US2277320A - Evaporative condenser - Google Patents

Description

March 24, 1942. E. GYGAX EVAPORATIVE CONDENSER a Sheets-Sheet 1 Fil ed Aug. 22, 1938 m h n r E i Y B .F m

March 24, 1942. E. GYGAX EVAPORATIVE CONDENSER Filed Aug. 22, 1938 3 Sheets-Sheet 2 INVENTOR. DP/VEsr @GAX We m (F/fin ATTORNEY.

March 24, 1942. E, GYGAX 2,277,320

EVAPORATIVE CONDENSER I Filed Aug. 22, 1938 3 Sheets-Sheet 3 hump" llhli ATTORNEY.

Patented Mar. 24, 1942 EVAPOBATIVE CONDENSER Ernest Gygax, St. 'Louis, Mo., assignor to Curtis Manufacturing Company, Wellston, Mo., a corporation of Missouri Application August 22, 1938, Serial No. 226,017

2 Claims.

This invention relates to refrigeration sys- Y tems and more particularly to means for converting refrigerant from the gaseous to the liquid state. a

In most large refrigeration systems, since it is impractical to use air alone as a cooling medium for condensers, various water cooling systems are employed. These water cooling systems may utilize a continuous supply from city mains, a continuous supply from wells, recirculated water which is cooled in cooling towers, or the cooling effect of evaporative condensers. A continuous supply of water-from city mains is obviously extremely expensive, while well water for cooling is not usually obtainable. The use of a continuous supply of water also introduces the problem of disposing of large quantities of water. This has become such a serious problem with the advent of air conditioning on a large scale that recent local ordinances have limited the amount of water which can be disposed of in the sewers by anyone user in a crowded metropolitan area.

The use of a. cooling tower to cool the recirculater water possesses advantages over the continuous supply system but in addition to a high initial cost, quantities of water must be pu ped to great heights in most instances. which is quite costly, and in a high wind large quantities of the water are lost.

For many uses the evaporative condenser is an improvement over the cooling tower. There are various types and forms of evaporative condensers most of which are in reality a combination cooling tower and condenser. Evaporative condensers are subject, however, to the disadvantage of a high initial cost as well as a high upkeep cost due to scaling of the sprays, coils, or containers used.

It is an object of this invention to provide an improved means for condensing gaseous refrigerant not subject to the above disadvantages of cooling towers, continuous supply, or evaporative condensers. V

The method of accomplishing this as well as additional objects and advantages will become apparent from the following description and the accompanying drawings.

For the purpose of illustration I show in the accompanying drawings one form of device embodying my invention. The following description and the accompanying drawings are for the purposes of illustration and are not intended to limit my invention which is defined by the appended claims.

Fig. 1 is a diagrammatic view of a refrigeration system to which my evaporative condenser may be connected.

Fig. 2 is a front view of the combination evapvention.

Fig. 3 is a rear view partially in section of the device shown in Fig. 2.

Fig. 4 is a partial side view of my device to show the water-softening and water admission connections.

Fig. 5 is a skeleton view of the water-softening and water admission valves.

Referring now to the drawings:

5 is a shell or housing which encloses tubes I (see Figs. 2 and 3) passing through an upper sheet 9 and lower sheet II and secured in gas tight-connection thereto in a manner similar to the methods used on tubes in a fire tube boiler. A multiblade blower I3 driven by any suitable means such as an electric motor i5 is supported as shown in a fan housing H. The fan housing may be supported as shown on the shell 5. A conical screen l8 shown in Fig. 3 but omitted in Fig. 2 may be positioned above the tops of the tubes as shown. Batlie plates iii are positioned in the fan discharge housing 2|. A drain 23 may be provided below the baflie plates. A water storage pan 25 rests on a base plate 21. The water storage pan 25 has a rear portion 25a in the form of a parallelepiped, that extends through anopening 29a in the back of the supporting base 29. A supporting base 29 surrounds the pan and may support the shell 5 as shown. An enclosure or jacket 3| extends part wayup the shell and is provided with openings 33 which may be provided with air filters 35. A circulating pump 31 driven by a motor 39 may be supported as shown. The motor mayhave electric 40 leads 40. A discharge line 4| from the pump enters theshell through an opening 43 while an intake line 45 communicates with the contents of the water storage pan 25. A portion of the intake line 45 extends into the pan 25 in such a manner that it may be withdrawn therefrom by moving the end of the line 45 upward. To remove the inlet, portion of line 45 from the rear.

