Refrigeration plant

Abstract

A refrigeration plant comprising a compressor having an inlet and an outlet, a condenser connected to the outlet of the compressor, an evaporator connected to the condenser and to the inlet of the compressor, and a regulation valve provided between the condenser and the evaporator. According to a peculiar feature of the present invention, the solenoid valve has no metering orifice through which the refrigerant fluid could be expanded. The condenser furnishes a high pressure refrigerant fluid to the regulation valve, which is constituted by a solenoid valve having solenoid actuator that, when is activated (energized), moves a valve member in its open position while when said actuator is deactivated (de-energized) it allows the valve member to return in its closed position by means of a suitable return spring.

1 . Refrigeration plant comprising a compressor ( 1 ) having an inlet ( 2 ) and an outlet ( 3 ), a condenser ( 9 ) connected to the outlet of the compressor ( 1 ), an evaporator ( 17 ) connected to the condenser ( 9 ) and to the inlet ( 2 ) of the compressor ( 1 ), and a refrigerant flow regulation valve ( 12 ) provided between the condenser ( 9 ) and the evaporator ( 17 ), characterized in that said regulation valve ( 12 ), which is specifically intended to regulate the refrigerant flow to obtain the desired working conditions, has no metering orifice through which the refrigerant fluid could be expanded and, when said regulation valve ( 12 ) is completely open, it has only its natural flow resistance and it does not provide any other flow limiting device; part of the refrigerant that is furnished to said regulation valve ( 12 ) being already in gaseous form when said valve is completely open, a remarkable part of the refrigerant expansion being performed in a part of pipeline ( 15 ,  16 ) between the condenser ( 9 ) and the evaporator ( 17 ).  
   
   
       2 . Refrigeration plant according to  claim 1 , characterized by the fact that the condenser ( 9 ) furnishes a high pressure refrigerant fluid to the regulation valve of ( 12 ) without metering orifice, which is constituted by a solenoid valve having solenoid actuator that, when is activated (energized), moves a valve member in its open position while when said actuator is de-activated (de-energized) it allows the valve member to return in its closed position by means of a suitable return spring.  
   
   
       3 . Refrigeration plant according to  claim 2 , characterized by the fact that said solenoid actuator is periodically activated/de-activated by a suitable electronic controller ( 21 ) in order to regulate the refrigerant flow through the regulation valve ( 12 ) as a function of predetermined operation parameters of the plant itself, e.g. the desired refrigerant overheating at the outlet of the evaporator ( 17 ).  
   
   
       4 . Refrigeration plant according to  claim 3 , characterized by the fact that said electronic controller ( 21 ) analyzes and elaborates the signals coming from a pressure probe ( 4 ) and from a temperature probe ( 5 ) which are positioned between the outlet ( 19 ) of the evaporator ( 17 ) and the inlet ( 2 ) of the compressor ( 1 ).  
   
   
       5 . Refrigeration plant according to  claim 1 , characterized by the fact that a hot gas refrigerant fluid pipeline ( 7 ) is provided between the outlet ( 3 ) of the compressor ( 1 ) and the inlet ( 18 ) of the evaporator ( 17 ); said pipeline ( 7 ), which by-passes the condenser ( 9 ) and the regulation valve ( 12 ), being controlled by an additional solenoid valve or hot gas valve ( 8 ) in order to carry out the defrosting and the heating of the evaporator ( 17 ).  
   
   
       6 . Refrigeration plant according to  claim 5 , characterized by the fact that the hot gas valve ( 8 ) is maintained closed (OFF) during the operation in refrigeration, and the desired overheating of the evaporator ( 17 ) is maintained and controlled by disarming (i.e. closing) and activating (i.e. opening) the regulation solenoid valve ( 12 ).  
   
   
       7 . Refrigeration plant according to  claim 1 , characterized by the fact that the driving of said regulation valve ( 12 ) provides that it is completely opened (ON) regularly, every N seconds, and maintained in such configuration for a variable time (“ON time”) from 0 to N seconds, to obtain the desired overheating of the evaporator ( 17 ).  
   
   
       8 . Refrigeration plant according to  claim 7  characterized by the fact that when the plant is started for the first time, the “ON time” is initially fixed to an interval of about two seconds, after which it is gradually increased or decreased by the controller ( 21 ) to control the overheating, preferably with a proportional, integral and/or differential control method.  
   
   
       9 . Refrigeration plant according to  claim 8 , characterized by the fact that, since the regulation valve ( 12 ) lacks of any metering orifice, in the case of some abrupt variations of the operational conditions of the refrigerator plant will occur during operation and/or during the filling operations of refrigerant, when the overheating falls below a preset value of “minimum overheating” the electronic controller ( 21 ) closes immediately the regulation valve ( 8 ) and delays the subsequent opening of the valve until the overheating increases over said minimum overheating value.  
   
   
       10 . Refrigeration plant according to  claim 8 , characterized by the fact that, since the regulation valve ( 12 ) lacks of any metering orifice, in the case of some abrupt variations of the operational conditions of the refrigerator plant will occur during operation and/or during the filling operations of refrigerant, when the overheating increases over a preset value of “maximum overheating” the controller ( 21 ) anticipates immediately the opening of the regulation valve if the latter is in closed configuration.  
   
   
       11 . Refrigeration plant according to the  claim 5 , characterized by the fact that to carry out the defrosting and the heating of the evaporator ( 17 ), the regulation valve ( 12 ) is maintained closed and the hot gas valve ( 8 ) is opened, while the compressor ( 1 ) is on, thereby supplying hot gas to the evaporator ( 17 ) without by-passing its inlet ( 18 ).  
   
   
       12 . Refrigeration plant according to  claim 11  characterized by the fact that in order to prevent the liquid from returning to the inlet ( 2 ) of the compressor ( 1 ), during the defrosting and the heating the controller ( 21 ) monitors the value of the overheating at the compressor and, when such overheating goes down below of a preset value, it closes the hot gas valve ( 8 ).  
   
   
       13 . Refrigeration plant according to  claim 1 , characterized by the fact that said refrigerant is a HFC as the R134a or the R404A or the R407A or the R410A or the R507A.  
   
   
       14 . (canceled)