US2137060A - Automatic control of refrigerating apparatus - Google Patents

Description

Nov. 15', 1938.- 5. OTTO ET AL 2,137,060

' AUTOMATIC CONTROL OF REFRIGERATING APPARATUS Filed Oct. 5,-1934 2 Sheets-Sheet l BY m 42W rww I ATTORNEYS Nov. 15, 1938. s. OTTO ET AL 2,137,060

AUTOMATIC CONTROL OF REFRIGERATING APPARATUS r: .2 7a 7 a I 7 A I w 79 6f 6 HEAT'NG PERIOD Filed 001;. 5, 1934 2 Sheets-Sheet 2 FIRST PART OF ABSORFTION PERIOD MIDDLE PART OF ABSORPTION ,PERIOD END PART OF ABSORPTION PERIOD 56 ww yfw B$awmwl2whl 4ZM7M/M ATTORNEY 5 I sorption may set in as quickly as Patented Nov. 15, 1938 UNITED STATES PATEN T, OFFICE AUTOMATIC CONTROL or nnmmnm'rmo APPARATUS Stuart Otto, New York, and Lawrence Bruehl, Brooklyn, N. Y., assignors to Gas Refrigeration Corporation, Scranton, Pa, a corporation of Delaware Application 0ctober'5, 1934, Serial No. 746,940

,. Y 110mm,.

ammonia or other refrigerating gas from the absorbent, and deliver it under pressure to a-condenser where it is liifuefled, and during. the coolmg period, operates as. an absorber to cause a reduction in pressure by the reabsorption of the gas, at reduced pressure and an evaporation of the liquefied gas in the evaporator. The lengths of the successive heating and cooling periods may i be controlled ,in accordance with the temperature of the evaporator, and/or in accordance with the temperature'in the boiler absorber, or in various other ways.

, One object of the present invention is to provide new and improved means for preventing the heat of the burner or heating element from being radiated or conducted to the storage chamber of the refrigerator during the heating period.

Another object is to provide new and improved means for dissipating the heat from the .boiler absorber as promptly as possible after the burner or heating element is turned off, so that abpossible after the end of the heating period.

Another object is to provide an automatic control of the cooling air circulation, which permits the-use of a minimum sized condenser, and, if a liquid cooling medium is used for condenser cooling, to permit the use of a minimum sized tank for said medium.

One way in which we may carry out the invention is to provide a casing substantially enclosing the boiler absorber and the burner, and forming a passageway around said boiler absorber for the circulation of air. As a feature of the present invention, the circulation of air through this passageway is controlled by an automatically oper-' able valve which is closed during the heating period to prevent undue circulation of air in this passageway except that necessary to maintain combustion from the burner in case combustible gas is used as the heating medium, and which is opened in accordance with certain predetermined conditions, such as the temperature near the boiler absorber to increase the circulation of air through said passageway either by natural air or by forced draft.

As another feature of the invention, we provide another casing substantially encircling and spaced from the first casing to form a second or outer passageway, the circulation of air through said second passageway being controlled by an automatically operable valve which is opened during the heating period, so that the heat radiated or conducted outwardly from the inner passageway will be carried awayby the circulation of air through said outer passageway, and

Y is thereby kept away from the storage chamber of the refrigerator. 'I'hisvalve is closed at the end of the heating period so that the major portion of the forced or induced air is permitted to go through the inner passageway and around the boiler absorber to dissipate the heat from said boiler absorber.

As another feature of the present invention, we provide a fan which is adapted to assist in the circulation of air .around the boiler absorber, and which is automatically controlled in accordance 'with predetermined phases of the refrigerating cycle.

Various other features and advantages of the invention will be apparent from the following particular description, and from an inspection of theaccompanying drawings in which:

Fig. 1 is a diagrammatic side view, partly in section, of a refrigerator having our improved automatically controlled cooling air circulatory system,

Figs. 2 and 3 are vertical sections showing different forms of automatically controlled cooling air systems, Fig. 4 is a somewhat diagrammatic view of a system for controlling the operation of a fan and/ phases in the refrigerating cycle.