portion of the line 45 extends to the bottom of the rear portion 25a of the pan 25 and is below the level of the water held by the pan 25, This orative-condenser-receiver provided by my in- I is shown in Fig. 3 where the inlet portion of line 45 and the water level in the rear portion 25a of pan 25 are indicated by dottedlines. An overflow tube 41 for the pan may be provided as shown. The tube 41 is secured to the rear portion 25a of pan 25 and is located above the lower end of the intake of line 45. This tube determines the maximum water level in the pan 25 and its rear portion 25a. This tube 41 is preferably flexible and may be made of garden hose or similar material. A gauge 48 may be connected with the pump by line 58 to indicate pressure in the pump line. A line 5| connects with the water supply. A water make-up valve 58 is connected with this line and with a line 55 which discharges into the water pan. This water makeup valve is actuated by the weight of the water in the pan- 25 through rod 51 and bar 58 which may be adjusted by the nut 5| on bolt 63. A spring 55 supports the bolt, bar, and rod and in turn, one end of the water pan. It can be seen that as the amount of water in the water pan becomes less than a predetermined amount, the water supply valve will open and water will enter the pan until the added weight pulls down rod 51 which will close the valve 53. Adjustment of the nut 8| will obviously determine the amount of water in the water pan. 8'! is a reservoir for water softener provided with a metering valve 88 and a discharge line H connected to an automatic water softener valve 13 which is also connected with the line 55 which discharges into the water pan. This automatic valve is arranged to open and admit water softener in proportion to the amount of water which is admitted when the weight of the pan opens the valve 53 to admit water.

The space enclosed by the shell 5 between end sheets 8 and II forms a combination receiver and condenser. The outlet of a refrigeration compressor enters the evaporator condenser-receiver through the high pressure connection TI via line 18., The condenser output may flow through the liquid line 8| to a suitable load,

In operation the compressed gas from the compressor is discharged into the space between sheets 8 and II and around the tubes I. These tubes are cooled by water which enters at the point 43 and is distributed between the tops of the vertical tubes and the sheet 8 as shown. A water distribution trough 88 and distribution tubes 80 may be provided so that as water enters this section, it will be evenly distributed around the tops of the tubes and will not splash or overflow down a particular tube or group of tubes near the inlet. The water will flow over the tops of the tubes and down the inside in a thin, evenly distributed film. The tubes are arranged so that the water will completely cover the inside of the tube as it flows down and will not form a single stream down one portion of the tube. This is accomplished by careful positioning and machining of the tubes so that the tops thereof will be perfectly level. Screens may be placed around the tops of the vertical tubes to distribute the water evenly around the inner periphery of each tube but that is not necessary if the tubes are carefully made.

The fan l3 draws air upward through the tubes 1 in a direction opposite to the flow of the water going downward. The fast moving air evaporates the water within the tubes, creating a cooling effect. The cool tubes then serve to condense the gaseous refrigerant entering at II to a liquid 18. The evaporation of the water 7 tubes as the air enters near that point. Such a progressive difference in pressure is advantageous in that it tends to increase evaporation progressively toward the top of the tubes. This is exactly what is desired to keep evaporation of water over the entire tube length uniform as the water is cooler at the top of the tubes and in a thicker film at the bottoms of the tubes. These factors would tend to decrease evaporation at the tops of the tubes and are offset by the pressure difference. By placing the fan at the top of the tubes a uniform air-flow is maintained through all the tubes. The liquid refrigerant is stored as in the usual receiver in the bottom of the condenser as indicated.

Water which is not evaporated as it runs down the tubes falls into the storage pan 25 and is picked up through the pump intake line 45 that extends into the rear portion 25a of pan 25 and is returned to the top of the condenser through outlet 43 by the pump, After a portion of the water has been evaporated, the weight of the tray as communicated to valve 53 by rod 51 is less and the valve opens to admit additionalv water. As the water valve opens, the valve 13 also opens allowing a proportionate amount of water softener to enter with the water. The amount of water softener which is admitted is varied by the metering valve 59 which may be adjusted for the particular type of water being used. Figures 4 and 5 illustrate in greater detail the water softener and water admission valves and connections.

The use of the water softener is a decided advantage since any scale which forms will be soft and can easily be removed.

The air which is drawn up through the tubes is admitted through openings 33 in the side of the base, passes through filters 35, which remove the dirt to prevent coating the inside surface of the tubes with dust and thus reduce their heattransferring capacity. Since the air passes up the tubes at a rather high velocity, it will carry some water with it. Part of this water is re moved by a conical screen l8 and any remaining water will be removed by the baffle plates l8 and returned to the pan through drain 23. The battle and screen save an appreciable amount of water. This is an important factor where the water is supplied through a water meter and paid for on the basis of the amount used.

