US2557573A - Air conditioning - Google Patents

Description

June 19, 1951 T. K. SHERWOOD AIR CONDITIONING Filed Aug. 27, 1946 INVENTOR W fizrwe ATTORNEY Patented June 19, 1951 UNITED STATES PATENT OFFICE v AIR CONDITIONING ration of Delaware Application August 27, 1946, Serial No. 693,317

This invention is a method of and an apparatus for both heating and cooling. Hot .vapor is v utilized as the heating medium and liquid rein the heat exchanger the necessary quantities of one or the other to do a good job of both heating and cooling without havingto depend upon valves or other mechanical contrivances in the fluid circuits of the apparatus.

own. (cl. zsv-ai 2 municating with an inlet chamber l1 and the upper ends thereof extending into and above the bottom of a separating vessel l8. A space I! within shell l5 and about the tubes l6 forms a steam chamber to which steam is supplied through a conduit 20 from a steam boiler 2 I. The boiler '2! is provided with fire or heating tubes 22 which are adapted to be heated by the prodnets of combustion from a gas burner 23. A combustible gas is delivered to burner 23 from a source of supply through a conduit in which is provided an electro-magnetically-operated valve 25 connected by conductors 26 and 2'! to a suit- Since low pressures and harmless fluids are much to' be desired in apparatus in our homes,

I prefer-to utilize a vacuum type apparatus which provides water for cooling and water vapor at ingly, one way to enjoy the invention is to take an absorption type water refrigerating apparatus, for instance, like that described in Patent No.

2,282,503 of A. R. Thomas and P. P. Anderson, J r.,

and make some connections which permit flow supplied to the evaporator for its usual cooling function.

The invention, together with its objects and advantages, is set forth in more technical detail in the following description and the accompanying drawing in which the single figure shows moreor less diagrammatically a dual function apparatus of this invention.

Referring to the drawing, the apparatus shown comprises basically a two pressure water absorptibn type refrigerating unit generally as described .in said Patent.No. 2,282,503. An apparatus of this type operates below atmospheric pressure and includes a generator I II, a condenser I I, an evaporator I2 and an absorber l4 which are inable source of electrical energy. The water in boiler, 2|. is heated by the hot gases passing through the heating tubes 22, thereby producing steam which. flows through conduit to gen- ,sub-atmospheric pressure for heating. Accorderator ill. The steam is produced at suitable pressures, so that the apparatus may operate as a heating unit as well as a cooling unit. Con- .densate formed in steam chamber I9 is returned to boiler2l through a conduit 3|, a condensate return pump 32 and a conduit 33. a

The system contains a water solution of refrigerant in absorbent liquid such as, for example, a water solution of lithium chloride or lithium bromide Or a mixture of the two. With steam suppliedsthrough conduit 20 to space It, heat is applied to tubes l6 whereby water vapor is expelled from solution. The residue absorption solution is raised by gas or vapor-lift action with the expelled water vapor forming a small core terconnected in such a manner that, when op-.-

erating as a cooling unit, flow of fluid between the high and low sides of the apparatus is regulated by liquid columns. By condenser as applied to the element II is meant the refrigerant liquifier for-cooling operations. By evaporator as applied to element I2 is meant the heat exchanger or air contact coil which functions as an evapora-.

tor or cooling element during cooling periods of operation, and as a condenser or heat radiator during heating periods of operation.

The generator Ill includes an outer shell l5 within which are disposed a plurality of vertical riser tubes l6 having the lower ends thereof comwithin an upwardly rising annulus of the solution. The expelled water vapor rises more rapidly than the solution with the solution flowing along the inside walls of the tubes IS.

The water vapor flows upwardly through the tubes or risersl8 into vessel l8 which serves as a vapor separator. Due to bailling in vessel I8, water vapor is separated from raised absorption solution and flows through conduit 34 into condenser I I. The liquid refrigerant formed in condenser ll flows through a pressure-balancing U-tube 35 into a flash chamber l3 and from there the liquid refrigerant flows through a conduit l3 into the upper part of evaporator l2. U-tube 35 has an internal cross-sectional area so small as a in evaporator 12' with consequent absorption of heat to produce a refrigerating effect which is utilized to cool an air stream flowing through a duct 36, which duct is indicated in dotted lines in the drawing.

