Monocoque shell and tube heat exchanger

A heat exchanger for transferring heat between a first fluid and a second fluid, comprising:

• a heat exchanger having a monocoque structure, the heat exchanger comprising a plurality of tubes through which a first fluid may flow in a direction, each of the plurality of tubes having a first mouth end, an opposing second mouth end and a waist region between the first mouth end and the second mouth end,
• the first mouth end, the second mouth end and the waist region of each of the plurality of tubes having a respective cross section, wherein the cross section of the waist region of one or more of the plurality of tubes is less than the respective cross section of the first mouth end and/or the second mouth end;
• one or more interconnected fluid channels through which a second fluid may flow, the one or more fluid channels lying generally in a plane, the plurality of tubes and the one or more fluid channels interleaving such that heat may be transferred between the plurality of tubes and the one or more fluid channels,
• wherein the direction of flow of the first fluid is generally perpendicular to the plane of the one or more fluid channels;
• and
• a multi-layered mesh/screen, having a pore size which is less than the cross section of the first mouth ends,
• wherein the multi-layered mesh/screen is attached to and covers the first mouth ends or the second mouth ends.