JPH05280813A - Heat pump for mixed mediums - Google Patents

Abstract

PURPOSE:To improve the heat-transfer performance of a condenser by providing an absorber on the side of the outlet for heat medium from a condenser in a setup to make the liquid residue from the evaporation on the side of the outlet for heat media from an evaporator absorb gas which has come to the vicinity of the outlet of the condenser without being condensed. CONSTITUTION:The part holding the liquid phase heat media of a mist separator 18 provided on the side of the outlet for the heat medium from an evaporator 2 is connected to a passageway 14a for the heat medium into an absorber 14. The passageway 14a for the heat medium at its outlet positioned on the lower side is connected to a closed loop 10. A drain pot 16 is provided on the side of the outlet for the heat medium from a condenser 6. The lower liquid-holding part of the drain pot 16 is connected to an expansion valve 8 and the upper liquid-holding part is connected to the passageway 14a for the heat media on the side of the inlet. The vapor of the heat medium produced at the evaporator 2 is separated from the liquid, fed to a compressor 4 and works, and then flows to the condenser 6 to be condensed. The liquid residua from the evaporation is sent into the passageway 14a to the absorber 14. The concentration of the low boiling point type component of the liquid residua from the evaporation is lowest in the system. On the other hand, the concentration of the low boiling point type component in the gaseous phase at the outlet of the condenser 6 is very high. Therefore, the low boiling point type gaseous component is absorbed by the liquid residuum from the evaporation which is sent into the absorber 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump used for the purpose of utilizing the phase change of a heat medium and utilizing the heat pumped from the low temperature side on the high temperature side. It is intended to improve performance when used.

[0002]

2. Description of the Related Art As shown in FIG. 3, a heat pump comprises a closed loop (10) in which an evaporator (2), a compressor (4), a condenser (6) and an expansion valve (8) are connected in series. When the heat medium is circulated in the closed loop (10), the heat medium first absorbs heat from the outside in the evaporator (2) and evaporates, and the generated vapor is compressed in the compressor (4) and rises. The heat medium, which has been heated / pressurized and whose heat is released to the outside by the condenser (6) and condensed into a liquid phase, is expanded by the expansion valve (8) and then returned to the evaporator (2). , This ends the cycle.

By the way, in such a heat cycle of a heat pump or the like, a Lorentz cycle may be constituted by using a non-azeotropic mixed medium as a heat medium in order to improve efficiency. FIG. 4 shows the simplest temperature-composition relationship of the two-component liquid-vapor system, with the horizontal axis representing the mole fraction of the low-boiling component. G and L are single phase, gas phase and liquid phase, L
The + G region is a two-phase region where liquid and vapor coexist. If the temperature of a liquid mixture containing 60 mol% of low-boiling components (molar fraction = 0.60) is increased under constant pressure, the change of this system can be considered along the straight line ab'cd "e. There is only a liquid phase in, but the vapor phase appears at the point b '. The composition of this vapor phase is given at the point b ", and the two conjugated phases are connected by the equilibrium connecting line b"b' in the figure. When the temperature is further increased, more vapor is produced, but in this case, the concentration of low boiling point components in the vapor is high, so this component is relatively reduced in the liquid phase, and the composition of the liquid is b '. It varies along c'd ', while the vapor composition varies along b "c" d ". At the temperature of t ° C, the total composition of the system in the two-phase region is represented by the point c, but the vapor composition and the liquid composition are given at both ends of the equilibrium connection line passing through the point c, the points c "and c '. The relative amounts of the two phases are derived from the principle of leverage in physics: the vapor to liquid mole ratio is the ratio of the lengths cc 'and c "c. When the temperature is further raised, more and more steam is generated, and when the temperature reaches the d "point, the liquid phase almost disappears, and when the temperature becomes higher than this, the liquid phase disappears and only the vapor phase (d" point) remains.

[0004]

In the vapor phase of the heat medium at the outlet of the condenser, the concentration of the low boiling point component is the highest in the system, and the gas of the low boiling point component stays near the condensation heat transfer surface. For this reason, the low-boiling component exists in the condenser in the same manner as the non-condensable gas that impedes the mass transfer and the heat transfer, and reduces the heat transfer performance.

Therefore, an object of the present invention is to provide a heat pump using a two-component mixed medium as a heat medium,
This is to reduce the concentration of uncondensed low-boiling component gas in the condenser and to achieve the same effect as eliminating non-condensed gas.

[0006]

SUMMARY OF THE INVENTION According to the present invention, an absorber is provided on the heat medium outlet side of a condenser so that uncondensed gas in the vicinity of the condenser outlet is absorbed by an evaporation residual liquid on the heat medium outlet side of an evaporator. Has solved the problem.

[0007]

Since the evaporation residual liquid at the heat medium outlet of the evaporator has the lowest concentration of the low boiling component in the system, the uncondensed low boiling component gas is easily absorbed in the evaporation residual liquid. Further, the absorption effect is further enhanced by the cooling action in the absorber.

In this way, the uncondensed low-boiling component gas is absorbed in the low-concentration low-boiling-point medium liquid, and as a result, the concentration of the uncondensed low-boiling component near the outlet of the condenser is lowered, which facilitates mass transfer and heat transfer. The heat transfer performance of the condenser is improved.

Further, the cooling action in the absorber not only enhances the absorption effect as described above, but also lowers the liquid temperature (saturation temperature) and accordingly lowers the pressure. Therefore, the power of the compressor can be reduced by lowering the condensing pressure.

[0010]

EXAMPLE As shown in FIG. 1, an absorber (14) which is a kind of heat exchanger equipped with a heat medium passage (14a) and a cooling water passage (14b) is provided, and a heat medium of an evaporator (2) is provided. The liquid phase of the mist separator (18) provided on the outlet side is connected to the heat medium passage (14a) of the absorber (14) through the liquid return pipe (20). The liquid return pipe (20) has a pump (22) on the way and goes through a preheater (24) before reaching the absorber (14). The lower outlet of the heat medium passage (14a) of the absorber (14) is connected to the closed loop (10) on the upstream side of the preheater (24). A drain pot (1) for separating uncondensed gas is provided at the heat medium outlet side of the condenser (6).
6) is provided, the liquid phase below the drain pot (16) reaches the expansion valve (8) via the preheater (24), and the gas phase above is the inlet of the heat medium passage (14a) of the absorber (14). Connect to the side. The cooling water supplied to the cooling water passage (14b) of the absorber (14) can be shared with that of the condenser (6), for example, but it can be a separate system.

The vapor of the heat medium generated in the evaporator (2) is
After being separated from the liquid by the mist separator (18), it is supplied to the compressor (4) to perform work, and then proceeds to the condenser (6) where heat is taken by the cooling water to be condensed. The evaporation residual liquid separated from the vapor by the mist separator (18), that is, the liquid-phase heat medium that cannot be completely evaporated, is passed through the liquid return pipe (20) by the pump (22) to the heat medium passage (14a) of the absorber (14). ) Is sent to.

In this case, the low boiling component concentrations of the evaporator (2) and the condenser (6) are as shown in FIG. The circled numbers in the figure indicate the following items. Condenser outlet liquid, evaporator inlet liquid, evaporator outlet liquid, evaporator outlet gas, condenser inlet (or overall average) gas, condenser outlet gas.
As can be understood from FIG. 2, the evaporator outlet liquid, that is, the evaporation residual liquid exhibits the lowest low boiling component concentration in the system. On the other hand, at the outlet of the condenser 6, the concentration of the low boiling point component gas in the state indicated by is very high. Therefore, the low boiling point component gas is absorbed in the evaporation residual liquid sent to the absorber (14). In addition, in the condenser (6), gases in various states of ~ exist,
The gas in the state where the low boiling point component concentration is the highest at the heat medium outlet of the condenser (6) is selectively absorbed. In this way, by sending the evaporation residual liquid at the evaporator outlet having the lowest low boiling component concentration to the condenser outlet side, the low boiling component gas is absorbed in this evaporation residual liquid, and as a result, the uncondensed low The boiling component gas concentration is reduced, and the heat transfer performance of the condenser is improved.

[0013]

As described above, according to the present invention, in a heat pump using a binary mixture medium as a heat medium, an absorber is provided on the heat medium outlet side of a condenser and a heat medium outlet side of an evaporator is provided. The evaporation residual liquid absorbs the uncondensed gas near the outlet of the condenser, so the evaporation residual liquid at the evaporator outlet that shows the lowest concentration of low boiling components in the system easily absorbs the low boiling components gas. Then, the concentration of the uncondensed low-boiling component gas near the outlet of the condenser is reduced to improve the heat transfer performance of the condenser. The cooling effect in the absorber further enhances the absorption effect, and in addition, it serves to lower the liquid temperature (saturation temperature) and accordingly reduce the pressure. Therefore, according to the present invention, it is possible to reduce the compressor power by reducing the condensing pressure, and the performance of the heat pump is generally improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a vapor-liquid equilibrium diagram of a heating medium.

FIG. 3 is a block diagram showing a conventional example.

FIG. 4 is a vapor-liquid equilibrium diagram showing a temperature-composition relationship of a binary mixed medium.

[Explanation of symbols]

 2 Evaporator 4 Compressor 6 Condenser 8 Expansion valve 10 Closed loop 12 Electric motor 14 Absorber 16 Drain pot 18 Mist separator 20 Liquid return pipe 22 Pump 24 Preheater

Claims (1)

[Claims] 1. A heat pump that uses a binary mixed medium as a heat medium, wherein an absorber is provided on the heat medium outlet side of the condenser, and the evaporation residual liquid on the heat medium outlet side of the evaporator is near the condenser outlet. A heat pump for mixed media, characterized by absorbing uncondensed gas.