Steam injector and heat pump device

Abstract

A steam injector including an introducing portion introducing a liquid flow of a refrigerant and a steam flow of the refrigerant; a mixing portion that has a shape with an internal cross-sectional area decreasing toward a moving direction of the liquid flow, and internally mixes the jet-like liquid flow with the steam flow to form a refrigerant flow; a throat portion formed on an outlet side of the mixing portion; and a diffuser portion that has a shape with an internal cross-sectional area increasing from the throat portion toward a moving direction of the refrigerant flow, and discharges the refrigerant flow at an increased pressure from a discharge portion. The throat portion has an internal cross-sectional area smaller than a critical cross-sectional area at which a discharge pressure of the refrigerant flow discharged from the discharge portion nonlinearly increases when the internal cross-sectional area of the throat portion is reduced.

1 : A steam injector comprising:
 an introducing portion introducing a liquid flow of a refrigerant and a steam flow of the refrigerant;   a mixing portion that has a shape with an internal cross-sectional area decreasing toward a moving direction of the liquid flow, and internally mixes the jet-like liquid flow with the steam flow to form a refrigerant flow;   a throat portion formed on an outlet side of the mixing portion; and   a diffuser portion that has a shape with an internal cross-sectional area increasing from the throat portion toward a moving direction of the refrigerant flow, and discharges the refrigerant flow at an increased pressure from a discharge portion, wherein   the throat portion has an internal cross-sectional area smaller than a critical cross-sectional area at which a discharge pressure of the refrigerant flow discharged from the discharge portion of the diffuser portion nonlinearly increases when the internal cross-sectional area of the throat portion is reduced.   
     
     
         2 : The steam injector according to  claim 1 , wherein the internal cross-sectional area of the throat portion is an internal cross-sectional area at which the first-order differential coefficient of a curve representing a change in the discharge pressure of the refrigerant flow with respect to a change in the internal cross-sectional area of the throat portion is smaller than zero, or the second-order differential coefficient of the curve is larger than zero. 
     
     
         3 : The steam injector according to  claim 1 , wherein the following Expression (1) is satisfied:
     P   D =( m   w0   ·u   w0 )/ A   1 +( m   s0   ·u   s0 )/ A   1 −( m   1   ·u   1 )/ A   1 +(1−ζ N )·(ρ· u   1   2 /2)−(ζ T +ζ D )·(ρ w   ·u   1   2 /2)  (1)
   where A 1  denotes the internal cross-sectional area of the throat portion; m w0  and u w0  denote a mass flow rate and a flow velocity, respectively, of the liquid flow in the introducing portion; m s0  and u s0  denote a mass flow rate and a flow velocity, respectively, of the steam flow in the introducing portion; m 1  and u 1  denote a mass flow rate and a flow velocity, respectively, of the refrigerant flow in the throat portion; □ N , □ T , and □ D  denote pressure loss coefficients in the mixing portion, the throat portion, and the diffuser portion, respectively; □ w  denotes a density of the liquid flow; and P D  denotes the discharge pressure of the refrigerant flow in the discharge portion.   
     
     
         4 : The steam injector according to  claim 1 , wherein the throat portion has a circular internal cross section, and the internal cross section has a diameter of 2 mm or smaller. 
     
     
         5 : The steam injector according to  claim 4 , wherein a diameter of the internal cross section is 1 mm or smaller. 
     
     
         6 : The steam injector according to  claim 1 , wherein A s0 /A w0  is in a range of 7 to 30, inclusive, where A w0  denotes a cross-sectional area of a region in the mixing portion into which the liquid flow is introduced, and A s0  denotes a cross-sectional area of a region in the mixing portion into which the steam flow is introduced. 
     
     
         7 : The steam injector according to  claim 6 , wherein the value of As0/Aw0 is in a range of 10 to 20, inclusive. 
     
     
         8 : The steam injector according to  claim 1 , further comprising a drain pipe formed so as to communicate inside of the mixing portion with external air. 
     
     
         9 : The steam injector according to  claim 8 , wherein the drain pipe is provided with a check valve. 
     
     
         10 : The steam injector according to  claim 1 , wherein the refrigerant is water or a chlorofluorocarbon-replacing material. 
     
     
         11 : A steam injector comprising:
 a plurality of unit steam injectors each serving as the steam injector as claimed in  claim 1 ;   a liquid flow passage and a steam flow passage for supplying the liquid flows and the steam flows of the refrigerant to the respective introducing portions of the corresponding unit steam injectors.   
     
     
         12 : The steam injector according to  claim 11 , wherein
 the steam injector is formed by joining together a set of component members, and   grooves or holes having shapes obtained by dividing the introducing portion, the mixing portion, the throat portion, and the diffuser portion into a plurality of parts thereof are formed in each of the set of component members, and the introducing portion, the mixing portion, the throat portion, and the diffuser portion are formed by the grooves or holes when the set of component members are joined together.   
     
     
         13 : The steam injector according to  claim 12 , wherein
 the set of component members have a plate-like shape and are joined with one another in a stacked state, and   at least two of the unit steam injectors are arranged along main surfaces of the plate-like component members.   
     
     
         14 : The steam injector according to  claim 13 , wherein a flow passage is formed that communicates together the introducing portions of the unit steam injectors arranged along the main surfaces of the plate-like component members. 
     
     
         15 : The steam injector according to  claim 12 , wherein
 the set of component members have a plate-like shape and are joined with one another in a stacked state, and   at least two of the unit steam injectors are arranged along a stacking direction of the plate-like component members.   
     
     
         16 : The steam injector according to  claim 15 , wherein a flow passage is formed that communicates together the introducing portions of the unit steam injectors arranged along the stacking direction of the plate-like component members. 
     
     
         17 : The steam injector according to  claim 12 , wherein
 the set of component members are joined with one another in a stacked state, and   the unit steam injectors extend along the stacking direction of the component members.   
     
     
         18 : The steam injector according to  claim 11 , wherein the set of component members are joined together by diffusion bonding. 
     
     
         19 : A heat pump device comprising:
 a compressor compressing a refrigerant;   a condenser condensing the refrigerant;   an evaporator evaporating the refrigerant; and   the steam injector as claimed in  claim 1  that introduces the steam flow of the refrigerant and the liquid flow of the refrigerant, and discharges the refrigerant flow at the increased pressure from the discharge portion of the diffuser portion.