A bladder control system for a two-phase pump loop (TPPL) includes an air compressor, an air line connected to the air compressor, first and second solenoid valves located along the air line, a refrigerant tank having a port operatively connected to the TPPL for selective flow of refrigerant between the refrigerant tank and the TPPL, an expandable bladder located within the refrigerant tank and having a port connected to the air line between the first and second solenoid valves for selective flow of air between the expandable bladder and the air line, and a controller. The controller selectively expands and contracts the expandable bladder to control flow of refrigerant out of the refrigerant tank to the TPPL and into the refrigerant tank from the TPPL for maintaining the system refrigerant pressure within a desired tight range. This is particularly useful for obtaining tight temperature control at the thermal load.

A refrigeration system comprises a compressor, a condenser, a receiver tank, an evaporator and a heat exchanger. The heat exchanger comprises an inlet positioned downstream of the receiver tank and an inlet positioned downstream of the compressor. The heat exchanger is configured to transfer heat between refrigerant received from the compressor and refrigerant received from the receiver tank, wherein a transfer of heat causes at least a portion of the refrigerant received from the receiver tank to transition from liquid to vapor. This process propels the head pressure of the compressor to increase to compensate for low ambient conditions. The heat exchanger comprises a first outlet in fluid communication with the first inlet, the first outlet configured to dispense the vapor refrigerant toward the receiver tank, and a second outlet in fluid communication with the second inlet and configured to dispense the refrigerant received from the compressor toward the condenser.