Refrigeration – Automatic control – Of closed system sorbent type
Reexamination Certificate
1999-07-29
2001-01-23
Doerrler, William (Department: 3744)
Refrigeration
Automatic control
Of closed system sorbent type
C062S476000
Reexamination Certificate
active
06176096
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an absorption type refrigerating apparatus and particularly to an absorption type refrigerating apparatus capable of maintaining the purity of a refrigerant liquid held in the evaporator to an appropriate level.
2. Description of the Related Art
In an absorption type refrigerating apparatus, the absorbent solution absorbs refrigerant vapor in the absorber thus being diluted. The diluted absorbent solution (diluted solution) is then conveyed to the regenerator where it releases the refrigerant and its concentration is increased. The absorbent solution at a higher concentration is returned back to the absorber. The refrigerant vapor extracted from the absorbent solution is condensed in the condenser and turned to a refrigerant liquid which is then conveyed to the evaporator. The refrigerant liquid conveyed to the evaporator is high in the purity but still contains a trace of the absorbent. The absorbent may be accumulated during a long-run of the operation and gradually decline the purity of the refrigerant liquid in the evaporator.
For avoiding declination of the purity of the refrigerant liquid, it is commonly practiced to withdraw a predetermined amount of the refrigerant liquid in the evaporator and convey it together with the diluted solution to the regenerator. In that case, the more the predetermined amount of the refrigerant liquid in the evaporator, the higher the purity of the refrigerant liquid is gained. However, increasing the predetermined amount of the refrigerant liquid to be withdrawn may lower the efficiency of the operation. As the refrigerant liquid accumulated by consumption of energy for the absorption has been added again to the absorbent solution, the loss of heat (particularly, latent heat) increases.
For minimizing the heat loss, it is proposed that the refrigerant liquid withdrawn from the evaporator is transferred to a rectifier involved in upper part of the regenerator where it is dropped down from the upper end to regain its purity. In that case, the refrigerant liquid is used as a vapor/liquid contact fluid required for the refining. This minimizes the heat loss and increases the efficiency of use of the refrigerant liquid as a primary agent for the absorption type refrigeration. Consequently, the thermal efficiency of the absorption type refrigerating system can be increased. The concentration of the absorbent solution may vary depending on the ambient conditions and the degree of load. Accordingly, if the supply of the refrigerant liquid as the vapor/liquid contact fluid is not properly controlled in response to a change in the concentration of the absorbent solution, the purity of the refrigerant vapor at the top of the rectifier will worsen. For overcoming this problem, it is known to detect the purity of the refrigerant liquid in the evaporator and adjust the supply of the vapor/liquid contact fluid. For example, when the boiling point of the refrigerant liquid in the evaporator is examined and its rise is detected, it is apparent that the purity of the refrigerant liquid worsens.
However, in assuming the deterioration of the purity of the refrigerant liquid from the rise of its boiling point, the supply of the vapor/liquid contact fluid is controlled only after deterioration of the purity of the refrigerant. This delay of action hardly ensures the accurate controlling over the supply. Also, the detection of the rise of the boiling point requires monitoring of both the temperature and the pressure in the evaporator, hence making the controlling procedure complex.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an absorption type refrigerating apparatus which has less delay of time during the controlling over the supply of a vapor/liquid contact fluid and can maintain the purity of a refrigerant liquid held in the evaporator to an appropriate level with a simple construction.
In an absorption type refrigerating apparatus according to the present invention comprising an evaporator for storing a refrigerant liquid, an absorber for storing an absorbent solution which includes an absorbent for absorbing a vapor of the refrigerant liquid generated in the evaporator, a regenerator for receiving and heating up a portion of the absorbent solution to extract the refrigerant vapor from the absorbent solution, a rectifier for rectifying the refrigerant vapor extracted in the regenerator, a condenser for condensing and feeding the refrigerant vapor rectified by the rectifier to the evaporator, a conduit for conveying a portion of the refrigerant vapor from the evaporator to the upper part of the rectifier for use as a vapor/liquid contact fluid in the rectifier, a temperature sensor for detecting the temperature of the refrigerant vapor rectified in the rectifier, a refrigerant liquid flow controlling means for increasing or decreasing the flow of the refrigerant liquid conveyed to the rectifier, and a controller responsive to a change in the temperature detected by the temperature sensor, which delivers a flow increase command to the refrigerant liquid flow controlling means when the temperature detected by the temperature sensor is higher than a reference temperature level and a flow decrease command to the refrigerant liquid flow controlling means when the temperature is not higher than the reference temperature level.
According to the above feature, the refrigerant with a higher purity to be conveyed to the rectifier can increase the purity of the refrigerant vapor to a higher level upon contacting with the refrigerant vapor. The refrigerant liquid flow controlling means is adapted for increasing or decreasing the supply of the refrigerant liquid to the rectifier in response to a change in the temperature at the top of the rectifier which is equal to the temperature of the refrigerant vapor. It is proved by the inventors through a series of experiments that the higher the temperature of the refrigerant vapor at the top of the rectifier, the more the purity of the refrigerant vapor is deteriorated. Referring to the result of the experiments, we, inventors, provide means for recovering and maintaining the purity of the refrigerant vapor to an appropriate level by increasing the supply of the refrigerant liquid from the evaporator when the temperature of the refrigerant vapor is higher.
REFERENCES:
patent: 4380909 (1983-04-01), Sung
patent: 5490393 (1996-02-01), Fuesting et al.
patent: 5901567 (1999-05-01), Suzuki et al.
patent: 5927086 (1999-07-01), Suzuki et al.
patent: 6009721 (2000-01-01), Fukuda et al.
Ishikawa Mitsuru
Kayanuma Hidetaka
Takaishi Toshimitsu
Yuri Nobuyuki
Armstrong, Westerman Hattori, McLeland & Naughton
Doerrler William
Honda Giken Kogyo Kabashika Kaisha
Jones Melvin
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