Abstract:
A heat exchange apparatus is provided with an indirect evaporative heat exchange section. An evaporative liquid is passed downwardly onto the indirect heat exchange section. The evaporative liquid is collected in a sump and then pumped upwardly to be distributed again across the indirect heat exchange section. 
     An improved heat exchange apparatus is provided with two indirect evaporative heat exchange sections separated by a vertical distance. A direct evaporative heat exchange section may be provided in the vertical spacing between the two indirect evaporative heat exchange sections.

Description:
[0001]    This application is a division of pending U.S. application Ser. No. 13/833,971, filed Mar. 15, 2013. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates generally to an improved heat exchange apparatus such as a closed circuit fluid cooler, fluid heater, condenser, evaporator, thermal storage system, air cooler or air heater. More specifically, the present invention relates to a combination or combinations of separate indirect and direct evaporative heat exchange sections or components arranged to achieve improved capacity and performance. 
         [0003]    The invention includes the use of a coil type heat exchanger as an indirect heat exchange section. Such indirect heat exchange section can be 
         [0004]    combined with a direct heat exchange section, which usually is comprised of a fill section over which an evaporative liquid such as water is transferred, usually in a downwardly flowing operation. Such combined indirect heat exchange section and direct heat exchange section together provide improved performance as an overall heat exchange apparatus such as a closed circuit fluid cooler, fluid heater, condenser, evaporator, air cooler or air heater. 
         [0005]    Part of the improved performance of the indirect heat exchange section comprising a coil type heat exchanger is the capability of the indirect heat exchange section to provide both sensible and latent heat exchange with the evaporative liquid which is streamed or otherwise transported downwardly over and through the indirect heat exchange section. Such indirect heat exchangers are usually comprised of a series of serpentine tube runs with each tube run providing a circuit of a coil. Improved performance of such indirect heat exchangers is achieved by opening the spacing between the generally horizontal tube runs in one or more of the serpentine coil return bends. Such opened spacing in the serpentine coil return bends creates a more efficient cooling zone for the evaporative liquid flowing downwardly over the serpentine coils. 
         [0006]    Various combinations of the heat exchange arrangements are possible in accordance with the present invention. Such arrangements could include an arrangement having an indirect heat exchange section with increased vertical spacing in the series of serpentine tube runs formed by increased height return bends. In such an arrangement, an evaporative liquid flows downwardly onto and through the indirect heat exchange section with such evaporative liquid, which is usually water, then exiting the indirect section to be collected in a sump and then pumped upwardly to again be distributed downwardly over the indirect heat exchange section. In this counterflow arrangement, embodiments work more efficiently with generally lower spray flow rates, in the order of 2-4 GPM/sq.ft. In other arrangements presented, the design spray flow rates may be higher. 
         [0007]    In another arrangement, a combined heat exchange apparatus is provided with an indirect heat exchange section comprised of serpentine tube runs over which and evaporative liquid is distributed downwardly onto and through the indirect heat exchange section. Such indirect heat exchange section is comprised of serpentine tube runs having an increased spacing between one or more return bends of increased height. Further, a direct heat exchange section comprised of fill can be located in one or more of the areas of increased vertical spacing formed by the return bends of the serpentine coil. In this arrangement, the embodiments work more efficiently with generally lower spray flow rates, in the order of 2-4 GPM/sq.ft. So not only are the embodiments presented within more efficient providing increased heat rejection but they also do it with less energy requirement for the spray water pump. In other arrangements presented, the design spray flow rates may be higher. 
         [0008]    Further, it is also part of the present invention to provide a second, intermediate spray water distribution arrangement whereby the evaporative liquid is distributed downwardly over the indirect and, if present, the direct heat exchange sections, at a point below the top of the indirect heat exchange section For this arrangement, there are several different modes of operation which further improve the heat transfer capabilities and customer benefits. In one mode of operation, both the top and intermediate spray sections are active and spray water onto the indirect and direct sections is present. In another mode of operation, the intermediate spray section is not active and the top spray arrangement provides the evaporative liquid to the entire assembly. In yet another mode of operation, the top spray section is not active and the intermediate spray section is active which can provide evaporative cooling for the lower coil section while providing dry sensible cooling for the dry upper coil section. In yet another mode of operation, the top spray section is not active, the intermediate spray section is active, there is selectively no heat transfer from the lower coil section beneath the intermediate spray section allowing the upwardly flowing air to become adiabatically saturated through the direct section if present before transferring sensible heat with the top portion of the coil above the intermediate spray section. This last mode of operation further reduces the amount of water use while providing lower temperature air to provide sensible cooling to the top portion of the coil above the intermediate spray arrangement. 
