United States Patent (19)

Transcription

1 United State Patent (19) Thompon (54) Two STAGE COOLING TOWER 75 Inventor: Tommy L. Thompon, Tucon, Ariz. 73 Aignee: Planetary Deign Corporation, Tucon, Ariz. (21) Appl. No.: 505,767 (22 Filed: Apr. 6, ) Int. Cli... F28D 5/00 52 U.S. C /311; 62/305 58) Field of Search... 62/304, 305, 309, 311; 261/109, 153, DIG. 11; 98/119 56) Reference Cited U.S. PATENT DOCUMENTS 3,116,612 1/1964 Pennington... 62/311 4,532,777 8/1985 Thompon... 62/434 [11] Patent Number: 5,031, Date of Patent: Jul. 16, ,827,733 5/1989 Dinh... 62/305 4,926,657 5/1990 Bomar... 62/3 Primary Examiner-Albert J. Makay Aitant Examiner-John Sollecito Attorney, Agent, or Firm-Mark E. Ogram 57 ABSTRACT A tower, or vertical haft, equipped with a two tage evaporative cooler near the top. The chimney effect, in revere, caue the cool air to flow by gravity down the tower. The air can be ued for cooling and ventilating tructure. In one embodiment of the invention, the ambient air flow i all that i required for the embodi ment to operate and all reliance upon electrical energy i eliminated. 23 Claim, 3 Drawing Sheet AvvavaavvywyavaNaxxYYAvXYVAVNNYYYYYA Y e a HIS H --OOO III Y III. V Y W. a S RA N S i.

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5 1. TWO STAGE COOLING TOWER BACKGROUND OF THE INVENTION Thi invention relate to evaporative cooling ytem and more particularly to cool tower. Natural draft evaporative cooler, popularly known a "cool tower', are recent development which pro vide very low cot cooling in dry climate. Thee tow er are ued for cooling reidence, wind heltered out door area, and even bu top, and are found in the outhwetern United State and Saudi Arabia. Operation of the tower depend on the denity dif ference between the tower and outide air. Evaporative cooling pad located around the upper tower perimeter fill the tower with cool air at a higher denity than ambient air. The cooler air fall through the tower at a rate which depend on the magnitude of the denity difference, the height of the tower, the reitance to air flow provided by the tower and the aociated truc ture, and wind force on the tower-tructure envelope. A the humidity of the outide air increae, perfor mance of the tower decreae. Becaue of thi, the range of cool tower i extremely limited, uually to area having particularly dry environ. In traditional evaporative cooler, a group of devel opment have arien which attempt to widen the range of evaporative cooler into more humid environ. Thee include two-tage cooling ytem. A number of two tage evaporative cooling ytem have been developed and are decribed in depth by Evaporative Air Conditioning Handbook, 2nd Ed, Chap mann & Hall, New York, incorporated herein by refer ence. All require a firt tage heat exchanger which cool outide air without humidification. The pre-cooled air, with a reduced wet bulb temperature, i further cooled by evaporation of water in the econd tage evaporative cooler. Heat i alo rejected from the firt tage heat exchanger by evaporation, either in an external cooling tower or uing an additional evaporative cooler, de pending on the type of heat exchanger ued. In U.S. Pat. No. 4,532,777, entitled Two Stage Cool ing Sytem' iued to Thompon on Aug. 6, 1985, a two tage cooler i decribed which utilize two evaporative tep wherein an oil-like material i cooled by contact with evaporating water. The cooled oil-like material i ued to pre-cool, without humidifying, air before a ec ond evaporative cooling tep. Thi patent i incorpo rated hereinto by reference. Unfortunately, in many application, a ready ource of electricity doe not exit to power the re-circulating pump, the blower, and other equipment neceary for two tage cooler to operate. It i clear from the foregoing that an energy efficient cooling mechanim doe not exit that can operate in humid environment. SUMMARY OF THE INVENTION Thi invention conit of a tower, or vertical haft, equipped with a two tage evaporative cooler near the top. The chimney effect, in revere, caue the cool air to flow by gravity down the tower. The air i ued for cooling and ventilating tructure. In one embodiment of the invention, the ambient air flow and hydraulic preure are all that i required for the embodiment to 5,031, operate and all reliance upon electrical energy i elimi nated. Even where ome electrical power i ued to re-circu late water over evaporative pad, electric power con umption i much le