Absorption Refrigeration Machine Pump

Abstract

An absorption refrigeration machine having a generator and condenser on the high side thereof and an evaporator and absorber on the low side employing a pulser-type solution pump to minimize "slugging," transfer noncondensible gases and solution from the low side to the high side of the machine, store noncondensible gases on the high side thereof and utilize the collected noncondensible gases to dampen pump discharge pulsations.

Description

BACKGROUND OF THE INVENTION

Absorption refrigeration systems comprising a high-pressure side, including a generator and a condenser, and a low-pressure side, including an evaporator and an absorber, require a solution transfer mechanism such as a pump to transfer weak solution from the low side of the system to the high side. The pressure difference across the system may be large, necessitating the use of a positive displacement reciprocating piston pump or a diaphragm pump, both of which provide a pulsed output which can create excessive noise in the system.

The solution to be pumped passes from the absorber to the pump. While the machine is operating, the pump receives "slugs" of liquid from the absorber, rather than a steady flow. This can cause undesirable fluctuating pump noise and could possibly damage the pump mechanism.

Another problem which may arise in the operation of an absorption refrigeration system is the generation of noncondensible gases such as hydrogen which may have a detrimental effect on the performance of the system. It is desirable to provide means to separate the noncondensible gases and retain them out of circulation in the system. It is difficult to separate the gases from the absorbent solution on the high-pressure side of the system due to the tendency of the gas to remain suspended in the solution in the form of fine bubbles. The gases are therefore ordinarily separated and collected on the low-pressure side of the machine. However, storage of the noncondensible gases on the low-pressure side of the system where separation is easily accomplished requires an undesirably large storage tank because of the volume of gas at low pressure. It is desirable to "pump" these separated gases to the high side of the machine along with the solution for storage on the high pressure side of the system.

SUMMARY OF THE INVENTION

This invention relates to an absorption refrigeration system employing a pump comprised of a housing having first and second partitions therein to provide a first low-pressure chamber for receiving solution and noncondensible gases from the absorber, a second chamber having transfer means therein for receiving solution and gases from the first chamber, and a third chamber for receiving solution and noncondensible gases from said transfer means and storing the noncondensible gases therein to dampen the pulsations generated by the transfer means.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic flow diagram of an absorption refrigeration system;

FIG. 2 is a sectional view of the preferred embodiment of the pump of the present invention; and

FIG. 3 is a sectional view taken along line III-III of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 of the drawing, there is shown a refrigeration system comprising an absorber 10, a condenser 12, an evaporator or chiller 14, a generator 16, a liquid-suction heat exchanger 18, and a vapor distributor 20 connected to provide refrigeration. A pump 22 is employed to circulate weak absorbent solution from absorber 10 to generator 16.

As used herein, the term "weak absorbent solution" refers to solution which is weak in absorbent power, and the term "strong absorbent solution" refers to a solution which is strong in absorbent power. A suitable absorbent for use in the system described is water; a suitable refrigerant is ammonia.

Liquid refrigerant condensed in condenser 12 passes through refrigerant liquid passage 24 to the liquid-suction heat exchanger. The liquid-suction heat exchanger 18 includes a housing 26 having a refrigerant restrictor 28 at the upstream end and a refrigerant restrictor 30 at the downstream end thereof. A portion of the liquid refrigerant supplied to the liquid-suction heat exchanger 18 flashes upon passing through restrictor 28 due to the low pressure existing downstream of the restrictor, thereby cooling the remainder of the refrigerant in the housing 26. The cooled refrigerant liquid and flashed refrigerant vapor then pass through restrictor 30 into heat exchanger 32 of chiller 14.

A heat exchange medium such as water is passed over the exterior of heat exchanger 32 where it is chilled by giving up heat to evaporate the refrigerant within the heat exchanger. The chilled heat exchange medium passes out of chiller 14 through line 34 to suitable remote heat exchangers (not shown) after which it is returned to the chiller through inlet 36 for rechilling.

