Patent Publication Number: US-2018051946-A1

Title: Heat exchanger arrangements and related methods

Description:
FEDERAL RESEARCH STATEMENT 
     This invention was made with government support under United States Navy Contract No. N00019-02-C-3003. The government has certain rights in the invention. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to thermal management, and more particularly to thermal management of fluid flows in vehicles like aircraft. 
     2. Description of Related Art 
     Vehicles such as aircraft commonly have electrical systems with electrical devices that generate heat during operation. In some electrical systems heat generation can be such that cooling is necessary. Cooling in such electrical systems is generally by provided by flowing a coolant flow to heat generating components, transferring heat to the coolant, and thereafter flowing the heated coolant to the external environment, where the heat is dissipated into the ambient environment. 
     With the advent of ‘more electric’ aircraft increasingly large amounts of heat from electrical devices and electrical systems require movement within the aircraft. One approach to moving heat within such aircraft is by moving coolant through the aircraft airframe between heat generating devices and the ambient environment. In this respect the ambient environment serves as an infinite heat sink into which waste heat from heat generating electrical devices can be dissipated. 
     Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved thermal management systems. The present disclosure provides a solution for this need. 
     SUMMARY OF THE INVENTION 
     A heat exchanger arrangement includes a heat exchange body, a first fluid path extending through the heat exchange body, and a second fluid path extending through the heat exchange body in thermal communication with the first fluid path and fluidly isolated from the first fluid path. A bypass path is arranged externally of the heat exchange body and is fluidly connected in parallel with the first fluid path. A control module is operably connected to the bypass path to control temperature of fluids traversing the first fluid path and the second fluid path. 
     In certain embodiments, the first bypass path can include a bypass valve disposed along the fluid path. The control module can be operatively connected to the bypass valve. A temperature sensor can be in thermal communication with the fluid path and downstream of the heat exchange body. The control module can be connected to the temperature sensor. The bypass path can be a first fluid path, and a second bypass path can be arranged external of the heat exchange body and fluidly connected in parallel with the second fluid path. 
     In accordance with certain embodiments, the bypass valve can be a first bypass valve and a second bypass valve can be disposed along the second fluid path. The control module can be operatively connected to the second bypass valve. A temperature sensor can be in thermal communication with the second fluid path. The temperature sensor can be disposed downstream of the heat exchange body. The control module can be connected to the temperature sensor. 
     It is also contemplated that, in accordance with certain embodiments, either or both the first fluid path and the second fluid path can be in fluid communication with a lubrication circuit of a gas turbine engine, a fuel circuit of a gas turbine engine, or a bleed air passage of a gas turbine engine compressor section, The control module can be configured to execute instructions recorded on a non-transitory machine-readable medium to flow a first fluid through a heat exchange body, flow a second fluid through the heat exchange body, and transfer heat between the first fluid flow and the second fluid flow. The instructions can also cause the control module to drive temperature of the first fluid flow to a predetermined temperature by throttling flow of the first fluid through the heat exchanger. The instructions can further cause the control module to drive temperature of the second fluid flow to a predetermined temperature by throttling flow of the second fluid through the heat exchanger. 
     A thermal management system includes a heat exchanger arrangement as described above, a first bypass valve disposed along the first bypass path, and a second bypass valve disposed along the second bypass path. A first temperature sensor is in thermal communication with the first fluid path downstream of the heat exchange body and a second temperature sensor in thermal communication with the second fluid path downstream of the heat exchange body. The control module is communicative with the first and second temperature sensors, and is operatively connected to the first and second bypass valves to access thermal margin of the fluid flows when either or both of the flows is below the respective fluid temperature limit. 
     A thermal management method includes flowing a first fluid through a heat exchange body, flowing a second fluid through the heat exchange body, and transferring heat between the first fluid flow and the second fluid flow. Temperature of the first fluid flow is driven to a predetermined temperature by throttling flow of the first fluid through the heat exchanger. Temperature of the second fluid flow is driven to a predetermined temperature by throttling flow of the second fluid through the heat exchanger. 
