Patent Publication Number: US-10323606-B2

Title: Cyclonic air-oil separating fuel cooled oil cooler

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 62/049,911, filed Sep. 12, 2014, the contents of which are hereby incorporated in their entirety 
    
    
     FIELD OF TECHNOLOGY 
     The present disclosure pertains to an air-oil separating system, and more particularly to a cyclonic air-oil separating fuel cooled oil cooler. 
     BACKGROUND 
     It has become increasingly helpful to improve air-oil separating systems in aerospace applications. Typically, oil is used as a lubricant that is circulated throughout an engine. Oil is pumped through supply lines to the engine. The process heats the oil and as such, typically an oil cooler is used in the circuit as well to properly maintain its working temperature. 
     The process also typically results in aeration of the oil, causing the oil to take on air which can compromise the oil lubricating properties as well as the ability for the oil to transfer heat. As such the oil may remain hotter than desired, which can cause increased engine wear both due to the increased temperature and the decreased lubricating ability. 
     As such, oil in such a circuit is commonly de-aerated in a de-aeration device, and then cooled using an oil cooler. However, aerospace applications typically have weight restrictions and it is desirable to minimize the amount of overall system mass for purposes of fuel efficiency. That is, two units having separate functionality are typically included in engine applications such as in an airplane, but each typically adds weight to the system, which can negatively impact fuel efficiency. 
     Overcoming these concerns would be helpful and it is therefore an object of the present disclosure to reduce overall component mass while providing both de-aeration and cooling of oil. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       While the claims are not limited to a specific illustration, an appreciation of the various aspects is best gained through a discussion of various examples thereof. Referring now to the drawings, exemplary illustrations are shown in detail. Although the drawings represent the illustrations, the drawings are not necessarily to scale and certain features may be exaggerated to better illustrate and explain an innovative aspect of an example. Further, the exemplary illustrations described herein are not intended to be exhaustive or otherwise limiting or restricted to the precise form and configuration shown in the drawings and disclosed in the following detailed description. Exemplary illustrations are described in detail by referring to the drawings as follows: 
         FIG. 1  illustrates a de-aeration system; 
         FIG. 2  is an exemplary vehicle having a de-aeration system; 
         FIG. 3  illustrates an air-oil separating unit having a plurality of nested cyclonic separator chambers or cylinders; and 
         FIG. 4  illustrates an air-oil separating and heat exchanging unit having a corner cut-away for illustration purposes. 
     
    
    