The cold refrigerant evaporated in heat exchanger 32, along with any small quantity of absorbent which may be carried over to the heat exchanger with the refrigerant from the condenser, passes into refrigerant vapor passage 38 of liquid-suction heat exchanger 18. The refrigerant vapor and absorbent liquid, which may have a large quantity of refrigerant absorbent therein, passes through refrigerant vapor passage 38 in heat exchange relation with the refrigerant passing through housing 26. Refrigerant vapor passage 38 is provided with a turbulator 39 which consists of a twisted metal strip to provide a tortuous flow path for the vapor to provide optimum heat transfer between the vapor and liquid in passage 38 and the liquid refrigerant in housing 26. By passing the vapor and liquid in passage 38 in heat transfer with the liquid refrigerant in housing 26, a large quantity of refrigerant in the absorbent liquid in passage 38 is vaporized. The heat required for vaporization is therefore removed from the liquid in housing 26, thereby reducing the temperature of the liquid refrigerant supplied to heat exchanger 32. This heat transfer within the liquid-suction heat exchanger 18 provides an increase in the absorption machine efficiency by transferring heat from the liquid supplied thereto from the condenser to the refrigerant vapor nd absorbent liquid discharged from the chiller.

Refrigerant vapor and absorbent solution from passage 38 is supplied to refrigerant distributor 20 through line 40. Strong solution which is supplied from the generator to distributor 20 through line 41 mixes with the vapor and solution supplied to the distributor through line 40. The refrigerant vapor-absorbent solution mixture from distributor 20 is supplied to individual circuits 42 of the absorber 10 through absorber supply tubes 43. A cooling medium, preferably ambient air is passed over the surface of the absorber in heat exchange relation with the solution therein for cooling the absorbent solution to promote the absorption of the refrigerant vapor by the solution. The same cooling medium may be supplied to condenser 12 in heat exchange relation with refrigerant vapor therein to condense the refrigerant.

Cold weak absorbent solution passes from absorber 10 through line 21 into pump 22.

Referring to FIG. 2, the pump 22 comprises a cylindrical casing 23 having a circular bottom closure 44 and a domed top closure 45 suitably affixed thereto as by welding. A first generally circular partition member 46, which is affixed to cylindrical casing 23 as by welding, and a cylindrical partition member 47, which is affixed to bottom closure 44 and partition member 46 by suitable means such as welding, divide the pump into an inlet chamber 48, a pump or transfer chamber 49 and a noncondensible gas storage chamber 50. An inlet fitting 51 is provided in casing 23 for passing solution and noncondensible gases from line 21 into chamber 48. An inlet valve 53 is suitably affixed to cylindrical partition 47 at a location just below the normal level of solution within chamber 48 for reasons to be hereinafter explained. The valve allows passage of fluid from chamber 48 into chamber 49 but prevents passage of fluid in the reverse direction. A discharge valve 54 is provided in partition member 46 to allow passage of solution and noncondensible gases from chamber 49 into chamber 50. A flexible diaphragm 55 having a generally cylindrical shape with a hemispherical-shaped end which is supported on a perforated mandrel 56 is disposed within chamber 49 and held in place by end plate 57 which is affixed to bottom closure 44 by suitable means such as bolts 58. A pulsating flow of hydraulic fluid from a suitable hydraulic pump 59 (refer to FIG. 1) is provided to the interior of mandrel 56 through hydraulic line 63.

When hydraulic fluid under pressure is supplied to the interior of mandrel 56, the diaphragm 55 is expanded toward partition member 47. The fluid and noncondensible gases within the space between diaphragm 55 and partition 47 is forced through discharge valve 54 into chamber 50. When the hydraulic pressure within diaphragm 55 is reduced, the diaphragm will return to its original shape, causing solution from chamber 48 to be drawn into chamber 49 through inlet valve 53. Since the inlet valve 53 is located just under the normal level of solution within chamber 48, the reduced pressure within chamber 49 will cause solution from chamber 48 to pass therein and create a vortex which causes a quantity of noncondensible gases collected in the upper portion of chamber 48 to be drawn into chamber 49.

A deflector 65 is provided in chamber 50 to deflect the solution and noncondensible gases discharged from chamber 49 through discharge valve 54 to prevent solution from spraying into the upper portion of chamber 50. In order to minimize absorption of noncondensible gases collected in the top portion of chamber 50, deflector 65 is utilized to minimize turbulence which may be created by the unrestricted discharge of solution and gas into the chamber 50 through discharge valve 54. A pump discharge tube 67 having its open lower end near the bottom of chamber 50 is provided for passing solution from chamber 50 into line 62 while retaining the noncondensible gases therein. The noncondensible gases which are passed from chamber 48 into chamber 50 collect in the upper portion of the chamber and are stored therein at pump discharge pressure. The collected gases form a cushioning layer. This cushioning layer of noncondensible gases in chamber 50 is very effective in dampening the pulses generated by the movement of diaphragm 55. A suitable valve 69 is provided for periodic purging of noncondensible gases from chamber 50. It should be understood that when the machine is initially started or purged, chamber 50 will fill with liquid before liquid flows out discharge tube 67. As noncondensible gases are pumped into chamber 50, they will collect in the top portion of the chamber which will force the liquid level down. Before an amount of compressed noncondensible gases is collected which would displace liquid to a level near the inlet to tube 67, the chamber should be purged to prevent passage of the gases from the chamber.

