Thermal compensated pressure relief valve using shape memory materials for high temperature application

A pressure relief valve (PRV) comprising

• an inlet and an outlet defining a fluid flow path therebetween;
• a plunger, the plunger being moveable between a closed position and an open position, wherein, in the closed position, the plunger blocks the fluid flow path, and, in the open position, fluid may flow through the fluid flow path, the plunger being configured such that pressure at the inlet applies an opening force on the plunger, urging the plunger towards the open position;
• a biasing means configured to apply a biasing force to the plunger, thereby biasing the plunger towards the closed position such that, when the biasing force is greater than the opening force, the plunger remains in the closed position, and when the opening force is greater than the biasing force and the plunger moves to the open position;
• and
• a variable preload means, the variable preload means configured to apply a preload to the biasing means so as to increase the biasing force;
• wherein the variable preload means comprises a shape memory material such that, above a transition temperature of the shape memory material, the variable preload means is configured to change shape so as to apply a higher preload to the biasing means.