Refrigeration system with expander-assisted cooling and methods of use

A method of operating a refrigeration system, the method comprising:

• cooling a refrigerant using a first high side heat exchanger;
• reducing a pressure of a first portion of the refrigerant received from the first high side heat exchanger using a first expansion valve in a first low side heat exchanger unit;
• cooling a first space with the refrigerant received from the first expansion valve using a first low side heat exchanger in the first low side heat exchanger unit;
• reducing the pressure of a second portion of the refrigerant received from the high side heat exchange using an expander of an expansion-compression unit;
• and
• compressing the refrigerant received from the first low side heat exchanger using a compressor of the expansion-compression unit.

A refrigeration system, comprising:

• a first high side heat exchanger configured to receive refrigerant, the first high side heat exchanger configured to cool the refrigerant;
• a first low side heat exchanger unit positioned downstream of the first high side heat exchanger, the first low side heat exchanger unit comprising a first expansion valve positioned upstream of a first low side heat exchanger, wherein the first expansion valve is configured to receive a first portion of the refrigerant from the first high side heat exchanger, and wherein the first low side heat exchanger is configured to cool a first space proximate to the first low side heat exchanger;
• and
• an expansion-compression unit positioned downstream of the first high side heat exchanger and the first low side heat exchanger unit, the expansion-compression unit comprising:
• an expander configured to receive a second portion of the refrigerant from the first high side heat exchanger, wherein the expander is configured to reduce a pressure of the second portion of the refrigerant;
• and
• a compressor configured to compress the refrigerant received from the first low side heat exchanger unit;
• a flash tank positioned downstream of the expansion-compression unit, wherein the flash tank is configured to receive the refrigerant from the expander of the expansion-compression unit;
• a controllable valve positioned downstream of the first high side heat exchanger and upstream of the flash tank;
• a controller communicatively coupled to the controllable valve, wherein the controller is configured to:
• (i) direct a flow of the refrigerant received to the flash tank when the controllable valve is positioned in an open position;
• and
• (ii) direct the first portion of the refrigerant to the first low side heat exchanger unit and the second portion of the refrigerant to the expander of the expansion-compression unit when the controllable valve is positioned in a closed position.