     These and other features of the systems and methods of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, embodiments thereof will be described in detail herein below with reference to certain figures, wherein: 
         FIG. 1  is a schematic view of an exemplary embodiment of thermal management system constructed in accordance with the present disclosure, showing an aircraft having a gas turbine engine in thermal communication with the thermal management system; 
         FIG. 2  is a schematic view of an exemplary embodiment of the thermal management system of  FIG. 1 , showing a heat exchanger arrangement in thermal communication with first and second flow paths for transferring heat between the first and second flow paths using a flow bypass path; 
         FIG. 3  is a schematic view of another embodiment of the thermal management system of  FIG. 1 , showing a heat exchanger arrangement in thermal communication with first and second flow paths for transferring heat between the first and second flow paths using first and second flow bypass paths; and 
         FIG. 4  is a chart of a thermal management method, showing steps for accessing thermal margin in a first fluid system using a second fluid system. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of a heat exchanger arrangement in accordance with the disclosure is shown in  FIG. 1  and is designated generally by reference character  102 . Other embodiments of heat exchanger arrangements, thermal management systems, and thermal management methods in accordance with the disclosure, or aspects thereof, are provided in  FIGS. 2-4 , as will be described. The systems and methods described herein can be used for managing heat flow in gas turbine engine fluid flows in aircraft, though the present disclosure is not limited to gas turbine engines or to aircraft in general. 
     Referring to  FIG. 1 , a vehicle, e,g., aircraft  10 , is shown. Aircraft  10  includes an electrical load  12 , a thermal management system  100 , a gas turbine engine  14  interconnected by a fluid system  16 . Gas turbine engine  14  includes a compressor section  18  coupled to a turbine section  20  by a shaft  22 , a fuel system  24 , a lubrication system  26 , and a bleed air system  8 . Electrical system  12  includes one or more heat generating component, e.g., avionics, environmental control devices, motor controllers, power converters, etc, Thermal management system  100  includes heat exchanger arrangement  102 , which is in thermal communication with two or more of fuel system  24 , lubrication system  26 , and bleed air system  28 . Electrical system  12  is also in thermal communication with one or more of fuel system  24 , lubrication system  26 , and bleed air system  28 . 
     With reference to  FIG. 2 , thermal management system  100  is shown. Thermal management system  100  includes heat exchanger arrangement  102 , a first fluid system  104 , and a second fluid system  106 . First fluid system  104  has a temperature target  108 , which may be selectable, and second fluid system  106  has thermal margin  110 , either or both of which may be a function of the operating regime of aircraft  10  (shown in  FIG. 1 ). First fluid system  104  and second fluid system  106  are in thermal communication with one another through heat exchanger arrangement  102 , heat thereby moving between first fluid system  104  and second fluid system  106 . It is contemplated that first fluid system  104  and/or second fluid system  106  can be in fluid communication with a fuel system, e.g., fuel system  24  (shown in  FIG. 1 ), a lubrication system, e.g., lubrication system  26  (shown in  FIG. 1 ), and/or a bleed air system, e.g., bleed air system  28  (shown in  FIG. 1 ). 
     Heat exchanger arrangement  102  is a unidirectional heat exchanger arrangement and includes a heat exchange body  116 , a first fluid path  118  extending through heat exchange body  116 , and a second fluid path  120  extending through heat exchange body  116 . First fluid path  118  is in thermal communication with the second fluid path  120  within heat exchange body  116  and is fluidly isolated from first fluid path  118 . A bypass path  122  is disposed externally to heat exchange body  116  and is fluidly connected in parallel with first fluid path  118 . As will be appreciated by those of skill in the art in view of the present disclosure, fluid traversing bypass path  122  bypasses heat exchange body  116 , thereby reducing (or eliminating) heat transfer between a portion of fluid traversing first fluid path  118  and second fluid path  120 . 
