Abstract:
A device for cooling a gas is provided. The device comprises an inlet having a first diameter, a mixing section downstream of the inlet and having a second diameter, and an opening in fluid communication with the mixing section and a source of air. The device is such that the second diameter is smaller than the first diameter and a vacuum is created for drawing in the air from the opening as gas passes from the inlet to the mixing section so that the air drawn into the mixing section mixes with the gas. A method for mixing two gases and an exhaust system are also provided.

Description:
TECHNICAL FIELD 
   The present disclosure relates generally to a cooling device and, more particularly, to an exhaust gas cooling device within the exhaust stream of an engine. 
   BACKGROUND 
   Internal and external combustion engines produce exhaust gases that may reach very high temperatures. These temperatures may be high enough to pose a safety hazard to any personnel present near the engine&#39;s exhaust outlet-to-atmosphere. 
   To correct this problem, some engine manufacturers use exhaust pipes of sufficient length to cool the exhaust gas before it enters the environment. Unfortunately, some exhaust temperatures are too high and require additional cooling solutions. 
   Today, many engines are equipped with catalytic converters and particulate filters in the exhaust system that may further increase the exhaust outlet-to-atmosphere temperatures. For example, particulate filters may be configured to collect unburned hydrocarbons—or soot—from the engine&#39;s exhaust. Periodically, the filter regenerates, which causes these collected hydrocarbons to undergo an exothermic reaction and burn. This exothermic reaction may result in a large release of thermal energy, thereby further increasing the exhaust-to-outlet temperature. 
   U.S. Pat. No. 3,875,745 to Franklin (“&#39;745”) discloses a device utilizing the Coanda effect to introduce exhaust gas around a lip on one end of a venturi tube, causing the exhaust gas to flow in a high velocity film adherent to the inner surface of the tube. The laminar flow of &#39;745 draws in a large volume flow of air through the center of the venturi, cooling 1000° F. exhaust gas down to almost ambient temperature in a distance of a few inches. 
   The device of &#39;745, however, may not be suitable for many applications. For example, according to &#39;745, “For effective operation, the gases must pass through catalytic converter at a temperature not lower than 1000° F.” Further, the device of &#39;745 may result in a prohibitively high exhaust back-pressure, thereby detrimentally affecting the engine&#39;s Brake Specific Fuel Consumption. Even further, the device of &#39;745 may be expensive to manufacture, making its cost prohibitively expensive. 
   The disclosed exhaust-gas cooling device is directed to overcoming one or more of the problems set forth above. 
   SUMMARY 
   In one embodiment of the present disclosure, a device for cooling a gas is provided. The device comprises an inlet having a first diameter, a mixing section downstream of the inlet and having a second diameter, and an opening in fluid communication with the mixing section and a source of air. In this embodiment, the second diameter is smaller than the first diameter and a vacuum is created for drawing in the air from the opening as gas passes from the inlet to the mixing section so that the air drawn into the mixing section mixes with the gas. 
   In another embodiment of the present disclosure, a method of cooling an exhaust gas of an engine is provided. The method comprises providing a venturi for receiving exhaust gas, drawing in aspirated air at a throat of the venturi, and cooling the exhaust gas by mixing the exhaust gas with the aspirated air. 
   In even another embodiment of the present disclosure, a method for mixing two gases is provided. The method comprises providing a first gas, providing a second gas, passing the first gas through a converging nozzle, creating a vacuum as the first gas passes through the converging nozzle, drawing in the second gas with the vacuum, and mixing the first gas with the second gas. 
   In yet another embodiment of the present disclosure, an exhaust system of an engine is provided. The exhaust system comprises an exhaust pipe comprising high pressure exhaust gas, a venturi tube positioned within the exhaust pipe for receiving the exhaust gas, and an opening within a throat of the venturi tube. In this particular embodiment, aspirated air is drawn in the throat of the venturi tube and mixes with the exhaust gas. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagrammatic illustration of an engine having an exhaust cooling device according to an exemplary embodiment of the present disclosure; and 
       FIG. 2  is a cross-sectional view of a particular exhaust cooling device; 
       FIG. 3  is a cross-sectional view of another particular exhaust cooling device; 
       FIG. 4  is a cross-sectional view of yet another particular exhaust cooling device; 
       FIG. 5  is a cross-sectional view of even yet another particular exhaust cooling device; and 
       FIG. 6  is a cross-sectional view of another particular exhaust cooling device. 
   

   DETAILED DESCRIPTION 
     FIG. 1  illustrates an engine  10  with a cooling device  100  according to an exemplary embodiment of the present disclosure. 
   In this particular embodiment, engine  10  has intake manifold  11  and exhaust manifold  12 . Intake air enters intake manifold  11  to facilitate the combustion within engine  10 . Exhaust gas  120 —shown in FIGS.  2 - 6 —from the combustion process then enters exhaust manifold  12 . 
