the liquid refrigerant is used to stably heat the make-up water to near the saturation temperature, and supply the heated make-up water into the steam generator. Can do. In addition, in the steam generator, makeup water that has been stably heated to near the saturation temperature is replenished, so that the makeup water is further heated by the latent heat of condensation of the refrigerant (including sensible heat in the refrigerant heating zone). Therefore, a large amount of steam can be stably generated.

However, this technique has the following technical problems due to the heat pump steam generation method. That is, formally, even if sensible heat exchange is performed in the supercooler and latent heat exchange is performed in the steam generator, it is difficult to perform sufficient sensible heat exchange in the subcooler. More specifically, in order to efficiently generate steam in the steam generator, the hot water is heated to the saturation temperature before flowing into the steam generator, and therefore the hot water until flowing into the steam generator. It is necessary to limit the flow rate of hot water until it flows into the steam generator on the premise of adjusting the flow rate of the steam generator, and thus it is difficult to ensure sufficient sensible heat exchange in the subcooler. In the first place, since the latent heat of vaporization of water is very large, the amount of make-up water as seen from the ratio of the refrigerant flow rate is remarkably small. It will only be around 10K.
JP 2012-247156 A

  In view of the above technical problems, the object of the present invention is to improve the efficiency of the refrigerant cycle without impairing the stability of the refrigeration cycle when the vapor compression refrigeration cycle is used as a hot water utilization heat pump for feed water heating. An object of the present invention is to provide a method of operating a refrigeration apparatus that can improve output (capacity).

In order to achieve the above object, the operation method of the refrigeration apparatus according to the present invention is such that a compressor, a condenser, a liquid receiver, an expansion mechanism, and an evaporator are sequentially connected by a refrigerant pipe in this order, and a vapor compression refrigeration In the operation method of the refrigeration apparatus constituting the cycle, the condenser is a hot water generator, and a refrigerant condensate and a heat medium from the liquid receiver are connected to a refrigerant pipe between the liquid receiver and the expansion valve. A supercooler that exchanges sensible heat with the first heat medium pipe through which the heat medium flows into the supercooler, and in the supercooler, the refrigerant condensate from the receiver Providing a second heat medium pipe for liquid-feeding the heated heat medium to the condenser, and a third heat medium pipe for allowing the heat medium heated by the refrigerant gas in the condenser to flow out of the condenser as hot water So that the heat exchange between the heat medium and the refrigerant is possible. Then, the sensible heat exchange and the latent heat exchange on the refrigerant side are separated without adjusting the temperature of the heat medium flowing through the second heat medium pipe, and after the sensible heat exchange by the subcooler, It is configured to perform latent heat exchange.

According to the operation method of the refrigeration apparatus having the above configuration, in the vapor compression refrigeration cycle, when used as a heat pump for heating the medium, sensible heat exchange with the refrigerant in the subcooler on the downstream side of the receiver is performed. In this order, heat medium heating is performed in this order by latent heat exchange on the refrigerant side in the hot water generator upstream of the liquid receiver, thereby reducing the efficiency and output (capacity) of the refrigeration cycle without impairing the stability of the refrigeration cycle. Can be significantly improved.
More specifically, first, in the subcooler, sensible heat exchange is performed between the heat medium flowing in through the first heat medium pipe and the refrigerant condensate from the liquid receiver, and then the second heat medium pipe is connected. Without adjusting the temperature of the flowing heat medium, in the hot water generator, the heat medium fed to the condenser by the second heat medium pipe and heated by the refrigerant condensate from the liquid receiver, and from the compressor Heat water is generated by exchanging latent heat with the refrigerant gas, and sensible heat exchange and latent heat exchange between the refrigerant and the heat medium are separated, and in this order, heat exchange is performed to heat the refrigerant side. (Heat dissipation) It becomes possible to fully utilize the enthalpy difference, for example, the heat exchanger is greatly reduced compared with the case where condensers are simply added in parallel or in series to increase sensible heat exchange It is possible to make it.