     Heat exchanger arrangement  102  also includes a control module  124 , a bypass valve  126 , and a temperature sensor  128 , which in the illustrated exemplary embodiment are disposed outside (i.e. externally) of heat exchange body  116 . Temperature sensor  128  is arranged along first fluid path  118  to acquire temperature information corresponding to the temperature of fluid downstream of heat exchange body  116 . Temperature sensor  128  is also arranged downstream of a location there fluid traversing bypass path  122  rejoins first fluid path  118 . 
     Bypass valve  126  is disposed along bypass path  122  and is arranged for throttling fluid traversing bypass path  122 , In this respect bypass valve  122  apportions fluid flow received from first fluid system  104  between bypass path  122  and heat exchange body  116 . As will be appreciated by those of skill in the art in view of the present disclosure, throttling fluid flow through bypass path  122  influences thermal communication between first fluid path  118  and second fluid path  120 . 
     Control module  124  is operatively connected to bypass valve  126  and is communicative with temperature sensor  128  through a link  130 . As illustrated in  FIG. 2 , link  130  is a communication bus, As will be appreciated by those of skill in the art, operative connection to bypass valve  126  and communication with temperature sensor  128  may be through discrete conductors, wireless devices, or optical devices, as suitable for a given application, 
     Control module  124  modulates the amount of heat transferred between first fluid path  118  and second fluid path  120 . In particular, control module  124  determines the temperature of fluid A traversing first fluid path  118  at a location downstream of heat exchange body  116 , and compares the determined temperature with a selectable temperature target  108 . Based on the comparison of the determined (i.e. actual) temperature, control module  124  throttles, i.e. increases or decreases, the proportion of fluid A flowing through bypass path  122  in relation. to the proportion of fluid A flowing through heat exchange body  116  from first fluid path  118 , thereby modulating temperature by throttling flow of fluid A through heat exchange body  116 . 
     Decreasing the proportion of fluid A flowing through heat exchange body  116  reduces the transfer of heat between fluid A and fluid B through heat exchange body  116 . This increases the temperature of fluid A returning to first fluid system  104 —which can be advantageous when fluid A is below temperature target  108 . Thus, if there is thermal margin in first fluid system  104 , margin meaning that additional waste heat can be temporarily stored in fluid A, increasing the fluid flow through bypass path  122  allows for utilization of thermal margin  110  of second fluid system  106  by first fluid system  104 . In systems where the cold side fluid, e.g., fluid B, otherwise requires a supplemental heat sink to maintain operation at its limit (such as a fuel recirculation system back to aircraft tank), making thermal margin  110  margin available in the cold side accessible to the hot side reduces or eliminates the need to recirculate the cold side fluid to a supplemental heat sink. In certain embodiments, it is contemplated that no supplemental heat sink is required for second fluid system  106 . 
     With reference to  FIG. 3 , a thermal management system  200  is shown. Thermal management system  200  is similar to thermal management system  100  and additionally a bidirectional heat exchanger arrangement  202 , a second bypass path  232 , a second bypass valve  234 , and a second temperature sensor  236 . Bidirectional heat exchanger arrangement  202  is configured to transfer heat between first fluid path  218  and second fluid path  220  in either direction. In this respect heat can flow from first fluid path  218  to second fluid path when temperature of fluid A is greater than that of fluid B. Heat can also flow from second fluid path  220  to first fluid path  218  when temperature of fluid B is greater than that of fluid A. 
     Second bypass path  232  is similar to first bypass path  222  with the difference that second bypass path  232  is arranged fluidly in parallel with a portion of second fluid  218  extending through heat exchange body  216 . In this respect second bypass path  222  is disposed externally to heat exchange body  216 , and is arranged to receive fluid from second fluid system  206  at a location upstream of heat exchange body  216  and to return the received fluid to second fluid path  220  at union disposed downstream of heat exchange body  216 . As will be appreciated by those of skill in the art in view of the present disclosure, fluid traversing second bypass path  232  bypasses heat exchange body  216 , reducing (or eliminating) heat transfer between portions of fluid A and fluid B traversing first fluid path  218  and second fluid path  220  through heat exchange body  216 . 