     DETAILED DESCRIPTION 
     An exemplary vehicle includes an engine, an oil circuit for providing oil to the engine, a fuel supply line, and an air-oil separating unit. The air-oil separating unit is configured to receive aerated oil from the engine via the oil circuit, flow the aerated oil in approximately a helical direction to de-aerate the oil, receive fuel from the fuel supply line, cool the aerated oil with the fuel while the aerated oil flows in the approximately helical direction, causing the fuel to heat, and pass the cooled and de-aerated oil and pass the heated fuel to the engine. 
     More generally, an exemplary illustration includes a de-aeration system having an air-fluid separating unit that is configured to receive aerated fluid, flow the aerated fluid in approximately a helical direction to de-aerate the aerated fluid, receive a coolant, cool the aerated fluid with the coolant while the aerated fluid flows in the approximately helical direction, causing the fluid to heat, and pass the cooled and de-aerated fluid and pass the heated coolant from the air-fluid separating unit. 
     Correspondingly, a method of separating aerated fluid includes passing aerated fluid into a cyclonic air-separating heat exchanger to cause air to separate from the aerated fluid into a first stream of air and a second stream of de-aerated fluid, and passing a coolant into a jacket that surrounds the cyclonic air-separating heat exchanger, wherein the coolant is at a temperature that is lower than the aerated fluid, causing the coolant to warm and the fluid to cool while passing through the cyclonic air-separating heat exchanger. 
     Referring now to the Figures,  FIG. 1  illustrates a de-aeration system  100 . System  100  includes an air-fluid separating unit  102 . Air-fluid separating unit  102  is coupled to a hot aerated fluid supply  104 , and a cool fluid supply  106  (hot and cold are defined relative to one another in this context). Air-fluid separating unit  102  is configured to receive aerated fluid  108 , and also to receive a coolant  110  from cool fluid supply  106 . Within air-fluid separating unit  102  is a cyclonic separation chamber that flows aerated fluid from hot aerated fluid supply  104  to air-fluid separating unit  102 , causing air to separate from the aerated fluid and flow in an air stream that is separate from the outflowing/de-aerated fluid. 
     According to the principles of cyclonic separation, air is removed from aerated fluid though the use of vortex separation. Rotational effects and gravity are used to separate the air from the aerated fluid. A high speed rotating and helical flow, or approximately helical flow, is established within the cyclonic separation chamber. The inertia of the aerated fluid causes the fluid to cyclonically rotate against the outer surface of the cyclonic separation chamber. The aerated fluid includes air (that is desired to be removed) that, due to its much lower density, tends toward the center of the cyclone where it can collect. Also, due to the density difference between the fluid and the air and due to gravity, the fluid tends to descend while the air tends to ascend, causing the air to separate from the aerated fluid. As such, the fluid that descends is de-aerated and the buoyant effect of the air within the fluid causes the air to ascend. 
     Returning to  FIG. 1 , air-fluid separating unit  102  is also a heat exchanger that exchanges heat between the received hot aerated fluid  108  and the received coolant  110 . Thus, not only does de-aeration occur within air-fluid separating unit  102  due to cyclonic separation, but the heat exchange between the hot aerated fluid  108  and the received coolant  110  causes the aerated fluid to cool (during de-aeration) and causing the coolant to warm. As such, relatively warmed coolant exits  112  after the de-aeration process, and cooled de-aerated fluid exits after the cooling process. That is, the hot aerated fluid  104  passes into air-fluid separating unit  102  and is caused to flow in approximately a helical direction to de-aerate the aerated fluid. The air-fluid separating unit  102  receives coolant  106 , and the aerated fluid is cooled with the coolant while the aerated fluid flows in the approximately helical direction, causing the fluid to heat during de-aeration. The cooled and de-aerated fluid and the heated coolant are passed from the air-fluid separating unit  102 . Air  116  passes out the top of air-fluid separating unit  102 . 
     In one example, air may be considered a waste by-product that is simply ejected from the system. However, in another example, instead of being considered a waste by-product, air  116  may be productively used, for instance, to balance system scavenge pump flowing air. In another example, an air-oil mix may be used for lubrication of, for instance, a high speed bearing system. Or, because of the heat removal during the heat exchange with the coolant, the air may be used as a cooling mist on high temperature components in a system. That is, the air itself may be saturated with mist of oil that can act as a convection heat transfer medium that, when impinged upon a warm or hot surface, may be caused to vaporize, causing very high convection coefficients. 
     In another example, fluid condition monitoring may be implemented with a condition monitor  118 . Fluid condition monitoring, in one example, is where a qualitative measurement of debris and particle contaminants in the fluid can be done once the air has been removed. Such methods may include using magnetic chip detection or a conductive/capacitive filter mesh. Conditioning can be in the form of filtration as a loop to an output of de-aerated fluid  114  with pressure differential over a media for contamination monitoring with differential pressure sensors. Monitoring of heat transfer can be done in condition monitor  118  and used to monitor heat transfer efficiency. Further, the air may be measured as it relates to the de-aerated fluid  114  for an expected amount of pump cavitation in a known volume sump system or potential failure or impending failure of a scavenge pump system. Additionally, condition monitor  118  may monitor debris of the de-aerated fluid  114 . Or, heat rejection may be determined by condition monitor  118  based on the temperature of the warmed coolant  112  with respect to inlet temperature of the hot aerated fluid  104  and the cool coolant  106 , to monitor for impending failure of a system where heat is generated by friction in the aerated fluid, and particle separation may trigger a monitor of the system. 
