JPH07174431A - Double effect absorption heat pump - Google Patents

Abstract

PURPOSE:To provide a double effect absorption heat pump which is constituted to increase a result factor and perform operation even when the temperature of low temperature heat source water is changed. CONSTITUTION:A second condenser 11 is mounted on the hot water outlet side of a double effect absorption type heat pump to form a single and double effect composite cycle. A hot water heating amount allotted to a single effect cycle is controlled by the pressure of a high temperature reproducer 8. A refrigerant at a vaporizer 1 is blown so that low temp heat source water is prevented from being overcooled and a pressure is reduced to a value lower than an atmospheric pressure by a second condenser 11. This constitution increases the result factor of an absorption type heat pump to a value 1.3-1.7 times as large as that of a conventional type and performs operation even when the temperature of low temperature heat source water is reduced, and improves facility of a heat pump.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a double-effect absorption heat pump.

[0002]

2. Description of the Related Art A conventional double-effect absorption heat pump is
Under conditions where the temperature of the low temperature heat source is low and the concentration of the absorbing solution is relatively high, if hot water of the temperature required for heating is taken out, the pressure of the high temperature regenerator exceeds atmospheric pressure, and the pressure vessel is required to do so. , The hot water could not be heated to the temperature required for heating.

Therefore, as described in JP-A-5-52438 or JP-A-5-52439, a heat medium having an intermediate temperature is produced by a double-effect heat pump cycle, and the heat medium having the intermediate temperature is used as a low temperature heat source. As a method, a single effect heat pump is operated to take out hot water of high temperature. When the temperature is raised in two stages as described above, hot water of high temperature can be taken out, but there is a drawback that the coefficient of performance (COP) is low.

For example, there are COP = 2.2 in the double-effect absorption heat pump and COP = 1.7 in the double-effect absorption heat pump as the highest COP in the present situation.

[0005]

[Equation 1]

Therefore, only 29% of the amount of heat for heating can utilize the exhaust heat.

[0007]

The above-mentioned prior art was able to take out hot water at a high temperature, but the thermal efficiency was low,
There was a problem that the waste heat utilization rate was low.

An object of the present invention is to recover heat from a relatively low exhaust heat source and efficiently produce hot water at a temperature required for heating,
It is to provide a double-effect absorption heat pump with a high utilization rate of waste heat.

Another object of the present invention is to provide a double-effect absorption heat pump which can take out hot water having a constant temperature level necessary for heating even if the temperature of the exhaust heat source is lowered.

[0010]

In order to achieve the above object, a condenser for directly condensing and heating hot water with a refrigerant vapor generated from a high temperature regenerator is provided at the hot water outlet side of a double-effect absorption heat pump to condense and liquefy. This refrigerant is returned to the evaporator via the condenser that constitutes the double-effect absorption heat pump.

Further, a passage bypassing the condenser is provided in the hot water system passage of the condenser for heating the warm water with the heat of condensation of the refrigerant vapor generated from the high temperature regenerator, and the condenser is controlled by the pressure of the high temperature regenerator. The amount of hot water that bypasses is controlled.

Further, under the condition that the exhaust heat temperature is lowered and the concentration of the absorbing solution is increased, if the concentration of the absorbing solution becomes higher than a certain level, the refrigerant liquid of the evaporator automatically enters the absorber side, and the solution of the absorber becomes It is designed so that it does not become darker than a certain level.

[0013]

[Function] A condenser that directly guides the refrigerant vapor generated in the high temperature regenerator and heats hot water to condense and liquefy it is an evaporator,
Combined with the absorber to form a single-effect absorption heat pump cycle. Therefore, if the solution concentration in the low temperature regenerator becomes high and the solution temperature rises under the condition that the temperature of the exhaust heat source is low and the absorption solution concentration is high, the high temperature regenerator pressure is large in the double-effect absorption heat pump cycle. If the hot water is heated by the absorber and the condenser within the range not exceeding the atmospheric pressure, and if the hot water does not reach the predetermined temperature, it is heated by the condenser that condenses and liquefies the refrigerant vapor generated in the high temperature regenerator, to obtain a single layer. It has been heated by the absorption heat pump cycle, and the total C
OP becomes an intermediate value between the single-effect absorption heat pump cycle and the double-effect absorption heat pump cycle, and the utilization rate of exhaust heat becomes high.

