Direct Expansion Evaporator

Abstract

A direct expansion evaporator includes a feeding channel having a feeding end and a dispensing end for raw material feeding therethrough, and a heat exchange channel thermally communicating with the feeding channel for guiding refrigerant passing through the heat exchange channel to heat-exchange with the raw material to form a frozen product. The heat exchange channel has a pre-cooling portion and a freezing portion, wherein the heat exchange channel is configured to ensure a traveling time of the refrigerant at the pre-cooling portion to be longer than a traveling time of the refrigerant at the freezing portion. The raw material is guided to flow from the pre-cooling portion to the freezing portion so as to initially pre-cool the raw material and to substantially freeze the raw material to form the frozen product before the frozen product is dispensed at the dispensing end of the feeding channel.

What is claimed is: 
     
         1 . A direct expansion evaporator for making frozen product from raw material, comprising:
 a feeding channel having a feeding end and a dispensing end for the raw material feeding through said feeding channel; and   a heat exchange channel thermally communicating with said feeding channel for guiding refrigerant passing through said heat exchange channel to heat-exchange with the raw material within said feeding channel to form the frozen product, wherein said heat exchange channel has a pre-cooling portion formed toward said feeding end of said feeding channel and a freezing portion formed toward said dispensing end, wherein said heat exchange channel is configured to ensure a traveling time of the refrigerant at said pre-cooling portion of said heat exchange channel to be longer than a traveling time of the refrigerant at said freezing portion of said heat exchange channel.   
     
     
         2 . The direct expansion evaporator, as recited in  claim 1 , wherein a traveling path at said pre-cooling portion of said heat exchange channel is different from a traveling path of said freezing portion of said heat exchange channel. 
     
     
         3 . The direct expansion evaporator, as recited in  claim 1 , wherein a traveling path at said pre-cooling portion of said heat exchange channel is longer than a traveling path of said freezing portion of said heat exchange channel. 
     
     
         4 . The direct expansion evaporator, as recited in  claim 1 , wherein said heat exchange channel has a helix path configuration defined at said pre-cooling portion and a straight forward path configuration defined at said freezing portion. 
     
     
         5 . The direct expansion evaporator, as recited in  claim 1 , wherein a longitudinal length of said freezing portion of said heat exchange channel is shorter than a longitudinal length of said pre-cooling portion of said heat exchange channel. 
     
     
         6 . The direct expansion evaporator, as recited in  claim 1 , wherein a feeding direction of said raw material along said feeding channel is opposite to a flowing direction of said refrigerant along said heat exchange channel. 
     
     
         7 . The direct expansion evaporator, as recited in  claim 1 , wherein a traveling path of said heat exchange channel is long enough for phase-changing the refrigerant that the refrigerant is in liquid phase under a predetermined high pressure when entering into said heat exchanging channel and is in gaseous phase when exiting said heat exchanging channel. 
     
     
         8 . The direct expansion evaporator, as recited in  claim 1 , further comprising an outer guiding duct and an inner guiding duct coaxially enclosed within said outer guiding duct to define said feeding channel within said inner guiding duct and said heat exchange channel between said outer and inner guiding ducts. 
     
     
         9 . The direct expansion evaporator, as recited in  claim 8 , wherein a helix indention is formed at said outer guiding duct to form said heat exchange channel partitioned by a helix partition, wherein a peak of said helix partition is biased against an outer surrounding wall of said inner guiding duct to conceal said heat exchange channel along said inner guiding duct in a weld-less manner. 
     
     
         10 . The direct expansion evaporator, as recited in  claim 9 , wherein said helix partition has a V-shaped configuration that a circumferential size of said peak of said helix partition is slightly smaller than a circumferential size of said outer surrounding wall of said inner guiding duct, such that when said inner guiding duct is coaxially received within said outer guiding duct, said peak of said helix partition is slightly elastic-deformed to bias against said outer surrounding wall of said inner guiding duct so as to form said heat exchange channel between said inner and outer guiding ducts. 
     