Moreover, it is good to have the step which maintains the liquid level of the refrigerant condensate in the said liquid receiver more than a predetermined level during the driving | operation of the said freezing apparatus.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a method for operating a refrigeration apparatus according to the present invention will be described in detail based on specific examples shown in the accompanying drawings.
First, as shown in FIG. 1, the refrigeration apparatus will be described. The other end of the refrigerant forward pipe 2 whose one end is connected to the discharge side of the compressor 1 is an oil separator 3 and a first heat exchanger. A hot water generator 4, a liquid receiver 5 that is a gas-liquid separator for refrigerant, a supercooler 6 that is a second heat exchanger, and an expansion valve 7 are connected to the primary side inlet of the heat recovery unit 8 and are connected to the outlet. The other end of the refrigerant return pipe 9 to which one end is connected is connected to the suction side of the compressor 1, thereby constituting a refrigerant circuit.

  The hot water generator 4 is composed of a plate heat exchanger, and moves the hot heat from the refrigerant gas flowing in the primary flow path to the water (hot water) flowing in the secondary flow path, thereby generating hot water. ing.

On the upstream side of the liquid receiver 5, the hot water generator 4 is disposed. On the other hand, on the downstream side of the liquid receiver 5, a supercooler 6 is disposed. Sensible heat exchange is performed between the condensate refrigerant and the feed water, and the hot water generator 4 is configured such that latent heat exchange is performed between the refrigerant gas and the feed water heated by the subcooler 6. The refrigerant flow and the feed water flow are opposed to each other to separate the sensible heat exchange and latent heat exchange, and then heat exchange in this order, so that the efficiency and output of the refrigeration cycle (as will be described below) Ability) has been improved.
During the operation of the refrigeration system, the liquid level of the refrigerant condensate in the liquid receiver 5 is set to a predetermined level so as to prevent the refrigerant gas from flowing downstream from the liquid receiver 5 when viewed from the refrigerant side. Maintained above level.

  A water supply pipe 16 from the outside is connected to the secondary side inlet of the subcooler 6 via a pump 17, and the other end of the hot water supply pipe 18 whose one end is connected to the secondary side outlet is hot water. Connected to the secondary inlet of the generator 4.

  The secondary side of the heat recovery unit 8 is connected to a supply pipe 22 and a drain pipe 23 of the exhaust hot water, and the residual heat of the exhaust hot water is recovered by the refrigerant flowing through the primary side of the heat recovery unit.

Next, the operation method of the refrigeration apparatus having the above-described configuration will be described in detail below with reference to FIG.
First, the high-temperature gas refrigerant discharged from the compressor 1 (state a in FIG. 2) is sent to the hot water generator 4 through the oil separator 3, and the secondary heat of the plate heat exchanger in the hot water generator. Heat exchange with the hot water flowing through the side channel is condensed and sent out, and the hot water is heated by the latent heat of the refrigerant.

  Next, the refrigerant condensed in the hot water generator 4 (state of symbol b in FIG. 2) is stored in the liquid receiver 5, and only the liquid refrigerant is sent to the subcooler 6 from the liquid phase in the liquid receiver. In the same supercooler 6, the pump 17 is driven to exchange sensible heat with water supplied from the outside, and is supercooled (in the state indicated by symbol c 'in FIG. 2).

  Next, the supercooled refrigerant as described above is sent to the heat recovery unit 8 through the expansion valve 7 (in the state indicated by reference numeral d ′ in FIG. 2), and from an external heat source such as exhaust hot water in the heat recovery unit. The exhausted water is cooled and the exhausted water is cooled, and the refrigerant itself is vaporized (in the state of symbol e in FIG. 2), and returned to the suction side of the compressor 1 by the refrigerant return pipe 9.

  The opening degree of the expansion valve 7 is such that the degree of superheat calculated using the calculator 28 by the temperature sensor 26 and the pressure sensor 27 provided near the outlet of the heat recovery unit 8 in the refrigerant return pipe 9 is 10 ° C. or more. So that the liquid back to the compressor 1 can be prevented.

  On the other hand, the temperature of the hot water delivered from the hot water generator 4 is detected by the temperature sensor 31 and the opening of the control valve 33 installed in the water supply pipe 16 is adjusted according to the detected temperature, thereby supplying hot water. The feed water flow rate of the pipe 18 is adjusted. In this case, the water supply temperature in the hot water supply pipe 18 connecting the hot water generator 4 and the subcooler 6 is appropriate, and the hot water supply pipe is used to adjust the water supply temperature in the hot water supply pipe 18. The feed water flow rate of 18 is not adjusted, the opening of the control valve 33 is completely throttled, and the flow rate is not adjusted on and off.