Further, when the temperature of the exhaust heat source is relatively high, the concentration of the absorber solution becomes thin, so that the hot water can be heated to a temperature close to a predetermined temperature in the double-effect absorption heat pump cycle. In this case, if the hot water passing through the condenser that condenses and liquefies the refrigerant vapor generated in the high temperature regenerator is bypassed and the amount of condensation is reduced, the rate of heating in the double-effect absorption heat pump cycle increases, and the total COP Becomes higher. Further, since the amount of hot water bypass of the condenser is controlled by the pressure of the high temperature regenerator, it is possible to maximize the rate of heating in the double-effect absorption heat pump cycle within the range where the high temperature regenerator pressure does not exceed atmospheric pressure. As a result, as the exhaust heat source temperature condition changes, the most efficient operation under that condition is performed.

When the temperature of the exhaust heat source decreases and the absorber solution concentration becomes thicker than a certain level, the refrigerant liquid automatically flows into the absorber solution from the evaporator so that the solution concentration does not become thicker than a certain amount. If the solution does not crystallize, the absorption heat pump acts as a heat exchanger that uses all the heat of the driving source to heat the hot water, and COP = 1. When the temperature of the exhaust heat source rises, the evaporator partially evaporates, and the COP becomes 1 or more. When the temperature of the exhaust heat source rises, the COP rises to 2.2, which is the maximum. In other words, in an absorption heat pump equipped with an evaporator that directly guides and condenses the refrigerant vapor generated in the high temperature regenerator, when the concentration of the absorber solution becomes higher than a certain level, the refrigerant liquid from the condenser automatically becomes the absorber solution. Providing an inflow device allows operation without heat loss even if the temperature of the exhaust heat source changes drastically.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will now be described with reference to FIGS.
It will be described with reference to the drawings. The low temperature heat source water 2 which is a low temperature heat source flows in the heat transfer tube passing through the evaporator 1, and the refrigerant outside the tube is dispersed by the refrigerant pump 3 onto the heat transfer tube, so that the heat is supplied from the low temperature heat source water 2 flowing in the tube. Take away and evaporate. The evaporated refrigerant reaches the absorber 4, and is absorbed by the warm water 5 flowing in the pipe into a solution kept at an appropriate temperature and concentration, and the solution is diluted. The diluted solution is sent to the low temperature regenerator 7 and the high temperature regenerator 8 by the solution pump 6, and is heated and concentrated in the high temperature regenerator 8 by the external heat source 9. The refrigerant vapor generated at this time reaches the inside of the tube of the low temperature regenerator 7, heats and concentrates the dilute solution outside the tube, and liquefies itself into the condenser 10. The liquids concentrated in the high temperature regenerator 8 and the low temperature regenerator 7 are merged and returned to the absorber 4, and sprayed on the heat transfer tube. The refrigerant liquid condensed in the condenser 10 and the low temperature regenerator 7 returns from the condenser 10 to the evaporator 1, and the cycle completes.
The hot water passing through the absorber 4 and the condenser 10 is heated by obtaining absorption heat and condensation heat, and is used for heating or heating.

The second condenser 11 passes the hot water heated by the condenser 10 through the heat transfer tube, and introduces the refrigerant vapor generated from the high temperature regenerator 8 to the outside of the tube to condense it for further heating. Raise the temperature. The refrigerant vapor generated in the high temperature regenerator 8 has a high saturation temperature at which the dilute solution can be heated and concentrated in the low temperature regenerator 7, and thus has the potential to heat the hot water up to about 90 ° C. The control valve 17 adjusts the amount of hot water passing through the second condenser 11,
Adjust the heating amount of.

In response to the signal from the pressure detector 15 of the high temperature regenerator 8, the pressure regulator 16 increases the amount of hot water passing through the second condenser 11 when the pressure of the high temperature regenerator 8 becomes close to the atmospheric pressure, On the contrary, when the heating amount is increased and the pressure is low, the amount of hot water passing through is reduced to control the heating amount.

The control valve 14 for controlling the input of the heating source operates according to the signal from the temperature controller 13 which receives and adjusts the signal from the temperature sensor 12 at the hot water outlet to control the hot water outlet temperature at a constant level.

In a heat pump having such a structure, the outlet temperature of hot water is often around 50 ° C. when used for general heating applications, and the higher the temperature, the higher
Even if the heat transfer area of the air conditioners is reduced, the required heating amount can be obtained, and the hot water transport power can be reduced.

