Patent ID: 7726151

Claim:
A refrigeration system comprising: a compressor including an inlet and an outlet; a working fluid present throughout the system, the working fluid capable of being in a mixed liquid/gaseous state; a condenser including an inlet and an outlet, said condenser inlet in fluid communication with said compressor outlet; a sub-cooler, said sub-cooler having first and second fluid passages, said first passage having an inlet and an outlet, said second passage having an inlet and an outlet, said first passage inlet in fluid communication with said condenser outlet, said first passage and said second passage in a heat exchange relationship; an expansion device having an inlet and an outlet, said expansion device inlet in fluid communication with said sub-cooler first passage outlet; and an evaporator having an inlet and an outlet, said evaporator inlet in fluid communication with said expansion device outlet; said sub-cooler second passage inlet in fluid communication with said evaporator outlet, said second passage outlet in fluid communication with said compressor inlet, the temperature of the working fluid at said second passage outlet being substantially constant and substantially equal to the temperature of the working fluid at said sub-cooler first passage inlet, wherein the mass flow rate of the working fluid is substantially constant and the pressure of the working fluid at said sub-cooler second passage outlet is substantially constant, whereby the pressure and temperature of the working fluid in said evaporator are substantially constant; said sub-cooler further including: a working fluid bypass flow passage, said bypass flow passage having a different length than said second passage, said bypass flow passage in fluid communication with said second passage inlet and outlet; and an apportioning valve fluidly connected to said sub-cooler second passage inlet, said apportioning valve further fluidly responsive to the liquid content of the working fluid connected to said second passage and said bypass flow passage.