Hereinafter, the hot water generator 4 and the supercooler 6 are arranged on the upstream and downstream sides of the liquid receiver 5 to separate heat exchange between the refrigerant and the feed water into sensible heat exchange and latent heat exchange. The technical effect of heat exchange in order will be described.
The Mollier diagram in the case where the heat exchanger (condenser) is arranged only on the upstream side of the liquid receiver 5 is indicated by a solid line abcde, and a plurality of heat exchangers (condensers) are connected in series on the upstream side of the liquid receiver 5. When arranged, and when a heat exchanger (condenser) and a heat exchanger (supercooler) are arranged on the upstream and downstream sides of the liquid receiver 5 respectively, the respective one-dot chain lines (abc′′d′′e) and Indicated by a dotted line (abc'd'e).
For example, when two heat exchangers are arranged in series on the upstream side of the liquid receiver 5, the heat transfer area for latent heat exchange is simply increased correspondingly, and the Mollier wire of FIG. 2 is increased. According to the figure, the refrigerant condensing temperature is lowered by that amount, and the supercooling is slightly increased (one-dot chain line).
On the other hand, on the assumption that the hot water generator 4 (condenser) is arranged upstream of the liquid receiver 5, a supercooler 6 (supercooler) is arranged downstream of the liquid receiver 5. In the case where the feed water and the refrigerant are counterflowed, first, the sensible heat exchange is performed between the liquid refrigerant of the liquid receiver 5 and the feed water by the supercooler, whereby the feed water is heated. On the other hand, the liquid refrigerant is cooled, and then, the latent heat exchange is mainly performed between the gas refrigerant and the feed water by the condenser, whereby the feed water is further heated, while the gas refrigerant is condensed. In this case, strictly speaking, in the condenser, the gas refrigerant is absorbed by the water supply, the temperature is lowered as the gas refrigerant by the sensible heat exchange, the latent heat exchange is performed in the process where the gas refrigerant becomes the liquid refrigerant, and the liquid refrigerant is further supplied by the water supply. The temperature is reduced as a liquid refrigerant by sensible heat exchange, but the ratio of sensible heat exchange before and after latent heat exchange is negligibly small.

In this case, according to the Mollier diagram of FIG. 2, only the supercooling increases while the condensation temperature is maintained as indicated by the dotted line, and it becomes possible to further utilize the heating (heat radiation) enthalpy difference on the refrigerant side. Thus, the efficiency and output (capacity) of the refrigeration cycle can be remarkably improved.
For example, if a water supply pipe is arranged in the liquid receiver 5 and heat exchange is performed between the refrigerant and the water supply, the ratio between the sensible heat exchange and the latent heat exchange is directly caused by the liquid level fluctuation accompanying the load fluctuation. It is also possible to avoid such a direct influence where the stability of the refrigeration cycle is impaired.
As an incidental effect, it is possible to stabilize the water temperature flowing into the condenser and to reduce the heating ΔT in the condenser by making more use of the heating (heat radiation) enthalpy difference on the refrigerant side. Therefore, it also contributes to stabilizing the discharge pressure of the compressor.

  The technical significance of setting the difference between the heat medium inlet temperature to the subcooler 6 and the refrigerant condensate outlet temperature from the liquid receiver 5 to be 5K or more is as follows. In general, the difference between the refrigerant outlet temperature from the supercooler 6 and the heat medium inlet temperature to the supercooler 6, which is a heat exchanger approach, is 3 to 7 K from the viewpoint of achieving both thermal efficiency and economy. Set to For example, when the approach is 5K on the average, the difference between the refrigerant inlet temperature to the subcooler 6 and the heat medium inlet temperature to the subcooler 6 is not less than 5K as long as the approach is 5K. On the other hand, the lower the refrigerant inlet temperature to the supercooler 6, the smaller the difference between the refrigerant inlet temperature to the supercooler 6 and the refrigerant outlet temperature from the supercooler 6, that is, the heat exchange amount. The technical significance of providing 6 becomes poor. From this point of view, the difference between the heat medium inlet temperature to the supercooler 6 and the refrigerant condensate outlet temperature from the liquid receiver 5 is set to 5K or more from a practical viewpoint.

