US3654988A - Freeze protection for outdoor cooler - Google Patents

Abstract

A room heating-cooling system of the type wherein a water loop extends through a plurality of room air conditioning units to exchange heat therewith, said water loop comprising an outdoor evaporative cooler and an indoor water heater: the improvement comprising branch water lines connecting the water loop with a heat exchange coil in the sump of the evaporative cooler for keeping the sump liquid above freezing level when the outdoor temperature drops below 32* F.

Description

United States Patent Clayton, III

[ Apr. 11, 1972 [54] FREEZE PROTECTION FOR OUTDOOR COOLER [72] Inventor: John B. Clayton, III, Shaker Heights, Ohio [73] Assignee: American Standard Inc., New York, NY.

[22] Filed: Feb. 24, 1970 [211 App]. No.: 13,498

[52] US. Cl. ..165/l7, 165/22, 165/29 [51] Int. Cl ..F25b 29/00 [58] Field of Search ..l65/l7, 22, 50, 29, 30, 60,

[56] References Cited UNITED STATES PATENTS 2,238,952 4/1941 Stacey, .Ir. 1 65/134 2,715,514 8/1951 Stair ..165/50 Primary ExaminerCharles Sukalo v Attorney-John E. McRae, Tennes l. Erstad and Robert G. Crooks [57] ABSTRACT A room heating-cooling system of the type wherein a water loop extends through a plurality of room air conditioning units to exchange heat therewith, said water loop comprising an outdoor evaporative cooler and an indoor water heater: the improvement comprising branch water lines connecting the water loop with a heat exchange coil in the sump of the evaporative cooler for keeping the sump liquid above freezing level when the outdoor temperature drops below 32 F.

3 Claims, 1 Drawing Figure warn uu'ren PATENTEUAPR 11 1972 llHllllllllllllllllllllll illlllllIIIIIIIHIIIIHIII HlllIIIIIIIIHIIIIIIIIIID INVENTOR. JoH/v 5 Cuwra/vE FREEZE PROTECTION FOR OUTDOOR COOLER THE DRAWINGS The single FIGURE is a schematic view of a room coolingheating system incorporating the invention. Numeral l denotes a conventional building (motel, office building, etc.) having a multiplicity of roomair conditioner units 12. A representative one of these air conditioning units comprises a self-contained reverse cycle refrigeration machine which includes arefrigerant compressor 14, air-contactedrefrigerant coil 16, water-contactedrefrigerant coil 18, andreversing valve 20. In its illustrated position valve allows high pressure refrigerant gas fromcompressor 14 to flow throughcoil 16.Fan 22 passes room air over the coil to condense the refrigerant and thus heat the air. Condensed refrigerant flows across arestriction 24 and throughcoil 18 where it undergoes evaporation; water flowing throughcoil 19 supplies the heat for vaporization of the refrigerant. Evaporated refrigerant is drawn throughlines 26 and 28 back to the compressor.

Rotational adjustment of reversingvalve 20 causes the high pressure gas fromcompressor 14 to be delivered throughline 26 for condensation incoil 18. Condensed refrigerant flows acrossrestriction 24 and throughcoil 16 where it undergoes evaporation, thus cooling the air supplied byfan 22.

It will be seen that in the illustrated position ofvalve 20coil 16 acts as a refrigerant condenser to heat the room air, whilecoil 18 acts as a refrigerant evaporator to cool the water flowing throughcoil 19. ln the non-illustrated position ofvalve 20coil 16 acts as a refrigerant evaporator to cool the air supplied byfan 22, whilecoil 18 acts as a refrigerant condenser to heat the water flowing throughcoil 19.

WATER LOOPVarious coils 19 in the roomair conditioning units 12 are each continually supplied with water by means of awater loop 15 which includes continuously energized water pump 30,indoor water heater 32,water supply line 34,branch supply lines 36 for the individual air conditioner units,branch return lines 38 for the individual units, and mainwater return lines 44 and 40.

Water line 44 delivers loop water to aheat exchange coil 50 which is intended to act as a loop water cooler. The heat exchanger is intended to be actuated when loop water temperatures rise above about 90 F., as by energization of the water spray pump 60 andblower 58 via thermostat control (not shown). In the loop water temperature range between about 70 F. and 90 F. it is intended that thewater cooler 50 andwater heater 32 both be inactive. When the loop water temperature drops below about 70 F. it is intended thatwater heater 32 become active, as by means of a thermostat control (not shown). The air is to continually maintain the loop water temperature in a range between 70 F. and 90 F. so that eachwater coil 19 can effectively exchange heat with the refrigerant in the associatedcoil 18. Pump preferably is energized on a continuous basis for a continuous circulation of water through the loop and through thevarious coils 19 in the various room conditioning units.

OUTDOOR COOLER 52Evaporative cooler 52 includes a duct-like casing 54 having anair inlet 56 and acentrifugal fan 58 for drawing air up wardly through thecoil 50. Evaporative cooling liquid is provided byoverhead spray nozzles 58 which are supplied with water fromline 59 going from sump pump 60. Make-up water is supplied to thesump 62 through a water line 64 conventionally connected to afloat valve 66 so that a predetermined water level is maintained in the sump. The general operation involves thermostatic control of pump 60 andfan 58 whereby loop water is caused to flow throughheat exchanger 50 while water is sprayed ontocoil 50 through thewater sprays 58; simultaneously air is flowed upwardly through the coil by means of thefan 58. This operation produces an evaporation of the water on the exterior surfaces ofcoil 50, and a cooling of the loop liquid within the coil.