         [0009]    The heat exchanger apparatus or fluid cooler of the present invention could be operated wherein both air and an evaporative liquid such as water are drawn or supplied across both the indirect and direct heat exchange section if present. It may be desirable to operate the heat exchanger without a supply of the evaporative liquid, wherein air only would be drawn across the indirect heat exchange section and across a direct section if present. It is also possible to operate a combined heat exchanger in accordance with the present invention wherein only evaporative liquid would be supplied across or downwardly through the indirect heat exchange section and the direct heat exchange section if present, and wherein air would not be drawn by typical means such as a fan. 
         [0010]    In the operation of an indirect heat exchange section, a fluid stream passing through the serpentine coils is cooled, heated, condensed, or evaporated in either or both a sensible heat exchange operation and a latent heat exchange operation by passing an evaporative liquid such as water together with air over the serpentine coils of the indirect heat exchange section. Such combined heat exchange results in a more efficient operation of the indirect heat exchange section, as does the presence of the increased spacing formed in one or more of the return bends of the serpentine tube runs of the indirect heat exchange section. Further efficiency in operation can also be achieved by the provision of a second or intermediate spray distribution system for providing evaporative liquid to flow downwardly onto and through the serpentine coils of the indirect heat exchange section. The evaporative liquid, which again is usually water, which passes generally downwardly through the indirect heat exchange section and generally downwardly through the direct heat exchange section which is typically a fill assembly, if such a direct heat exchange section is provided in the increased vertical spacing in one or more of the increased height return bends of the serpentine coils of the indirect heat exchange section. Heat in the evaporative liquid is passed to air which is drawn generally passing downwardly or upwardly through the indirect heat exchange section and outwardly from the closed circuit fluid cooler or heat exchanger assembly by an air moving system such as a fan. The evaporative liquid draining from the indirect or direct heat exchange section is typically collected in a sump and then pumped upwardly for redistribution across the indirect or direct evaporative heat exchange section. 
         [0011]    The type of fan system whether induced or forced draft, belt drive, gear drive or direct drive can be used with all embodiments presented. The type of fan whether axial, centrifugal or other can be used with all embodiments presented. The type of tubes, material of tubes, tube diameters, tube shape, whether finned or un-finned, the number of tube passes, number of return bends, number of increased vertical spaces, can be used with all embodiments presented. Further, the coil may consist of tubes or may be a plate fin type or may be any type of plates in any material which can be used with all embodiments presented within. The type of fill, whether efficient counterflow fill, contaminated water application fills or any material fill can be used with all embodiments presented. 
         [0012]    Accordingly, it is an object of the present invention to provide an improved heat exchange apparatus, which could be a closed circuit fluid cooler, fluid heater, condenser, evaporator, air cooler or air heater, which includes an indirect heat exchange section with increased spacing formed in one or more return bends of the serpentine tube forming the indirect heat exchange section. 
         [0013]    It is another object of the present invention to provide an improved heat exchange apparatus such as a closed circuit fluid cooler, fluid heater, condenser, evaporator, air cooler or air heater, including an indirect heat exchange section that comprises a series of serpentine tube runs with increased vertical spacing between one or more of the tube runs and with a direct heat exchange located in one or more of the areas of increased vertical spacing. 
         [0014]    It is another object of the invention to provide an improved heat exchange apparatus comprising an indirect heat exchange section comprised of serpentine coils with both a primary evaporative liquid distribution system at or near the top of the serpentine coils and a secondary evaporative liquid distribution system located below the top of the serpentine coils. Further the primary and secondary evaporative liquid distribution systems may be selectively operated such that water may be preserved. 
         [0015]    It is another object of the present invention to provide an improved evaporative heat exchange apparatus such as a closed circuit fluid cooler, fluid heater, condenser, evaporator, air cooler or air heater, including at least two indirect heat exchange sections that comprise a series of serpentine tube runs with increased vertical spacing between one or more tube runs and with a direct heat exchange located in one or more of the areas of increased vertical spacing between tube runs. 
         [0016]    It is another object of the present invention to provide an improved evaporative heat exchange apparatus such as a closed circuit fluid cooler, fluid heater, condenser, evaporator, air cooler or air heater, including at least two indirect heat exchange sections separated by an increased vertical spacing with an optional direct heat exchange located in the increased vertical space between indirect heat exchange sections. 
         [0017]    It is another object of the present invention to provide an improved evaporative heat exchange apparatus such as a closed circuit fluid cooler, fluid heater, condenser, evaporator, air cooler or air heater, where direct heat exchange sections located in one or more of the areas of increased vertical spacing between tube runs or alternatively located between increased vertical space between indirect heat exchange sections are easily accessible and replaceable for serviceability. 