than i required for conventional mechanical air conditioning or evaporative cooling, and no fan or blower i required for air movement. Thi invention achieve lower air temperature than previ ou natural draft evaporative cooler operating under the ame condition. The need for electric power i reduced ignificantly by uing a urging valve uch a thoe commercially available from Energy Saver Mfg. and known a an "Aqua Saver'. Thi type of valve eliminate the need for a re-circulating pump ince it "guhe' or pule the required amount of water over the evaporative pad. A certain amount of water i permitted to go to wate o that caling doe not occur. Total independence from electrical requirement i obtained by uing the invention' timed puled water valve which relie upon hydraulic preure in the timing of the pule. A float valve or ballcock in a mall tank or reervoir with a variable orifice outlet i ued. The float valve control water flow to the pad ditribution ytem and to the tank containing the float. A the orifice permit the tank to drain, the float valve reache a point where the float valve open the line which both charge the evaporative cooling pad and refill the tank with wa ter. Once the tank i filled, the float valve cloe the line to the pad and the cycle repeat. The rate of flow into the tank control the length of time water flow over the pad. The rate of flow through the outlet orifice control the time the flow i turned off. Both critical timing conideration are con trolled. Exce water from the pad i collected in mall pan under the pad, and dicharged by gravity either to wate or ued for plant irrigation. In one embodiment of the invention, the float and tank are placed under the pad and the line refilling the tank i eliminated. The tank i refilled with the water flow from the pad. Thi thereby control the time water flow over the pad. With thi device, the hydraulic preure in the water line upplying the pad provide the timing meaure ment. Rather than re-circulating water over the pad, a device i ued to periodically urge water over the pad. The urge are timed o that the pad never dry com pletely and enough water i allowed to run to wate o that caling or mineral depoition doe not take place. The invention, together with variou embodiment thereof will be more fully decribed by the following drawing and their accompanying decription. DRAWINGS IN BRIEF FIG. 1a i a cutaway functional view of an embodi ment of the invention that operate without electrical power. FIG. 1b i a end view of the heat exchange tube of FIG. d. FIG. 2 i pychrometric chart illutrating the cooling capability of the preent invention. FIG. 3 i a cutaway functional view of another em bodiment of the invention. FIG. 4 i a cutaway functional view of till another embodiment of the invention.

6 3 FIG. 5 i a cutaway functional view of a valve which utilize hydraulic preure from the water ource for timing control. DRAWING IN DETAIL FIG. 1 i a cutaway view of the preferred embodi ment of the invention that operate without electrical power. The tower conit of three part: a wind catching turret 10; a heat exchanger with extended urface on both ide of the tube 17; and an evaporative cooler ection 18. Turret 10 ha inect creen on four ide and a rain tight roof. Gravity damper 11 are mounted on inclined frame inide turret 10. In the abence of wind, gravity. damper 11 are open; the preence of wind caue the winward damper to open and the leeward damper to cloe, directing air into the heat exchanger tube 17, a indicated by arrow 12B. Water from water ource 16 i electively depoited over heat exchanger 17 by flow control 13. (FIG. 1b give a cro ection view of the heat exchanger). Flow control 13 modulate the water o that heat exchanger 17 tay moitened and therefore are cooled by evapora tive cooling. The exterior of the tube contituting heat exchanger 17 are cooled by wind-driven evaporation. Exce water from heat exchanger 17 i collected and reditributed 15 by a pan at the bae of the tube and piping over evaporative cooler pad 18. In thi manner, water i depoited, in a erial manner, firt on the heat exchanger 17 and then on evaporative pad 18. Air flow from the turret, a indicated by arrow 12A and 12B, through the interior of heat exchanger tube 17, to cooler pad 18. The air i further cooled and humidified by cooler pad 18 a the air fall through tower 18, and finally into the tructure (a indicated by arrow 12E) to be air conditioned. In thi