Abstract:
The method can include injecting fuel from a liquefied fuel source into a combustion chamber having a combustion path, by circulating the fuel out from an inlet conduit into an evaporator housing, along the evaporator housing in a direction opposite the combustion path and across an evaporator element receiving fuel in the liquid state and exposing a multiplied surface of the liquid fuel to heat from the combustion path to evaporate the liquid fuel, and conveying the evaporated fuel into the combustion chamber and into the combustion path.

Description:
CROSS-REFERENCE TO RELATED INVENTIONS 
       [0001]    This application claims the benefit provisional application No. 61/787,656, filed Mar. 15, 2013. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Liquefied fuels (i.e. fuel that is stored in pressurized, liquefied form and evaporated from the liquid state into the gaseous state before combustion, such as propane, butane, natural gas, ethanol, etc.) are used in various applications. Many well-known, household applications use a fuel tank as an evaporator and rely on the fuel tank to feed the liquefied fuel in a pure gaseous form to a burner. 
         [0003]    Some applications cannot rely solely on the use of the fuel tank as an evaporator, which poses a particular challenge in using liquefied fuels as a fuel source. There thus remained room for improvement. 
         [0004]    The foregoing has outlined some of the pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings. 
       SUMMARY OF THE INVENTION 
       [0005]    A liquefied fuel burner is provided which has an integrated evaporator having a housing provided inside a combustion chamber, and where the housing operates as a counter current heat exchanger with the surrounding flame to evaporate the fuel inside the housing. 
         [0006]    In accordance with one aspect, there is provided a liquefied fuel combustor comprising: a combustion chamber having an intake, an exhaust, and a combustion path therebetween; an evaporation and injection device having : an evaporator housing provided inside the combustion chamber and extending along a portion of the combustion path and at least one evaporator outlet aperture to allow fuel out from the evaporator housing into the combustion chamber; an inlet conduit having an inlet end connectable to a liquefied fuel source outside the combustion chamber, an outlet end protruding inside the evaporator housing, and at least one evaporator inlet aperture associated to the outlet end, to allow fuel out from the inlet conduit into the evaporator housing; an evaporation path extending from the evaporator inlet aperture to the evaporator outlet aperture in a counter-current flow direction opposite to the combustion path aperture along at least a portion of the length of the housing; and an evaporation element positioned in the evaporation path, to receive fuel in the liquid state from the evaporator inlet aperture, and to expose a multiplied surface of the liquid fuel to heat from the combustion path for evaporation. 
         [0007]    In accordance with another aspect, there is provided a method of injecting fuel from a liquefied fuel source into a combustion chamber having a combustion path, the method comprising circulating the fuel out from an inlet conduit into an evaporator housing, along the evaporator housing in a direction opposite the combustion path and across an evaporator element receiving fuel in the liquid state and exposing a multiplied surface of the liquid fuel to heat from the combustion path to evaporate the liquid fuel, and conveying the evaporated fuel into the combustion chamber and into the combustion path. 
         [0008]    In accordance with another aspect, there is provided a fuel injector for evaporating liquid fuel as it is injected into a combustion chamber, the fuel injector comprising: an evaporation chamber having an evaporation section opposite an outlet section, the evaporation chamber having a closed wall with a plurality of outlet apertures provided at the outlet section; metal strands housed in the evaporation section of the evaporation chamber; an inlet having an inlet end connectable to a source of the liquid fuel, and an injector tube penetrating into the evaporation chamber and leading to the evaporation section, the inlet having an orifice forming a spray nozzle in the inlet end and leading to the evaporation section across the injector tube. 
         [0009]    The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description of the invention that follows may be better understood so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings in which: 
           [0011]      FIG. 1  is an axial cross-sectional view of an example of a combustor; 
           [0012]      FIG. 2  is an axial cross-sectional view of an evaporation and injection device of the combustor of  FIG. 1 , with  FIG. 2A  being an enlarged portion thereof; 
           [0013]      FIG. 3  is side elevational view of the evaporation and injection device of  FIG. 2 , with  FIG. 3A  being an enlarged portion thereof; 
           [0014]      FIG. 4  is an oblique view of another embodiment of an evaporation and injection device for a combustor; and 
           [0015]      FIG. 5  is an axial cross-sectional view of the evaporation and injection device of  FIG. 4 , with  FIGS. 5A and 5B  being enlarged portions thereof. 
       