     
         11 . A method of manufacturing a direct expansion evaporator for making frozen product from raw material, comprising the steps of:
 (a) configuring a feeding channel which has a feeding end and a dispensing end for the raw material feeding through said feeding channel;   (b) configuring a heat exchange channel for guiding refrigerant passing through said heat exchange channel to thermally communicate with the raw material within said feeding channel, wherein said heat exchange channel is configured by the steps of:   (b.1) forming a pre-cooling portion to be extended toward said feeding end of said feeding channel;   (b.2) forming a freezing portion to be extended toward said dispensing end of said feeding channel; and   (b.3) a traveling time of the refrigerant at said pre-cooling portion of said heat exchange channel being longer than a traveling time of the refrigerant at said freezing portion of said heat exchange channel; and   (c) guiding the raw material and the refrigerant passing through said feeding channel and said heat exchange channel respectively for heat-exchanging to form said frozen product before said frozen product is dispensed at said dispensing end of said feeding channel.   
     
     
         12 . The method, as recited in  claim 11 , wherein said step (b) further comprises a step of configuring a traveling path at said pre-cooling portion of said heat exchange channel different from a traveling path of said freezing portion of said heat exchange channel. 
     
     
         13 . The method, as recited in  claim 11 , wherein said step (b) further comprises a step of configuring a traveling path at said pre-cooling portion of said heat exchange channel longer than a traveling path of said freezing portion of said heat exchange channel. 
     
     
         14 . The method as recited in  claim 11  wherein, in said steps (b.1) and (b.2), wherein said heat exchange channel has a helix path configuration defined at said pre-cooling portion and a straight forward path configuration defined at said freezing portion. 
     
     
         15 . The method, as recited in  claim 11 , wherein said step (b) further comprises a step of configuring a longitudinal length of said freezing portion of said heat exchange channel shorter than a longitudinal length of said pre-cooling portion of said heat exchange channel. 
     
     
         16 . A direct expansion evaporator for making frozen product from raw material, comprising:
 an inner guiding duct defining a feeding channel therealong and having a feeding end and a dispensing end for guiding the raw material flowing along said feeding channel from said feeding end to said dispensing end; and   an outer guiding duct, wherein said inner guiding duct is enclosed within said outer guiding duct to form a heat exchange channel between said outer and inner guiding ducts for guiding refrigerant flowing along said heat exchange channel from an inlet to an outlet thereof so as to heat-exchange with said raw material along said feeding channel, wherein said heat exchange channel has a helix path toward said feeding end of said feeding channel and a straight forward path toward said dispensing end, such that said heat exchange channel provides two different traveling paths for guiding the refrigerant to heat-exchange with the raw material to form the frozen product.   
     
     
         17 . The direct expansion evaporator, as recited in  claim 1 , wherein a traveling time of the refrigerant at said helix path of said heat exchange channel to be longer than a traveling time of the refrigerant at said straight forward path of said heat exchange channel. 
     
     
         18 . The direct expansion evaporator, as recited in  claim 16 , wherein a longitudinal length of said straight forward path of said heat exchange channel is shorter than a longitudinal length of said helix path of said heat exchange channel. 
     
     
         19 . The direct expansion evaporator, as recited in  claim 16 , wherein a helix indention is formed at said outer guiding duct to form said heat exchange channel partitioned by a helix partition, wherein a peak of said helix partition is biased against an outer surrounding wall of said inner guiding duct to conceal said heat exchange channel along said inner guiding duct in a weld-less manner. 
     
     
         20 . The direct expansion evaporator, as recited in  claim 19 , wherein said helix partition has a V-shaped configuration that a circumferential size of said peak of said helix partition is slightly smaller than a circumferential size of said outer surrounding wall of said inner guiding duct, such that when said inner guiding duct is coaxially received within said outer guiding duct, said peak of said helix partition is slightly elastic-deformed to bias against said outer surrounding wall of said inner guiding duct so as to form said heat exchange channel between said inner and outer guiding ducts.