JPS5841424B2 - heat pump system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat pump system, and relates to a combined heat pump system for waste heat recovery consisting of a compression heat pump and an absorption heat pump, and absorbs refrigerant vapor generated in the regenerator of the absorption heat pump. A heat pump system is provided in which the refrigerant is cooled and condensed and then heated while being transferred in an absorption refrigerant evaporator 1, thereby improving the coefficient of performance of the entire system.

An embodiment of the present invention will be described below based on the drawings.

The drawing shows a composite heat pump system, in which 1 is a compression heat pump placed in the front stage near the low-temperature heat source 3 to obtain medium-temperature heat from a relatively low-temperature heat source 3, and 2 is supplied by the compression heat pump 1. In order to obtain high-temperature heat using the medium-temperature heat generated by the evaporator 4 as a heat source, the absorption heat pump is placed on the side closer to the utilization plant, which will be described later, that is, after the compression heat pump 1. , a compressor 5, a drive motor 6, an expansion valve T, etc., and an absorption heat pump includes an absorption refrigerant evaporator 8, a regenerator 9, etc.
, a generator (absorber) 10, a condenser 11, etc.

12 is a refrigerant circulation circuit that sequentially circulates the refrigerant of the compression heat pump 1 from the evaporator 4 to the compressor 5, and then through the expansion valve 7 and back to the evaporator 4; The refrigerant is connected to the expansion valve 7 through the absorption refrigerant evaporator 8.

For the compression heat pump 1, the refrigerant vapor that has exchanged heat with the relatively low-temperature heat source 3 in the evaporator 4 passes through the refrigerant circulation circuit 12, and is compressed by the compressor 5 driven by the drive motor 6 to produce medium-temperature heat. This medium-temperature heat source causes the absorption refrigerant evaporator 8 of the absorption heat pump 2 to evaporate the absorbed refrigerant, and then the refrigerant vapor of the compression heat pump 1 is condensed and passed through the expansion valve I to evaporate again. The absorption refrigerant vapor evaporated in the absorption refrigerant evaporator 8 of the absorption heat pump 2 is evaporated in the absorption refrigerant evaporator 8 of the absorption heat pump 2, and reaches the generator (absorber) 10 in the same tank through the steam separator 13, where it is concentrated and absorbed. It is absorbed by the liquid and generates high temperature heat,
The heat is sent to the utilization plant 15 through the high temperature water circuit 14.

On the other hand, the absorption liquid that has absorbed the absorption refrigerant vapor becomes a diluted absorption liquid and moves through the diluted absorption liquid circuit 16, and heats the concentrated absorption liquid in the concentrated absorption liquid supply circuit 18 via the heat recovery device 17, as well as the regenerator 9. sent to.

In addition to the regenerator 9, the dilute absorption liquid is supplied to the low temperature heat source fluid circuit 19.
The fluid from the relatively low temperature heat source 3 supplied through the refrigerant evaporates and concentrates the absorbed refrigerant.

The evaporated absorption refrigerant vapor passes through the steam/water separator 20 and reaches the condenser 11 in the same tank, where it is condensed by the cooling liquid from the cooling tower 21 and is transferred to the absorption refrigerant supply circuit 2.
2, the refrigerant is circulated and supplied to the absorption refrigerant evaporator 8.

The concentrated absorption liquid in the casing passes through the concentrated absorption liquid supply circuit 18, is heated in the heat recovery device 17, becomes high temperature, and is circulated and supplied to the generator 10.

Here, 23 to 27 are pumps. In such a composite heat pump system, the coefficient of performance η1 is expressed by the following equation.

However, QA: Amount of heat generated at high temperature QE: Amount of heat given to heat and evaporate the absorption refrigerant of the compression heat pump 1 and the absorption heat pump 2.

LW: Compressor power η used to compress and heat up the refrigerant of the compression heat pump 1.

: Coefficient of performance of the compression heat pump 1 η : Coefficient of performance of the absorption heat pump 2 In the drawing, 28 indicates the refrigerant output from the absorption refrigerant evaporator 8 of the absorption heat pump 2 via the compressor 5 on the outlet side of the evaporator 4 of the compression heat pump 1. After that, the absorption refrigerant preheater is interposed between the old refrigerant circulation circuit part leading to the expansion valve 7 and the absorption refrigerant supply circuit part of the absorption heat pump 2. If not, use a compression heat pump 1
When the refrigerant releases heat and condenses in the absorption refrigerant evaporator 8, only the latent heat of condensation is used, and the sensible heat of the condensed liquid is not used.

Therefore, in order to utilize the sensible heat of the refrigerant condensate of the compression heat pump 1, an absorption refrigerant preheater 28 is provided to supercool the refrigerant condensate of the compression heat pump 1, and at the same time absorb the refrigerant supplied to the absorption refrigerant evaporator 8. Heating the refrigerant to raise its temperature.

When the absorption refrigerant preheater 28 is provided in this way, the amount of heat Q0 obtained by the absorption refrigerant of the absorption heat pump 2 is the sum of the latent heat of condensation and the amount of subcooling heat of the refrigerant of the compression heat pump 1, and Q
Since the value of , is larger than that of the latent heat of condensation alone, the coefficient of performance η.

becomes a dog.

At this time, the coefficient of performance η21 of the absorption heat pump 2 =Q
Since A//QE hardly changes in terms of thermal equilibrium, the overall coefficient of performance η1 becomes large, which is advantageous in terms of thermoeconomics.

Next, specific examples will be described.

