Two-stage expansion cooling system and evaporator thereof

A two-stage expansion cooling system, adapted to remove heats from a heat generating object by a working fluid circulated therein, the system comprising:

• a compressor, for compressing the working fluid to form a high-pressure liquid working fluid;
• a condenser, for reducing a temperature of the high-pressure liquid working fluid;
• a first stage expansion device, for reducing the pressure and the temperature of the high-pressure liquid working fluid, wherein the temperature of the high-pressure liquid working fluid is above a dew point temperature of the ambient;
• and
• an evaporator, for receiving the cooled high-pressure liquid working fluid, wherein the evaporator further comprises:
• a thermal-conductive block, having a channel system therein, wherein the channel system further comprises:
• a high-pressure channel, provided for the high-pressure liquid working fluid to enter the thermal-conductive block through the high-pressure channel;
• a low-pressure channel, communicated with the compressor;
• and
• an second stage expansion channel, having an input end and an output end, wherein the input end is communicated with the high-pressure channel, the output end is communicated with the low-pressure channel and has a cross-sectional area smaller than that of the low-pressure channel, the high-pressure liquid working fluid enters the second stage expansion channel through the input end, a part of the high-pressure liquid working fluid expands into a saturated low-pressure liquid working fluid of which the temperature is below the dew point at the output end and enters the low-pressure channel, and the low-pressure liquid working fluid in the low-pressure channel absorbs heats from the heat generating object through the thermal-conductive block and then enters the compressor.