       SUMMARY OF THE INVENTION 
       [0018]    The present invention provides an improved heat exchange apparatus which typically is comprised of an indirect heat exchange section. The indirect heat exchange section provides improved performance by utilizing a serpentine coil arrangement comprised of tube run sections and return bends, with a means of increasing the distance between one or more of the tube runs of the serpentine coils. One way to accomplish this vertical separation between the generally horizontal or sloped tube runs is by increasing one or more of the return bend radius in the return bends of the serpentine tube runs in the serpentine coil. Another way to accomplish this vertical separation between generally horizontal or sloped tube runs is to install a purposeful vertical spacing between two or more serpentine coils or other indirect heat exchange sections such as plate heat exchangers. The tube run sections of the serpentine coil arrangement may be generally horizontal and can be slanted downwardly from the inlet end of the coils toward the outlet end of the coils to improve flow of the fluid stream there through. Such serpentine coils are designed to allow a fluid stream to be passed there through, exposing the fluid stream indirectly to air or an evaporative liquid such as water, or a combination of air and an evaporative liquid, to provide both sensible and latent heat exchange from the outside surfaces of the serpentine coils of the indirect heat exchanger. Such utilization of an indirect heat exchanger in the closed circuit fluid cooler, fluid heater, condenser, evaporator, air cooler or air heater of the present invention provides improved performance and also allows for combined operation or alternative operation wherein only air or only an evaporative liquid or a combination of the two can be passed through or across the outside of the serpentine coils of the indirect heat exchanger. 
         [0019]    A direct heat exchange section or sections can be located generally within the indirect heat exchange section in the vertical spacing between the increased height return bends of the generally horizontal tube runs of the serpentine coil. Accordingly, the evaporative liquid is allowed to pass across and through the indirect and direct sections comprising the heat exchange section. Heat is drawn from such evaporative liquid by a passage of air across or through the indirect and direct heat exchange sections by air moving apparatus such as a fan. Such evaporative liquid is collected in a sump in the bottom of closed circuit fluid cooler, fluid heater, condenser, evaporator, air cooler or air heater and pumped back for distribution, usually downwardly, across or through the indirect heat exchange section. Further a secondary evaporative liquid distribution system may located below the top of the indirect serpentine coils within the indirect heat exchange section or between two indirect sections in the vertical spacing and selectively operated with the primary evaporative liquid distribution system such that water may be conserved. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    In the drawings, 
           [0021]      FIG. 1  is a side view of a prior art indirect heat exchanger including a series of serpentine tube runs; 
           [0022]      FIG. 2  is a side view of a prior art indirect heat exchanger serpentine coil; 
           [0023]      FIG. 3  is a side view of a first embodiment of an indirect heat exchanger with a series of serpentine slanted tube runs in accordance with the present invention; 
           [0024]      FIG. 4  is a side view of a second embodiment of an indirect heat exchanger with a series of serpentine tube runs in accordance with the present invention; 
           [0025]      FIG. 5  is a side view of a third embodiment of an indirect heat exchanger with secondary evaporative liquid distribution in accordance with the present invention; 
           [0026]      FIG. 6  is a side view of a fourth embodiment of an indirect heat exchanger with direct heat exchange sections in accordance with the present invention; 
           [0027]      FIG. 7  is a perspective view of the fourth embodiment of a closed circuit cooling tower with an indirect heat exchange section with direct heat exchange sections in accordance with the present invention; 
           [0028]      FIG. 8  is a side view of a fifth embodiment of two indirect heat exchanger sections with five direct heat exchange sections in accordance with the present invention; 
           [0029]      FIG. 9  is a side view of a sixth embodiment of two indirect heat exchangers with one direct heat exchange section in accordance with the present invention; 
           [0030]      FIG. 10  is an end view of a seventh embodiment of two indirect heat exchangers with direct heat exchange sections in accordance with the present invention; 
           [0031]      FIG. 11  is a side view of an eighth embodiment of two indirect heat exchangers with direct heat exchange sections and with secondary evaporative liquid distribution in accordance with the present invention; 
           [0032]      FIG. 12  is a side view of a ninth embodiment to two plate style indirect heat exchangers with two direct heat exchange sections in accordance with the present invention; 
           [0033]      FIG. 13  is a chart of performance of heat exchangers constructed in accordance with the present invention. 
           [0034]      FIG. 14  is a end view of an embodiment of an indirect heat exchanger with direct heat exchange sections in accordance with the present invention; 
           [0035]      FIG. 15  is an end view of plate style indirect heat exchangers with direct heat exchange sections in accordance with the present invention; 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0036]    Referring now to  FIG. 1 , a prior art evaporatively cooled coil product  10  which could be a closed circuit cooling tower or an evaporative condenser. Both of these products are well known and can operate wet in the evaporative mode or can operate dry, with the spray pump  12  turned off when ambient conditions or lower loads permit. Pump  12  receives the coldest cooled evaporatively sprayed fluid, usually water, from cold water sump  11  and pumps it to spray water header  19  where the water comes out of nozzles or orifices  17  to distribute water over coil  14 . Spray water header  19  and nozzles  17  serve to evenly distribute the water over the top of the coil(s)  14 . As the coldest water is distributed over the top of coil  14 , motor  21  spins fan  22  which induces or pulls ambient air in through inlet louvers  13 , up through coil  14 , then through drift eliminators  20  which serve to prevent drift from leaving the unit, and then the warmed air is blown to the environment. The air generally flowing in a counterflow direction to the falling spray water. Although  FIG. 1  and all following Figures are shown with axial fan  22  inducing or pulling air through the unit, the actual fan system may be any style fan system that moves air through the unit including but not limited to induced and forced draft. Additionally, motor  21  may be belt drive as shown, gear drive or directly connected to the fan. It should be understood that in all the embodiments presented, there are many circuits in parallel with tube runs but only the outside circuit is shown for clarity. Coil  14  is shown with an inlet header  15  and outlet header  16  which connects to all the serpentine tubes having normal height return bend sections  18 . It should be further understood that the number of circuits within a serpentine coil is not a limitation to embodiments presented. 