The illustrated system is usable in northerly climates on a year-round basis. Due to variations in heat-cool loads at different zones in the building (electric lighting, cooling of electronic gear, high-low density occupancy areas, effect of sunlight on large glass areas, wall insulation, wind direction, etc.) some of theunits 12 may be on air-cooling cycles while others are on air-heating cycles. This mode of operation may exist even when the outdoor temperatures drop below 32 F. Cooler 52 operation during such low temperature periods is hampered by possible freeze-up of thesump 62 liquid.

The present invention proposes that liquid in the water loop be used as a source of heat to prevent the sump liquid from freezing during winter operations. As shown in the drawing, the water loop connects with a branch water line 70 which admits loop liquid to aheat exchange coil 72 emersed in thesump 62 liquid.Coil 72 liquid is returned to the main loop through asecond line 74.

As previously mentioned, pump 30 is operated on a continuous basis for maintaining a continual flow of water throughloop 15. Therefore in the illustrated arrangement a small portion of the loop water is continuously supplied to coil 72.Coil 72 will therefore maintain thesump 62 liquid at a fairly high temperature somewhat near 70 F., even during the winter months. It is contemplated that a thermostatic valve could be provided inbranch lines 70 or 74 to prevent flow of water throughcoil 72 when such flow is not needed, as during the summer months. However such a valveis not believed essential. The water flow throughcoil 72 is very minor compared to the main flow through the loop.

Preferably pump 60 andspray supply line 59 are located within the confines ofduct 54 to semi-insulate them from outdoor ambient wind effects. Also, the system is preferably selfdraining so that all or most of the liquid is eithin the sump where it can be heated bycoil 72. As a further anti-freeze measure the water supply line 64 may be run into thecooler 52 alongside thepipes 70 and 74 to be heated thereby.

The volume ofsump 62 liquid is preferably kept fairly small to permit employment of smallsize heater coil 72. Attainment of satisfactory liquid sump levels with low sump volumes can be achieved by forming the sump as a V-shaped trough; thecoil 72 would preferably run parallel to and within the trough for its full length (normal to the V).

It will be under stood that cooler 52 can be disposed in its conventional outdoor location, usually on a concrete slab at ground level, or on the building roof top.

Iclaim:

1. In a building air conditioner system operable to provide simultaneous and selective heating or cooling in individual room air conditioning units; said conditioning units individually comprising an air-contacted refrigerant coil, a liquid-contacted refrigerant coil, a refrigerant compressor, and refrigerant control means operable to selectively (1) cause the air-contacted coil to act as a refrigerant condenser and the liquid-contacted coil to act as a refrigerant evaporator or (2) cause the air-contacted coil to act as a refrigerant condenser and the liquid-contacted coil to act as a refrigerant evaporator; a closed liquid circulation loop including branches connected with each liquid-contacted coil, a continuously operating pump, a loop liquid heating means, an outdoor loop liquid cooling means, and means for selectively energizing the heating means and cooling means to maintain the temperature of the loop liquid in a range appreciably above its freeze point; said outdoor liquid cooling means comprising an evaporative cooler having a liquid supply sump subject to freeze-up when outdoor temperatures drop below the aforementioned freeze point: the improvement comprising a liquid heater coil located in the sump below the sump liquid level, and liquid connections between the loop and said liquid heater coil whereby relatively hot liquid is diverted from the loop through the heater coil to prevent freeze up of the sump liquid.

2. The system of claim 1 wherein the evaporative cooler comprises a heat exchanger having overhead liquid sprays, a liquid pump disposed in the sump, and spray supply piping connecting the sump pump discharge with the overhead sprays; said sump pump and supply piping being disposed within the confines of the cooler.

3. The system of claim 1 wherein the heating means and cooling means are selectively operated to maintain the loop liquid temperature in the range between about 70 F. and 90 F., whereby the sump heater coil is supplied with liquid having a temperature appreciably above 32 F.

Claims (3)

1. In a building air conditioner system operable to provide simultaneous and selective heating or cooling in individual room air conditioning units; said conditioning units individually comprising an air-contacted refrigerant coil, a liquid-contacted refrigerant coil, a refrigerant cOmpressor, and refrigerant control means operable to selectively (1) cause the air-contacted coil to act as a refrigerant condenser and the liquid-contacted coil to act as a refrigerant evaporator or (2) cause the aircontacted coil to act as a refrigerant condenser and the liquidcontacted coil to act as a refrigerant evaporator; a closed liquid circulation loop including branches connected with each liquid-contacted coil, a continuously operating pump, a loop liquid heating means, an outdoor loop liquid cooling means, and means for selectively energizing the heating means and cooling means to maintain the temperature of the loop liquid in a range appreciably above its freeze point; said outdoor liquid cooling means comprising an evaporative cooler having a liquid supply sump subject to freeze-up when outdoor temperatures drop below the aforementioned freeze point: the improvement comprising a liquid heater coil located in the sump below the sump liquid level, and liquid connections between the loop and said liquid heater coil whereby relatively hot liquid is diverted from the loop through the heater coil to prevent freeze up of the sump liquid.

2. The system of claim 1 wherein the evaporative cooler comprises a heat exchanger having overhead liquid sprays, a liquid pump disposed in the sump, and spray supply piping connecting the sump pump discharge with the overhead sprays; said sump pump and supply piping being disposed within the confines of the cooler.

3. The system of claim 1 wherein the heating means and cooling means are selectively operated to maintain the loop liquid temperature in the range between about 70* F. and 90* F., whereby the sump heater coil is supplied with liquid having a temperature appreciably above 32* F.

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