manner, the air to be cooled i pre-cooled by heat exchanger 17 without raiing the moiture content of the air. A econd cooling tep i performed by cooler pad 18 providing a greatly enhanced cooling ytem. FIG. 1b i a cro ectional view of the heat exchange tube of FIG. 1. The heat exchanger tube have longitudinal internal fin 8 with circumferential fin 9 outide. The outide fin 9 are preferrably coated with a wettable material, uch a floc, to retain water. The heat exchanger alo operate with plain tube, without fin or extended ur face. Drain lot 7 permit water to pa from one circum ferntial fin to another in an organized manner. The inide tube area hould be about four time the outide area a the outide heat tranfer coefficient are larger than thoe for the dry inide urface where the primary air flow exit. Water i ditributed over the outide of the finned tube a dicued in FIG. 1A. A portion of the water evaporate, cooling the air inide the tube without humidifying it. The heat exchanger tube permit one urface (the exterior in thi cae) to be cooled through evaporation and let the primary air (that which i ued to cool the building) to be cooled by a econd urface (the interior and fin 8 in thi example) without raiing the moiture content of the primary air tream. The proce i further illutrated on the pychometric chart of FIG. 2. 5,031, Outide air at point A, 100 degree F. dry bulb and 70 degree F. wet bulb in thi example, i cooled without humidification to point B in the heat exchanger. Air i cooled by the evaporative cooler pad to point C, or roughly 63 degree F. A ingle tage cooler tower of the prior art can pro duce air at approximately 75 degree F. The air flow through the tower i proportional to the quare root of the difference between the outide and tower tempera ture, in the windle cae. Hence, the driving force for air flow would be about 20% greater for the two tage tower. FIG. 3 i a cutaway functional view of another en bodiment of the invention. In thi embodiment, the heat exchanger 32 i a heat pipe aembly. Heat pipe are characterized by a very low longitudinal reitance to heat flow, and a wide variety of deign are commercially available. Thoe of ordinary kill in the art readily recognize variou de vice that work in thi capacity. The finned heat exchanger heat pipe 32 pa through a partition 35, dividing the exchanger into a wet ection 36 and a dry ection37. The area ratio of the dry ection 37 to wet ection 36 i ideally about four to one with the wet ide fin treated for wettability. That i, a floc or other water retaining material i preferrably placed around the heat exchange pipe 36. The pipe are wet ited by flow control 13 which i any of the common valve or urging valve known to thoe of ordinary kill in the art. Tower 30 i imilarly divided vertically into two ection by partition 35: a dry ection leading to the evaporative cooler pad 18 and the cooled tructure 31F; and a parallel ection dicharging to wate 31D. Air flow into the turret a decribed for FIG. 1 i plit into two tream. One tream 31C flow over the wetted finned heat pipe 36 and which are reduced in temperature by evaporative cooling while heat i re moved from the dry cooling ection. In another embodiment careful deign i required to aure that the temperature drop through heat ex changer 36 i ufficient to operate a an auxiliary cool tower. "Wate' air tream 31D i uually cool enough to ventilate baement, garage, or other area where great comfort i not required. Dry ection 31B operate a decribed for FIG. 1, with a reduction in temperature a air flow through the dry ection of the heat exchanger 37 and final cool ing in the evaporative cooler. A indicated by arrow 31E, air from heat exchanger 37 flow over the evaporative cooling pad 18 and gen erate cooled air flow 31F. FIG. 4 alo employ the plit tower concept, with the oil-water ytem of U.S. Pat. No. 4,532,777. In thi example packed tower are ued, which could be packed with Rachig ring, Pall Ring, or a uitable cooling tower fill, well known to thoe of ordinary kill in the art. Water and oil are pumped over packing in the heat rejecting ection 45. Utilizing air flow 41A, heat i tranferred from the oil to the water, which evaporate into the wate air tream 48C. At the bae of packing 45, the water-oil mixture i collected by pan 46A and epa rated in chamber 43. Oil from the eparator i pumped to the water free packed tower 44 which remove enible heat from the primary air tream.

