Cooling apparatus with evaporator

Abstract

A cooling apparatus for objects such as convenience foods and beverages has an enclosure and a vapour cycle refrigeration system. The refrigeration system includes a compressor, a condenser, a metering device and an evaporator, all connected in a circuit. Fans force air across the evaporator coils during operation of the compressor. When the compressor is ‘off’, or dormant, the evaporator fans are operated in a partial or reduced duty cycle in which the overall power draw and average power consumption is less than it would be if the evaporator fans were run continuously.

1 . A cooling apparatus including:
 an enclosure in which to place objects to be cooled;   a compressor, a condensor, an expansion member, and an evaporator connected together in a vapour cycle cooling circuit;   said evaporator being located within said enclosure;   air moving apparatus mounted within said enclosure;   control circuitry, said control circuitry being connected to operate said compressor and said air mover;   said compressor having a duty cycle, said compressor duty cycle including a first portion and a second portion, said compressor being in operation in said first portion and dormant in said second portion;   said air moving apparatus having a duty cycle, said air moving apparatus duty cycle including a first portion and a second portion;   in said first portion of said air moving apparatus duty cycle said air moving apparatus being in operation while said compressor is in operation;   in said second portion of said air moving apparatus duty cycle said compressor is dormant and said air moving apparatus alternates between ‘on’ and ‘off’ conditions.   
   
   
       2 . The cooling apparatus of  claim 1  wherein, during steady state operation, said second potion of said air moving apparatus duty cycle includes at least three alternations between ‘on’ and ‘off’ while said compressor remains in a single dormant portion of its duty cycle. 
   
   
       3 . The cooling apparatus of  claim 1  wherein said enclosure has a volume V, a resistance to heat loss R, and a thermal time constant T; and, in steady state operation when said compressor is dormant said second portion of said air moving apparatus duty cycle includes one of (a) an ‘on’ portion that is less than 5% as long as said time constant; and (b) the combination of an ‘on’ portion and a following ‘off’ portion that sum to a length of time that is less than 15% of said time constant. 
   
   
       4 . The cooling apparatus of  claim 1  wherein said air moving apparatus is ‘on’ less than 80% of the time when said compressor is dormant. 
   
   
       5 . The cooling apparatus of  claim 1  wherein said second portion of said duty cycle of said compressor is longer than said first portion, and said air moving apparatus cycles ‘on’ and ‘off’ during said second portion, each ‘on’ cycle of said air moving apparatus during said second portion of said duty cycle of said compressor being less than 10% as long as said second portion. 
   
   
       6 . The cooling apparatus of  claim 1  wherein, during said second portion of said duty cycle of said compressor said air moving apparatus is more often ‘off’ than ‘on’. 
   
   
       7 . The cooling apparatus of  claim 6  wherein said air moving apparatus remains ‘off’ no longer than 5 minutes at a time. 
   
   
       8 . The cooling apparatus of  claim 6  wherein said air moving apparatus is ‘off’ between 25 and 80% of the time. 
   
   
       9 . The cooling apparatus of  claim 6  wherein during said second portion of said duty cycle of said compressor said cycle of ‘on’ and ‘off’ portions of said air moving apparatus has a total cycle duration in the range of 1 minute to 10 minutes. 
   
   
       10 . The cooling apparatus of  claim 9  wherein said total cycle time is in the range of 2 minutes to 5 minutes. 
   
   
       11 . The cooling apparatus of  claim 1  wherein said enclosure has first and second temperature sensors operable to sense first and second temperatures at respective first and second locations in said enclosure, said control circuitry being operable to observe a temperature difference between said first and second temperatures, and, when said compressor is dormant, said air moving apparatus comes ‘on’ when said temperature difference exceeds a first threshold value, and turns ‘off’ when said temperature difference falls below a second threshold value. 
   
   
       12 . The cooling apparatus of  claim 11 , wherein said cooling apparatus has a temperature sensor mounted to observe a temperature within said enclosure, and said compressor comes ‘on’ when said sensor senses a high temperature T H , and turns off when said sensor senses a low temperature, T L ; and said first threshold value is less than the difference between T H  and T L . 
   
   
       13 . The cooling apparatus of  claim 11  wherein said cooling apparatus monitors an internal temperature therein, said compressor comes ‘on’ when said internal temperature exceeds a high temperature threshold T H , and turns off when said internal temperature falls below a low temperature threshold, T L ; and said air moving apparatus is operable in response to readings from another monitored temperature within said enclosure; and said apparatus operates to maintain ripple in said other monitored temperature as compared to said internal temperature exceeds 40% of the difference between T H  and T L . 
   
   
       14 . The cooling apparatus of  claim 13  wherein said air moving apparatus operates in an ‘on’ condition when the sum of said internal temperature and said ripple exceeds T H . 
   
   
       15 . A method of operating cooling apparatus, the cooling apparatus including an enclosure in which to place objects to be cooled; a compressor, a condenser, an expansion member, and an evaporator connected together in a vapour cycle cooling circuit; said evaporator being located within said enclosure; air moving apparatus mounted within said enclosure; control circuitry, said control circuitry being connected to operate said compressor and said air mover, said method comprising:
 operating the compressor on a duty cycle, the duty cycle including a first portion and a second portion, said compressor being in operation in said first portion and dormant in said second portion;   operating the air moving apparatus for at least a portion of the time in which said compressor is in operation; and   operating the air moving apparatus intermittently when the compressor is dormant.