According to the operation method of the refrigeration apparatus having the above configuration, in the vapor compression refrigeration cycle, when used as a heat pump for heating the medium, sensible heat exchange with the refrigerant in the subcooler 6 on the downstream side of the liquid receiver. And the latent heat exchange on the refrigerant side in the hot water generator 4 on the upstream side of the receiver, in this order, heat medium heating is performed, so that the efficiency and output of the refrigeration cycle (without sacrificing the stability of the refrigeration cycle) Ability) can be significantly improved.
More specifically, first, in the supercooler 6, sensible heat exchange is performed between the heat medium flowing in through the first heat medium pipe and the refrigerant condensate from the liquid receiver 5, and then the second heat medium. Without adjusting the temperature of the heat medium flowing through the pipe, in the hot water generator 4, the heat medium heated by the refrigerant condensate from the liquid receiver 5 sent to the condenser through the second heat medium pipe By performing latent heat exchange with the refrigerant gas from the compressor 1, hot water is generated, sensible heat exchange and latent heat exchange between the refrigerant and the heat medium are separated, and heat exchange is performed in this order. This makes it possible to make full use of the enthalpy difference on the refrigerant side (heat dissipation), for example, heat exchange compared to simply adding condensers in parallel or in series to increase sensible heat exchange. It is possible to remarkably reduce the vessel.
In this case, particularly when the difference between the heat medium inlet temperature to the subcooler 6 and the refrigerant condensate outlet temperature from the receiver 5 is 5K or more, the efficiency and output (capacity) of the refrigeration cycle are improved. The effect is remarkable.

The embodiments of the present invention have been described in detail above, but various modifications or changes can be made by those skilled in the art without departing from the scope of the present invention.

  Although the thing of embodiment mentioned above is all as a refrigerant | coolant circuit of a single stage structure, it may be comprised by multistage refrigeration cycles, such as a two-stage | paragraph multistage refrigeration cycle and a binary.

It is a block diagram which shows embodiment of the freezing apparatus in the operating method of the freezing apparatus which concerns on this invention. It is a Mollier diagram which shows an example of the effect | action by embodiment of the freezing apparatus in the operating method of the freezing apparatus of this invention.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Refrigerant outbound pipe 3 Oil separator 4 Hot water generator 5 Receiver 6 Subcooler 7 Expansion valve 8 Heat recovery device 8 Heat recovery device 9 Refrigerant return pipe 10 Steam delivery pipe 11 Gas-liquid separator 12 for water supply Steam supply pipe 13 Valve 14 Hot water return pipe 15 Check valve 16 Water supply pipe 17 Pump 18 Hot water supply pipe 21 Check valve 22 Waste water supply pipe 23 Drain pipe 24 Heater 25 Liquid level detector 26 Temperature sensing cylinder

Claims (1)

In the operating method of the refrigerating apparatus in which the compressor, the condenser, the liquid receiver, the expansion mechanism, and the evaporator are sequentially connected in this order by the refrigerant pipe to constitute a vapor compression refrigeration cycle, the condenser has a desired temperature. Is a hot water generator that generates hot water, and is configured to supercool the sensible heat exchange between the refrigerant condensate from the liquid receiver and the heat medium in the refrigerant pipe between the liquid receiver and the expansion mechanism And a first heat medium pipe for introducing a heat medium into the supercooler and a heat medium heated by the refrigerant condensate from the liquid receiver in the supercooler to the condenser. Providing a second heat medium pipe to be sent and a third heat medium pipe for letting out the heat medium heated by the refrigerant gas in the condenser as hot water from the condenser;
During operation of the refrigeration apparatus, the liquid level of the refrigerant condensate in the receiver is maintained at a predetermined level or higher regardless of fluctuations in operating conditions, and according to the hot water temperature on the outlet side of the condenser, Adjusting the flow rate of the heat medium flowing through the first heat medium pipe ,
Thereby, the heat exchange between the heat medium and the refrigerant, without adjusting the temperature of the heat medium flowing through the second heat medium pipe, always separate the sensible heat exchange and latent exchange in the refrigerant, the A method for operating a refrigeration apparatus, comprising heating a heat medium only by heat exchange with a refrigerant, comprising sensible heat exchange by a subcooler and subsequent latent heat exchange by the condenser .

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