Compact refrigeration system

Abstract

A selectively controllable valve is arranged in a refrigeration circuit which interconnects the evaporator and the condenser and is controlled so that a pressure differential is built up across the valve. The valve is selectively opened to allow “batches” of working fluid to pass therethrough. In some embodiments, the working fluid which is allowed to pass through the valve, is heated in a chamber to increase the amount of pressure on the downstream side of the valve. This produces expanded pressurized working fluid which increases the pressure in the condenser and forces previously condensed and liquefied working fluid through a flow restricting transfer device into an evaporator. Condensation of the just heated gas in the condenser subsequently reduces the pressure on the downstream side of the valve and establishes conditions suitable for the passage of a further amount of gaseous working fluid while itself becoming liquid to be forced through the flow restricting transfer device. Quick repetition of these cycles establishes a dynamic flow conditions and maintains the flow of liquefied working fluid into the evaporator. In other embodiments, the pressure differential is produced and/or augmented by pump such as a piston pump, or a combination of the pump and the heating chamber. If sufficient condensation can be induced using the operation of the condenser or by some other means and the required pressure differential developed, then both the heater and the pump can, depending on the circumstances and the cooling capacity that is required, be omitted. The flow of liquid working fluid from the condenser is transferred to the evaporator via either a capillary tube or a selectively controllable valve arrangement which can also posses pumping characteristics if so desired.

What is claimed is:  
     
         1 . A refrigerating arrangement having a condenser and an evaporator which are fluidly connected by a working fluid transfer device and wherein a pressure differential is produced in a manner which induces working fluid to flow from the evaporator to the condenser, comprising: 
 a flow control device operatively disposed between the downstream end of the evaporator and the upstream end of the condenser for selectively interrupting the flow of gaseous working fluid therebetween in a timed relationship with the rate of condensation of working fluid in the condenser so as to maintain a pressure differential across the working fluid transfer device to force liquefied working fluid to the evaporator.    
     
     
         2 . A refrigerating arrangement as set forth in  claim 1 , further comprising: 
 a controller responsive to a sensor arrangement for selectively controlling the flow control device and for controlling the timing of the flow interruption so as to occur a plurality of times per second.    
     
     
         3 . A refrigerating arrangement as set forth in  claim 2 , wherein the sensor arrangement comprises at least one of a first pressure sensor disposed upstream of the valve, and a second pressure sensor disposed downstream of the valve.  
     
     
         4 . A refrigerating arrangement as set forth in  claim 1 , further comprising a heating chamber disposed downstream of said flow control device, said heating chamber being operatively connected with the controller and adapted to heat working fluid which has been permitted to pass through the flow control device.  
     
     
         5 . A refrigerating arrangement as set forth in  claim 4 , further comprising a temperature sensor which is associated with the heating chamber for detecting the temperature of the working fluid which is heated and expanded in the chamber.  
     
     
         6 . A refrigerating arrangement as set forth in  claim 2 , further comprising a pump disposed upstream of said flow control device, said pump being operatively connected with the controller and adapted to be at least one of continuously operated or activated in a timed relationship with the opening of said flow control device.  
     
     
         7 . A refrigerating arrangement as set forth in  claim 1 , wherein the working fluid transfer device, which fluidly connects the condenser and the evaporator, comprises a capillary tube.  
     
     
         8 . A refrigerating arrangement as set forth in  claim 1 , wherein the working fluid transfer device which fluidly connects the condenser and the evaporator, comprises a selectively operable valve having a variable orifice for controlling the amount of working fluid which is permitted to be released into the evaporator.  
     
     
         9 . A refrigerating arrangement as set forth in  claim 1 , further comprising a dryer which is fluidly interposed between the working fluid transfer device and the condenser for removing predetermined contaminants from the working fluid.  
     
     
         10 . A refrigerating arrangement as set forth in  claim 1 , wherein the flow control device comprises a pump which is adapted to selectively pump fluid therethrough in a timed relationship with the opening of the flow control device.  
     
     
         11 . A method of operating a refrigeration unit having a condenser and an evaporator which are fluidly connected by a working fluid transfer device and wherein a pressure differential is produced in a manner which induces working fluid to flow from the evaporator to the condenser, comprising the step of selectively interrupting the flow of working fluid from the downstream end of the evaporator to the upstream end of the condenser using a rapidly operating operable flow control device which is operatively disposed between the downstream end of the evaporator and the upstream end of the condenser so as to maintain a pressure differential across the working fluid transfer device to force liquefied working fluid into the evaporator.  
     
     
         12 . A method as set forth in  claim 11 , further comprising the step of controlling the operation of the flow control device using a controller which is responsive at least one sensed parameter.  
     
     
         13 . A method as set forth in  claim 12 , further comprising the step of heating a portion of the working fluid which has passed through the flow control device to produce working fluid vapor and to increase the pressure on the downstream side of the flow control device.  
     
