Methods and devices for optimizing heat transfer within a compression and/or expansion device

A method of compressing a gas in an energy storage and recovery system using a pressure vessel defining a working chamber having a volume, the pressure vessel having a gas conduit through which gas can be introduced into the working chamber and discharged from the working chamber and having a liquid conduit through which liquid can be introduced into the working chamber and discharged from the working chamber, the pressure vessel having a heat transfer element disposed within the working chamber, the method comprising:

• introducing a quantity of gas into the working chamber;
• reducing the volume of the working chamber, causing the pressure of the gas to increase and causing the temperature of the gas to increase to a temperature above a temperature of the heat transfer element and causing heat energy produced by the compression to be transferred from the gas to the heat transfer element;
• introducing liquid into the working chamber via the liquid conduit;
• causing the liquid to contact a portion of the heat transfer element to which heat energy has been transferred from the gas, causing the heat energy to be transferred from the heat transfer element to the liquid;
• introducing a quantity of high pressure gas into the working chamber via the gas conduit;
• and
• increasing the volume of the working chamber, causing the pressure of the high pressure gas to decrease and causing the temperature of the high pressure gas to decrease to a temperature below a temperature of the heat transfer element and causing heat energy to be transferred from the heat transfer element to the high pressure gas.

An apparatus suitable for use in a compressed gas-based energy storage and recovery system, the apparatus comprising

• a pressure vessel having a working chamber therein in which gas can be contained, having one or more gas conduits through which gas can be introduced into and discharged from the working chamber, and having one or more liquid conduits through which liquid can be introduced into or expelled from the working chamber;
• and
• a heat transfer element disposed within the working chamber,
• the working chamber having a volume, when a liquid is contained within the working chamber, a first portion of the volume being occupied by liquid and a second portion being available to be occupied by gas,
• the pressure vessel being operable to reduce the volume of the second portion of the working chamber to compress gas contained therein, to transfer heat energy from the compressed gas to the heat transfer element, and to cause liquid in the first portion of the working chamber to contact the heat transfer element to transfer to the liquid heat energy transferred from the compressed gas to the heat transfer element,
• the pressure vessel being operable to expand high pressure gas introduced into the working chamber through the one or more gas conduits by increasing the volume of the second portion of the working chamber and causing heat energy to be transferred from the heat transfer element to the expanded gas to increase the temperature of the expanded gas.