A valve 81 may connect the water supply line 5| to a line 52 which discharges into the distribution trough 88. This valve may be actuated by pressure communicated to it by line 88 which is connected to the interior of the condenser through connector 8|. This valve is arranged to admit water from the supply line into line 52 and thence into trough 88 whenever the pressure communicated to it by line 88 is above a predetermined value. Under such conditions the condenser functions as the ordinary water tube condenser. The excess water flows out through drain 41. This is a safety feature and allows the refrigeration system to function even though the efficiency of the evaporative condenser may be temporarily impaired by dirt or other causes.

A line 83 carries the gas pressure within the shell to a gauge 85. Another gauge 81 is used to indicate suction pressure and may be conwhenever the refrigerant pressure within the shell gets dangerously high.

This condensing device serves as a combined receiver, condenser. and water tower. It hasnumerous advantages over many-of the previous types of evaporative condensers, chief of which is its accessibility for cleaning. when it is considered that practically all of the cooling achieved by this type of apparatus is due to the evaporation of water, it can be seen that such apparatus is subject to scale and mineral deposits even more than steam boilers. Many evaporative condensers have been found to be useless after a few months operation due to enormous s'cale deposits. The device provided by this invention, however, is easily cleaned in much the same way as a flre tube boiler is cleaned, The housing I1 and fan I8 may be removed in a few minutes and the tubes are then accessible for cleaning .with a wire brush or other suitable tool. The scale that is removed from the tubes by the wire brush or other suitable'tool will drop into the water pan 25. This pan must be removed to permit disposal of the scale. To remove the pan 25, pin 51a that connects rod 51 with bar 58 is forced out. The pipe union "a in line 45 is then loosened and the inlet end of the line 45 is lifted out of the rear portion 25a of pan 25. The removal of pin 51a and the lifting of the inlet of line 45 frees the pan 25 of any positive connection to the condenser. Since the tube 41 is not connected to a sewer pipe, it moves with the pan when the pan 25 is withdrawn and emptied. The pan is then replaced, the inlet of line 45 replaced by tightening union 45a, and pin 51a is replaced. The entire cleaning operation can'be carried out in an hour or so and when completed, the condenser will function as well as now. The importance of the accessibility for cleaning is appreciated when it is considered that the amount of scale forming in a condenser operated with a ten ton compressor may be from 20 to 30 pounds a month for water having a 25 grain hardness.

By combining the receiver with the condenser and water cooling device, an important economy has been effected as the usual liquid receiver may be dispensed with and its cost saved.

I have niade numerous tests with the condenser and have found that the temperature of the air entering and leaving the condenser may be practically the same while the relative humidity of the air leaving is nearly always 100%. This indicates the high efliciency of the condenser and shows that most of the cooling effect is due to the evaporation of the water.

I carryout this evaporation in a manner designed to create a highly eflicient transfer of heat from the gaseous refrigerant to the water flowing down the tubes. The tubes are arranged to cause a very thin uniform film of water to flow down them instead of an irregular stream or current. This means that the heat transfer will not be impaired by a thick layer of water or intervening air bubbles. The thickness of this him of water flow may be controlled by the pump and the size of its associated fittings.

It is obvious that this combined evaporatorcondenser-receiver may be applied in different manners to various refrigeration systems. For

the purpose of illustration, I will now describe how it may be connected and controlled with one particular exemplative system which I show in Figure l. The lines bearing numerals in- Figs. 2 and 3 would be connected to the corresponding lines shown in Fig, 1.

The compressor cylinders I4 are connected withan oil receiver 15 which in turn is connected by line I8 to a high pressure connection 11 of the condenser. Condensed refrigerant leaves the condenser through a liquid shut-off valve 82 and line 8I. Line 8| connects with an expansion valve H2 and evaporating coil 83. The flow of the refrigerant to the expansion valve may be controlled by a solenoid valve Ill which may be electrically connected to a thermostat'IIG and to source of electric supply by wires 1. The return from the evaporator to the compressor is through suction line 85.

The compressor is driven by an electric motor II8 connected to a suitable electric supply and to a pressure switch I20 by electric wires I2I as shown. The running of the compressor is thus controlled by switch I20 which may be operated in accordance with the suction pressure communicated to it by line I22. This switch may be set to cause the compressor to run until it pumps down to a predetermined suction pressure. This switch may also be provided with a safety section which stops the compressor when the head pressure communicated to it by the line I24 rises above a safe value.

