US3505827A - Refrigeration system having generator fuel supply control means - Google Patents

Description

Filed Aug. 27. 1968 Aprll 14, 1970 L. A. M NEELY EI'AL 3,50

REFRIGERATION SYSTEM HAVING GENERATOR FUEL SUPPLY CONTROL MEANS 2 Sheets-Sheet 1 INVENTORS. LOWELL A. MC NEELY. PATRICK L. MURPHY.

ATTORNEY.

A ril '14, 1970 L. A. M NEELY ETA!- 3,505,327

REFRIGERATION SYSTEM HAVING GENERATOR FUEL SUPPLY CONTROL MEANS Filed Aug. 27, 1968 2 Sheets-Sheet 2 I H3 I I, I n2 "I I l XIQI NW2 INVENTORS.

LOWELL A. MC NEELY. BY PATRICK L. MURPHY.

ATTORNEY.

United States Patent 3,505,827 REFRIGERATION SYSTEM HAVING GENERATOR FUEL SUPPLY CONTROL MEANS Lowell A. McNeely and Patrick L. Murphy, Indianapolis, Ind., assignors to Carrier Corporation, Syracuse, N. a corporation of Delaware Filed Aug. 27, 1968, Ser. No. 755,639 Int. Cl. F25b 15/00 U.S. Cl. 62-148 3 Claims ABSTRACT OF THE DISCLOSURE A refrigeration system comprised of a generator, solution-cooled absorber, primary absorber, condenser, liquidsuction heat exchanger, and chiller, wherein there is incorporated in the system circuitry associated with the fuel combustion source for the generator Which assures that under low main line fuel pressure conditions input of fuel to the system will be essentially terminated, or at least significantly reduced, thereby markedly improving the safety of the system and preventing the possibility of damage to one or more of the components thereof.

BACKGROUND OF THE INVENTION It is believed novel in the art to provide in a refrigeration system of the character herein generally disclosed what is referred to as an electrical reignition mechanism, including circuitry related thereto, which guards against possible malfunctions in the system should the line pressure in the main fuel gas source drop below a predetermined level. Conventionally, there is employed a pilot for ignition of the gas burner serving the generator as the needs of the generator require, and in such an arrangement it is contemplated that the pilot will at all times remain lit. However, a decrease in the main line gas pressure, or other conditions, may cause the pilot to go out, requiring manual relighting thereof, but more importantly, creating in the meantime a potentially hazardous condition by reason of the ensuing gas leakage.

To obviate these problems and other disadvantageous conditions associated therewith, electrical ignition systems have been devised which generally take the form of glow coils. However, in a refrigeration system of the type herein contemplated, the condenser fan or blower forces primary air in the direction of the gas burner employed to heat the refrigerant solution in the generator, with the result that the burner, even though connected to sensing means, is unable to detect a reduction in line gas pressure, and the glow coil or like means accordingly does not ignite the burner when additional heat to the generator is required.

SUMMARY OF THE INVENTION The present invention is particularly directed to a refrigeration system incorporating a generator of shell construction having in relatively close proximity thereto a heat energy source, the fuel supply for which is under control of line pressure switch means associatedthrough suitable electrical circuitry with pilot operated switch means, gas valve means, and pilot ignition coil means. In this novel arrangement, it is assured that in the event of a significant reduction in the main line fuel pressure, the fuel supply control means, illustratively taking the form of a solenoid operated gas valve, will not operate and any possibility of damage to the ignition coil resulting from the pilot not being able to be lit will be eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 illustrates schematically, with portionsthereof taken in section, a preferred form of air conditioning system incorporating the present invention; and

3,505,827 Patented Apr. 14, 1970 FIGURE 2 is a diagram of an exemplary electrical circut for accomplishing the purposes of the instant invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, there is shown in FIG- URE l a refrigeration system comprising a primary absorber 10, a condenser 11, an evaporator or chiller 12, a generator 13 to which the present invention is directed, a solution-cooled absorber 14 and a liquid-suction heat exchanger 15 connected to provide a refrigeration cycle. Pump means 16 are employed to circulate weak absorbent solution from the primary absorber 10 to the generator 13. As used herein, the term weak absorbent solution refers to a solution which is relatively lowin absorbent power, and the expression strong absorbent solution designates a solution which is high in absorptive capacity. A suitable absorbent for use in the system described is water, and a desirable refrigerant is ammonia.