On the other hand, considering from the side of the absorption heat pump, in the double-effect cycle, when the hot water outlet temperature of the condenser 11 influences the refrigerant condensing pressure of the condenser 11 and the condensing pressure of the refrigerant becomes high, the condenser 11 The refrigerant evaporating pressure generated in the low temperature regenerator 7 communicating with is increased. When the refrigerant evaporation pressure increases, the solution temperature in equilibrium with the refrigerant evaporation increases, so the condensation temperature of the refrigerant vapor in the tube that heats this solution increases, and the saturation pressure for this condensation temperature becomes the pressure of the high temperature regenerator. Therefore, the pressure of the high temperature regenerator 8 is increased.

In summary, the relationship that the higher the hot water outlet temperature, the higher the pressure of the high temperature regenerator 8 is established.

These relationships will be described with reference to the Duhring diagram shown in FIG. 2. For example, the outlet temperature of the low temperature heat source water (te
o) is 10 ° C and the hot water outlet temperature (thc) is 47 ° C,
The solution concentration of the absorber 4 becomes about 58%, the refrigerant condensation temperature (Tc) of the condenser 11 is 48.5 ° C, and the saturation pressure (Pc) is 8
6mmHgabs and the solution temperature at the outlet of the low temperature regenerator is 97
℃, the refrigerant condensation temperature in the tube (Tgc) is 100 ℃,
The high temperature regenerator pressure (PHG) becomes atmospheric pressure. When the temperature level of the low temperature heat source water rises and the low temperature heat source water outlet temperature (teo) reaches about 15 ° C, the evaporation pressure (Pe) rises and the solution concentration of the absorber 4 becomes about 56%. At the hot water outlet 47 ° C. The temperature of the solution at the outlet of the low temperature regenerator drops to 93 ° C, and the pressure of the high temperature regenerator also becomes lower than atmospheric pressure.

As described above, when low-temperature wastewater such as sewage treated water is used as a low-temperature heat source, the high-temperature regenerator pressure is atmospheric when the high-temperature hot water required for heating is obtained in the double-effect cycle. That's all.

When the inside of the machine exceeds the atmospheric pressure, the entire absorption heat pump becomes a pressure vessel, which requires strict safety consideration, becomes an expensive heat pump, and requires special qualification for the driver who operates the heat pump. There are safety issues such as Therefore, in the actual heat pump, in order to prevent the operating pressure from exceeding the atmospheric pressure, a safety switch is provided to stop the machine or the hot water outlet temperature is lowered by limiting the load. .

In the present invention, a part of the refrigerant vapor generated in the high temperature regenerator 8 is guided to the second condenser 11, and the hot water discharged from the condenser 10 is transferred to the outside of the heat transfer tube of the second condenser 11. Is configured to be heated by the heat of condensation of the refrigerant vapor.

In this way, when the hot water temperature at the outlet of the second condenser 11 is set to 47 ° C., the condenser 1
The outlet hot water temperature of 0 becomes about 45 ° C., and the internal pressure of the high temperature regenerator can be made sufficiently lower than the atmospheric pressure.

The refrigerant liquid condensed and liquefied by heating the warm water in the second condenser 11 is passed through the condenser 10 to
Since it is returned to the evaporator 1, the evaporator 1 is utilized for pumping heat from the low temperature heat source. That is, the heat of condensation used for heating the hot water in the second condenser 11 acts as a single-effect cycle and is effectively used for heat recovery from the low-temperature heat source. As mentioned above, the coefficient of performance of the heat pump of the single-effect cycle is about 1.7.

On the other hand, the heat of condensation used for heating the hot water in the condenser 10 acts as a double-effect cycle, the efficiency of heat recovery from the low-temperature heat source is increased, and the coefficient of performance as a heat pump is about 2.2. . Therefore, the overall coefficient of performance is higher when the amount of heated hot water in the second condenser 11 is reduced and the amount of heated warm water in the condenser 10 is increased. For example, when the temperature of the low-temperature heat source is high and the solution concentration of the absorber 4 is low as described above, the warm water can be heated to a predetermined temperature in the condenser 10, so the heating amount in the second condenser is set to 0. Yes, the highest coefficient of performance is 2.2. On the contrary, when the temperature of the low temperature heat source is low, the solution concentration in the absorber becomes high, so that the condenser 10
The heating amount in the second condenser must be increased by keeping the heating amount in the second high temperature regenerator within a range not exceeding the atmospheric pressure. In this case, the coefficient of performance of the heat pump becomes low, and the minimum heating amount of the condenser 10 is 1.7, which is 1.7. That is,
The coefficient of performance is 1.7 depending on the amount of heat in the second condenser 11.
It will change between ~ 2.2.