The refrigerant vapor formed in evaporator l2 flows into headers l 2' at each end of the evaporator and from there to the absorber ll in which the vapor is absorbed by the absorption solution which enters the upper part of the absorber through a conduit 31. The absorption solution enriched in refrigerant is conducted from absorber ll through a conduit 3!, an inner passage in a liquid heat exchanger 39, a conduit 40, a

stabilizing vessel ll, and a conduit 42 into chamber ll of generator l0. Refrigerant vapor is expelled out of solution in generator III by heating, and the solution is raised by gas or vapor-lift action in riser tubes It, as explained above.

The absorption solution weak in refrigerant which has been lifted in the risertubes it into vessel ll flows therefrom through a conduit ll, an outer passage in liquid heat exchanger is, and conduit 81 into the upper part of absorber ll.

This circulation of absorption solution results from the rising of solution in riser tubes l6, whereby such solution can flow to the absorber and return from the latter to the generator by force of gravity. The upper part Of vessel ll and vessel II are connected by a vent conduit ll When the apparatus is operating as a cooling unit, the absorber i4 and condenser H constitute heat rejecting parts of the refrigeration apparatus and are cooled by a suitable cooling medium such as water, for example, which is conducted from a suitable source of supply through a conduit H to a bank of tubes 45 within the absorber, whereby heat of absorption is given up to the cooling water. The cooling water is conducted from the absorber through a conduit 46 to condenser I l in which heat of condensation is given up to the cooling water. The cooling water leaves the condenser through a conduit 41. Conduit 44 is provided with a suitable valve a, for cutting oi! the supply of cooling Water to the absorber and condenser during heating periods of operation.

In accordance with this invention a vapor bypass, designated generally by numeral 50, is connected between vapor conduit 34 and the evaporator II for flow of hot water vapor from generatcr iii to the evaporator. The by-pass includes a liquid trap 5| comprising a downleg 52 connected to conduit 34 and an upleg 53 connected to a reservoir or separating vessel H, which vessel is connected by a conduit 55 to one of the vapor manifolds ii of the evaporator. A second liquid trap 51 is connected between the bottom of trap 5i and the bottom of vessel 54. An overflow conduit 58 connects vessel 54 with the conduit 43 which conveys absorption solution from the separating vessel is to the liquid heat exchanger as. A conduit 58 connects separating vessel is to the downleg of trap 5 I. A baffle or lip I is provided in separating vessel I! at the entrance of conduit 59 for trapping absorption solution and leading it into this conduit. It is to be noted that absorption liquid enters vessel II from riser tubes is with suflicient velocity that it rises an appreciable distance in this vessel and due to the baffle arrangement in the vessel a small amount of solution is continuously trapped and led into conduit 59.

On cooling cycles of operation the hydrostatic 4 v head from the bottom of trap ii to the level of the bottom of vessel 54 when filled with absorption solution must be at least as great as the maximum pressure differential encountered on cooling cycles of operation. Assuming that the trap II is filled with solution, the level of solution in downleg M will depress when a cooling cycle is commenced, and the level of solution in the uplegs of traps II and I1 will rise as the pressure rises in the generator II and condenser I i. when the pressure in the condenserreaches condensing pressure for the cooling water temperature the vap r will begin to condense and no further depression of liquid level will take place.

in downleg 62. The condensed refrigerant passes through the U-trap ll into the evaporator ii. If a previous shut-down followed a coolin cycle of operation there will be sufficient absorption solution in trap ii to fill vessel N up to the top of overflow conduit 5. almost immediately and then any additional absorption solution flowing from the separating vessel ll through conduit 58 into trap 5i will flow through trap 51 into vessel 54 from whence it overflows into conduit 58. The diameter of the conduit which forms liquid trap 5! should be of such size that absorption solution which backs out of vessel 54 through trap 51 into trap Ii on shut-down periods will not rise in conduit 52 to the point that it overflows through conduit us into vessel It and robs the trap of solution. Otherwise it would be necessary to establish trap ii at the beginning of each cycle of operation.

