Evaporator for refrigeration plant delimiting two respectively high-pressure and low-pressure evaporation chambers and separated by a filter screen

Abstract

An evaporator for a refrigeration plant including a high-pressure chamber, a low-pressure chamber, a filter screen interposed between the high-pressure chamber and the low-pressure chamber, and a communication conduit linking the high-pressure chamber to the low-pressure chamber. The filter screen passes the working fluid in the gaseous phase from the high-pressure chamber towards the low-pressure chamber, and blocks the passage of the working fluid in the liquid phase from the high-pressure chamber towards the low-pressure chamber and vice versa. The communication conduit essentially allows the working fluid in the liquid phase to pass from the high-pressure chamber to the low-pressure chamber, and opposes a free passage of the working fluid in the gaseous phase from the high-pressure chamber to the low-pressure chamber and vice versa.

1 . An evaporator for a refrigeration plant where the refrigeration plant includes a circuit in which a working fluid circulates, the evaporator comprising a main chamber containing a working fluid where a gaseous phase and a liquid phase of the working fluid coexist, the main chamber comprising a supply inlet intended to be connected to the circuit to supply the main chamber with working fluid in the liquid state and an extraction outlet intended to extract from the main chamber working fluid in the gaseous state towards the circuit, the evaporator comprising a heat exchange device capable of heating the working fluid contained in the main chamber, wherein the evaporator comprises:
 a high-pressure chamber delimited within the main chamber, at which the supply inlet is arranged so that the high-pressure chamber is supplied with working fluid in the liquid state through the circuit, the high-pressure chamber containing working fluid in the gaseous phase at a first pressure value and working fluid in the liquid phase, the high-pressure chamber delimiting at least one tray containing the working fluid in the liquid phase present in the high-pressure chamber, the at least one tray of the high-pressure chamber providing a surface for evaporation of the working fluid in the liquid phase contained in the high-pressure chamber to a first evaporation pressure value,   a low-pressure chamber delimited within the main chamber, containing a working fluid in the gaseous phase at a second pressure value strictly lower than the first pressure value and a working fluid in the liquid phase, the extraction outlet being arranged at the level of the low-pressure chamber so that a working fluid in the gaseous phase contained in the low-pressure chamber is extracted towards the circuit, the low-pressure chamber delimiting at least one tray containing the working fluid in the liquid phase present in the low-pressure chamber, the at least one tray of the low-pressure chamber providing a surface for evaporation of the working fluid in the liquid phase contained in the low-pressure chamber at a second evaporation pressure value strictly different from the first evaporation pressure value,   a filter screen interposed between the high-pressure chamber and the low-pressure chamber, the filter screen allowing the working fluid at the gaseous phase to pass from the high-pressure chamber to the low-pressure chamber, and blocking the passage of the working fluid in the liquid phase from the high-pressure chamber towards the low-pressure chamber and vice versa,   a communication conduit linking the high-pressure chamber to the low-pressure chamber, the communication conduit essentially allowing the working fluid in the liquid phase to pass from the high-pressure chamber towards the low-pressure chamber, and opposing a free passage of the working fluid in the gaseous phase from the high-pressure chamber towards the low-pressure chamber and vice versa.   
     
     
         2 . The evaporator according to  claim 1 , wherein the communication conduit is an overflow type spill system arranged at the at least one tray of the high-pressure chamber. 
     
     
         3 . The evaporator according to  claim 2 , wherein the spill system is configured to act in the manner of a siphon between the working fluid in the liquid phase of at least one tray of the high-pressure chamber and the working fluid in the liquid phase of at least one tray of the low-pressure chamber. 
     
     
         4 . The evaporator according to  claim 1 , wherein the ratio between the surface for evaporation of the working fluid in the liquid phase contained in the low-pressure chamber and the surface for evaporation of the working fluid in the liquid phase contained in the high-pressure chamber is greater than 2. 
     
     
         5 . The evaporator according to  claim 1 , wherein the working fluid communication in the gaseous phase from the low-pressure chamber towards the circuit is free, devoid of filtration. 
     
     
         6 . The evaporator according to  claim 1 , wherein the ratio between the mass flow rate of working fluid evaporated in the high-pressure chamber and the mass flow rate of working fluid evaporated in the low-pressure chamber is comprised between 5 and 10. 
     
     
         7 . The evaporator according to  claim 1 , wherein the ratio between the mass flow rate of working fluid in the gaseous phase circulating through the filter screen and the mass flow rate of working fluid in the gaseous phase circulating in the communication conduit is greater than 100. 
     
     
         8 . The evaporator according to  claim 1 , wherein the high-pressure chamber comprises at least two trays superimposed and successively supplied with working fluid in the liquid phase by gravity flow through a pouring device fitted to at least one tray of the high-pressure chamber. 
     
     
         9 . The evaporator according to  claim 1 , wherein the low-pressure chamber comprises at least two trays superimposed and successively supplied with working fluid in the liquid phase by gravity flow through a pouring device fitted to at least one tray of the low-pressure chamber. 
     
     
         10 . The evaporator according to  claim 1 , wherein the filter screen is a wall, having through pores adapted to allow the working fluid in the gaseous phase to pass on either side of this wall, and having undulations along the height of the wall. 
     
     
         11 . A refrigeration plant comprising a circuit in which a working fluid circulates, the refrigeration plant comprising the following elements staggered along the circuit and through which the working fluid successively circulates: an evaporator according to  claim 1  in which the working fluid in the liquid phase undergoes a loss of calories due to the evaporation occurring in the high-pressure chamber and in the low-pressure chamber, a compression machine, a condenser. 
     
     
         12 . The refrigeration plant according to  claim 11 , wherein the working fluid contains essentially water. 
     
     
         13 . The refrigeration plant according to  claim 11 , wherein the mass flow rate of the gaseous phase of the working fluid circulating in the circuit is comprised between 15 g/s and 15 kg/s. 
     
     
         14 . The refrigeration plant according to  claim 11 , wherein the low-pressure chamber of the evaporator comprises a discharge outlet making it possible to extract from the main chamber working fluid in the liquid phase from the at least one tray of the low-pressure chamber. 
     
     
         15 . The refrigeration plant according to  claim 14 , wherein the high-pressure chamber of the evaporator comprises an intake pipe making it possible to supply at least one tray of the high-pressure chamber with working fluid in the liquid phase previously extracted from the low-pressure chamber through the discharge outlet. 
     
     
         16 . The refrigeration plant according to  claim 11 , wherein the refrigeration plant comprises a second circuit in which circulates an operational fluid distinct from the working fluid and a heat exchanger between the operational fluid circulating in the second circuit and a working fluid in the liquid phase present in, or coming from, the main chamber of the evaporator. 
     
     
         17 . The refrigeration plant of the air conditioning system type, comprising an evaporator according to  claim 1  and in which the working fluid which circulates in the evaporator being maintained at a pressure comprised between 5 and 100 mbar ensures a decontamination function against predetermined bacteria.