     
         14 . A method as set forth in  claim 13 , further comprising the step of sensing the temperature of the working fluid which is heated and supplying an indication of the sensed temperature to the controller.  
     
     
         15 . A method as set forth in  claim 14 , wherein said step of heating is carried out under the control of the controller and in a timed relationship with the opening of the flow control device and the delivery of the portion of the working fluid into a heating chamber which is located downstream of the flow control device.  
     
     
         16 . A method as set forth in  claim 11 , further comprising the step of pumping working fluid toward the flow control device using a pump which is disposed upstream of the flow control device in a predetermined timed relationship with the opening of the flow control device.  
     
     
         17 . A method as set forth in  claim 11 , further comprising the steps of: 
 sensing pressure at a location downstream of the flow control device; and    controlling the operation of the flow control device in accordance with the pressure which is sensed at the downstream position.    
     
     
         18 . A method as set forth in  claim 11 , further comprising the steps of: 
 sensing pressure at a location which is upstream of the flow control device; and    controlling the operation of the flow control device in accordance with the pressure which is sensed at the upstream position.    
     
     
         19 . A method of operating a refrigeration unit comprising the steps of: 
 condensing the working fluid vapor back to a liquid form via a first heat exchange on a downstream side of a flow control device to reduce the working fluid pressure on said downstream side of the flow control device;    expanding the condensed liquid working fluid via a flow restriction device in a manner in which heat is absorbed via a second heat exchange;    recycling the working fluid back to the flow control device; and    timing the opening of the flow control device to establish a dynamic fluid control which permits a quantity of working fluid to pass therethrough in accordance with a pressure differential which prevails thereacross and in a manner which maintains a necessary pressure differential to force the liquid working fluid through the flow restricting device.    
     
     
         20 . A refrigeration unit comprising: 
 means for condensing a working fluid vapor back to a liquid form via a first heat exchange on a downstream side of a flow control device to reduce the working fluid pressure on said downstream side of the flow control device;    means for expanding the condensed liquid working fluid via which has passed through a flow restriction device in a manner in which heat is absorbed via a second heat exchange, and recycling the working fluid back to the flow control device; and    means for timing the opening of the flow control device to establish a dynamic fluid flow which permits a quantity of working fluid to pass therethrough in accordance with the reduced pressure which prevails on the downstream side of the flow control devices and which maintains a pressure differential sufficient to force liquefied working fluid through the flow restriction device.    
     
     
         21 . A refrigeration system having a closed loop including a condenser, an evaporator and a flow transfer device via which working fluid is transferred from the condenser to the evaporator, comprising: 
 a pressure differential generator comprising a heating chamber or a pump via which a pressure differential in the loop is augmented to move working fluid toward the condenser;    a control parameter sensor associated with the pressure differential generator for sensing a parameter which is indicative of the magnitude of the pressure differential which tends to move the working fluid toward the condenser; and    a rapidly operated flow control device which is arranged with the pressure differential generator so that it selectively permits discrete amounts of working fluid to flow therethrough in the direction of the condenser, said flow control device being controlled in accordance with the output of said control parameter sensor in a manner to establish dynamic flow.    
     
     
         22 . A method of operating a refrigeration unit comprising the steps of: 
 transferring heat to an amount of a working fluid in a chamber to expand and pressurize the working fluid;    transferring the pressurized working fluid to a condenser;    condensing the working fluid vapor to a liquid in a condenser;    introducing a further amount of working fluid into the chamber when the pressure in the chamber has lowered due to the condensation of the working fluid vapor in the condenser;    transferring liquid working fluid from the condenser to an evaporator via a flow control device under the influence of the pressure produced by the heating of the working fluid;    recycling working fluid to the chamber via a flow control arrangement and introducing a further amount of working fluid into the chamber when the pressure in the chamber has lowered due to the condensation of the working fluid vapor in the condenser; and    rapidly repeating the repeating the steps of heating, condensing, transferring and recycling.    
     
     
         23 . A method as set forth in  claim 22 , further comprising the step of pumping working fluid from the evaporator toward the flow control arrangement.  
     
     
         24 . A refrigeration system having: 
 a condenser,    an evaporator,    a transfer device via which working fluid is transferred from the condenser to the evaporator,    a flow control device which permits amounts of working fluid from the evaporator to pass therethrough in spaced discrete intervals toward the condenser, and    a pump which is located either upstream or downstream of the flow control device and which comprises:    a reciprocal pump element;    a linear acting motor operatively connected with the pump element;    a control circuit operatively connected with said linear acting motor for controlling the linear drive force which is applied to said pump element and the manner in which working fluid which is displaced by pump, said control circuit being responsive to one or more sensors which determine a pressure differential across the flow control device.    
     
     
         25 . A refrigeration system as set forth in  claim 24 , wherein the flow control device is operatively connected with said control circuit so that it is opened and closed in a timed relationship with reciprocation of the pump element in a manner wherein columns of working fluid can be inertia rammed through the flow control device.