The compressor head may be cooled by water entering line I28 and leaving line I26. Such circulation may be accomplished by connecting line I28 in the pump discharge line H (see Figs. 2 and 3) and allowing the line I26 to discharge into line 52 and thence into the trough 88. The pump thus circulates compressor-cooling water.

The motor I5 operating the fan I3 maybe con-' nected by electric wires I28 to a pressure switch I38 and suitable source of supply as shown. The pressure within the condenser may be communicated to switch I30 by line 89. The switch I30 is thus controlled by the pressure of the refrigerant gas entering the shell andmay be so arranged that it starts the fan when a pressure of, say 150 pounds is reached and stops'it when the pressure falls below pounds. Such a method of control is advantageous since it staggers the starting of the motors of the fan and compressor and results in a smaller peak electrical load. It also allows the condenser tubes to reach a temperature high enough to evaporate the water and thus prevent excess water being drawn out by the fan. The electric leads 40 of the pump motor may be connected-with the leads of either the fan or condenser motor as desired.

In operation the thermostat I I6 may be placed in a room or substance to be cooled and when the temperature thereof rises above a predetermined temperature, the thermostat will operate to open the solenoid valve Ill and allow liquid refrigerant to flow through the expansion valve into the evaporator or expansion coils to remove heat from the room or substance being cooled. When the pressure at the switch I28 rises above a predetermined value, the compressor will start and run until it reduces the suction pressure to a predetermined value. Thus the compressor may bev set to start when the suction pressure reaches 30 pounds and to stop again when the suction-pressure is 5 pounds. Whenever the room or substance being cooled is cool enough, the thermostat allows the solenoid valve to close and thus no more liquid refrigerant will flow into the evaporator coils. The compressor, however, may continue to operate even though the solenoid valve is closed until the coils are pumped down to the predetermined pressure at which the compressor switch I20 stops the compressor. This method of control has been found to work satisfactorily in the system shown and I have used it in order to show a system in-which my device has been used.

It is obvious that the refrigeration system shown is only one of the many types of refrigeration systems with which my combination evaporative-condenser-receiver may be used. Like wise, various additions, modifications, substitutions, and omissions in the embodiment of the invention shown will become apparent to those skilled in the art and it is not intended that the scope of the invention be limited thereby but is to be defined by the appended claims.

I claim:

1. An evaporative condenser arranged to condense gaseous refrigerant in a refrigeration system, comprising a vertical shell adapted to receive said gaseous refrigerant, horizontal tube sheets at opposite ends of the vertical shell, a

plurality of tubes extending between and passing through the tube sheets, said tubes being secured to the tube sheets in such a manner that the vertical shell is air tight, said tubes being arranged to have all of the tops thereof at the same level, a water storage receptacle beneath the tubes, means for lifting water from the storage receptacle and discharging it around the tops of the tubes, said means comprising a pump discharging water into an annular trough extending about the circumference of the vertical shell, said trough being above the level of the tops of the tubes, and a plurality of pipes in communication with the water in the said annular trough, said pipes extending inwardly from the trough and being arranged to distribute the water in the trough between the upper ends of the tubes,

a, fan positioned for moving air through the tubes, and a valve responsive to the amount of water in the water storage receptacle for admitting make-up water from a supply line to the storage receptacle.

2. An evaporative condenser arranged to condense gaseous refrigerant in a refrigeration system, comprising a vertical shell adapted to receive said gaseous refrigerant, horizontal tube sheets at opposite ends of the vertical shell, a plurality of tubes extending between and passing through the tube sheets, said tubes being secured to the tube sheets in such a manner that the vertical shell is air tight, said tubes being arranged to have all of the tops thereof at the same level, a housing for a fan positioned above the tops of said tubes, said fan being arranged to move air through the tubes, a water storage receptacle beneath the tubes, means for raising water from the storage receptacle and discharging it around the tops of the tubes, said means comprising a pump discharging water into an annular trough extending about the circumference of the vertical shell, said trough being above the level of the tops of the tubes, and a plurality of pipes in communication with the water in the said annular trough, said pipes extending inwardly from the trough and being arranged to conduct the water from the trough into the space between the upper ends of the tubes, a base support holding the shell above the water storage receptacle whereby the bottom of the tubes are above the water in the water storage receptacle, means enclosing the base support and ex-

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