7 5,031,415 5 The cooled oil in packed tower 44 aborb heat from the primary air flow. Thi exchange of heat from air to oil at packed tower 44 doe not raie the moiture level of the air permitting evaporative pad 47 to effectively cool air flow 48A generating cool air flow 48B. 5 Warmed oil i caught in pan 46B from packed tower 44 and i re-circulated to packed tower 45 to repeat the cycle. Evaporative pad 47 utilize water from the oil/water eparator 43. Exce water from evaporative pad 47 i 10 collected in pan 46C and dicharged a wate 19. FIG. 5 i a cutaway view of a valve which utilize hydraulic preure from the water ource a it timing device. A common float 51A and float valve 52 are ued in a 15 mall tank 50 having a outlet orifice 55. The flow of water from tank 50 through outlet orifice 55 i con troiled via valve 56. Water through valve 56 i di charged a wate Float valve 52 i ued to control the flow of water over the evaporative cooler pad 53A and 53B (not hown) which are decribed in FIGS. 1A, 3, and 4. Float valve 52 alo control water flow to tank 50 con taining float 51A. 25 Beginning the decription with the valve cloed and the float 51A at it highet poition a controlled by water level 58A in tank 50, valve 56 i adjuted for the water to drain lowly from tank 50. The rate at which the water drain and the volume of the tank largely 30 control the cycle duration of the aembly. When the water level drop to 58B, a point deter mined by the float valve aembly (51A and 52) and intallation, valve 52 open, allowing water from water ource 16 to: (i) flow to the pad 53A and 53B through 35 the main line; and, (ii) a much maller amount of water to flow through a econd line, through adjutable valve 54 and into tank 50, thereby raiing the water level eventually to level 58A. When tank 50 fill, float valve 52, reponding to float 51A, top flow to the pad and into tank 50, and the operating cycle i completed. The tank continue to drain and the cycle naturally repeat. Note that the rate of flow through adjutable valve 54 into tank 50 control the length of time water flow 45 over the pad. The rate of flow through the variable orifice 55 and valve 56 control the time the water flow i turned off. It i clear from the foregoing that the preent inven tion create an energy efficient cooling mechanim that 50 i capable of operating in environment that heretofore were too humid. What i claimed i: 1. A cooling tower compriing: a) a tower having, 55 1) at leat one wind opening for admiion of an ambient air flow caued by naturally occurring wind or downdraft, 2) at leat one exhaut window at the bottom, and 3) damper mean for preventing aid ambient air flow from exiting through aid at leat one wind opening; b) water upply; c) heat exchanger; d) a primary cooling ytem having mean for evapo 65 ratively cooling a firt urface of aid heat ex changer uing water from aid water upply and a firt portion of aid ambient air flow; 6 e) a firt cooling mean for cooling a econd portion of aid ambient air flow through contact with a econd urface of aid heat exchanger; and, f) a econd cooling mean for, 1) evaporatively cooling aid econd portion of aid ambient air flow from aid firt cooling mean, and, 2) exhauting aid econd portion of aid ambient air flow through aid at leat one exhaut win dow. 2. The cooling tower according to claim 1 further including mean for trapping exce water from aid primary cooling ytem and for directing aid exce water to aid econd cooling mean. 3. The cooling tower according to claim 1 wherein aid primary cooling ytem include evaporative pad in contact with aid heat exchanger. 4. The cooling tower according to claim 3 wherein aid heat exchanger include heat pipe. 5. The cooling tower according to claim 3 wherein aid heat exchanger include at leat two pipe for con duction of aid econd portion of aid ambient air flow. 6. The cooling tower according to claim 5 wherein aid at leat two pipe further include heat exchange fin on the interior thereof. 7. The cooling tower according to claim 6 wherein aid at leat one wind opening on aid tower i ubtan tially at the top of aid tower. 8. A mechanim for cooling ambient air compriing: a) a tower having, 1) an airflow path, 2) at leat one wind opening for admiion of an ambient air flow caued by naturally occurring wind or downdraft to aid airflow chamber, 3) damper mean for preventing aid ambient air flow from exiting through aid at leat one wind opening, and, 4) at leat one exhaut window for exhauting air from aid airflow chamber; b) a water upply line upplying preurized water to aid tower; c) a heat exchanger having a firt urface and a ec ond urface; d) a primary cooling ytem having mean for evapo ratively cooling the firt urface of aid heat ex changer uing water from aid water upply line and a firt portion of aid ambient air flow; e) a firt cooling mean for cooling a econd portion of aid ambient air flow through contact with the econd urface of aid heat exchanger; f) mean for capturing exce water from aid primary cooling ytem; and, g) a econd cooling mean for, 1) evaporatively cooling aid econd portion of aid ambient air flow uing water from aid mean for capturing exce water, and, 2) exhauting aid econd portion of aid ambient air flow through aid at leat one exhaut win dow. 9. The mechanim according to claim 8 wherein aid primary cooling ytem include evaporative pad in contact with aid heat exchanger. 10. The mechanim according to claim 9 wherein aid heat exchanger include heat pipe. 11. The mechanim according to claim 9 wherein aid heat exchanger include at leat two pipe for conduc tion of aid econd portion of aid ambient air flow.