         [0037]    Referring now to  FIG. 2 , prior art coil  30  has inlet and outlet headers  37  and  31  respectively, is supported by coil clips  32  and  38  with center support  41 . There are two circuits coming out of the inlet header shown as generally horizontal tube runs  39  and  40 . Coil  30  is built with short radius or normal return bends  36  with a small slope to allow for proper drainage. In some prior art coils, this slope of the generally horizontal tube runs can vary with the last set of tube runs on the bottom having more slope. The spacing  35  between tube runs on the left side can be seen as nearly zero and accordingly allows very little interaction between the falling spray water and generally counter flowing air before the spray water hits the next set of tube runs. Similarly, the larger space  33  and  34  between generally horizontal tube runs is seen as little larger but still there is insufficient interaction between the falling spray water and generally counter flowing air before the spray water hits the next set of tube runs compared to the embodiments presented within. In addition, there is not enough room in gaps  33 ,  34  or  35  to install a direct heat exchange section such as counterflow fill or to install an intermediate spray system to further increase the spray water cooling such as the embodiments presented within. 
         [0038]    Referring to  FIG. 3 , a cooling tower in accordance with the first embodiment of the invention is shown at  70  with the coolest spray water being pumped from cold water sump  71  by pump  72  to spray header arrangement  79  with nozzles or orifices  78  to uniformly distribute water over coil  75 . Motor  81  operates fan  82  to induce air first through inlet louvers  73 , generally upwards through coil  75  then through eliminators  80  then dispelling it to the environment. First embodiment coil  75  has an alternating combination of tight return bends  76  and wide radius return bend  83  in serpentine coil  75 . The substantially wide return bend  83  forms a spray water cooling zone  74  where the spray water is additionally cooled by the up flowing air before it contacts the next set of tube runs having tight or normal return bends  76 . In this embodiment, coil  75  has four sets of three tight or normal return bend radius rows  76  separated by three intentionally large return bends  83  forming three large spray water cooling zones  74  within coil assembly  75 . Coil  75  is shown with inlet header  77  and outlet header  84  which connects to all the serpentine tubes. It should noted in this and all other embodiments that the inlet header  77  and outlet header  84  may be reversed depending on the particular application and is not a limitation of the invention. The first embodiment is shown with the generally horizontal tube runs having a slight pitch or slope from one end to the other to allow the coils to drain better and aids condensers so the liquid condensate can drain easier. It should be noted that for the sake of simplicity, all further embodiments are shown without tube pitch but it must be understood that tubes may be sloped or not. The first embodiment shows twelve generally horizontal tube runs or as commonly called passes however, other embodiments can employ any number of tube runs or passes and is not a limitation of the invention. Once the spray water leaves the bottom of coil  75  there is additional spray water cooling before the spray water cascades down to cold water basin  71 . Substantial space  74  between tight return bend tube rows  76  allows the spray water droplets to be cooled by the counter-flowing air before picking up more heat from next set of tube runs. The height of spray water cooling zone  74  should be at least one inch. Users in the art will recognize that the number of tube run or passes, number of spray water cooling zones  74 , and the height of the spray water cooling zone  74  can be optimized to achieve desired performance and overall height of embodiment  70 . Further the tubes may be of any diameter or shape and are not a limitation of the invention. 
         [0039]    Referring now to  FIG. 4 , a cooling tower in accordance with a second embodiment  130  is shown. The components in second embodiment  130  including cold water basin  131 , pump  132 , inlet louvers  133 , spray arrangement  140  nozzles or orifices  139 , inlet header  138 , outlet header  144 , drift eliminators  141 , motor  142  and fan  143  are shown as identical and function the same as that presented in the first embodiment. Coil  134  in the second embodiment has been changed to illustrate the variation that users in the art may take to optimize performance and height. In coil  134 , there are still twelve generally horizontal tube runs as in the first embodiment but coil  134  now has six sets of two, tight or normal return bend  137 , tube runs separated by five large spray water cooling zones  136  formed by large return bends  135 . It should be noted that the tube runs in coil  134  are shown as horizontal for clarity but can be sloped or slanted as shown in the first embodiment. In this and all future embodiments, the generally horizontal tube runs are shown as horizontal for clarity yet they may be slanted or sloped. The second embodiment shows a variation on the first embodiment and it should be noted that the number of tube runs between large spray water cooling zones, the number of large spray water cooling zones, number of total tube runs, the height of large spray water cooling zone can all be varied to optimize performance and unit height. 
