Two-phase refrigeration system

A heat transfer system, comprising:

• a first heat transfer fluid circulation loop including:
• a fluid pumping device;
• a heat exchanger condenser configured to reject heat from a first heat transfer fluid flowing therethrough;
• a flow metering device;
• and
• a heat exchanger evaporator/condenser configured to absorb thermal energy into the first heat transfer fluid;
• wherein a first conduit in a closed fluid circulation loop circulates the first heat transfer fluid therethrough;
• and
• a second two-phase heat transfer fluid circulation loop configured to exchange heat with the first heat transfer fluid circulation loop through the heat exchanger evaporator/condenser, including:
• a liquid pump;
• a heat exchanger evaporator configured to evaporate a second heat transfer fluid via a thermal energy exchange with an airflow urged across the heat exchanger evaporator;
• and
• a receiver disposed between the heat exchanger evaporator/condenser and the liquid pump, the receiver configured to condense the second heat transfer fluid to a liquid state without subcooling;
• wherein a second conduit in a closed fluid circulation loop circulates the second heat transfer fluid through the heat exchanger evaporator/condenser, the receiver, the liquid pump, and the heat exchanger evaporator, the second heat transfer fluid having an ASHRAE Class A toxicity rating and an ASHRAE Class 1 or 2L flammability rating or their ISO 817 equivalents.