Fig. 5 is a diagrammatic view showing different provided a boiler absorber l0 including an upper chamber or vessel I I, and a lower vessel H. The boiler absorber I0 is shown attached to the rear of a refrigerator storage chamber I3 containing an evaporator Ill. ,PAbove the boiler absorber III and alongside of the storage chamber I3 is a condenser Hi; In case the condenser is water cooled, the water tank therefor may be positioned in the position indicated for the condenser.

For heating the boiler absorber Hi there is provided one or more burner tubes l6 disposed directly under the vessel l2 in position to direct the heat therefrom onto said vessel.

The refrigerating system shown is of the usual intermittently operated absorption type in which, during the heating period, the refrigerating. medium, such as ammonia, is boiled off from the boiler absorber l0, and delivered to the condenser l5 where it is liquefied and then to the evaporator. When the heating period terminates the boiler absorber is cooled and the liquefied refrigerating medium is evaporated in the evaporator l4, and returned to the boiler absorber Ill where it is reabsorbed.

The connections between the boiler absorber, the evaporator and the condenser, may be the usual ones and have not been illustrated as we claim no novelty in that part of the system.

The boiler absorber I is substantially enclosed in a casing II which is spaced from the boiler absorber ID to form an air circulatory passageway around said boiler absorber, and which has the sides thereof substantially following the contour of the sides of the two vessels H and I2, so that the hot gaseous products of combustion from the burners l6 will be kept very close to the walls of the boiler absorber. The casing I1 is connected at the top with a flue l9 extending upwardly to an outlet at the top of the refrigerator.

The lower end of the casing I'I extends to a position near to or below the burners l6, and is provided with an opening 20 formed between a side wall 2| and a bottom wall 22 of said casing.

ubstantially enclosing the casing I1 is an o ter casing 23 spaced from the walls of the inner casing I1 and forming therewith a second air circulatory passageway 24 around said casing il. As shown, the outer rear wall 25 of this outer casing 23 may constitute the rear wall of the refrigerator.

The outer casing 23 has a flue 26 encircling the flue [9 but spaced therefrom, and extending to an outlet at the top of the refrigerator. The inner front wall 21 of the outer casing 23 is spaced from the facing wall of the storage chamber l3 so as to form an air passageway 28 between said chamber and said outer casing 23.

The flues l9 and 26 are disposed towards the rear sides of the casings I! and 23, and the condenser l is disposed between said flues and the rear of the storage chamber l3 to form a passageway 29 around said condenser.

As an important featureofthe present invention, the passage of air through the opening 20 of the inner casing I1 is controlled by a valve in the form of a damper 30 which is automatically operable so as to close the opening 20 during the heating period so that substantially all of the heat from the burners I6 is retained in the inner casing l1, and which is moved in open position at the end of the heating period to increase the circulation of air into the inner casing l1 and around the boiler absorber ID to cool said boiler absorber so that absorption may set,in as quickly as possible after the: end of the heating period.

In the form shown in Fig. 1, the damper 30 is thermostatically controlled and for that purpose is connected .to the bottom wall 22 of the inner casing H by a thermostatic bimetallic strip 32 so that the unequal expansion" or contraction between the component metals of the strip causes said strip to curve in accordance with the local temperature-conditions. This bimetallic strip is so constructed that during the heating period when the burners iii are on, the damper 30 is in closed position as shown. As soon as the burners l6 are shut off the lowering of the temperature aroundthe bimetallic strip 32 causes the damper 30 to be moved into open position indicated in dotted lines. The inner casing I1 is provided with apertures 3! to permit the passage of sufficient air into said casing to support combustion from the burners it during the heating period if combustible gas is used as the heating medium.

As another feature of the present invention, the circulation of air through the passageway 24 between the two casings l1 and 23 and through i the passageways 28 and 29, is controlled by means of the damper 30 and an automatically operable valve in the form of a damper 33. This damper 33 in the form shown in Fig. 1, is thermostatically operated and for that purpose is fixed to the side wall- 2| of the inner casing I! by means of a thermostatic bimetallic strip 34. The damper 33 is advantageously curved to conform with the side portion of the inner casing .il opposite thereto, so that in open position shown, said damper will be close to said side portion to permit the free passage of air through the two passageways 28 and 29. In closed position indicated in dotted lines, the upper portion of the damper 33 will extend through a slot 35 in the outer casing 23 and transversely through the passageway 28, so that the circulation of air through said passageway 28 and the front side of the passageway 24, is blocked. The passage of air through the rear side of the passageway 24 is advantageously controlled by the damper 30 which, when disposed in open position shown in dotted lines, engages a wall 36 extending transversely from the lower end of the rear wall 25 of the outer casing 23, and thereby blocks the passage of air through said rear side.

The bimetallic strip 34 is so constructed and arranged that when the damper 30 is in open position, at the end of the heating period, the

damper 33 is in the position shown in dotted lines to block the passage of air through the passageways 24 and 28. However, when the damper 30 is in closed position, the damper 33 is in position closely adjacent to the walls of the inner casing I! as shown, so that the passageways 24 and 28 are free to permit circulation of air therethr'ough.

In the operation of the form of device shown I -ers l6 may be kept very close to the walls of the boiler absorber ID. The heat absorbed by the inner casing walls will be radiated inwardly towards the boiler absorber In so that the heat is effectively applied to the parts to be heated. Some of the heat from the interior of the inner casing I! will be radiated or conducted outwardly, but it will be carried away by the air which enters the passageway 24 between the two casings I1 and 23. If natural draft is utilized, this air current will be induced by the heating action of the inner casing and also by the ejector action of the inner flue l9. Also, during the heating period, there is induced or created an air circulation in the passageways 28 and around the condenser l5, so that radiation from the'outer casing 23 to the condenser l5 or the storage chamber I3 is minimized during this period.

The cooling of the inner casing. I! by the air current between the two casings l1 and 23' is such that even when the boiler absorber is at its highest temperature, there will be very little heat radiated or conducted to the atmosphere of the room from the apparatus. Furthermore, the air drawn through the passageway 24 between the two casings and through the passageway 28 mixes with, dilutes and'cools the gases from the flue I9, so that there is the minimum heat radiated to the room from said flue.

At the end of the heating period, the burners l6 are turned off. The consequent lowering of the temperature adjacent to the bimetallic strips 32 and 34 causes the opening of the damper and the closing of the damper 33. Under these conditions, air is permitted to circulate freely within the inner casing l1, and around the boiler absorber l0, so that said boiler absorber is quickly cooled and absorption will set in as quickly as possible. The closing of the passageways'24 and 28 during the absorption period causes a larger amount of air to be induced or forced through the inner casing l1.

In order to. assist in the circulation of air through the various air passageways and flues, a fan 39 may be used as shown, secured to the bottom of the refrigerator and adapted to blow air through the various passageways and lines.

.The fan may be continuously operated or may be intermittently operated in accordance with the cycle of operation of the refrigerating system, and in accordance with certain features of the invention, as will be more fully described hereinat er.- 1

In Fig. 2 is shown another form of damper arrangement for controlling the circulation oif air through the various passageways and flues. In this construction, the invention is shown,as applied to a" boiler absorber comprising a single vessel or chamber 40. In this construction, the

' vessel 40 and burners l6 are substantially enclosed in an inner casing 4| open on its front side, spaced from the walls of said vessel 40 to form an air passageway 42 around said vessel, and having the top wall thereof substantially following the contour of said vessel. This inner casing 4| at the top thereof has a flue 43 which communicates with the passageway 42.

1 Substantially encircling the inner casing 4| is an outer casing 44 spaced from the walls of said inner casing and-forming therewith apassageway 45. 45 and a bottom wall 41, andterminates at its inner side in a tubular extension 49. At the upper end of the outer casing 44 is a flue 49, en-

circling the flue 43 but spaced therefrom.

'innercasing4l through a bimetallic strip 52, '70

The circulation of air between the passageways and flues in this construction, is controlled by a pair of automatically operable valves in the form of dampers 50 and 5| cooperating with the open side of the inner casing 4| and thermostatically controlled. Forthat purpose, the damp-' er 50 is connected to the "bottom wall of the while the damper 5| is bimetallic in its entirety, and is connected to the top wall of said casing.