         [0040]    Referring to  FIG. 5 , a cooling tower in accordance with third embodiment is shown at  180 . The components in third embodiment  180  including cold water basin  181 , pump  182 , inlet louvers  183 , primary spray arrangement  194 , nozzles or orifices  192 , inlet header  191 , outlet header  198 , drift eliminators  195 , motor  196  and fan  197  all function the same as that presented in the first embodiment. Coil  189  has normal height return bends  190  and increased height return bends  184 A. Within large spray water cooling zone  184 , third embodiment  180  also contains secondary or intermediate spray header  187  with nozzles or orifices  185  to evenly spray coil  189  with additional spray water, drift eliminators  188 , and selectively operated valves  193  and  186 . It should be noted that instead of valves  193  and  186 , two spray pumps may be used to accomplish the same desired modes of operation. It should also be noted that the two shown large spray water cooling zones  184  formed by large return bends  184 A may also have a direct section if desired. There are four main modes of operation with embodiment 3. The first mode of operation is with spray pump  182  on, with valves  186  and  193  open, water is sprayed over the top of coil  189  and also within coil  189 . The spray flow variation and larger total spray flow on the bottom section of coil  189  causes unit  180  to operate more efficiently. During mode one, the fan can operate at any speed desired or can be off. For the second mode of operation, valve  193  can be closed allowing only spray water to flow over the bottom section of coil  189 . In this hybrid mode, the bottom part of coil  189  operates in the evaporatively cooled mode while the top section of coil  189  above drift eliminators  188  operates dry. This mode of operation can serve to save water and also abate plume if desired. During mode two, the fan can operate at any speed desired or can be off. The third mode of operation can by turning spray pump  182  off such that only sensible cooling of coil  189  is accomplished. 
         [0041]    Referring now to  FIG. 6 , a cooling tower in accordance with a fourth embodiment is shown at  210 . The components in fourth embodiment  210  including cold water basin  211 , pump  212 , inlet louvers  213 , spray arrangement  221 , nozzles or orifices  220 , inlet header  219 , outlet header  225 , drift eliminators  222 , motor  223  and fan  224  function the same as that presented in the first embodiment. Note there are alternating tight or normal return bends  218  and then larger return bends  217  forming large spray water cooling zone  214  in coil  216 . In this preferred embodiment, there is at least one direct heat exchange section. Direct heat exchange section  215  can be counterflow fill which is installed inside the large spray water cooling zone  214 . Direct section  215  increases the efficiency of the cooling of the spray water within the large spray water cooling section  214 . In this embodiment, there are repeating sets of four tube runs or passes with tight radius or normal return bends  218  following each by three large radius bends  217  forming three large spray water cooling zones  214  to exist within the confines of the coil. In this case, up to three direct sections can be used if desired and as shown. The efficiency gained in further cooling the spray water between the tubes  214  far exceeded the loss of airflow from the added direct sections or fill decks  215  to apparatus  210 . The type of direct section can be counterflow fill, contaminated water fill or any substrate that increases the surface area of the spray water within the large spray water cooling zone. In coil  216 , there are still twelve generally horizontal tube runs as in the first embodiment but coil  216  now has four sets of three tight return bend  218  tube runs separated by three large spray water cooling zones  214 . It should be noted that the tube runs in coil  216  are shown as horizontal for clarity but can be sloped or slanted as shown in the first embodiment. It should be noted that the number of tube runs between large spray water cooling zones, the number of large spray water cooling zones, number of total tube runs, the height of large spray water cooling zone can all be varied to optimize performance and unit height. Further it should be noted that one may use any means for supporting the direct sections within the large spray water cooling zones in indirect coil  216  within spray water cooling zone  214 . One such support means would be to rest the direct section  215  onto indirect tube runs in coil  216 . Another such method would be for the direct section to be placed on top of small rods that are installed on the tube runs of indirect section  216  such that the direct section does not directly come in contact with the indirect section. Another such method would be for the direct section to be supported from a frame structure such that the direct section does note direct come in contact with the indirect section. 
         [0042]      FIG. 7  is a perspective view of a cooling tower  280  in accordance with the fourth embodiment. More specifically, the cutaway views show that direct sections  285  may be easily removed for cleaning and replacement by opening or removing panels  284 . Removal of panels  284  allows access to clean indirect heat exchanger  283  as well. It should be noted that panels  284  could be connected to selectively partially open during operation to act as fresh air inlets. In embodiment  280 , indirect coil  283  is shown with panels  284  removed for clarity where the large spray water cooling zones are located. A means for supporting the direct sections within the large spray water cooling zones in indirect coil  283  can be the direct section  285  resting on the indirect section, or sitting on small rods that are installed on top of indirect section  283  or any means to hang the direct section without it touching the indirect section if desired. The means to install the direct section within the large spray cooling zone is not a limitation. Spray water inlet  287  serves to distribute the spray water uniformly to the top of coil  283 . Air inlet  282  is shown without the inlet louvers installed so the inside of cold water basin  281  can be seen. Coil inlet  286  and outlet  289  are shown for connection for the incoming fluid to be cooled or condensed. Fan shaft  288 , is connected to the fan and motor (shown) and the fan system pulls air though the air inlet  282  through indirect coil  283  and direct sections  285  through the drift eliminators (not shown) and then generally upwards to the environment. 
