JP2000064906A - Engine-drive type heat pump cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease smoke concentration in exhaust gas in a case of a cooling load (a heat load) being high during a summer season by providing a cooler to effect heat-exchange between intake air sucked in a diesel engine and a low pressure refrigerant flowing out from a depressurizer and cool intake air during cooling operation. SOLUTION: When a four-way valve 7 is switched during cooling operation, a refrigerant increased in temperature and a pressure by a compressor 3 flows in an outdoor heat-exchanger 2, the refrigerant is cooled in the atmosphere and condensed and liquefied. A liquefied high pressure refrigerant is decreased in a pressure by an expansion valve 5 (a pressure reducer) and forms a low pressure refrigerant in a vapor-liquid two-phase state, and deprives air, supplied in a room by an indoor heat-exchanger 1, of heat for vaporization. In which case, after a refrigerant flowing out from the indoor heat-exchanger 1 flows in a cooler 8 through an intake air cooling circuit to cool intake air, the refrigerant flows in an accumulator 6 for separation into a vapor-phase refrigerant and a liquid phase refrigerant. This constitution prevents the decrease of an intake air amount by increasing density of air and reduces smoke concentration in exhaust gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine driven heat pump cycle having a diesel engine (hereinafter abbreviated as engine) for driving a compressor, and is effective when applied to an air conditioner.

[0002]

2. Description of the Related Art In an engine-driven heat pump cycle, in order to increase the refrigerating capacity (cooling capacity), it is necessary to increase the amount of fuel injected into an engine to increase the compression work performed by a compressor.

[0003]

In the conventional engine-driven heat pump cycle, when the outside air temperature is high in summer or the like, the cooling load (heat load) increases and the amount of fuel injected into the engine must be increased. In addition to the above, since the density of the air taken into the engine is reduced, the actual amount (mass) of the intake air is smaller than the fuel injection amount injected into the engine. For this reason, there has been a problem that the concentration of unburned fuel (smoke) in the exhaust gas increases.

[0004] In view of the above, it is an object of the present invention to reduce the smoke density when the cooling load (heat load) is large in summer or the like.

[0005]

The present invention uses the following technical means to achieve the above object. According to the first aspect of the present invention, during the cooling operation, heat exchange is performed between the intake air sucked into the diesel engine (4) and the low-pressure refrigerant flowing out of the pressure reducer (5) to cool the intake air. A vessel (8).

Accordingly, it is possible to prevent the density of the intake air from increasing and the actual amount (mass) of the intake air from decreasing relative to the fuel injection amount. Therefore, the output of the diesel engine (4) is improved, and the concentration of the unburned fuel (smoke) in the exhaust gas can be prevented from increasing. According to the second aspect of the present invention, there is provided a cooler (8) for exchanging heat between the intake air taken into the diesel engine (4) and the low-pressure refrigerant flowing out of the pressure reducer (5) to cool the intake air. It is characterized by the following.

As a result, the output of the diesel engine (4) can be improved and the concentration of unburned fuel (smoke) in the exhaust gas can be prevented from increasing, as in the first aspect of the invention. Incidentally, the reference numerals in parentheses of the above means are examples showing the correspondence with specific means described in the embodiments described later.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In this embodiment, an engine-driven heat pump cycle according to the present invention is applied to an air conditioner for cooling and heating a room. FIG. 1 is a schematic diagram of a heat pump air conditioner according to this embodiment. FIG. In FIG. 1, 1
Is air and refrigerant blown into the room (CFC in this embodiment)
And 2 is an outdoor heat exchanger for exchanging heat between outdoor air and a refrigerant. Reference numeral 3 denotes a compressor that sucks and compresses the refrigerant, and reference numeral 4 denotes a diesel engine that drives the compressor 3.

As is well known, a diesel engine 4 (hereinafter, abbreviated as engine 4) only sucks and compresses air, and injects fuel (light oil) into air (combustion chamber) which has been compressed to a high temperature. By doing so, the internal combustion engine obtains a driving force by spontaneously igniting (exploding) the fuel. By the way, 4a
Reference numeral 4 denotes an exhaust pipe for discharging exhaust gas from the engine 4 into the atmosphere, and reference numeral 4b denotes a muffler (muffler) for reducing noise of the exhaust gas.

