Refrigeration – Refrigeration producer – Compressor-condenser-evaporator circuit
Reexamination Certificate
2002-01-25
2004-02-03
Jones, Melvin (Department: 3744)
Refrigeration
Refrigeration producer
Compressor-condenser-evaporator circuit
C062S511000
Reexamination Certificate
active
06684662
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a refrigeration system for air-conditioners including a refrigeration cycle which employs a decompressing tube as decompressing means such as an orifice-tube or a capillary tube, and also relates to a condenser for use in a decompressing-tube system.
2. Description of Related Art
Generally, as a refrigeration system to be adopted for car air-conditioners or the like, the following refrigeration systems are well known: (1) an expansion-valve type refrigeration system including an automatic thermal expansion valve (TXV) as a decompressing means (hereinafter referred to as “expansion valve system”); and (2) an orifice-tube type refrigeration system (CCOT) including a decompressing tube as decompressing means such as an orifice-tube or a capillary tube (hereinafter referred to as “orifice-tube system” or “decompressing-tube system”).
As shown in
FIG. 13
, in the orifice-tube system, the gaseous refrigerant of high temperature and high pressure from the compressor
1
flows into the condenser
2
to be condensed therein. Then, the condensed refrigerant passes through the orifice-tube
3
to be decompressed and then flows into the evaporator
4
. In the evaporator
4
, the condensed refrigerant exchanges heat with the ambient air to be evaporated, and then is introduced into the accumulator
5
. In the accumulator
5
, only the gaseous refrigerant is separated from the refrigerant introduced in the accumulator
5
, and the gaseous refrigerant returns to the aforementioned compressor
1
. Thus, a refrigeration cycle is formed.
As compared with the expansion valve system, this orifice-tube system has fewer components and can be fabricated by fewer steps. Furthermore, the orifice-tube system is simple in structure and low in manufacturing cost.
The orifice-tube system is, however, inferior in response to load fluctuations.
That is, in the orifice-tube system, a liquefied refrigerant R stagnates at the subcooling area ranging from near the inlet of the orifice-tube
3
to the outlet of the condenser
2
. This liquefied refrigerant R increases when the thermal load of the condenser
2
is small. For example, when an automobile mounting this refrigeration system is running at a high speed, the thermal load of the condenser
2
is small because of an enough amount of ventilation. In this case, the condenser performance can be fully demonstrated, resulting in an enhanced condensation of the refrigerant therein.
By the way, the amount of refrigerant passing through the orifice-tube
3
(i.e., circulation amount of refrigerant) is constant, and the amount of refrigerant passing through the orifice-tube
3
is limited. Accordingly, in cases where the thermal load of the condenser decreases suddenly, for example, when the running speed of the car is changed from a low-speed to a high-speed, the amount of liquefied refrigerant increases suddenly, and the subcooling area spreads even in the condenser
2
. As a result, a large amount of liquefied refrigerant is temporarily accumulated in the condenser
2
. When a large amount of liquefied refrigerant is accumulated in the condenser
2
, the condensation of refrigerant will not be performed in the liquefied refrigerant stagnated portion. Accordingly, the effective area for condensing the refrigerant decreases, which in turn decreases the condenser performance.
To the contrary, in cases where the thermal load of the condenser increases suddenly, for example, when the running speed of the car is changed from a high-speed to a low-speed, the refrigerant is not condensed smoothly in the condenser
2
. As a result, the amount of liquefied refrigerant accumulated in the outlet side portion in the condenser
2
decreases, resulting in insufficient subcooling degree of the liquefied refrigerant. This deteriorates the condenser performance temporarily. As will be apparent from the above, the orifice-tube system is inferior in response characteristic to load fluctuations, and cannot obtain sufficient refrigeration performance.
It is an object of the present invention to provide a refrigeration system that is excellent in response characteristic to load fluctuations and can obtain sufficient refrigeration performance irrespective of load fluctuations.
It is an object of the present invention to provide a condenser for use in a decompressing-tube system that is excellent in response characteristic to load fluctuations and can obtain sufficient refrigeration performance irrespective of load fluctuations.
Another object of the present invention will be apparent from the following embodiments.
DISCLOSURE OF THE INVENTION
According to the first aspect of the present invention, a refrigeration system having a refrigeration cycle, comprises:
a compressor for compressing a refrigerant;
a condenser for condensing the refrigerant compressed by the compressor;
a decompressing tube for decompressing the refrigerant condensed by the condenser;
an evaporator for evaporating the refrigerant decompressed by the decompressing tube; and
an accumulator for separating a gaseous refrigerant from the refrigerant evaporated by the evaporator,
wherein the condenser includes a refrigerant inlet for introducing the refrigerant compressed by the compressor, a refrigerant outlet for discharging the refrigerant condensed by the condenser, a refrigerant passage for leading the refrigerant introduced from the refrigerant inlet to the refrigerant outlet while condensing the refrigerant, and decompressing means provided at a part of the refrigerant passage to decompress the refrigerant passing through the decompressing means.
In this refrigeration system, when the thermal load of the condenser decreases, the condensation of refrigerant in the condenser is enhanced at the upstream side of the decompressing means, and therefore only the completely liquefied refrigerant passes through the decompressing means. Thus, the resistance of the refrigerant passing through the decompressing means decreases, thereby increasing the flow rate. Accordingly, at the upstream side of the decompressing means and the downstream side thereof, the condensation of refrigerant is performed efficiently. Thus, the performance of the condenser is sufficiently demonstrated.
To the contrary, when the thermal load of the condenser increases, the condensation of refrigerant in the condenser deteriorates at the upstream side of the decompressing means, and therefore incompletely liquefied refrigerant passes through the decompressing means. At this time, the amount of gas in the refrigerant increases, i.e., the volume of the refrigerant passing through the decompressing means increases, resulting in increased flow resistance of the refrigerant passing through the decompressing means, which in turn decreases the flow rate. As the flow rate decreases in this way, the condensation load at the upstream side of the decompressing means decreases. Accordingly, the condensation will be performed fully, resulting in enhanced condenser performance.
As will be apparent from the above, since the refrigerant flow rate can be appropriately adjusted in response to fluctuations of thermal load in the condenser, this refrigeration system is excellent in response characteristics to load fluctuations. Accordingly, sufficient refrigeration performance can be obtained.
In this refrigeration system, an orifice-tube can be suitably used as the decompressing tube.
Furthermore, in this refrigeration system, it is preferable that at least a part of the condensed refrigerant is evaporated by the decompressing means and then re-condensed.
That is, in this refrigeration system, it is preferable that at least a part of the refrigerant condensed at an upstream side of the decompressing means in the refrigerant passage is decompressed by the decompressing means into a low-pressure gaseous refrigerant, and the low-pressure gaseous refrigerant is re-condensed at a downstream side of the decompressing means in the refrigerant passage.
According to the second aspect of the
Hoshino Ryoichi
Manaka Hideaki
Takahashi Yasuhiro
Watanabe Hirohiko
Jones Melvin
Showa Denko K.K.
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