At the beginning of a heating cycle of operation, as the pressure rises in the generator II and condenser II, the pressure in the evaporator i! will not continue to rise as the pressure there is set by the condensing pressure for water vapor at the temperature of 'air passing over the evaporator to be heated. The liquid level in downleg 52 will then depress and the level will rise in upleg I3 of'trap 5i and in the upleg of trap 51. Since the cooling water to the condenser has been cut off, the pressure in the generator will continue to rise and the level of solution in downleg 52 will fall until it reaches the bottom of trap i I. This will allow vapor to begin to flow from conduit 34 through downleg 52 into upleg 53 and the solution in upleg 53 will either be pumped into separating vessel 54 or it will fall back to the bottom of trap 5i and be forced from there through trap 51 into vessel 54. So long as the resistance to vapor flow from the bottom 01' trap ii to separating vessel 54 through conduit 53 is not greater than that corresponding to the hydrostatic head between the bottom of trap 51 and the level of solution in vessel 54 the vapor will all pass into vessel 54 through conduit 53. The vapor flows from vessel 54 through conduit 55 into the evaporator heater l2 and from there into the evaporator tubes wherein the vapor is condensed giving up its heat of condensation to the air flowing over the tubes thereby heating the air. The condensate formed in the evaporator flows into the absorber and from there it is returned to the generator, or, if preferred, the condensate may be returned to the bottom of the generator by a separate conduit, not shown.

During heating cycles of operation most of the solution will separate from the vapor at the bottom of trap ii and flow through trap 51 into vessel and from there through overflow conduit 58 into conduit 43. If the resistance to vapor flow through upleg 53 is not great enough to correspond to the hydrostatic head of trap 51 some solution would stand in upleg 53 and be carried along with the vapor through this conduit into vessel 54 suflicient to raise the resistance to the above mentioned value. If this requires more solution than is delivered from the separating vessel I8 through conduit 59, the additional solution will fall back from vessel 54 through trap 51 into the bottom of trap The volume of liquid in the vessel 54 up to the top of the overflow conduit 58 should be such that on shut-down this liquid will be sumcient to fill trap 5| with that required to fill upleg 53 from the bottom of trap 5| to the level of the bottom of vessel 54 and also to fill trap 51.

Upon a sudden switch from a cooling cycle to a heating cycle the pressure in the condenser rises until vapor starts passing through the upleg 53 and the operation will continue as explained above. A sudden switch from a heating cycle to a cooling cycle will result in a decreased pressure differential across trap 5| below that corresponding to the hydrostatic head from the bottom of trap 5| to the solution level in vessel 54. Solution will then back out of vessel 55 through trap 51 and into the bottom of trap 5! and at first some solution may be pumped through upleg 53 into vessel 54 allowing some passage of vapor to the evaporator. However, this solution will return constantly through trap 51 into the bottom of trap 5| and the resistance to flow of vapor caused by this solution will soon be high enough to cause condensation of vapor in the condenser I I. Vapor flow through trap 5| will them cease and the condensate formed in the condenser will flow through the U-trap 35 into the evaporator, as previously explained. The trap 51 should be of suflicient cross sectional area that resistance to flow of liquid back and forth therethrough is not appreciable so that liquid may flow quickly from vessel 54 through this trap to fill trap 5|.

While a single embodiment of the invention has been illustrated and described, it will be apparent scribed, an absorption refrigerating apparatus of the two pressure type comprising a generator, a condenser, a heat exchanger, an absorber and conduits interconnecting said elements for flow of a refrigerating medium and an absorption solution and for regulating the flow of fluid between the high and low pressure sides of the apparatus, a, by-pass connection between the generator and the heat exchanger for flow of hot refrigerant vapor to the heat exchanger, liquid column forming means in said by-pass for establishing a barrier between the generator and heat exchanger, means for cooling the condenser, whereby refrigerant vapor supplied thereto is liquefied and flows to the heat exchanger wherein the liquid is vaporized to produce a desired coolin eifect, and means for discontinuing the cooling of the condenser whereby the pressure in the generator is increased to the extent that the barrier in the by-pass is removed and hot refrigerant vapor flows from the generator to the heat exchanger wherein the vapor is condensed to produce a desired heating effect.

THOMAS K. SHERWOOD.

REFERENCES CITED The following references are of record in the file 01 this patent:

UNITED STATES PATENTS Number Name Date 2,019,290 Brace Oct. 29, 1935 2,064,040 Smith Dec. 15, 1936 2,365,797 Bichowsky Dec. 26, 1944 2,402,416 Kogel June 18, 1946 2,468,104 Phillips Apr. 26, 1949

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