     Referring to  FIG. 2 , an exemplary vehicle  200 , such as an aircraft, includes an engine  202 , and an oil circuit  204  for providing oil to engine  202 . Thus, in one example, engine  202  is a gas turbine engine for an aircraft. A liquid fuel supply  206  provides the relatively cool fuel to an air-separating heat exchanger  208  via a fuel supply line  210 . Air-separating heat exchanger  208  is configured to receive aerated oil from the engine via the oil circuit, flow the aerated oil in approximately a helical direction and according to the principles of cyclonic separation. Heat exchange between the fuel and the hot aerated oil causes the fuel to warm and the oil to cool. As such, warm fuel passes along a first port or fuel supply line  212  to engine  202 , and warm and de-aerated oil passes along a second port or oil supply line  214  to engine  202 . That is, the hot aerated oil and the cool fuel supply flow into air-separating heat exchanger  208 , de-aeration occurs, warmed fuel and cooled (i.e., warm as opposed to hot) oil pass to engine  202 . Air is removed  216  and may be waste air, or may be used for other purposes as a by-product, as described. 
     Fuel from fuel supply  206  may include moisture that may negatively impact combustion performance within engine  202 . Further, if the fuel is cold enough, the moisture contained within fuel may be frozen if the fuel is below the freezing point of water (i.e., 0° C. at ambient pressure). As such, it is typically desirable to heat the fuel at least above the melt point of water to eliminate any ice that may have formed therein, as well as to improve combustion thermodynamic efficiency. In one example, the fuel is raised 40° C. in temperature to above the melt point of water. 
     Referring to  FIG. 3 , an air-oil separating unit  300  includes a plurality of nested cyclonic separator chambers or cylinders  302 . Air-oil separating unit  300  includes an air-out chamber  304 , an oil-in chamber  306 , an oil-out chamber  308 , and a fuel jacket pass-through chamber  310 . According to the principles described, aerated oil flows into oil-in chamber  306 , is caused to flow in approximately a helical direction  312 , during which time de-aeration occurs. Air flows upward and into air-out chamber  304 , and de-aerated oil flows downward to oil out chamber  308 . Fuel also flows into fuel jacket pass-through chamber  310 , causing the fuel to warm and the oil to cool during de-aeration. Thus, as shown, air-oil separating unit  300  includes a plurality of nested cylinders  302 , each of which comprises a cyclonic separation chamber that flows the aerated oil in the approximately helical direction. A cooling jacket  311  is external to each cyclonic separation chamber that receives the fuel from a fuel supply line, and passes the heated fuel to an engine. 
     Referring to  FIG. 4 , an air-oil separating and heat exchanging unit  400  is shown having a corner cut-away  402 , to illustrate internal features of one of one of the nested cyclonic separation chambers or cylinders  404 , as described in  FIG. 3 . The illustrated cylinder  404  includes an air-out orifice  406 , and a labyrinthine de-aerated oil-out port  408 . That is, the cyclonic air-separating heat exchanger  400  includes a plurality of nested cylinders that includes passing different streams of the aerated fluid into each of the plurality of nested cylinders to cause the air to separate, and passing the coolant into the jacket that surrounds each of the plurality of nested cylinders. 
     The disclosed system is not limited to an aerospace or aircraft fuel cooled oil cooler and oil de-aerator. In one example, such as a helicopter application, aerated engine oil may be de-aerated, but instead of using a liquid fuel as a coolant, blast air may be used, or ram or induced bleed air may be used from an engine compressor. 
     Other applications may include a marine gas turbine or diesel engine where the coolant is cooling water, instead of fuel, and aerated engine oil is de-aerated. Another example may include an agricultural or industrial diesel engine where the coolant is engine coolant, and the engine oil is de-aerated. Another example may include industrial process equipment where the process requires a de-aeration of a fluid, and heat can be removed by a coolant or by a counter flow of warmed fluid that exits from the air-separating heat exchanger, which allows heating of a process fluid. Another example may include agricultural application of chemicals that have a tendency to foam or aerate when pumped, and could thus be reduced to a de-aerated flow while heating or cooling the process with inlet coolant or a counter-flow from another source of engine oil or coolant. Another example may be to prevent ventilation or cavitation of a pump when de-aerated fluid is used at an inlet of a pump system, and the system needs heat added to the fluid counter-flow by exiting fluid or removed by a coolant. 
     As such, this disclosure combines two separate units into one unit, providing both functions of de-aeration and heat exchange in a single process. That is, an air separator is combined with a liquid-liquid heat exchanger. The design uses a plurality of small cyclone separator cylinders to separate air and oil, while the cylinders are jacketed by fuel flow to exchange heat to the fuel. More generally, the disclosed device and method applies to any two liquids where one aerated liquid is de-aerated and the heat is exchanged to the other liquid. 
     With regard to the processes, systems, methods, heuristics, etc. described herein, it should be understood that, although the steps of such processes, etc. have been described as occurring according to a certain ordered sequence, such processes could be practiced with the described steps performed in an order other than the order described herein. It further should be understood that certain steps could be performed simultaneously, that other steps could be added, or that certain steps described herein could be omitted. In other words, the descriptions of processes herein are provided for the purpose of illustrating certain embodiments, and should in no way be construed so as to limit the claims. 
     All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those knowledgeable in the technologies described herein unless an explicit indication to the contrary is made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.