Patent Publication Number: US-4317333-A

Title: Remote water cooled heat engine

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a heat engine. 
     2. Description of the Prior Art 
     Heat engines are known which operate on a Brayton or constant pressure cycle. That is an engine which operates with a compressor and expander where air from a compressor is fed to a heater where it is heated at constant pressure. The heated air is then fed to an expander and from the expander to a cooler where it is cooled at constant pressure. The cooled air is returned to the compressor to complete the cycle. This cycle is of course the basis of operation of a gas turbine where a rotary compressor and turbine are used. 
     My present invention relates to a heat engine using such a cycle but aims to dispense with the requirement of a turbine/compressor or expanding cylinder/compressor for the expansion and compression phases of the cycle. 
     SUMMARY OF THE INVENTION 
     Broadly the invention can be said to consist of a method of operating a heat engine wherein heated gas is introduced into a venturi of converging/diverging nozzle, the heated gas is then cooled in the low pressure region by fluid injection the resulting mixture then passing through the divergent or diffuser part of the venturi or nozzle to a working area. 
     According to a second broad aspect of the invention the invention consists of a heat engine comprising a heat source for gas, a venturi or converging/diverging nozzle, a loop or cyclone at the low pressure region of the venturi or nozzle and means for injecting fluid into the gas stream at said loop or cyclone. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     To more fully describe the invention reference will be made to the accompanying drawings in which: 
     FIG. 1 is a schematic elevation view of one form of the invention, 
     FIG. 2 is a schematic elevation view of a second form of the invention, and 
     FIG. 3 is a cross-sectional view of the invention as illustrated in FIG. 2. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The source of heated air is preferably derived from waste heat sources such as for example the waste gas from a boiler or alternatively from a solar heater. The heated air, which is relatively dry and near atmospheric pressure is introduced into the nozzle of a venturi directly into a loop or cyclone. 
     Referring firstly to FIG. 1 of the drawings the venturi 10 has a nozzle 11, a throat 12 and a diffuser 13. A conduit portion 14 is shown which couples nozzle 11 to the heat source (not shown). The throat portion 12 includes a loop 15 which communicates with nozzle 11 and diffuser 13 at junctures 18a and 18b, respectively, and is of the same cross sectional area as the throat so that the pressure of the air within the loop remains substantially constant and is equal to the pressure in the low pressure area or throat 12 where nozzle 11 joins loop 15, i.e. 18a. 
     Fluid injection means, not illustrated but shown generally at 16, is located in the upstream portion of loop 15 and permits the injection of fluid, typically water, with a high latent heat of evaporation into the air flow. 
     Air passing through nozzle 11 of the venturi 10 is thus expanded to a high velocity and low pressure. The relatively dry air thus has fluid injection by injection means 16 and the fluid and air are mixed during their passage through loop 15. The moist air thus issues from the downstream portion of throat 12 at high velocity, lower temperature, low pressure. 
     The resultant mixture thus passes through the diffuser 13 to issue at low velocity, higher temperature than that at the throat 12, and near atmospheric pressure. The issuing mixture thus passes through a turbine indicated at 17 thereby constituting the work portion of the cycle. The turbine 17 can be replaced by other expansion means or used as increased gas pressure. 
     Downstream of turbine 17 all fluid injected in the loop 15 is removed by say evaporation, by venting to atmosphere, or by a heat exchanger so as to recover the coolant. The air can thus be returned to the heat source for heating. 
     The machine may also incorporate conventional expansion and compression turbines in the system since the pressure ratio of the venturi may be limited by sonic effects if a greater pressure ratio is required. 
     Referring to FIGS. 2 and 3 an alternative embodiment is shown. The loop portion 15 of the embodiment shown in FIG. 1 is replaced by a cyclone 15&#39; and the entry 12&#39;a and exit thereto are coupled to a nozzle portion 11&#39; and diffuser 12b portion 13&#39;; respectively. The injection means 16&#39; is formed by a nozzle which is coaxial with cyclone 15&#39; as more clearly shown in FIG. 3. The cyclone 15&#39; could provide the expansion and compression means on its own rather than purely a replacement for loop portion 15. The vortices generated in the cyclone can also give a similar expansion and compression effect as the venturi due to the centrifugal forces generated. 
     Fluid injections at 16 or 16&#39; would typically be at high pressure to minimise mixing losses (also parallel to gas flow as much as possible). The loop illustrated in FIG. 1 is only recommended for mixing purposes and may be only a bend or even eliminated. 
     Throughout this disclosure reference has been made to the working medium as air but it will be appreciated by those skilled in the art that other gases could be used if desired.