Microchannel-Type Evaporator and System Using the Same

Abstract

In an evaporator 1, space between two heat transfer plates 2 opposite to each other serves as a liquid path 3, and the outsides of the heat transfer plates 2 serve as a gas path 4. At the lower end of the liquid path 3, a liquid inlet, through which liquid to be evaporated is supplied to the evaporator 1, is provided, and at the upper end of the liquid path 3, a vapor outlet is provided. The liquid to be evaporated vaporizes while flowing from bottom to top. The heating gas is supplied form a gas inlet 7, which is provided at the upper end of the evaporator, and discharged from a gas outlet 8, which is provided at the lower end of the evaporator. Size of space S of the liquid path 3 gradually increases from bottom to top in a gas-liquid two phase region 11.

1 . A microchannel-type evaporator, comprising: 
 a path provided substantially vertically, through which a liquid to be evaporated passes,    wherein a space size of the path is smaller than diameters of bubbles departing from a heat transfer surface of the path, and the space size of the path in a gas-liquid two phase region is a minimum size satisfying that a heat flux is not more than a critical heat flux with respect to a quality.    
   
   
       2 . A microchannel-type evaporator according to  claim 1 , 
 wherein the space size of the path varies depending on a position in the path in the evaporator.    
   
   
       3 . A microchannel-type evaporator according to  claim 2 , 
 wherein the space size of the path varies along a direction of a flow of the liquid to be evaporated.    
   
   
       4 . A microchannel-type evaporator according to  claim 2 , 
 wherein the space size of the path in a gas phase region gradually decreases in a direction of a flow of the liquid to be evaporated.    
   
   
       5 . A microchannel-type evaporator according to  claim 3 , 
 wherein the flow of the liquid to be evaporated is substantially opposite to a flow of a heating gas, and    the space size of the path in the gas-liquid two phase region gradually increases in the direction of the flow of the liquid to be evaporated.    
   
   
       6 . A microchannel-type evaporator according to  claim 3 , 
 wherein the flow direction of the liquid to be evaporated and a flow direction of a heating gas are substantially in a same direction, and    a channel space of the path in the gas-liquid two phase region gradually decreases in the direction of the flow of the liquid to be evaporated.    
   
   
       7 . A microchannel-type evaporator according to  claim 2 , 
 wherein the flow of the liquid to be evaporated is substantially orthogonal to a flow of a heating gas, and    a channel space of the liquid to be evaporated varies in a direction of a high temperature gas.    
   
   
       8 . A microchannel-type evaporator according to  claim 7 , further comprising: 
 a plurality of turning sections in a heating gas path.    
   
   
       9 . A microchannel-type evaporator according to  claim 1 , 
 wherein flow directions of the liquid to be evaporated and a heating gas are substantially in a same direction, and    a thin liquid film is formed on the heat transfer surface by controlling a mass flow rate and/or a temperature of a heating gas by use of a map of the mass flow rate and a temperature of the heating gas with respect to a mass flow rate and a temperature of the liquid to be evaporated.    
   
   
       10 . A system using a microchannel evaporator, comprising: 
 a microchannel-type evaporator comprising a path provided substantially vertically, through which a liquid to be evaporated passes, wherein a space size of the path is smaller than diameters of bubbles departing from a heat transfer surface of the path, and the space size of the path in a gas-liquid two phase region is a minimum size satisfying that a heat flux is not more than a critical heat flux with respect to a quality; and    a superheater which further heats vapor from the microchannel-type evaporator to generate superheated vapor.    
   
   
       11 . A system using a microchannel evaporator according to  claim 10 , 
 wherein, in the microchannel-type evaporator, flow directions of the liquid to be evaporated and a heating gas are substantially in a same direction, and    when a mass flow rate of the heating gas is not less than a prescribed value, the heating gas is supplied to the superheater and the microchannel-type evaporator in parallel.    
   
   
       12 . A system using a microchannel evaporator according to  claim 10 , 
 wherein, in the microchannel-type evaporator, flow directions of the liquid to be evaporated and a heating gas are substantially in a same direction, and    when a temperature of the heating gas is not less than a prescribed value, the heating gas is supplied to the superheater and then supplied to the microchannel-type evaporator.    
   
   
       13 . A system using a microchannel evaporator according to  claim 10 , 
 wherein, in the microchannel-type evaporator, flow directions of the liquid to be evaporated and a heating gas are substantially in a same direction, and    when a mass flow rate and a temperature of the heating gas are not less than respective prescribed values, the heating gas is supplied to the superheater and the microchannel-type evaporator in parallel, and the heating gas discharged from the superheater is further supplied to the microchannel-type evaporator.