In a refrigerant passage connecting the indoor heat exchanger 1 and the outdoor heat exchanger 2, an expansion valve (decompressor) 5 for decompressing and expanding the high-pressure refrigerant compressed by the compressor 3 is provided. The expansion valve 5 is of a type having a fixed throttle with a fixed opening. Reference numeral 6 denotes an accumulator (gas-liquid separation unit) that stores excess refrigerant in the heat pump cycle, separates the refrigerant into a gas-phase refrigerant and a liquid-phase refrigerant, and allows only the gas-phase refrigerant to flow to the suction side of the compressor 3. 7
Is an electromagnetic switching four-way valve (hereinafter abbreviated as a four-way valve) that switches between a case where the refrigerant discharged from the compressor 3 is circulated toward the outdoor heat exchanger 2 and a case where the refrigerant is circulated toward the indoor heat exchanger 1. is there.

The operating states of the four-way valve 7 and the engine 4 (the amount of fuel injected into the engine 4) are controlled by a control device (not shown). Reference numeral 8 denotes a cooler (intercooler) that exchanges heat between the refrigerant flowing out of the indoor heat exchanger 1 and intake air drawn into the engine 4 during cooling operation to cool the intake air, as described below. The cooler 8 is provided between the engine 4 and an air cleaner (not shown) for removing dust in the intake air in the intake pipe 4c.

Reference numerals 9a and 9b denote check valves which allow the refrigerant to flow in only one direction.
The a and 9b prevent the refrigerant from flowing to the intake cooling circuit 10 during the heating operation, as described later. next,
The operation of the present embodiment will be described. 1. At the time of cooling operation (see FIG. 1) At the time of cooling operation, the four-way valve 7 operates so that the refrigerant discharged from the compressor 3 flows toward the outdoor heat exchanger 2.

For this reason, the high temperature and high pressure (gas phase) refrigerant in the compressor 3 is cooled in the atmosphere by the outdoor heat exchanger 2 and condensed and liquefied. Thereafter, the liquefied high-pressure refrigerant is reduced in pressure by the expansion valve 5 to become a low-pressure refrigerant in a gas-liquid two-phase state, and takes heat from the air blown into the room by the indoor heat exchanger 1 (cools the air blown into the room). E) evaporate. And
The refrigerant flowing out of the indoor heat exchanger 1 is supplied to the intake cooling circuit 10
Flows into the cooler 8 to cool the intake air, flows into the accumulator 6, is separated into the gaseous refrigerant and the liquid refrigerant, and then only the gaseous refrigerant is sucked into the compressor 3 again. .

As apparent from the above description, during the cooling operation, the outdoor heat exchanger 2 operates as a condenser for cooling and condensing the refrigerant, and the indoor heat exchanger 1 operates as an evaporator for evaporating the refrigerant. . 2. During the heating operation (see FIG. 2) During the heating operation, the four-way valve 7 operates so that the refrigerant discharged from the compressor 3 flows toward the indoor heat exchanger 1.
At this time, the refrigerant discharged from the compressor 3 by the check valves 9a and 9b flows into the indoor heat exchanger 1 without flowing into the intake air cooling circuit 10.

Therefore, the (gas-phase) refrigerant which has become high temperature and high pressure in the compressor 3 is cooled and condensed by the air blown into the room by the indoor heat exchanger 1, and the condensed heat is discharged toward the room. (Heat dissipation). Thereafter, the liquefied high-pressure refrigerant is supplied to the expansion valve 5.
Is reduced to a low-pressure refrigerant in a gas-liquid two-phase state. The outdoor heat exchanger 12 removes heat from the atmosphere and evaporates. And
The refrigerant flowing out of the outdoor heat exchanger 2 is supplied to the accumulator 6
, And is separated into a gas-phase refrigerant and a liquid-phase refrigerant, and then only the gas-phase refrigerant is sucked into the compressor 3 again.

As apparent from the above description, during the heating operation, the indoor heat exchanger 1 operates as a condenser for cooling and condensing the refrigerant, and the outdoor heat exchanger 2 operates as an evaporator for evaporating the refrigerant. . And in this embodiment, the compressor 3, the indoor heat exchanger 1, the outdoor heat exchanger 2, the expansion valve 5,
The accumulator 6 and the four-way valve 7 constitute a heat pump cycle Rc capable of switching between cooling and heating.

