Absorption refrigerator

Details Absorption refrigerator Absorption refrigerator

2001-03-22

2002-06-25

Doerrler, William (Department: 3744)

Refrigeration

Refrigeration producer

Sorbent type

C062S483000, C062S488000, C062S101000

Reexamination Certificate

active

06408643

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
The present invention relates to an absorption refrigerator. More particularly, the invention relates to a multiple-effect absorption refrigerator in which three-stage or four-stage regenerators are connected thereto, and improves efficiency. The absorption refrigerator includes an absorption cold/hot water type.
BACKGROUND ART
Single-effect or double-effect absorption refrigerators having one or two stages of regenerators for steamizing the coolant by increasing temperature/pressure of the absorption fluid have conventionally occupied the main current in the industry.
When heating and concentrating an absorption fluid in a regenerator by a heat fed from outside, and reusing coolant steam generated therefrom as a heating source of the absorption fluid of the regenerator having a low inner pressure, in general, it is possible to accomplish heating and concentrating in a regenerator of a low inner pressure without supplying heat from outside. In the heating and concentrating method using such a pressure difference, the thermal efficiency is improved according as the number of regenerators is increased. More specifically, when each regenerator has an efficiency &eegr; of 65% and the heat feed quantity is a, a case with a simple regenerator gives a coolant fluid of a ×&eegr;=0.65a is obtained.
With two regenerators, there is available a coolant fluid of (a×&eegr;)+(a×&eegr;×&eegr;)=(a×&eegr;)×(1+&eegr;)=1.07
1
. That is, the case with two regenerators gives a coolant fluid of 1.07/0.65≈3/2 times as large as compared with the case of a single regenerator: it suffices to use a heat feed quantity 0.65/1.07≈2/3 times for obtaining a coolant fluid in the same quantity.
For similar reasons, increasing the number of regenerators leads to a decreased heat feed quantity, thus permitting energy saving. Various triple-effect type absorption refrigerators having regenerators in three stages are proposed and industrialized for further improvement of cooling ability and efficiency (see Japanese Laid-Open Patent Publication No. 2000-171123 and Japanese Patent Publication No. 3040475).
FIG. 7
illustrates a triple-effect type absorption refrigerator proposed by Japanese Laid-Open Patent Publication No. 2000-171123. This absorption refrigerator
100
comprises an absorber
101
, a low-temperature regenerator
102
, a medium-temperature regenerator
103
, a high-temperature regenerator
104
, a condenser
105
, an generator
106
, heat exchangers
107
to
109
, a fluid pump
110
, and a coolant pump
111
; wherein the high-temperature regenerator
104
has a pressure sensor
112
, fluid level sensors
113
and
113
′ are provided at the exit of the high-temperature regenerator
104
so that a revolutions controller
120
sets a basic number of revolutions for the fluid pump
110
in response to output of the pressure sensor
112
, and corrects the thus set revolutions on the basis of an output signal of a fluid level sensor
113
.
However, in a method of setting a basic revolutions of the fluid pump
110
on the basis of only the detected value of inner pressure of the high-temperature regenerator
104
and correcting the thus set revolutions in response to an output signal of the fluid level sensor
113
, as in the conventional absorption refrigerator
100
, the fluid level frequently rises up or lowers down, making it impossible to achieve a stable operation. Another problem is that, because all the regenerators are fed with the absorption fluid from the fluid pump
110
alone, an optimum feed cannot be made for the individual regenerators.
And, increasing the number of regenerators may lead to a more complicated structure and a higher cost. Furthermore, even when the number of regenerators is increased, the ratio of reducing the heating quantity is decreased, so that it is necessary to select an optimum number of regenerators taking account of the balance between the cost and the efficiency.
However, the optimum number of regenerators and the ratio of circulation of the absorption fluid in a multiple-effect type absorption refrigerator are not yet known.
The present invention is developed in view of these problems in the conventional art, and has an object to provide a reverse-cycle type multiple-effect absorption refrigerator having an optimum number of regenerators with an improved efficiency, which permits stable operation with a desired cooling performance through simple means even when there is fluctuations of load.
SUMMARY OF THE INVENTION
As a result of extensive studies on the aforementioned problems, the present inventors found that the number of regenerators permitting stable operation by a simple technique was three or four, and obtained some findings about the optimum ratio of circulation of absorption fluid meeting a number of regenerators. They thus completed the present invention.
Particularly, a first aspect of the present invention relates to a triple-effect type absorption refrigerator, and a second aspect of the invention relates to a quadruple-effect type absorption refrigerator.
More specifically, a first embodiment of the first aspect of the absorption refrigerator of the invention provides an absorption refrigerator having three-stage regenerators including a low-temperature, medium-temperature and high-temperature regenerators connected in series, comprising a diluted fluid pump feeding the low-temperature regenerator with dilute fluid obtained by causing an absorption fluid to absorb a coolant by means of an absorber; an intermediate fluid pump feeding an intermediate absorption fluid obtained through heating and concentration of the diluted absorption fluid to the medium-temperature regenerator by means of the low-temperature regenerator; a concentrated fluid pump feeding a concentrated absorption fluid obtained through heating and concentration of the intermediate absorption fluid in the medium-temperature regenerator to the high-temperature regenerator; an intermediate fluid bypass piping feeding back a part of the intermediate absorption fluid directly to the absorber so as to feed only a prescribed ratio of the intermediate absorption fluid obtained in the low-temperature regenerator to the medium-temperature regenerator by means of the intermediate fluid pump; and a concentrated fluid bypass piping feeding back a part of the concentrated absorption fluid directly to the absorber so as to feed back only a prescribed ratio of the concentrated absorption fluid obtained in the medium-temperature regenerator to the high-temperature regenerator by means of the concentrated fluid pump.
A second embodiment of the first aspect of the absorption refrigerator of the invention provides an absorption refrigerator having three-stage regenerators including a low-temperature, medium-temperature and high-temperature regenerators connected in series, comprising load detecting means detecting a load; heat feeding means feeding the high-temperature regenerator with a heat quantity as a heating source; fed heat control means controlling a heat quantity fed by the heat feeding means to the high-temperature regenerator on the basis of the load detected by the load detecting means; a diluted fluid pump feeding the low-temperature regenerator with diluted fluid obtained by causing an absorption fluid to absorb a coolant by means of an absorber; an intermediate fluid pump feeding an intermediate absorption fluid obtained through heating and concentration of the diluted absorption fluid to the medium-temperature regenerator by means of the low-temperature regenerator; a concentrated-fluid pump feeding a concentrated absorption fluid obtained through heating and concentration of the intermediate absorption fluid in the medium-temperature regenerator to the high-temperature regenerator; an intermediate fluid bypass piping feeding back a part of the intermediate absorption fluid directly to the absorber so as to feed back only a prescribed ratio of the intermediate absorption fluid

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