     Second bypass valve  234  is disposed along second bypass path  222  and is arranged for throttling fluid traversing second bypass path  222 . In this respect bypass valve  226  apportions fluid flow received from second fluid system  206  between bypass path  222  and a portion of second fluid path  220  extending through heat exchange body  216 . As will be appreciated by those of skill in the art in view of the present disclosure, throttling fluid flow through bypass path  222  influences (e.g., increase or decrease) thermal communication between second fluid path  220  and first fluid path  218 . 
     Second temperature sensor  236  is arranged along second fluid path  220  at a location downstream of heat exchange body  216  and the union of second bypass path  222  with second fluid path  220 , In this respect second temperature sensor  236  is configured to acquire temperature information of fluid B as fluid B returns to second fluid system  206 . 
     Control module  224  is operatively connected to by link  230  to both first bypass valve  226  and second bypass valve  234 . Control module  224  is also communicative with both first temperature sensor  228  and second temperature sensor  236 . Being communicative with both first temperature sensor  228  and second temperature sensor  236 , and further operatively connected to both first bypass valve  226  and second bypass valve  234 , control module  224  is arranged to determine temperatures of both fluid A and fluid B at locations downstream of heat exchange body  116  and compare the determined temperatures to selectable temperature targets for fluid A and fluid B (e.g., first temperature target  208  and second temperature target  238 ). Based on the comparison, control module  224  throttles either (or both) of portions of fluid A and fluid B traversing first bypass path  222  and second bypass path  232 . This allows first fluid system  204  to utilize available margin  210  of second fluid system  206 . It also allows second fluid system  206  to utilize available margin  240  of first fluid system  204 . Thus, both first fluid system  204  and second fluid system  206  can be controlled, potentially allowing both fluid A and fluid B to be returned to first fluid system  204  and second fluid system  206  at their respective selected target temperatures. As will be appreciated, this can optimize the thermal operation of each system, for example, by heating fuel flowing to combustors of gas turbine engine  14  (shown in  FIG. 1 ) while maintaining lubricant provided to gas turbine engine  10  at a predetermined target temperature. 
     With reference to  FIG. 4 , a thermal management method  300  is shown. Method  300  includes throttling flow of a first fluid, e.g., fluid A (shown in  FIG. 2 ) flowing through a heat exchange body, e.g., heat exchange body  116  (shown in  FIG. 2 ), as shown with box  310 . Method  300  also includes throttling flow of a second fluid, e.g., second fluid B (shown in  FIG. 2 ), flowing through the heat exchange body as shown with box  320 . Heat flows between the first fluid and the second fluid, as shown with box  330 , Heat flow can be unidirectional, e.g., from first fluid A to second fluid B or vice versa, as shown by box  332 . The temperature of first fluid flow is driven to a selected target temperature, e.g., temperature target  108  (shown in  FIG. 2 ), using margin available in the second fluid, e.g., thermal margin  110  (shown in  FIG. 2 ), as shown with box  340 . 
     In certain embodiments, method  300  also includes driving the temperature of the second fluid to a second selected temperature target, e.g., temperature target  238  (shown in  FIG. 3 ), using margin available in the first fluid system, e.g., margin  214  (shown in  FIG. 3 ), as shown with box  350 . Driving fluid in the second fluid system to the second fluid temperature target can be done coincidently, i.e. simultaneously, with driving fluid in the first fluid system to the first fluid temperature target, as shown with box  252 . 
     The methods and systems of the present disclosure, as described above and shown in the drawings, provide for heat exchanger arrangements, thermal management systems, and thermal management methods with superior properties including access to thermal margin present in a fluid flowing through a first fluid path by fluid flowing through a second fluid path. While the apparatus and methods of the subject disclosure have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure.