JP3244087B2 - Heat pump for mixed media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As shown in FIG. 3, a heat pump comprises an evaporator (2), a compressor (4), a condenser (6), and an expansion valve (8) connected in series to form a closed loop (10). When the heat medium is circulated in the closed loop (10), the heat medium first evaporates by absorbing heat from the outside in the evaporator (2), and the generated steam is compressed by the compressor (4) to rise. The temperature and pressure are increased, the heat is released to the outside in the condenser (6), and the heat medium condensed into a liquid phase is throttled and expanded by the expansion valve (8) and returned to the evaporator (2). This ends the cycle.

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 relationship between the temperature and the composition of the simplest two-component liquid-vapor system in terms of the mole fraction of low boiling components on the horizontal axis. G and L are single phases, gas phase and liquid phase, L
The region of + G is a two-phase region where liquid and vapor coexist. If the temperature of a liquid mixture of 60 mol% (mol fraction = 0.60) of the low boiling components is increased under constant pressure, the change in this system can be considered along a straight line ab'cd "e. Has only a liquid phase, but a vapor phase appears at point b '. The composition of this vapor phase is given at point b ", and the two conjugate phases are connected by the equilibrium connection line b"b' in the figure. If the temperature is further increased, more vapor is generated, in which case the concentration of low-boiling components in the vapor is high, so that this component is relatively reduced in the liquid phase and the composition of the liquid is b ' varies along c'd ', while the composition of the vapor varies along b "c" d ". At the temperature t ° C., the total composition of the system in the two-phase region is represented by the point c, while the vapor composition and the liquid composition are respectively given at both ends of the equilibrium connection line passing the point c, the points c ″ and c ′. The relative amounts of the two phases can be determined from the principle of leverage in physics: the ratio of the moles of vapor to liquid is expressed as the ratio of the length of cc 'to c "c. When the temperature is further increased, more and more steam is generated, and at the point d ", almost no liquid phase is left. At a higher temperature, the liquid phase disappears and only the vapor phase (point d") remains.

[0004]

In the gas phase of the heat medium at the outlet of the condenser, the concentration of the low-boiling component is the highest in the system, and the low-boiling component gas also stays near the condensation heat transfer surface. For this reason, low-boiling components are present in the same manner as non-condensable gas that hinders mass transfer and heat transfer to the condenser, and reduce 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.
The purpose of the present invention is to reduce the concentration of uncondensed low-boiling gas in the condenser and to achieve the same effect as eliminating non-condensable gas.

[0006]

According to the present invention, an absorber is provided on a heat medium outlet side of a condenser, and uncondensed gas in the vicinity of the condenser outlet is absorbed by an evaporation residue on the heat medium outlet side of the evaporator. Solved the problem.

[0007]

Means for Solving the Problems According to the present invention, an evaporator, a compressor, a condenser, and an expansion valve are connected in series to form a closed loop, and a heat medium is circulated in the closed loop. In a heat pump using a two-component mixed medium as a heat medium, an absorber is provided on the heat medium outlet side of the condenser, and the evaporation residue on the heat medium outlet side of the evaporator is upstream of the expansion valve via the absorber. By leading to the closed loop on the side
The problem was solved by allowing the unreacted gas in the vicinity of the outlet of the condenser to be absorbed by the residual liquid in the absorber.

As a result of the absorption of the uncondensed low-boiling component gas in the low-concentration low-boiling-point medium liquid in this manner, the concentration of the uncondensed low-boiling component near the outlet of the condenser decreases, so that mass transfer and heat transfer are facilitated. The condenser heat transfer performance 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 thereby lowers the pressure. Therefore, the compressor power can be reduced by lowering the condensing pressure.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, an absorber (14) which is a kind of heat exchanger having 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) by the liquid return pipe (20). The liquid return pipe (20) has a pump (22) on the way and passes 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 a closed loop (10) upstream 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), the lower liquid phase of the drain pot (16) reaches the expansion valve (8) via the preheater (24), and the upper gas phase is the inlet of the heat medium passage (14a) of the absorber (14). To the side. As the cooling water supplied to the cooling water passage (14b) of the absorber (14), for example, the cooling water can be shared with that of the condenser (6), but may be provided in another system.

The heat medium vapor 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) to be deprived of heat by the cooling water and condensed. The evaporation residual liquid separated from the vapor by the mist separator (18), that is, the liquid-phase heat medium that has not been completely evaporated, is pumped by the pump (22) through the liquid return pipe (20) to the heat medium passage (14a) of the absorber (14). ).

In this case, the low-boiling component concentrations in the evaporator (2) and the condenser (6) are as shown in FIG. The circled numbers in the figure indicate the following items, respectively. 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, has 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 component gas in the state indicated by is very high. Therefore, the low-boiling component gas is absorbed by the evaporation residue sent to the absorber (14). In the condenser (6), there are gases in various states of
The gas having the highest concentration of low boiling components at the outlet of the heat medium of the condenser (6) is selectively absorbed. As described above, the low-boiling component gas is absorbed in the evaporating residue by sending the evaporating residue at the evaporator outlet having the lowest low-boiling component concentration in the system to the condenser outlet side. The boiling component gas concentration is reduced, and the condenser heat transfer performance is improved.

[0013]

As described above, according to the present invention, in a heat pump using a two-component mixed medium as a heat medium, an absorber is provided on the heat medium outlet side of the condenser and the heat medium outlet side of the evaporator is provided. Because the uncondensed gas near the condenser outlet is absorbed by the evaporation residue, the evaporation residue at the evaporator outlet showing the lowest low boiling component concentration in the system easily absorbs the low boiling component gas. To reduce the concentration of uncondensed low-boiling gas near the outlet of the condenser to improve the heat transfer performance of the condenser. The cooling effect in the absorber further enhances the absorption effect, and in addition, serves to lower the liquid temperature (saturation temperature) and thereby reduce the pressure. Therefore, according to the present invention, the effect that the power of the compressor can be reduced by lowering the condensing pressure is obtained, and the performance of the heat pump is generally improved.

[Brief description of the drawings]

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

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

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

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

[Explanation of symbols]

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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-210565 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F25B 7/00 F25B 1/00

Claims (1)

(57) [Claims] 1. An evaporator, a compressor, a condenser, and an expansion valve.
Are connected in series to form a closed loop.
In was such that the heat medium is circulated, the heat pump using a mixed medium of two-component as a heat medium, the absorber provided in the heat medium outlet side of the condenser, evaporation residual liquid of the heat medium outlet side of the evaporator Closed loop upstream of the expansion valve via the absorber
A heat pump for a mixed medium , wherein the non-condensed gas near the outlet of the condenser is absorbed by the evaporating residual liquid in the absorber by being guided to the pump.