Forming liquid sprays in compressed-gas energy storage systems for effective heat exchange

A compressed-gas energy storage and recovery system comprising:

• a cylinder assembly for at least one of compressing gas to store energy or expanding gas to recover energy;
• a movable boundary mechanism separating the cylinder assembly into two chambers;
• a crankshaft, mechanically coupled to the boundary mechanism, for converting reciprocal motion of the boundary mechanism into rotary motion;
• a heat-transfer mechanism, comprising a plurality of nozzles, for introducing heat-transfer fluid within a chamber of the cylinder assembly to exchange heat with gas therein, thereby increasing efficiency of the energy storage and recovery;
• an actuating mechanism for controlling a number of active nozzles introducing heat-transfer fluid within the chamber during a single cycle of compression or expansion of gas, the actuating mechanism comprising a plurality of valves and a control system for controlling the valves based at least on a pressure within the cylinder assembly;
• and
• a sensor for measuring the pressure within the cylinder assembly, the control system being responsive to the sensor,
• wherein the plurality of nozzles is organized into at least two nozzle groups, at least one nozzle group not being active during a portion of the single cycle of compression or expansion.