8 7 12. The mechanim according to claim 11 further including mean for exhauting aid firt portion of ambient air. 13. The mechanim according to claim 12 wherein aid at leat two pipe further include heat exchange fin on the interior thereof. 14. The mechanim according to claim 9 wherein aid at leat one wind opening on aid tower i ubtantially 5,031,415 at the top of aid tower. 15. An energy efficient cooling mechanim compri- 10 ing: a) a tower having, 1) a firt airflow path, 2) a econd airflow path, 15 3) at leat one wind opening for admiion of an ambient air flow caued by naturally occurring wind or downdraft to aid firt airflow path, 4) gravity damper mean for preventing aid ambi ent air flow from exiting through aid at leat one 20 wind opening;. 5) mean for directing a firt portion of an ambient air flow through aid firt airflow path, 6) at leat one exhaut window for exhauting air from aid firt airflow path, 7) mean for directing a econd portion of the ambi ent air flow through aid econd airflow path, and, 8) at leat one exhaut window for exhauting air from aid econd airflow path; b) a water upply line upplying preurized water to aid tower; c) a heat exchanger having a firt urface and a ec ond urface, aid firt urface communicating with aid firt airflow path, aid econd urface commu nicating with aid econd airflow path; d) a primary cooling ytem having mean for evapo ratively cooling the firt urface of aid heat ex changer uing water from aid water upply line and the firt portion of aid ambient air flow; e) a firt cooling mean for cooling the econd portion of aid ambient air flow through contact with the econd urface of aid heat exchanger; f) mean for capturing exce water from aid primary cooling ytem; and, g) a econd cooling mean for, ) evaporatively cooling aid econd portion of aid ambient air flow in aid econd air flow path uing water from aid mean for capturing exce water, and, 2) exhauting aid econd portion of aid ambient The mechanim according to claim 15 wherein aid primary cooling ytem include evaporative pad in contact with aid heat exchanger. 17. The mechanim according to claim 16 wherein aid heat exchanger include heat pipe. 18. The mechanim according to claim 16 wherein aid heat exchanger include at leat two pipe for con duction of aid econd portion of aid ambient air flow. 19. The mechanim according to claim 18 further including mean for exhauting aid firt portion of ambient air. 20. The mechanim according to claim 19 wherein aid at leat two pipe further include heat exchange fin on the interior thereof. 21. The mechanim according to claim 16 wherein aid at leat one wind opening on aid tower i ubtan tially at the top of aid tower. 22. A method of cooling an air flow of ambient air compriing the tep of: a) admitting aid air flow of ambient air into a top portion of a tower; b) preventing aid ambient air flow from exiting through aid top portion of a tower; b) evaporatively cooling a firt urface of a heat ex changer uing water from a water upply and a firt portion of aid ambient air flow; c) cooling a econd portion of aid ambient air flow through contact with a econd urface of aid heat exchanger; d) evaporatively cooling aid econd portion of aid embient air flow; and, e) exhauting aid econd portion of aid ambient air flow through at leat one exhaut window located at a bottom portion of aid tower. 23. The method of cooling an air flow according to claim 22 further compriing the tep of: a) trapping exce water from aid firt urface of aid heat exchanger; and, b) directing aid exce water to a econd cooling eas k it i it