The amount of hot water heated in the second condenser 11 can be adjusted by controlling the control valve 17 that adjusts the amount of hot water that bypasses the second condenser 11. The control of the control valve 17 is performed by the pressure detector 1 of the high temperature regenerator 8.
The signal of No. 5 is supplied to the regulator 16 so that the bypass amount is reduced when the high temperature regenerator pressure is high, and the bypass amount is increased when the high temperature regenerator pressure is low.

By the above control, the pressure of the high temperature regenerator 8 of the absorption heat pump can be set to the atmospheric pressure or less, and the operation can be performed at the highest coefficient of performance in accordance with the temperature level of the low temperature heat source.

FIG. 3 shows another embodiment. All the refrigerant vapor generated in the high temperature regenerator 8 flows into the low temperature regenerator 7,
The solution in the low temperature regenerator 7 is heated and a part thereof is condensed to become a refrigerant liquid and flows into the condenser 10, while the uncondensed refrigerant vapor is separated from the refrigerant liquid in the separator 19, In the condenser 11, the hot water is directly heated to be condensed and liquefied, and then flows into the condenser 10 through the gas blow-through prevention float valve 18. With this configuration, the heat of the superheat of the refrigerant vapor generated in the high temperature regenerator 8 (about 5
%) Can be used for heating the solution of the low temperature regenerator 7, and a high coefficient of performance can be obtained even when the low temperature heat source temperature is low.

FIG. 4 shows still another embodiment. When the temperature of the low temperature heat source decreases, the evaporation temperature (TE) decreases, and the evaporation pressure (PE) decreases, so that the concentration of the absorbing solution becomes thick. When the temperature of the low temperature heat source is extremely decreased, the absorption capacity is lost, the refrigerant in the absorbing solution is separated, the solution concentration is increased, and the amount is decreased at the same time, so that the liquid level of the absorber 4 is decreased. On the other hand, in the evaporator 1, the amount of the refrigerant separated from the solution increases, and the liquid level rises. The refrigerant return device 20 is a device that returns the refrigerant liquid to the absorber 4 when the refrigerant liquid level of the evaporator 1 reaches a certain level or more, and adjusts the attachment level so that the solution does not become thicker than an arbitrary concentration. be able to. For example, when the low temperature heat source temperature is low and the liquid level of the refrigerant becomes equal to or higher than the level of the refrigerant return device 20, the refrigerant flows from the evaporator 1 into the absorber 4, the solution concentration does not become thicker than a certain level, and crystals do not occur. The circulation of the solution is continued, and the solution exchanges heat with the warm water 5 and is kept at a constant temperature. In the low temperature regenerator 7, the solution is heated by the refrigerant vapor generated in the high temperature regenerator 8, but the refrigerant is hardly regenerated. Most of the refrigerant vapor generated in the high temperature regenerator 8 heats hot water in the second condenser 11, condenses itself into liquid, and flows into the condenser 10. At this time, the control valve 17 is controlled by the high temperature regenerator pressure to increase the amount of hot water passing through the second condenser 11, so that the high temperature regenerator pressure is maintained below atmospheric pressure. All the heat that has entered the heat pump from the heat source 9 is transferred to the hot water 5 and does not escape to the outside.

FIG. 5 shows still another embodiment. The temperature controller 2 receives the signal from the low temperature heat source water outlet temperature detector 21.
2 controls the refrigerant blow valve 23. When the temperature of the low temperature heat source water falls too low, the refrigerant blow valve 23 is opened to blow the refrigerant into the absorber 4 to reduce the absorption capacity and prevent the low temperature heat source water from being overcooled. This helps prevent the supercooling of the low temperature heat source water when the temperature of the low temperature heat source water is low and the inlet temperature of the hot water 5 drops.

[0035]

According to the present invention, even if the temperature level of the low temperature heat source changes, hot water of a constant temperature can be taken out, and the operation can be performed in the state where the coefficient of performance is the highest according to the load and the low temperature heat source temperature level.

If the temperature of the low temperature heat source is above a certain level, CO
P is in the range of 1.7 to 2.2, 1.3 ~
It will be 1.7 times.

Further, since the heat pump uses the exhaust heat as a low temperature heat source, it is necessary that the temperature conditions are not constant and that the heat pump can be operated in a wide temperature range. You can drive to a range you could not.