    
    
       [0016]    Similar reference characters refer to similar parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0017]      FIG. 1  shows an example of a combustor  10  generally having a combustion chamber  12  and an evaporation and injection device  14 . The combustion chamber  12  has an intake  16  at one end and an exhaust  18  at the other end. A combustion path  20  can be generally defined as extending from the intake  16  to the exhaust  18  of the combustion chamber  12 . The evaporation and injection device  14  generally has an evaporator housing  22  protruding into the combustion chamber  12  along a portion of the combustion path  20 , and an inlet conduit  24 , provided here in the form of a tube, having an inlet end  26  connectable to a liquefied fuel source externally to the combustion chamber and an outlet end  28  protruding inside the evaporator housing  22 . The outlet end  28  can have one or more apertures to allow the fuel out of the inlet conduit  24  and into the evaporation area between the evaporator housing  22  and the inlet conduit  24 . The evaporator housing  22  also has one or more apertures to allow evaporated fuel out of the evaporator housing  22  and into the combustion chamber  12  for combustion. Accordingly, a fuel supply path  30  can be defined as extending between the inlet  26  and the outlet  28  of the inlet conduit  24 , and an evaporation path  32  (shown in  FIG. 2 ) can be defined between the outlet  28  of the inlet conduit  24  and the outlet of the evaporator housing  22 . 
         [0018]    It will be noted here that the evaporation path  32  is separated from the combustion chamber  12  by the wall of the evaporator housing  22  which, in this case, is conveniently made of a material having high heat resistance and high heat conductivity, such as stainless steel for instance, to allow the evaporator housing  22  to both withstand the heat prevailing in the combustion chamber  12  during use and favour heat transfer between the combustion chamber  12  and the fuel circulating in the evaporation path  32 . Moreover, it will be noted that the evaporation path  32  is directed opposite to the combustion path  20  and can thus be said to form a counter-current flow heat exchanger therewith. 
         [0019]    For the sake of simplicity and convenience, the aperture(s) at the outlet end  28  of the inlet conduit  24  will be referred to as evaporator inlet aperture(s)  36  and the aperture(s) forming the outlet of the evaporator housing  22  will be referred to as evaporator outlet aperture(s) hereinafter. 
         [0020]    An evaporation element  40  is positioned in the evaporation path  32 . The exact construction of the evaporation element  40  can vary, and it can be adapted to play either one or both of the following functions: 1) multiplying the exposed surface of liquid fuel to increase the evaporation rate and 2) causing drag or otherwise straining the flow of liquid along the evaporation path  32  to provide more time for the evaporation to occur. As a result of one, or both of these functions, combined with the heat exchanger function of the configuration of the combustor as a whole, fuel being in the liquid state at the evaporator inlet apertures  36  can be efficiently evaporated into the gaseous state and the resulting arrangement can be considered relatively simple and be achieved at a satisfactorily low cost. 
         [0021]    In this particular embodiment, the combustor  10  is generally tubular, as well as the injector and evaporator device  14  which is further provided concentrically therein. The inlet conduit  24  penetrates deep into the evaporator housing  22  and the evaporator outlet apertures  38  are well recessed from the evaporator inlet apertures  36 . Both the evaporator outlet apertures  38  and the evaporator inlet apertures  36  are oriented radially. The evaporation element  40  is provided here in the form of two or more intertwined helical springs of stainless steel having a satisfactorily resistant gauge stretched along the evaporator housing  22 . In alternate embodiments, many of the latter design considerations can vary while still achieving satisfactory results. In particular, the shape of the evaporator conduit can be adapted to the shape of the flame. Although the transversal cross-sectional shape can have another geometric shape than a circle, a circular shape can be preferred for various reasons, such as the ability to fill it with a suitable evaporation element  40  (which can be one or more helical springs, wire mesh, or any other suitable alternative for instance) and heat transfer considerations. It will be noted here that although the depicted liquefied fuel combustor described above is provided with a relatively high capacity to evaporate fuel in liquid state, the fuel fed to it does not necessarily have to be in the liquid state and it can handle many different ratios of liquid vs. gaseous state at the evaporation inlet in a satisfactory manner. 
         [0022]      FIGS. 4 through 5B  illustrate another embodiment of an injector and evaporator device  114 . The general construction of this other embodiment is relatively similar to the one described above, but the internal workings are somewhat different. In this embodiment, the outlet end  128  of the inlet conduit  124  only partially penetrates into the evaporation housing  122  and has an axial outlet  142  oriented to inject or spray the fuel into the evaporation element  140 , provided here in the form of a wire mesh. The evaporation outlet apertures  138  are provided here recessed from the evaporation inlet aperture  136  by a given axial distance  144  to reduce the likelihood of liquid escaping into the combustion chamber unevaporated be it by splashing or other reason. 
         [0023]    The present disclosure includes that contained in the appended claims, as well as that of the foregoing description. Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention. 
         [0024]    Now that the invention has been described,