Liquid refrigerant condensed in the condenser 11 passes through refrigerant liquid passage 18, and refrigerant restriction 20 to heat exchange tube 22 of the liquid-suction heat exchanger 15. The liquid refrigerant is cooled in the tube 22 and emerges from the liquid-suction heat exchanger and passes through refrigerant restriction 24 into the heat exchanger in the chiller 12.

A fluid medium such as water to be chilled passes over the exterior of the heat exchanger where it is chilled by giving up heat to evaporate refrigerant within the heat exchanger. The chilled medium passes out of the chiller 12 through line 28a under action of pump means 28 to suitable remotely located heat exchangers (not shown), after which it is returned to the chiller through inlet 30- for rechilling.

The cold refrigerant evaporated in the heat exchanger passes through refrigerant vapor passage 32 and through the liquid-suction heat exchanger 15 in heat exchange relation with liquid refrigerant passing through the tube 22. The refrigerant vapor then passes through refrigerant vapor passage 34 into the solution-cooled absorber 14.

The solution-cooled absorber 14 is formed within a substantially tubular or cylindrical vessel 38 exemplified by a tubular and preferably generally cylindrical. internal baffie 36 which divides the vessel 38 into the solution-cooled absorber 14 and a second solution chamber 40. The vessel 38 is preferably closed at opposite ends. The battle 36 may be provided with a cover plate 39 having a plurality of vapor discharge apertures 42 therein which allow vapor to escape from the solution-cooled absorber 14 into the chamber 40.

A weak solution heat exchanger 44, preferably comprising a helical coil, is disposed within the solutioncooled absorber 14. A plurality of horizontally extending plates 46 are suitably secured to a central support member 48 and arranged interiorly of the baflie 36 to cooperate with annular grooves 50 and the heat exchanger 44 to provide a tortuous continual flow or passage for vapor and solution through the solution-cooled absorber 14. Suitable packing means, such as Raschig rings 52, may fill the space between the uppermost plate 46 and the top of solution-cooled absorber to reduce the tendency for solution froth to escape through the discharge apertures 42.

A refrigerant vapor distributor header 54 is secured to close the bottom of the =bafile 36. The header 54 is provided with refrigerant vapor ports 56 for passage of refrigerant vapor from the line 34 into the solution-cooled absorber 14 and the chamber 40. Strong solution from the generator 13 is admitted to the top portion of the solution-cooled absorber 14 through line 58. The strong solution moves downwardly through the solution-cooled absorber in counter-flow relation with upwardly passing refrigerant vapor and weak solution passing through the coil 44. A strong solution discharge passage 60 is provided adjacent the lower portion of the bafile 36 for movement of solution from the solution-cooled absorber into the chamber 40.

Solution discharge passages 62 are provided for passing a mixture of refrigerant vapor and solution from the chamber 40 to the primary absorber 10. Each of the discharge passages may take the form of a tubular member having open upper ends for admission of vapor and a solution inlet aperture 64 disposed 'below the level of absorbent solution in the chamber 40'. This construction insures a mixed flow of liquid and vapor to the primary absorber.

A cooling medium, preferably ambient air, is passed through the primary absorber in heat exchange relationship with the absorbent solution to cool the same ad promote the absorption of the refrigerant vapor in the absorber. The same cooling medium may be supplied to the condenser 11 in heat exchange relationship with refrigerant therein to condense the refrigerant.

Cold weak absorbent solution passes from the primary absorber 10 through line '66 into pump inlet tank 68. Weak solution from the inlet tank 68 is supplied to the weak solution pump 16 through line 72. Liquid from the pump 16 passes through pump discharge tank 74 to a rectifier heat exchange coil 76. From the coil 76 the weak solution moves through line 78 to the weak solution heat exchanger 44 in the solution-cooled absorber 14. The weak solution from the coil 44 passes through line 80 into the upper portion of the generator 13 together with any vapor formed in the coil 44.

The generator 13 comprises a shell 82 having fins 84 suitably affixed thereto, as by welding. The generator is heated by a gas burner 86 or any other desired heating means. The weak solution is boiled in the generator 13 to form a strong solution and refrigerant vapor.