When the burners l6 are, on, the temperature,

adjacent to the thermostatic members 5| and 52 is such as to bring the two dampers together into engagement as shown, so that the open side of the This outer casing 44 comprises a rear wall inner casing 4| is blocked while the passageway 45 between the two casings 4| and 44 is open for the passage of air therethrough. When the burner |6 has been turned oil? the lowering of the temperature causes the dampers 50 and 5| to move apart and into engagement with the walls of the outer casing 44, as shown in dotted lines, to permit the free entry of air into the inner casing 4| and to block the passage of air in the passageway 45 between the inner and outer casings. I

The open side of the inner casing 55 is controlled by the damper 54 connected to one end of a pair of brackets 6| by means of bimetallic strips 62, the other ends of the brackets being connected to the rear wall of said casing. The damper 54 is in the form of a hood having an end wall 63 and a pair of side walls 54 spaced a slightly greater distance than the width of the wall extension 51- so that said damper may swing freely under the action of the thermostatic strips When the burners it are on, the damper 54 will be in the position shown, with the-end wall 63 thereof extending between the bottom wall 55 and the wall extension 59 of the inner casing, so that the passage of air into the interior of the inner casing 55 is blocked, while the air is permitted to enter the space between the two casings 44 and 55. When the burners l6 are shut oil, the damper 54 will -be automatically moved in its uppermost position into contact'with the wall of .the outer casing 44 so as to permit air to enter freely into the interior of the inner casing 55- and to block the upper portion of the inlet end of the passageways between the'inner and outer casings. Although the lower portion of thepassagewa'y between the inner-and outer casings is,

open in this position of the damper 54, very little air will pass through this'lower portion of the passageway at this .point, due to the fact that most of the air induced or forced will pass into the interior of the. casing 55 as a result of its comparatively larger opening.

'- In Figs. 4 and 5 is shown a unit for automatically controlling the damper and/or the-fan according to-certain phaseslin the refrigerating cycle. This feature of the invention is shown as applied to an electrical system in which an electrical burner is but as far ascertain aspects of this feature are concerned, it may be applied to a system in, which combustible gas,

steam, hot oil, or other suitable fluid is used as v the heating medium. In this construction, there is provided-a pair of valves 65 and 65 for control ling the flow of heating medium, such as electric, l

current. the form of mercury switches thermostatically controlled from the boiler absorber and evaporator respectively. For that purpose, within the boiler-or associated in heat' exchange relationship thereto, there is employed a temperature bulb 61 for a fluid medium which will expand These valves 55 and 56 are shown in and contract with changes in temperature in the boiler absorber, and this is connected to the switch 65 by a suitable operating mechanism 68. In the evaporator, there is employed a similar temperature bulb 18 connected to the switch 66 by the operating mechanism The operating mechanisms 68 and II are of the snap type, so that the switches 65 and 66 are held in position between predetermined temperature phases in the boiler absorber and the evaporator.

The current comes in through a pair of main lines 12 and 13, the line I2 having a branch connection 14 to one side of a heating element or burner 15, and abranch connection 16a to one side of the fan 39. The other line 13 comes into the middle contact point of the switch 66.

The right-hand contact point of the switch 66 is connected by means of a line 16 to the righthand contact point of the switch 65, while the left-hand contact point of the switch 66 is connected to the middle contact point of the switch 65 by means of a line 11. The line H is connected to the other side of the fan 39 by means of a line 11a. The left-hand contact point of the switch 65 has a branch connection." to the other side of the heating element 15 and another branch connection 19 to one side of an electrically operated mechanism 88 for a damper 8|. The other side of this operating mechanism 88 is connected to the branch connection "a by means of a connection 82.

The operating mechanism 88 may be of any suitable construction. For instance, it may comprise a solenoid 83 having a plunger 84, one

end of which is in the form of a rack bar meshing with'a toothed wheel 85, the shaft of which carries the damper 8|, so that as the circuit through the solenoid 83 is opened or closed the corresponding movement of the plunger 84 causes a movement of the damper 8|.