[Brief description of drawings]

FIG. 1 is a cycle flow chart showing an embodiment of the present invention.

FIG. 2 is a Dühring diagram showing the relationship between the hot water outlet temperature, the low temperature heat source temperature, and the high temperature regenerator pressure.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing still another embodiment of the present invention.

FIG. 5 is a diagram showing still another embodiment of the present invention.

[Explanation of symbols]

1 ... Evaporator, 2 ... Low temperature heat source water, 3 ... Refrigerant pump, 4 ... Absorber, 5 ... Hot water, 6 ... Solution pump, 7 ... Low temperature regenerator, 8
High temperature regenerator, 9 ... Heat source, 10 ... Condenser, 11 ... Second condenser, 12 ... Hot water outlet temperature detector, 13 ... Hot water outlet temperature controller, 14 ... Heat reduction control valve, 15 ... High temperature regenerator Pressure detector, 16 ... Pressure controller, 17 ... Hot water control valve, 18 ... Float valve, 19 ... Separator, 20 ... Refrigerant return device, 21 ... Low temperature heat source water outlet temperature detector, 22 ... Low temperature heat source water outlet temperature adjustment Total, 23 ... Refrigerant blow valve.

Claims (7)

[Claims] 1. A double-effect absorption heat pump comprising an evaporator, an absorber, a low-temperature regenerator, a condenser constituting a double-effect cycle, a high-temperature regenerator, a solution pump, a refrigerant pump, and pipes connecting these. A second condenser that directly introduces the refrigerant vapor generated from the high temperature regenerator to condense and liquefy is provided downstream of the condenser that constitutes the double effect cycle, and hot water is added to the absorber and the double effect cycle. Is provided with a passage for introducing the refrigerant liquid heated by the second condenser and then condensed by the second condenser to the condenser constituting the double effect cycle. Double-effect absorption heat pump. 2. The double-effect absorption heat pump according to claim 1, wherein a passage for bypassing a part of the hot water entering the second condenser is provided, and the bypass passage is joined at the outlet side of the second condenser. The double-effect absorption heat pump is provided with control means for increasing or decreasing the bypass amount of hot water according to the pressure of the high temperature regenerator. 3. An evaporator, an absorber, a low temperature regenerator, a condenser constituting a double effect cycle, a high temperature regenerator, a solution pump, a refrigerant pump, and a double effect absorption heat pump having a passage connecting them, The refrigerant vapor generated in the high-temperature regenerator is introduced into the low-temperature regenerator, and the second condenser for introducing and liquefying the vapor exiting the low-temperature regenerator is condensed into the double-effect cycle. Provided downstream, the hot water is heated by the absorber and the condenser constituting the double-effect cycle, and then heated by the second condenser, and the refrigerant liquid condensed by the second condenser is used by the double-effect. A double-effect absorption heat pump, characterized in that it is provided with a passage to be introduced into a condenser forming a cycle. 4. The double-effect absorption heat pump according to claim 3, wherein a passage for bypassing a part of the hot water entering the second condenser is provided, and the bypass passage is joined on the outlet side of the second condenser. The double-effect absorption heat pump is provided with control means for increasing or decreasing the bypass amount of hot water according to the pressure of the high temperature regenerator. 5. The double-effect absorption heat pump according to claim 3, wherein a float valve is provided in the middle of a passage for introducing the refrigerant liquid condensed in the second condenser into the condenser constituting the double-effect cycle. Double-effect absorption heat pump characterized by. 6. A double-effect absorption heat pump comprising an evaporator, an absorber, a low-temperature regenerator, a condenser constituting a double-effect cycle, a high-temperature regenerator, a solution pump, a refrigerant pump, and pipes connecting these. A second condenser that directly introduces the refrigerant vapor generated from the high temperature regenerator to condense and liquefy is provided downstream of the condenser that constitutes the double effect cycle to supply hot water to the absorber and the double effect cycle. The evaporator is provided with a passage for introducing the refrigerant liquid heated by the second condenser and then heated by the second condenser and condensed by the second condenser into the condenser constituting the double-effect cycle. A double-effect absorption heat pump is provided with means for mixing the refrigerant liquid in the evaporator with the absorption solution in the absorber when the amount of the refrigerant in (1) exceeds a certain level. 7. The double-effect absorption heat pump according to claim 6, further comprising control means for increasing or decreasing the amount of the refrigerant liquid in the evaporator mixed with the absorption solution in the absorber depending on the temperature of the low-temperature heat source. Double-effect absorption heat pump.