The storage of noncondensible gases in chamber 50 is very effective in dampening the pulses generated by the movement of diaphragm 55.

The weak solution in line 62 is passed through rectifier heat exchange coil 64 in heat exchange relation with hot strong solution passing through heat exchange coil 66 disposed within coil 64 and with the hot refrigerant vapor flowing through rectifier shell 68 in contact with the outer surface of coil 64. The weak solution from coil 64 is discharged into the upper portion of generator 16 along with any vapor which is formed in coil 64 due to heat exchange with the hot vapor passing thereover and the hot solution flowing therethrough.

Generator 16 comprises a shell 70 having tapered fins 72 suitably affixed thereto as by welding. The generator is heated by a gas burner 74 or other suitable heating means. The weak solution is boiled in generator 16 to concentrate the solution, thereby forming a strong solution and refrigerant vapor.

The hot strong absorbent solution passes upwardly through the analyzer section of generator 16 through analyzer coil 76 in heat exchange with the weak solution passing downwardly over the coil. The warm strong solution then passes through heat exchange coil 66 within coil 64 and line 41 into the distributor 20. A restrictor 78 is provided in line 41 so that the solution supplied to the vapor distributor 20 is at the same pressure as the vapor in line 40.

Refrigerant vapor formed in generator 16 passes upwardly through the analyzer section thereof where it is concentrated by mass heat transfer with weak solution passing downwardly over analyzer coil 76. Analyzer plates 80 in generator 16 provide a tortuous path for flow of solution and vapor to assure intimate contact therebetween to improve the mass heat transfer. The vapor then passes through rectifier 68 in heat exchange relation with the weak solution passing through coil 64. Absorbent condensed in rectifier 68 flows downwardly into the generator along with the weak solution discharged from coil 64. Refrigerant vapor passes from rectifier 68 through line 82 to condenser 12 to complete the refrigeration cycle.

While we have described a preferred embodiment of our invention, it is to be understood the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

Claims

We claim:

1. A pump for use in an absorption refrigeration system comprising a cylindrical casing having a circular bottom closure and a domed top closure,

a first partition dividing said casing into a noncondensible gas storage chamber and a second chamber, said first partition being a generally circular member affixed to said cylindrical casing,

a second partition associated with said casing and said first partition to divide said second chamber into an inlet chamber and a transfer chamber, said second partition being cylindrical and affixed to said bottom closure and said generally circular first partition,

inlet valve means associated with said second partition to allow passage of liquid and gases from the inlet chamber to the transfer chamber,

discharge valve means associated with said second partition to allow passage of liquid and gases from the transfer chamber to the storage chamber,

means disposed in the transfer chamber for pumping a mixture of liquid and gases from the inlet chamber to the storage chamber, the gases passing into the storage chamber separating from the liquid and collecting in an upper portion of the storage chamber to form a cushioned layer to dampen pump pulsations, and

discharge means communicating with the storage chamber closely adjacent with bottom of the chamber of passage of liquid from the discharge chamber.

2. A pump according to claim 1 wherein said discharge means comprises a tube projecting downwardly through said domed top closure toward said generally cylindrical partition to said casing, the open lower end of said tube being spaced closely adjacent the generally circular partition for passage of liquid from the storage chamber.

3. A pump according to claim 2, wherein said inlet valve means is positioned below the normal level of collected fluid within the inlet chamber but closely adjacent the surface of the fluid so that passage of liquid from the inlet chamber to the transfer chamber creates a vortex to induce gas collected in the inlet chamber into the transfer chamber.

4. A pump according to claim 2 further including deflector means disposed in the storage chamber opposite said discharge valve means to prevent discharge of liquid from the valve into the upper portion of the storage chamber.

5. A pump according to claim 2 wherein said means for pumping fluid includes a resilient diaphragm adapted to be cyclically flexed by pulsating hydraulic pressure.

6. A pump according to claim 5 wherein said resilient diaphragm has a generally cylindrical shape with a hemispherical end thereto, said diaphragm being disposed within said cylindrical partition.

7. A pump according to claim 6 further including a purge valve affixed to said domed top closure and communicating with the interior of said storage chamber for bleeding excess noncondensible gases from said storage chamber.