An energy transfer system, a method of manufacturing thereof, and a method of increasing a thermal stability of a working fluid therein

Abstract

The invention relates to an energy transfer system comprising a thermal circuit with a working fluid configured to perform a thermodynamic cycle and/or an energy transfer process, the thermal circuit comprising a piping system for conveying the working fluid, and at least one energy transfer device, wherein the energy transfer device is configured to transfer a portion of energy from one part of the thermal circuit to another part of the thermal circuit, and wherein at least a portion of the thermal circuit comprises a coating layer on surfaces in contact with the working fluid, wherein the coating layer includes an inert material that is inert with respect to the working fluid during operation and that maintains structural integrity at a temperature above 550 K. and wherein the inert material, when in a pure state/form, has a thermal conductivity above 1000 W/mK at room temperature.

1 . An energy transfer system comprising a thermal circuit with a working fluid configured to perform a thermodynamic cycle and/or an energy transfer process, the thermal circuit comprising a piping system for conveying the working fluid, and at least one energy transfer device, wherein the energy transfer device is configured to transfer a portion of energy from one part of the thermal circuit to another part of the thermal circuit, and wherein at least a portion of the thermal circuit comprises a coating layer on surfaces in contact with the working fluid, wherein the coating layer includes an inert material that is inert with respect to the working fluid during operation and that maintains structural integrity at a temperature above 550 K, and wherein the inert material in a pure state/form has a thermal conductivity above 500 W/mK at room temperature. 
     
     
         2 . The energy transfer system according to  claim 1 , wherein the inert material has a damage temperature above 620 K. 
     
     
         3 . The energy transfer system according to  claim 1 , wherein the inert material in a pure state/form has a thermal conductivity in a range of 500 to 5000 W/mK at room temperature. 
     
     
         4 . The energy transfer system according to  claim 1 , wherein the inert material is graphene or contains graphene. 
     
     
         5 . The energy transfer system according to  claim 1 , wherein the coating layer is applied locally only in one or more parts of the thermal circuit. 
     
     
         6 . The energy transfer system according to  claim 1 , wherein the heat transfer circuit of the energy transfer system comprises a first portion and a second portion, wherein the first portion is configured to convey the working fluid in a first temperature range, and wherein the second portion is configured to convey the working fluid in a second temperature range, wherein the first temperature range is below 550 K, wherein the second temperature range is above 570 K, and wherein only surfaces in contact with working fluid in the second portion of the heat transfer circuit are coated with the coating layer. 
     
     
         7 . The energy transfer system according to  claim 6 , wherein the second temperature range is between 570 K to 870 K. 
     
     
         8 . The energy transfer system according to  claim 1 , wherein the coating layer forms a surface. 
     
     
         9 . The energy transfer system according to  claim 1 , wherein the working fluid is non-corrosive. 
     
     
         10 . The energy transfer system according to  claim 1 , wherein the working fluid is an organic liquid. 
     
     
         11 . The energy transfer system according to  claim 1 , wherein the coating layer forms a smooth film with a surface roughness in a range of about 0.1 micrometer to 5 micrometer. 
     
     
         12 . The energy transfer system according to  claim 1 , wherein the heat transfer system is a thermal oil system, a geothermal loop or a concentrated solar collector system, a thermal conversion system such as an organic Rankine cycle electrical generator, or a heat pump system. 
     
     
         13 . The energy transfer system according to  claim 1 , wherein the one or more surfaces coated with the coating layer are made of stainless steel. 
     
     
         14 . A method of manufacturing an energy transfer system, the method comprising:
 providing a thermal circuit with a working fluid configured to perform a thermodynamic cycle and/or an energy transfer process, the thermal circuit provided with a piping system for conveying the working fluid and at least one energy transfer device, wherein the energy transfer device is configured to transfer a portion of energy from one part of the thermal circuit to another part of the thermal circuit; and   providing at least a portion of the thermal circuit with a coating layer on surfaces in contact with the working fluid, wherein the coating layer includes inert material that is inert with respect to the working fluid during operation and which maintains structural integrity at a temperature above 550 K, and wherein the inert material when in a pure state/form has a thermal conductivity above 500 W/mK at room temperature.   
     
     
         15 . A method of increasing a thermal stability limit temperature of a working fluid in an energy transfer system, the method including coating one or more surfaces in contact with the working fluid with a coating layer, wherein the coating layer includes an inert material which maintains structural integrity at a temperature above 550 K, and wherein the inert material when in a pure state/form has a thermal conductivity above 500 W/mK at room temperature. 
     
     
         16 . The energy transfer system according to  claim 1 , wherein the thermal conductivity is above 1000 W/mK at room temperature. 
     
     
         17 . The energy transfer system according to  claim 2 , wherein the damage temperature is above 670 K. 
     
     
         18 . The energy transfer system according to  claim 6 , wherein the first temperature is below 520 K and the second temperature is above 600 K. 
     
     
         19 . The energy transfer system according to  claim 8 , wherein the surface has a thickness in a range of 1 to 2000 micrometer. 
     
     
         20 . The method of  claim 14 , wherein the thermal conductivity is in a range of 500 to 5000 W/mK at room temperature.