Using Freon 114 as the refrigerant of the compression heat pump 1, a screw compressor as the compressor 5, and a LiBr-water system as the working medium of the absorption heat pump 2, the evaporation temperature of the Freon 114 in the evaporator 4 was set to 49°C, and the utilization plant 15 The temperature of the high-temperature water to be sent was set at 135°C, and the coefficient of performance of the entire system was calculated under conditions that minimized the unit cost of heat.

At this time, when the degree of supercooling of the Freon 114 in the absorption refrigerant preheater 28 is 5°C to 18°C, the overall coefficient of performance is 6 and 10 more than in the case without the absorption refrigerant preheater 28, respectively.
It's gotten a lot bigger.

29 is a low-temperature heat source preheater, which connects the expansion valve 70 input section of the refrigerant circulation circuit 12 of the compression heat pump 1 and the outgoing path of the low-temperature heat source fluid circuit 19 that supplies fluid from the relatively low-temperature heat source 3 to the regenerator 9. The heating temperature for the dilute absorption liquid in the regenerator 9 is increased.

As a result, the temperature of the concentrated absorption liquid at the outlet of the regenerator 9 can be increased, the concentration can be further increased, and the temperature of the absorption liquid of the generator 10 can therefore be increased, generating heat at a high temperature required by the utilization plant 15. will be obtained.

Furthermore, since the concentration on the concentrated absorption liquid side of the absorption heat pump cycle is increased, which increases the temperature rise range in the generator 10, conversely, the condensation temperature of the refrigerant in the compression heat pump 1 can be lowered. The coefficient of performance of the compression heat pump 1 can be entered.

Due to the low temperature heat source preheater 29, the heat transfer area in the regenerator 9 can be expected to be reduced, and at the same time, the heat transfer area in the generator 10 can also be expected to be reduced.

The housing 30 is a liquid gas heat exchanger that is inserted into the system of the compression heat pump 1 and interposed between the circuit parts on the expander 7 side and the evaporator 4 outlet side.

FIG. 2 shows another embodiment in which the dilute absorption liquid is heated in the regenerator 39 by a portion of the refrigerant vapor from the compressor 5;
The insufficient amount of heat is compensated for by the fluid from the relatively low-temperature heat source 3 supplied through the low-temperature heat source fluid circuit 19.

In this case, the remainder of the refrigerant vapor discharged from the compressor 5 passes through the absorption refrigerant evaporator 8 , mixes with the refrigerant used in the heating of the regenerator 30 on the way, and is configured to reach the absorption refrigerant preheater 28 . There is.

FIG. 3 shows yet another embodiment, in which the refrigerant condensed in the absorption refrigerant evaporator 8 after exiting the compressor 5 is directly supplied to the regenerator 39 in series to utilize its sensible heat. The dilute absorption liquid is heated in the regenerator 39 by the sensible heat of the condensed refrigerant supplied in series from the absorption refrigerant evaporator 8.

In this case, the absorption refrigerant preheater 28 and the low temperature heat source preheater 29
The liquid gas heat exchanger 30 is located on the outlet side of the regenerator 39 and is installed in the absorption refrigerant supply circuit 22 section, the outgoing section of the low temperature heat source fluid circuit 19, and the circuit section on the evaporator 4 outlet side, respectively.

In FIGS. 1 to 3, the arrangement relationship of 28, 29, and 30 is not limited to this, and it goes without saying that the order may be changed.

The encased absorption refrigerant preheater 28 may be used alone, or may be combined with the low temperature heat source preheater 29 and incorporated into a unit.

In this embodiment, an absorption heat pump is used in combination with a compression heat pump at the front stage thereof, but an absorption heat pump may be used instead of the compression heat pump at the front stage.

As described above, according to the present invention, the coefficient of performance of the heat pump at the front stage is increased, and as a result, it has the effect of increasing the coefficient of performance of the entire system, which is extremely advantageous in terms of thermoeconomics.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic configuration diagram when it is implemented in a composite heat pump system, and FIGS. 2 and 3 are schematic configuration diagrams showing other embodiments. 1... Compression heat pump, 2... Absorption heat pump, 5... Compressor, 8...
...Absorption refrigerant evaporator, 9...Regenerator, 10...
... Generator (absorber), 11 ... Condenser, 1
2... Refrigerant circulation circuit, 15... Utilization plant, 22... Absorption refrigerant supply circuit, 28...
...Absorption refrigerant preheater.

Claims (1)

[Claims] 1. A compression heat pump consisting of an evaporator, a compressor, and an expansion valve arranged at the front stage to obtain medium-temperature heat from a relatively low-temperature heat source, and using the medium-temperature heat supplied by the compression heat pump as a heat source. In a heat pump system for exhaust heat recovery that combines an absorption heat pump consisting of an absorption refrigerant evaporator, a regenerator, a generator (absorber), and a condenser arranged at a subsequent stage to obtain high-temperature heat, The refrigerant circulation circuit of the compression heat pump is configured in sequence from the evaporator to the compressor, after leaving the compressor, passing through the absorption refrigerant evaporator of the absorption heat pump to the expansion valve, and from the expansion valve to the evaporator again. At the same time, an absorption refrigerant preheater that heats the absorption refrigerant vapor generated in the regenerator of the absorption heat pump after being cooled and condensed while being transferred in the absorption refrigerant evaporator 1 is installed in the refrigerant circulation circuit of the compression heat pump. A heat pump system characterized by being installed in the circuit from the absorption refrigerant evaporator to the expansion valve.