The switches 65 and 66 are so operated as to cause the operation of the fan 39 during the heatm period and during a portion of the absorption period, and also causes the operation of the damper 8| coincidentally with the closing and opening of the circuit through the heating element [5.

In Fig. 5 is shown the diiferent positions of the thermostatic switches 65 and 66 during the refrigerating cycle. During the heating period, the switches 65 and 66 are in the position indicated in Fig. 4 and at A in'Fig. 5. In this position, the heating element 15 is on, the circuit of the fan 39 is closed, and also the circuit of the electrical operating mechanism 88 so that the damper 8| is closed, and the air is blowing between the inner and outer casings, thereby preventing outward radiation of heat from the inner casing. During this period, there is a compara tively low temperature in the boiler absorber as the gas is passing of]? freely to the condenser, and

there is comparatively high temperature in the evaporator as there is no evaporationor cooling efiect taking place.

As the. heating of the boiler absorber continues, the operation will reach a point at which all of the ammonia or other refrigerant gas has been driven ofi, and the temperature will rise to such a point in the boiler absorber that the fluid in thetemperature bulb 61 in expanding will exert suflicient pressure to cause the reversal of the switch 65 to the position B shown in Fig. 5, while the thermostatic switch 66 remains unchanged. In this position of the switches, the circuit through the heating element 15 will be opened so that the heat from said element will be shut off. Also, during this phase, the circuit of the electrically operated mechanism 88 will be opened so that the damper 8| will move into position to permit passage'o'f air into the inner casing and around the boiler absorber unit to cool said unit. The temperature of the boiler absorber will then drop and evaporation in the evaporator will begin.

. During the middle portion of the absorption period, as the evaporator temperature drops, the pressure of the thermostatic medium in the temperature bulb 18 will decrease sufficiently to cause the switch 66 to reverse into position C shown in Fig. 5, While the switch 65 remains unchanged. In this position, the circuit of the fan 39 will still be closed so that the fan will still be operating while the circuits of the heating elements 15 and the operating mechanism 88 will still be open so that no change takes place in the operation of these members.

During the latter part of the absorption period, the cooling of the boiler absorber unit will cause the switch 65 to move into the position D shown in Fig. 5, while the position of the switch 66 the damper operating mechanism 88, the fan 39,

and the heating element 15 will be closed so that these members will be operated and the heating period will begin.

The constructions shown in Figs. 4 and 5 may be applied to the constructions shown in Figs. 1-3 for operating the dampers and the fan.

In Fig. 6 is shown another form of unit for controlling the operation of the fan 39. Inthis construction the fan 39 may be operated independently of the operation of the heating member flow through a fluidv supply pipe 9|, while the other line 81 is connected to the other pole of this fiuid valve 98. The supply pipe 9| is connected to a heating element 92 shown in the form of a gas burner, and hasa pilot 93 in its line.

Connected across the lines 86 and 81 is the fan 39 and an automatic temperature switch 95 disposed in the boiler absorber unit.

In the operation of this system, during the heating period, both switches 88 and 89 are closed so that the circuit of the electrical operating mechanism of the fluid valve 98 is closed,

and said valve is opened to permit the passage of gas to the burner 92. As soon as the temperature of the boiler absorber unit has reached a predetermined temperature, the switch 88 is opened while the switch 89 remains closed, so that 92, thereby starting the boiling period.

The temperature switch 95 can be so regulated as to effect any desired operation of the fan 39. For instance, it may be so regulated as to operate the fan during the boiling period, and during a portion of the absorption period, or it may be operated only during the absorption period, de-.

pending upon the adjustment of the switch 95.