         [0043]    Referring now to  FIG. 8 , a cooling tower in accordance with a fifth embodiment is shown at  250 . The components in the fifth embodiment  250  including cold water basin  251 , pump  252 , inlet louvers  253 , spray arrangement  265 , nozzles or orifices  264 , inlet header  263 , outlet header  275 , drift eliminators  266 , motor  267  and fan  268  function the same as that presented in the first embodiment. Fifth embodiment  250  utilizes at least two separate coils  261  and  256 . Coil  261  has inlet and outlet headers  263  and  275  respectively while coil  256  has inlet and outlet headers  258  and  276  respectively. Coil  261  and coil  256  may be piped in a series or in a parallel arrangement as desired. Coil  261  and coil  256  are shown with three sets of two tube runs with tight return bend  262  and  257  and both with two large spray water cooling zones  260  and  255  formed by large return bends  260 A and  255 A, respectively. It should be noted that coils  261  and  256  are separated by a large spray water cooling zone  272  and this zone has optionally a direct heat exchanger  270  installed within it. It should be understood that in all large spray water cooling zones  260 ,  272  and  255 , users in the art may have empty space, an intermediate spray arrangement or direct heat exchange  259 ,  270  and  254  respectively installed as shown. It should be understood that the main feature in embodiment  250  is that it utilizes more than one coil compared to prior embodiments which may be used for further optimization and manufacturing reasons. 
         [0044]    Referring now to  FIG. 9 , a cooling tower in accordance with sixth embodiment is shown at  300 . The components in the sixth embodiment including cold water basin  301 , pump  302 , inlet louvers  303 , spray arrangement  312 , nozzles or orifices  311 , eliminators  313 , motor  314  and fan  315  function the same as that presented in the first embodiment. Sixth embodiment  300  also utilizes at least two separate indirect heat exchange coils shown as  308  and  304  having inlet headers  310  and  306 , respectively and outlet headers  317  and  318 , respectively. Coil  308  and coil  304  may be piped in a series or in a parallel arrangement or even with different fluids as is well known in the art. Coil  308  and coil  304  are shown with six sets of two tube runs with tight or normal return bends  309  and  305  respectively and both coils do not have within them a large spray water cooling zone. However coils  308  and  304  are separated by a large spray water cooling zone  316  and this zone has optionally a direct heat exchanger  307  installed within it. It should be understood that in all large spray water cooling zones  316  may have empty space for extra spray water cooling, an intermediate spray arrangement or direct heat exchange installed shown as  307 . Both embodiments  250  and  300  have at least two indirect heat exchangers. It should be understood that embodiment  250  utilizes more than one indirect heat exchanger or coil and that each coil has large spray water cooling zone within the coil while embodiment  300  has at least two indirect heat exchangers with no large spray water zones within the coil but the vertical separation between coils forms the large spray water cooling zone. It should be noted that any number of tube runs per coil section can be used, any number indirect coil sections may be used and any height of spray water cooling zone between the indirect section coils can be used is not a limitation to the invention. One of the coils shown in embodiment  300  can also be made with large spray water cooling zones within the coils. 
         [0045]    Referring now to  FIG. 10 , a cooling tower in accordance with seventh embodiment is presented at  330 . This embodiment has all the same features as previous Figures describe but it should be noted that the embodiment has been rotated to show divider wall  332  and pump  333  and  343  more clearly. In this embodiment, there are substantially wide return bends  346  forming a spray water cooling zone  347  where the spray water is additionally cooled by the generally up-flowing air before it contacts the next set of tube runs having tight or normal return bends  345 . In this embodiment there are four sets of three tight return bend radius rows  345  separated by three intentionally large return bends  346  forming three large spray water cooling zones  338  within coil assemblies  336  and  345 . In this water savings embodiment, left coil  335  and right coil  344  can be bare tubes of any tube diameter or any tube shape, be spirally finned, plate finned or be plate coils. Coils  335  and  344  may be both operated wet as having pumps  333  and  343  both on, or one coil may be operated wet and one operated dry by having for example pump  333  on and pump  343  off, or both coil  335  and  344  can be operated dry by having pump  333  and  343  off. Note that wall  332  keeps water and air from migrating from side to side during operation. It should be noted that the number of sets of tight bend radius rows and large radius bends forming the spray water cooling zones is not a limitation of the invention. 