Next, the features of this embodiment will be described. During the cooling operation, the intake air of the engine 4 is supplied to the indoor heat exchanger 1.
Since the air is cooled by the low-pressure refrigerant flowing out of the fuel cell, the density of the intake air is increased, and it is possible to prevent the actual amount (mass) of the intake air from decreasing relative to the fuel injection amount. Therefore, the output of the engine 4 can be improved and the concentration of the unburned fuel (smoke) in the exhaust gas can be prevented from increasing.

FIG. 3 is a test result showing the relationship between the intake air temperature, the smoke concentration and the engine output. As is clear from FIG. 3, as the intake air temperature decreases, the smoke concentration decreases and the engine concentration decreases. It can be seen that the output has improved. Incidentally, the load factor is the engine output (W
1) Ratio of power consumption (W2) of compressor 3 to the ratio (W2 / W1)
). For this reason, if the refrigerating capacity (heat load) is constant, the power consumption (W2) of the compressor 3 is constant, so that the load factor decreases as the intake air temperature decreases.

Further, since the smoke concentration is reduced and the engine output is improved, the fuel consumption rate of the engine 4 is improved. In the above-described embodiment, since the intake air is cooled by the refrigeration capacity (cooling capacity) exhibited by the heat pump cycle Rc, strictly speaking, the refrigeration capacity contributing to cooling is reduced. According to trial calculations, the amount of reduction is as small as about 1%, and there is no practical problem with cooling operation.

In the above-described embodiment, since the intake air is cooled by the refrigerant flowing out of the indoor heat exchanger 1 (evaporator), the intake air is cooled by the sensible heat of the refrigerant. . However, in the present invention, the intake air is cooled by the low-pressure refrigerant flowing out of the expansion valve 5, so that the intake air may be cooled by the latent heat of vaporization of the liquid-phase low-pressure refrigerant. Further, in the above-described embodiment, the expansion valve using the fixed restrictor is used as the pressure reducing device. However, the opening degree of the expansion valve is adjusted so that the degree of superheat of the refrigerant on the inlet side of the compressor 3 becomes a predetermined value. A so-called temperature type expansion valve may be used.

In the above-described embodiment, the heat pump cycle uses chlorofluorocarbon as a refrigerant. However, a supercritical refrigeration cycle using carbon dioxide as a refrigerant and the pressure on the high pressure side exceeding the critical pressure of the refrigerant may be used. In this case, since the refrigerant does not condense on the high pressure side, the heat exchanger on the high pressure side is a simple radiator that only cools the refrigerant.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an engine-driven heat pump cycle during a cooling operation.

FIG. 2 is a schematic diagram of an engine-driven heat pump cycle during a heating operation.

FIG. 3 is a graph showing a relationship between intake air temperature, smoke concentration, and engine output.

[Explanation of Signs] 1 ... Indoor heat exchanger, 2 ... Outdoor heat exchanger, 3 ... Compressor, 4
... Diesel engine, 5 ... Expansion valve (decompressor), 6 ... Accumulator, 7 ... Electromagnetic switching four-way valve, 8 ... Cooler.

Claims (2)

[Claims] 1. It comprises a compressor (3), an indoor heat exchanger (1), an outdoor heat exchanger (2), and a pressure reducer (5),
A heat pump cycle (Rc) capable of switching between cooling and heating, and a diesel engine (4) for driving the compressor (3)
And a cooler (8) that exchanges heat between the intake air sucked into the diesel engine (4) and the low-pressure refrigerant flowing out of the pressure reducer (5) during cooling operation to cool the intake air. An engine-driven heat pump cycle comprising: 2. A radiator (2) for cooling the refrigerant, a decompressor (5) for decompressing the refrigerant flowing out of the radiator (2), and an evaporator for evaporating the refrigerant flowing out of the decompressor (5). Device (1), a compressor (3) that sucks and compresses refrigerant flowing out of the evaporator (1), and discharges the refrigerant toward the radiator (2); and a diesel engine that drives the compressor (3). (4)
And a cooler (8) that exchanges heat between the intake air sucked into the diesel engine (4) and the low-pressure refrigerant flowing out of the pressure reducer (5) to cool the intake air. The engine type refrigeration cycle.