   The oftentimes high-temperature and high-pressure exhaust  120  may then be used to drive a high-pressure turbocharger  20 . In this case, exhaust gas  120  drives turbine  21  to impart rotational energy to compressor wheel  22 . Compressor wheel  22  is connected to turbine  21  via a common shaft. As the high-pressure exhaust  120  drives turbine  21 , the rotational energy imparted on compressor  22  helps pressurize intake air prior to entering intake manifold  11 . 
   In some embodiments, it may be desirable to add a second turbocharger  30 . Low-pressure turbocharger  30 , like turbocharger  20 , may have a turbine  31  and compressor  32  for further pressurizing intake air. 
   In the particular embodiment of  FIG. 1 , once exhaust gas  120  exits turbine  31 , exhaust gas  120  enters particulate filter  51 . In this embodiment, a regeneration device  50  is positioned upstream of filter  51 . Regeneration device may be, for example, a burner configured to generate heat for regenerating filter  51 . 
   As exhaust gas  120  enters filter  51 , soot, ash, and/or any other particulate material may be deposited within filter  51 . Periodically, it may be desirable to regenerate filter  51  in order to burn any collected hydrocarbons—soot. In this particular embodiment, the regeneration may be initiated by regeneration device  50 . Device  50  may be configured to generate heat to begin the regeneration of filter  51 . During the regeneration of filter  51 , an exothermic reaction occurs as the soot burns, resulting in very high temperatures. These temperatures may even exit filter  51  at or above 650° C. 
   After exhaust gas  120  exits filter  51 , some exhaust gas  120  may enter gas induction line  60 . In this particular embodiment, cooler  61  may then cool the exhaust gas  120  that enters line  60 . Cooler  61  may be any type of heat exchanger that is known in the art, such as a parallel-flow heat exchanger that uses engine  10  jacket water (not shown) as a cooling sink. 
   In this particular embodiment, once exhaust gas  120  exits cooler  61 , control valve  62  may be actuated for regulating the amount of exhaust gas  120  that mixes with ambient air  70 . Control valve  62  permits for a controlled mixing of recirculated exhaust gas  120  with ambient air  70  prior to entering compressors  32  and  22  of turbochargers  30  and  20 , respectively. 
   After the pressurized mixture of ambient air  70  and recirculated exhaust gas  120  leaves compressor  22 , it may then be cooled in cooler  75 . Cooler  75  may be any known heat exchanger known in the art. In one particular embodiment, cooler  75  is an air-cooled air cooler. 
   In some embodiments, as the one depicted in  FIG. 1 , crankcase air from engine  10  block may be vented. In this particular embodiment, crankcase ventilation exits engine  10  block via line  40 , where it is sent to the engine&#39;s  10  exhaust line. In other embodiments, which are not shown, the crankcase ventilation may be vented to atmosphere and it may further be filtered to remove any particulates. 
   For the particular embodiment of  FIG. 1 , exhaust gas  120  that is not recirculated via loop  60  enters exhaust line  90 . As stated, exhaust gas  120  entering line  90  may be high. For example, during regeneration of filter  51 , the exhaust temperature may be in excess of 650° C. To help minimize the risk of hazard to personnel and equipment, cooling device  100  cools exhaust  120  before exhaust  120  enters environment  80 . 
   Referring to  FIGS. 2-6 , various embodiments of exhaust gas  120  cooling device  100  are depicted. In particular,  FIGS. 2-6  depict cross-sectional views of various cooling devices  100 . In these various embodiments, exhaust gas  120  enters device  100  from the left, the inlet, and exits to the right. Air  101  enters device  100  and mixes with exhaust gas  120 . In most cases, air  101  entering device  100  is much cooler than exhaust gas  120  and the mixture  125  of air  101  and exhaust gas  120  results in a cool blend. In many cases, the mixture  125  exiting device  100  is sufficiently cooled for safe release to environment  80 . 
   Referring to the particular embodiment of  FIG. 2 , as gas  120  enters device  100 , the converging shape of device  100  from the inlet to the middle section—or throat—results in an increase in velocity of gas  120  from left to right. As the velocity of gas  120  increases, an associated pressure drop results. This associated pressure drop is well understood by one skilled in the art as Bernoulli&#39;s principle. The resultant pressure drop creates a slight vacuum in device  100 . As the pressure within device  100  is slightly lower than atmospheric pressure, aspirated air  101  is drawn into device  100  from opening  124 . The drawn in aspirated air  101  mixes and dilutes with exhaust gas  120  downstream of opening  124 , resulting in a mixture  125  with a cooler overall temperature. 
   Now referring to  FIG. 3 , another embodiment of cooling device  100  is provided. The operation of device  100  in  FIG. 3  is similar to the operation of device  100  in  FIG. 2 , in that the converging shape of device  100  and opening  124  allow for the mixing of exhaust gas  120  with aspirated air  101 . 