         [0046]    Referring now to  FIG. 11 , a cooling tower in accordance with an eighth embodiment is shown at  390 . The components in the eighth embodiment including cold water basin  391 , pump  392 , inlet louvers  393 , top spray arrangement  410 , nozzles or orifices  408 , inlet header  407 , outlet header  416 , drift eliminators  411 , motor  412  and fan  413  function the same as that presented in the first embodiment. Eighth embodiment  390  contains two indirect heat exchange sections. The top indirect section  405  has inlet out outlet headers  407  and  416  respectively, extended surface area fins  415 , and can be seen with tight or normal return bends  406  and also large radius return bends  403  which form large spray water cooling zone  404 . It should be noted that the two shown large spray water cooling zones  404  in top coil  405  may also have a direct section such as  394  installed if desired. The bottom indirect section  396  has inlet and outlet headers  398  and  417  respectively, and also tight or normal return bends  397  and large return bends forming large spray water cooling zone  395 . Eighth embodiment  390  also contains secondary or intermediate spray header  401  with nozzles or orifices  399  to evenly spray coil  396  with spray water, drift eliminators  402 , and selectively operated valves  409  and  400 . It should be noted that instead of valves  409  and  400 , two spray pumps may be used to accomplish the same desired modes of operation. In this eighth hybrid embodiment, there are five modes of operation. The first mode of operation is with spray pump  392  on, with valves  409  and  400  both open water is sprayed over the top of coil  405  and also onto coil  396 . During mode one, the fan can operate at any speed desired or can be off. For the second mode of operation, pump  392  is on and valve  409  is open and valve  400  is closed. This allows less spray pump energy to be consumed and slightly less unit capacity when desired. During mode two, the fan can operate at any speed desired or can be off. For the third mode of operation, valve  409  is closed and valve is open allowing only spray water to flow over the bottom indirect coil  396 . In this hybrid mode, the bottom coil  396  operates in the evaporatively cooled mode while the top coil  405  above drift eliminators  402  operates dry. This mode of operation can serve to save water, abate plume or be used to desuperheat if desired. During mode three, the fan can operate at any speed desired or can be off. In a fourth mode of operation, valve  409  is closed and valve  400  is again open allowing only spray water to flow over the bottom coil  396  but this time the heat transfer to coil  396  is turned off such that there is no heat transfer between the tube runs in coil  396  and the spray water. Now the spray water along with direct section  394  operate to adiabatically cool the air that entered inlet louvers  393  to have the dry bulb temperature of the air approach the wet bulb temperature of the air. In this way, the operating top coil section  405  can operate in a sensible dry cooling mode while consuming much less water. During mode four, the fan can operate at any speed desired or can be off. The fifth mode of operation is with spray pump  392  off and the unit operates in the dry mode to sensibly cool the indirect heat exchangers  405  and  396 . 
         [0047]    Referring now to  FIG. 12 , a closed circuit cooling tower or condenser in accordance with ninth embodiment is shown at  470 . The components in the ninth embodiment including cold water basin  471 , pump  472 , inlet louvers  473 , inlet header  477 , outlet header  476 , top spray arrangement  482 , nozzles or orifices  481 , drift eliminators  483 , motor  484  and fan  485  function the same as that presented in the first embodiment. Ninth embodiment  470  utilizes at least two separate indirect heat exchange plate style heat exchangers shown as  487  and  488 . Plate coil  487  and plate coil  488  may be piped in a series or in a parallel arrangement as is well known in the art. Plate coil  487  has inlet and outlet headers  477  and  476  respectively while plate coil  488  has inlet and outlet headers  490  and  491  respectively. Plate coil  487  and  488  are each shown with approximately forty eight sets of parallel plates  480  or cassettes where there are internal passages where the heat transfer fluid to be cooled or condensed travels and also external open channels between the sealed plates where the evaporative fluid, usually water flows generally downward and the air flow generally flows in a counter flow upwards motion. Plate coil heat exchangers  487  and  488  are separated by a large spray water cooling zone  479  and this zone has optionally a direct heat exchanger  478  installed within it. Below plate coil  488  another large spray water cooling zone  475  exists and has optionally a direct heat exchange section  474  within it. It should be understood that in all large spray water cooling zones  479  and  475  may have empty space for extra spray water cooling, an intermediate spray arrangement or direct heat exchange installed. It should be understood that plate coils  487  and  488  do not have large spray water cooling zones within them but the plate coils are separated by large spray water cooling zones. It should be noted that any number of plates, style of plates, material of plates, size of plates, pattern of the plates and height of the plates can be used and is not a limitation of the invention. It should also be noted that any height of spray water cooling zones greater than one inch can exist and are not limitations of the invention. 