Having thus described our invention, what we clairin; as new and desire to secure by Letters Pat- 8H2 1. A refrigerating apparatus of the intermittently operating absorption type, including a boiler absorber, a casing extending around said boiler absorber, spaced therefrom to form a passageway therewith, and having .an inlet opening, means for heating said boiler absorber intermittently, a damper extending across said inlet opening, and thermostatic means directly connected to said damper for automatically moving the latter into closed position while said heating means is in operation, and for moving said damper into o iifen position when said heating means is turned 0 2. A refrigerating apparatus of the intermittently operating absorption type, including a boiler absorber, a casing extending around said boiler absorber, spaced therefrom to form a passageway therewith, and having an inlet opening, means for heating said boiler absorber intermittently, a damper extending across said inlet openin, and a bimetallic thermostatic strip connected between said damper and the wall of said casing for moving said damper into closed position while said heating means is in operation, and for moving said damper into open heating means is-turned oflf. I

3. A refrigerating apparatus of the intermittently operating absorption type, including a boiler absorber, an inner casing extending around said boiler absorber and spaced therefrom to form position when said a passageway therearound, an outer casing extending around said inner casing and spaced therefrom, means for heating said boiler absorber intermittently, thermostaticallyoperated valve means for controlling the circulation of air between said casings, and separate thermostatically operated valve fneans for controlling the circulation of air through the inner casing.

4. A refrigerating, apparatus of the intermittently operating absorption type, in which the cycle of operation includes a heating period and an absorption period, including a boiler, an inner casing surro' inding said boiler and spaced therefrom, said casing being provided with an inlet opening, an outer casing extending around said inner casing and spaced therefrom to form a passageway therewith, a damper for the inlet opening of said inner casing and means thermostatically operable for moving said damper v.altemately in closed and open position at the beginning and end of the heating period respectively, said damper in open position engaging the outer cas 'ing wall and blocking the passage of at least a into engagement with the outer casing at the portion of the air into the said casings.

5. A refrigerating apparatus of the intermittently operating absorption type in which the cycle of operation includes a heating period and an absorption period, including a boiler absorber, an inner casing surrounding said boiler absorber and spacedtherefrom, said casing being provided with an inlet opening, an outer casing extending around said inner casing, spaced therefrom, and also having an inlet opening, a pair of dampers connected to the wall of said inner casing, and means for automatically controlling said dampers whereby the latter, during the heating period, will be together to block the passage of air into the inner casing, and will be moved apart and passageway between end of the heating period to permit free passage of air into said inner casing while blocking the passage of air between said casings.

6. A refrigerating apparatus of the intermit- "tently'operating absorption type in which the cycle of operation includes a heating period and an absorption period, including a. boiler absorber,

a casing around said boiler absorber, a condenser outside'of said casing, a fan, means for automatically controlling the operation of said fan, whereby said fan is operated during the heating period and shut off before the end of the absorption period, and automatically operable means for directing the air from said fan only over said condenser to cool the latter during the heating period, and only through said casing during the absorption period to cool said boiler absorber.

7. A refrigerating apparatus of the intermittently operating absorption type, in which the cycle of operation includes a heating period and an absorption period, including a boiler absorber, an evaporator, a heating element for said boiler absorber, a fan, a valve for-controlling the circulation of cooling air from said fan and around said boiler absorber, means for operating said valve and Tsaid heating element coincidpntly and intermittently in accordance with temperature conditions in said boiler absorber, and means an absorption period, including a boiler absorber,

an evaporator, an electric heating element for said boiler absorber, a fan for circulating cooling air, an electrically operated member for con-' trolling the circulation of air around said boiler absorber, and a pair of switches for controlling the passage of electric current to said heating element, to said member, and to said fan, and

automatically operable respectively by the temperature in the boiler absorber and the evaporator, whereby said electrically operated valve is operatd at the beginning and end of the heatlng period, and said fan is operated during'said boiling period and during a portion of said ,ab-

sorption period, and is turned off before the end of said absorption period.

9. A refrigerating apparatus of the intermittently operating absorption type, including an absorber, a casing around said absorber, and means for circulating cooling air around substantially the entire outerperiphery of said casing 11. A refrigerating apparatus of the intermittently operating absorption type, including a boiler absorber, an inner casing extending around "said boiler absorber and spaced therefrom to form a passageway therearound, an outer casing extending around said inner casing and spaced therefrom to form a passageway, and means for circulating cooling air alternately through said inner casing and through the passageway between said casings.

' I STUART OTTO.

LAWRENCE BRUEHL.

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