The hot strong absorbent solution passes upwardly through the analyzer section of the generator 13 through analyzer coil 88 in heat exchange relationship with the weak solution passing downwardly over the coil. The warm strong solution then moves through the line 58, which has a solution restrictor 87 therein, and is then discharged into the upper portion of the solution-cooled absorber 14.

Refrigerant vapor formed in the generator 13 passes upwardly through the analyzer section thereof Where it is concentrated by mass transfer with weak solution passing downwardly over the analyzer coil 88. Analyzer plates 90 within the generator 13 provides a tortuous path for flow of solution and vapor to assure intimate contact therebetween and to thus improve the mass transfer. The refrigerant vapor from the analyzer section passes through reflux plate 92 in heat exchange relationship with absorbent condensed in rectifier 94. The vapor is then directed through the rectifier 94 in heat exchange relationship with the rectifier heat exchange coil 76. Absorbent condensed in the rectifier 94 flows downwardly onto the plate 92 where it is heated by the refrigerant vapor passing therethrough. The heated absorbent is the passed to the generator along with the Weak solution discharged into the generator from line 80. Vapor is directed through line 96 to the condenser 11 to complete the refrigeration cycle.

The novel circuitry of the present invention as employed in connection with a refrigeration system featuring the structure described above embodies the arrangement appearing in FIGURE 2. A suitable source of alternating current (not shown) is adapted to supply current via leads L and L to energize transformer 100 when contacts 101 and 102 are closed. The transformer is electrically connected to pilot ignition coil 103, which may take the form of a glow coil, leading through a temperature responsive switch assembly generally designated as 104 to pilot operated switch means 105, a line therefrom passing to pressure switch means 106 and solenoid operated gas valve means 107 to accomplish the novel purposes of the invention in the manner to be later more fully described.

The connection from the valve means 107 passes through a secondary limit switch 108, a part load switch 109 to a sail switch 110 and through a lead to solenoid means 111 which is also connected, as shown, to the pressure switch means 106. Through suitable insulation means, designed by dotted lines as 112, the solenoid 111 is in control of relay means 113 leading to condenser fan means 114 and the pump means 16 and 28, designated in FIGURE 2 by the same numerals as employed in FIGURE 1.

To complete the description of the circuitry elements herein provided, the transformer is electrically connected to contact 117a of thermostat 117, when the latter is actuated, and from other contact 117b of the thermostat a lead runs to limit switch means 118 and a solenoid operated manual reset device 119, thereby completing the circuit as thus far explained.

In operation of the electrical system conceived for the refrigeration cycle of FIGURE 1, the following takes place. Closing of the contacts 101 and 102 from main line leads L and L energizes the transformer 100' and supplies current to the pilot ignition coil 103 and therefrom to temperature sensitive switch portion 104a through resistor portion 104]; of the switch assembly or heat motor 104. Assuming adequate fuel line pressure from main conduit 120 into hand manipulatable valve means 121 (FIGURE 1), bellows portion 106a of the pressure switch 106 causes contact member 106b to move from the open position of FIGURE 2 to a closed position.

With sufficient fuel pressure in the main line 120 and the pressure switch closed, actuation of the pilot ignition coil 103 and the switch assembly 104 causes pilot gas means 122' (FIGURE 1) to ignite, whereupon bimetallic element a or its general equivalent forming a part of the pilot operated switch 105 senses the pilot flame and causes contact portion 105b to close and contact portion 1050 to simultaneously open. Opening the contact 105c will thus break the subcircuit through the heat motor 104, and the resistor 1041) will cool down.

Should a condition exist in which there is an inadequate supply of heat from the pilot 122, or no pilot flame whatsoever, the bimetallic element 105a of switch means 105 will fail to open the nonnally closed contact portion 105a. The ignition glow coil 103 would then remain energized, and after a predetermined time interval as sensed by the heat motor 104, the resistance element 10% thereof will slowly heat the bimetallic contact portion 104a to open the subcircuit and deenergize the glow coil. Switch portion or resistance element 10412, when the temperature thereof is reduced, will close the contact portion 104a and thus reenergize the pilot ignition circuit.

