Low Temperature High Efficiency Condensing Heat Engine for Propelling Road Vehicles

Abstract

A non-polluting, closed-cycle condensing heat engine and operating method is provided for propelling road vehicles at high efficiencies and high power densities by using a phase-changing working fluid having a critical temperature close to the natural ambient temperature of the surrounding atmosphere and shifting the high temperature heat reservoir downward by several hundred degrees by creating an artificial low temperature heat reservoir below ambient temperature by evaporating water. By isentropically compressing the liquefied working fluid at sub-ambient temperatures to very high pressure utilizing the fact that water has an unusually high latent heat of evaporation, and heating it to a compressed gas at a relatively low temperature in the high temperature heat reservoir by burning small amounts of fuel, it is possible for the engine to operate at high power densities by expanding the compressed gas back to the initial sub-ambient temperature where it is re-condensed to propel road vehicles several hundred miles on a tank of water holding only 40 gallons using a small fraction of the amount of fuel used by vehicles propelled by conventional internal combustion engines.

1 . A method for generating mechanical power at high efficiency comprising the steps of:
 creating an artificial low temperature heat sink at a temperature below ambient temperature by evaporating water;   condensing a vaporized phase-changing working fluid at sub-ambient temperature having a critical temperature close to said ambient temperature and above said low temperature heat sink by extracting its latent heat of condensation by said low temperature heat sink by evaporating said water;   compressing said condensed working fluid;   heating said compressed working fluid into a compressed gas by absorbing heat energy generated by burning a combustible fuel;   expanding said vaporized compressed working fluid inside an expander means thereby converting a portion of said absorbed heat energy into mechanical work; and   repeating said condensing, compressing, vaporizing, and expanding steps in a cyclic process by evaporating additional water and burning additional fuel.   
     
     
         2 . A method as set forth in  claim 1  wherein said working fluid is a refrigerant. 
     
     
         3 . A method as set forth in  claim 1  wherein said working fluid is R32 refrigerant. 
     
     
         4 . A method as set fourth in  claim 1  wherein said step of creating said artificial low temperature heat sink comprises at least one condensing tube and the steps of:
 mounting water absorbing padding means in thermal contact with said condensing tube; and 
 dispensing water on said padding means such that the evaporation of said water generates said low temperature heat sink inside said condensing tube such that when vaporized working fluid enters said condensing tube its latent heat of condensation is absorbed by said evaporating water and condenses into a liquid at sub-ambient temperature inside said condensing tube. 
 
     
     
         5 . A method as set forth in  claim 1  further comprising the step of interposing compressed gas storage vessel means between said heating step and said expansion step as a load-leveling system for varying the amount of power generated by said expander means by varying the mass flow rate at which said compressed heated working fluid is fed into said expander means. 
     
     
         6 . A method as set forth in  claim 1  wherein said mechanical power is used to propel a road vehicle. 
     
     
         7 . A method as set forth in  claim 1  wherein said condensing, compressing, heating, and expanding steps can be performed independently of each other and at different times. 
     
     
         8 . A method for operating a condensing heat engine for generating mechanical power at high efficiency comprising the steps of:
 utilizing a phase-changing working fluid having a critical temperature close to ambient temperature and above the temperature of evaporating water;   creating a high temperature heat reservoir not far above ambient temperature by burning small amounts of a combustible fuel;   creating a low temperature heat reservoir below ambient temperature by evaporating small amounts of water; and   operating said condensing heat engine between said high temperature heat reservoir and said low temperature heat reservoir such that relatively high mechanical power can be generated by burning relatively small amounts of said combustible fuel.   
     
     
         9 . A method for generating mechanical power comprising the steps of:
 creating an artificial low temperature heat sink at a temperature below ambient temperature by evaporating water;   generating a high temperature heat reservoir above said ambient temperature; and   converting a portion of the thermal potential difference between said low temperature heat sink and said high temperature heat reservoir into mechanical power.   
     