   In the embodiment of  FIG. 3 , however, perforations  121  are present to promote mixture of aspirated air  101  with exhaust gas  120 . In this particular embodiment, some of the exhaust gas  120  and aspirated air  101  mixture  125  may exit cooling device via perforations  121 . In some cases, additional aspirated air  101  may enter perforations  121  to further mix and dilute exhaust gas  120 . 
   Now referring to  FIG. 4 , another embodiment of cooling device  100  is provided. The operation of device  100  in  FIG. 4  is similar to the operation of device  100  in  FIG. 3 , in that the converging shape of device  100 , opening  124 , and perforations  121  allow for the mixing of exhaust gas  120  with aspirated air  101 . 
   In the embodiment of  FIG. 4 , however, cooling fins  122  are present for promoting the transfer of heat from cooling device  100  to the outside atmosphere. Cooling fins  122  are connected to device  100  and project outward from device  100 , as shown. The cooling fins  122  conduct heat from device  100  and, through convection, transfer heat to the surrounding environment. 
   Now referring to  FIG. 5 , another embodiment of cooling device  100  is provided. The operation of opening  124  and perforations  121  is similar to the operation of  FIGS. 3 and 4  for mixing exhaust gas  120  with aspirated air  101 . 
   In the embodiment of  FIG. 5 , however, cooling fins  123  are present for promoting the transfer of heat from exhaust gas  120  to cooling device  100 . Cooling fins  123  are connected to device  100  and project inward from device  100 , as shown. Through convection, exhaust gas  120  transfers heat to cooling fins  123 , which in turn transfer heat to device  100  through conduction. 
   Now referring to  FIG. 6 , another embodiment of cooling device  100  is provided. In this particular embodiment—as with the others of FIGS.  2 - 5 —exhaust gas  120  enters device  100  from the left. Unlike the venturi-shape of devices  100  in embodiments of  FIGS. 2-5 , however, the middle-throat section of device  100  in  FIG. 6  does not diverge from the throat to the outlet. As the passage of device  100  converges, the velocity of gas  120  increases, thus creating a pressure drop. A slight vacuum is created and draws aspirated air  101  into device  100 , where it mixes with exhaust gas  120 . The resultant mixture  125  of exhaust gas  120  and air  101  then exits device  100  to the right. 
   INDUSTRIAL APPLICABILITY 
   Referring back to  FIG. 1 , in operation, cooling device  100  cools at least some of the exhaust gas  120  exiting engine  10  before it is released to environment  80 . 
   During operation of engine  10 , exhaust gas  120  may or may not pass through one or two turbochargers  20  and  30 . Afterwards, exhaust gas  120  may or may not then pass through particulate filter  51 . 
   Particulate filter  51  may be configured to collect particulate matter from exhaust gas  120 , such as soot or hydrocarbons. Once filter  51  collects any soot or hydrocarbons, filter  51  may regenerate to burn at least some of the filtered soot or hydrocarbons. 
   In the embodiment of  FIG. 1 , regeneration may be initiated with the addition of thermal energy from regeneration device  50 . In at least one example, device  50  may be a burner configured to direct heat to filter  51 , thus causing soot or hydrocarbons to burn within filter  51 . As depicted, burner  50  may be positioned upstream of filter  51 . This burn results in the release of thermal energy, which may further increase the temperature of exhaust gas  120 . In some cases, the temperature of exhaust gas during regeneration may be as high as 650° C. or higher. 
   Some, all, or none of exhaust gas  120  may then enter recirculation line  60 , where it would be mixed with ambient air from intake  70 . Some of this exhaust gas may also be cooled prior to mixing with cooler  61 . In at least one example, cooler  61  may be a jacket-water cooled parallel-flow heat exchanger. The reader should appreciate, however, that any heat exchanger known in the art may be used to cool exhaust gas  120  within line  60 . The reader should also appreciate that a cooler  61  is also not necessary. 
   For the exhaust gas  120  that is not mixed with intake air  70 , the gas  120  enters cooling device  100 , where some or all of the gas  120  may be cooled to a level safe for discharge to environment  80 . 
   Referring to  FIGS. 2-6 , as exhaust gas  120  enters device  100  from the left, a vacuum is created as the velocity of the gas  120  increases with the converging passageway. This increase in velocity results in a corresponding pressure drop, which creates a vacuum within device  100 . The vacuum then draws in aspirated air  100  through opening  124 . 
   As aspirated air  101  mixes with exhaust gas  120 , the temperature of exhaust gas  120  most often drops, as the temperature of air  101  is usually lower than the temperature of exhaust gas  120 . The resultant mixture  125  then leaves device  100  from the right, as shown, towards environment  80 . 
   Other embodiments of the disclosed exhaust treatment system  10  will be apparent to those skilled in the art from consideration of the specification. It is intended that the specification and examples be considered as exemplary only, with the true scope of the invention being indicated by the following claims.