Assuming now that the thermostat 117 is closed as a result of a requirement for cooling air, electrical energy passes from the transformer 100 through the thermostat 117 and in a dual path across the limit switch 118 and solenoid operated reset device 119 to the solenoid 111, thereby closing the relay 113 to the condenser fan 114 and motors of pump means 16 and 28, causing activation of the last three named elements. The circuit described thus far is of course completed from the transformer 100 to the solenoid 111 following the path shown on the right hand side of the diagram of FIGURE 2.

With the compressor fan 114 in operation the sail switch is caused to close and a subcircuit is activated in one direction from the transformer 100 through the now closed switches 106 and 105 to solenoid portion 107a of the gas valve 107, and in the opposite direction from the trans former through the thermostat, limit switch 118, reset device 119, closed sail switch 110, part load switch 109, secondary limit switch 108 and terminating in the solenoid portion of the gas valve 107. With the pilot 122 ignited in the manner earlier described, actuation of the gas valve by the solenoid 107a causes the main fuel burner 86 to be ignited and the temperature of the refrigerant solution within the generator shell 82 will shortly be elevated to its boiling point to initiate the refrigeration cycle described earlier herein;

It is believed manifest from the foregoing that when a situation exists under'which the pressure in the main fuel supply conduit 120 drops below a predetermined level, by provision of pressure switch means 106 positioned as shown in the drawings, in combination with the other elements shown best in FIGURE 2, there is effectively precluded any possibility of significant;fuel flow to the valve means 107 and assures that the pilot ignition coil 103 will not be damaged under low main line pressure conditions. To illustrate, in the absence of fuel pressure control means 106, or the equivalent thereof, insuflicient fuel would flow to the pilot 122 tosactuate the pilot operated switch means 105 and accordingly said switch would remain in the normally open position of FIGURE 2. Under such a circumstance the switch portion 104a of the heat motor 104 will return to the closedposition of FIG- URE 2 and the heat motor will periodically cycle in re sponse to current input to the ignition coil until eventually, since the subcircuit at contact point 105a is not broken, the coil 103 would be burned out.

Further, by provision of the pressure switch 106 in the arrangement of the drawings, the flow of gas or other fuel to the entire system is terminated by simply choosing a predetermined set point on this particular switch. By this means the main gas valve cannot be actuated, and there results little or no chance of damage to the refrigeration system by reason of inadequate gas input. A significant safety advantage is thus also achieved.

Numerous modifications may of course be practiced in the arrangement herein disclosed without departing from the spirit of the invention or the scope of the subjoined claims.

We claim:

1. In a refrigeration system having a generator, an absorber, a condenser, an evaporator, combustion means for heating said generator, conduit means for supplying fuel from a source to said combustion means, a pilot fuel line communicating with said conduit means terminating adjacent said combustion means, valve means connected to said conduit means for controlling the fuel flow therethrough, and ignition means for said pilot fuel line, the improvement which comprises switch means in communication with said conduit means for sensing the fuel pressure therein, and means electrically connecting said ignition means, said switch means and said valve means to assure that if the fuel source pressure in said conduit means is below a predetremined level, said ignition, switch and valve means will not be activated.

2. A refrigeration system of the character defined in claim 1, in which the electrical connection means includes a switch device having contact members movable in unison and a thermally responsive member connected thereto effective when there is an inadequate fuel supply to the pilot to deenergize the ignition means.

3. A refrigeration system of the character defined in claim 2, in which the electrical connection means also includes a switch member in circuit with the ignition means and switch device and having a thermally responsive portion and resistor portion in series therewith, said switch member being effective when said switch device senses failure of the pilot to ignite to cause said resistor portion to heat and open said thermally responsive portion to deactivate the ignition means and the resistor portion, whereupon said resistor portion and said thermally responsive portion cool down, thereby closing said thermally responsive portion to energize said resistor portion and said ignition means, said alternate opening and closing of said thermally responsive portion causing cyclical operation of said ignition means to prevent overheating thereof until the switch device is activated when the pilot lights.

References Cited UNITED STATES PATENTS 3,105,363 10/1963 Scher 62--l48 3,253,421 5/1966 Grubb 62l48 3,295,334 1/ 1967 Hu'ltgren 62l48 3,370,436 2/ 1968 Romanelli 62l48 LLOYD L. KING, Primary Examiner

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