     
         10 . An apparatus for generating mechanical power at high efficiency comprising:
 a phase-changing working fluid having a critical temperature close to ambient temperature and above the temperature of evaporating water;   condenser means maintained at sub-ambient temperature by evaporating water in thermal contact with said condenser means;   heating means by burning a combustible fuel;   means for feeding vaporized working fluid into said condenser means thereby condensing said vapor by extracting latent heat of condensation by said evaporating water at sub-ambient temperature;   means for compressing said condensed working fluid;   means for heating said compressed working fluid into a heated compressed gas by feeding said compressed working fluid into said heating means thereby absorbing heat energy from said combustible fuel;   means for feeding said heated compressed gas into an expander means thereby converting a portion of said heat energy absorbed from said burning fuel into mechanical work; and   means for repeating said condensing, compressing, heating, and expanding steps in a cyclic process for generating more mechanical work.   
     
     
         11 . An apparatus as set forth in  claim 10  wherein said working fluid is a refrigerant. 
     
     
         12 . An apparatus as set forth in  claim 10  wherein said working fluid is refrigerant R32. 
     
     
         13 . An apparatus as set forth in  claim 10  wherein said condenser means comprises:
 at least one condensing tube; 
 water absorbing padding means mounted on the external surfaces of said condensing tube in thermal contact with said condensing tube; 
 means for dispensing water on said padding means that evaporates on said padding means thereby reducing the temperature of said condensing tube below said ambient temperature; and 
 means for introducing vaporized working fluid into said condensing tube which condenses into a liquid at sub-ambient temperature by extracting its latent heat of condensation by said evaporating water. 
 
     
     
         14 . An apparatus as set forth in  claim 10  further comprising:
 compressed gas storage vessel means interposed between said heating means and said expander means as a load-leveling system; and 
 means for varying the amount of mechanical power generated by said expander means by varying the mass flow rate at which said compressed working fluid is fed into said expander means. 
 
     
     
         15 . An apparatus as set forth in  claim 10  wherein said mechanical power is used to propel road vehicles. 
     
     
         16 . An apparatus as set forth in  claim 10  wherein said condensing means, compressing means, heating means, and expanding means can occur independently of each other and at different times. 
     
     
         17 . An apparatus for generating mechanical power at high efficiency comprising:
 a phase-changing working fluid having a critical temperature close to ambient temperature and above the temperature of evaporating water;   condenser means maintained at sub-ambient temperature by evaporating water in thermal contact with said condenser means;   means for feeding vaporized working fluid into said condenser means thereby condensing said vapor by extracting latent heat of condensation by said evaporating water at sub-ambient temperature;   means for compressing said condensed working fluid;   means for heating said compressed working at a temperature above said critical temperature by absorbing heat energy from a combustible fuel;   means for feeding said compressed working fluid into said heating means;   means for feeding said heated compressed gas into an expander means thereby converting a portion of said absorbed heat energy into mechanical work; and   means for repeating said condensing, compression, heating, and expanding steps in a cyclic process for generating more mechanical work.   
     
     
         18 . An apparatus for generating mechanical power at high efficiency comprising:
 a phase-changing working fluid having a critical temperature close to ambient temperature and above the temperature of evaporating water;   condenser means maintained at sub-ambient temperature by evaporating water in thermal contact with said condenser means;   means for feeding vaporized working fluid into said condenser means thereby condensing said vapor by extracting latent heat of condensation by said evaporating water at sub-ambient temperature;   means for compressing said condensed working fluid;   means for heating said compressed working at a temperature above said critical temperature by absorbing heat energy from a combustible fuel;   means expanding said heated compressed gas thereby generating mechanical power; and   means for repeating said condensing, compression, heating, and expanding steps in a cyclic process for generating more mechanical work.   
     
     
         19 . A condensing heat engine for generating mechanical power at high efficiency comprising:
 a phase-changing working fluid having a critical temperature close to ambient temperature and above the temperature of evaporating water;   means for creating a high temperature heat reservoir not far above ambient temperature by burning small amounts of a combustible fuel;   means for creating a low temperature heat reservoir below ambient temperature by evaporating small amounts of water; and   means for operating said condensing heat engine between said high temperature heat reservoir and said low temperature heat reservoir such that relatively high mechanical power can be generated by burning relatively small amounts of said combustible fuel.