Compressor oil recovery in hybrid VCC pumped two phase loops

A method of recovering a lubricant in a hybrid vapor compression cooling system, the method comprising:

• separating, by a separator, a vapor form of a working fluid from a liquid form of a working fluid, wherein the working fluid comprises the lubricant and wherein the lubricant is preferentially separated with the liquid form of the working fluid;
• delivering the liquid form of the working fluid from the separator to a liquid loop, the liquid loop comprising a pump and a cold sink fluidly coupled in flow series, the pump disposed in fluid communication between a separator outlet and each of a cold sink inlet and a heat exchanger inlet, the cold sink disposed in fluid communication with a separator inlet;
• delivering the vapor form of the working fluid from the separator to a vapor compression cycle loop, the vapor compression cycle loop fluidly coupled to the liquid loop by the separator and comprising a compressor, a condenser, and an expansion valve fluidly coupled in flow series, the expansion valve fluidly coupled to a separator inlet;
• delivering a first portion of the working fluid in the liquid loop to the cold sink;
• and
• delivering a second portion of the working fluid in the liquid loop to the vapor compression cycle loop, wherein delivering the second portion of the working fluid to the vapor compression cycle loop comprises delivering the second portion of the working fluid to a heat exchanger upstream of the compressor of the vapor compression cycle loop;
• wherein a first fluid metering element is disposed in a fluid line fluidly coupling the cold sink inlet and a pump outlet, the first fluid metering element configured to meter a flow of the working fluid delivered to the cold sink;
• and
• wherein each of the cold sink and the heat exchanger is disposed to receive a liquid form of the working fluid from the separator.

A cooling system comprising:

• a liquid loop comprising a cold sink for cooling a heat load;
• a vapor compression cycle loop fluidly coupled to the liquid loop by a separator, the vapor compression cycle loop comprising:
• a compressor;
• a condenser disposed downstream of the compressor;
• and
• an expansion valve disposed downstream of the condenser and upstream of the separator;
• wherein the separator is configured to separate a two-phase form of a working fluid received from the cold sink into a vapor form of the working fluid and a liquid form of the working fluid;
• and
• a heat exchanger in fluid communication with each of the liquid loop and the vapor compression cycle loop and configured to provide thermal communication between the working fluid in the liquid loop and the working fluid in the vapor compression cycle loop, the heat exchanger disposed between the condenser and the expansion valve and configured to place the working fluid received from the condenser in thermal communication with the working fluid received from the separator via a pump;
• wherein the compressor is fluidly coupled to a heat exchanger outlet and a separator outlet to receive the vapor form of the working fluid from each of the heat exchanger and the separator.