         [0048]      FIG. 13  is a chart showing data from the prior art unit shown in  FIG. 1  and the improved heat exchanger in the fourth embodiment employing indirect and direct sections. Specifically, the process fluid is represented in both prior art and the fourth embodiment by the top solid line (curve PF TempTest) showing the closed circuit cooling tower cooled the internal indirect coil fluid, in this case water, from 100 F to 88 F. It should be noted that in the prior art coil test, the top dotted line shows the spray water temperature at the top and bottom of the coil to be approximately 86 F while the maximum spray water temperature reached is approximately 91 F. However, note that with forth embodiment test data of the spray water temperature represented by the squiggly solid line, the spray water temperature at the top and bottom of the indirect coil section was 84 F and the maximum spray water temperature was 93 F. The improvement of the large spray water cooling zones can be seen as the spray water temperatures are both cooler displaying the ability to absorb more heat from the indirect tube runs yet overall the spray temperature was cooler as noted by the squiggly lines. The bottom two lines are the entering and leaving wet bulb temperatures. The bottom dotted line is from the prior art coil test showing the wet bulb entered at 78 F and left the unit at 89 F. The bottom solid line shows the wet bulb entering and leaving temperatures from test data from the fourth embodiment. Note that again the wet bulb entering temperature was 78 F yet the leaving wet bulb is higher than the prior art data leaving at 94 F. This increase in leaving wet bulb temperature shows the increased performance at identical operating test unit power draw (motors from both tests were both at 30 HP). In the fourth embodiment test data, because the spray water temperature profile is pushed up and the air wet bulb line (WB_Coil&amp;Fill) is also pushed up, this allows air to have a larger enthalpy increase. So by adding direct sections to a prior art indirect coil only product, the efficiency gain from having large spray water cooling zones between the tube runs can be seen to be much more beneficial than a slight loss in airflow caused by adding the direct sections. With fill decks sandwiched between coil tubes, the efficiency of heat rejection is increased as the spray water picks up more sensible heat and transfers it to air in both latent and sensible fashions. 
         [0049]    Referring now to  FIG. 14 , a cooling tower in accordance with a tenth embodiment is shown at  500 . In this embodiment fan motor  510  operates fan  514  to pull air through air inlet  503  then through direct heat exchanger  502  which serves to further cool spray water leaving indirect section  508 . Spray water is pumped (pump not shown) from cold water basin  501  up through spray header pipe  513  making it through the spray header to be uniformly sprayed from nozzles or orifices  512  onto indirect heat exchanger  508 . The heated spray water then makes it way from the indirect coil section with optional direct fill installed in the large spray water cooling zones to re-spray tray  505  which catches all the spray water and redistributes it uniformly from nozzle or orifices  504  to the direct fill section  502 . Fan motor  516  runs fan  517  to induce air generally upwards through air opening  506 , up through indirect section  508 , through drift eliminators  515  and then is blown to the environment. The air inlet to the indirect section  508  may be of any height, may be one, two, or three sides and may have air blowing generally downward and is not a limitation of the invention. Indirect coil  508  is constructed with tight or normal return bends  509  then with larger return bends to create large spray water cooling zones as in the other embodiments. In this case, direct fill sections  507  are installed in the large spray water cooling zones to increase the efficiency of the heat transfer within the indirect coil section before the spray water leaves the indirect section to be further cooled in the direct section below it  502 . Indirect heat exchanger coil header  511  may be inlet or outlet depending on the fluid to be used and is not a limitation of the invention. It is important to note that the tenth embodiment has exactly the indirect coil and direct fill sections within that coil from the fourth embodiment installed into a different style unit to show variations of how users in the art may employ this technology. 
         [0050]    Referring now to  FIG. 15 , a cooling tower in accordance with the eleventh embodiment is shown at  530 . In this embodiment fan motor  540  operates fan  542  to pull air through air inlet louvers  533  then through direct heat exchanger  532  which serves to further cool spray water leaving indirect section  548 . Air also enters the top of indirect section  548  at  549 , travels generally downwards through indirect section  548  then through drift eliminators  536  and out of fan  542 . Spray water is pumped (pump not shown) from cold water basin  531  up through spray header  543  into spray header  547  to be uniformly sprayed from nozzles or orifices  541  onto indirect heat exchanger  548 . Indirect heat exchanger  548  is constructed with the plate coils  535  as presented in the ninth embodiment but can also be of the form presented in the tenth embodiment and is not a limitation of the invention. In this embodiment, there are at least two indirect heat exchanges separated by a large vertical water cooling zone  538  and direct fill section  539  is installed in the large spray water cooling zones to increase the efficiency of the heat transfer within the indirect coil section before the spray water leaves the indirect section to be further cooled in the direct section below it  532 . Indirect heat exchanger coil headers  537  and  534  and indirect heat exchanger coil headers  545  and  546  may be piped in series or parallel and the inlet and outlets may be in any position that fits the application and is not a limitation of the invention. It is important to note that the eleventh embodiment has the indirect plate coil and direct fill sections from the ninth embodiment installed without the optional direct section installed beneath the bottom indirect plate coil section into a different style unit to show variations of how users in the art may employ this technology.