System and method for converting waste heat into electricity

An integrated expander-generator assembly comprising:

• a plurality of permanent magnets;
• a plurality of coils;
• a piston;
• and
• a cylinder,
• arranged such that the plurality of permanent magnets are arranged inside the piston and the plurality of coils are arranged along a length of the cylinder,
• and wherein, when in use, pressurized gas expanding in the integrated expander-generator assembly produces a mechanical force that actuates the piston in the cylinder, and wherein upon such actuation, a relative motion between the plurality of permanent magnets and the plurality of coils produces electricity.

A method for converting waste heat into electricity, the method comprising:

• arranging a heat capture subsystem to hold a heat transfer fluid therein, wherein the heat capture subsystem, in use, enables the heat transfer fluid to absorb the waste heat;
• arranging an evaporation subsystem comprising a phase change heat exchanger to be coupled to the heat capture subsystem, and filling the phase change heat exchanger with a working fluid, wherein the working fluid is vaporized from a liquid phase to a gaseous phase when the working fluid absorbs the waste heat from the heat transfer fluid, the working fluid being selected based upon the temperature of the waste heat;
• arranging an expander subsystem to be coupled to the evaporator subsystem via at least one fluid flow control element, wherein pressurized vapour of the working fluid that emanates from the evaporator subsystem is directed towards the expander subsystem using the at least one fluid flow control element, and wherein when the expander subsystem is in use, the pressurized working fluid vapour is allowed to expand in the expander subsystem, producing a mechanical force for actuating the expander;
• arranging a generator subsystem to be coupled to the expander subsystem, wherein the generator, when in operation, produces electricity using the mechanical force created by the expansion of the pressurized working fluid vapour;
• arranging a condenser subsystem to be connected to the expander subsystem, wherein the condenser, when in operation, liquifies the expanded working fluid vapour from the gaseous phase to the liquid phase, and wherein the condensed working fluid is returned under pressure to the evaporator subsystem;
• configuring a control subsystem for controlling operations of the other subsystems and
• arranging a variable frequency drive (VFD) to be electrically coupled to the generator, wherein the VFD is operable for providing an electrical load to the generator to produce a resistive force opposing the mechanical force produced by the pressurized vapour of the working fluid.