Harvesting electrical power from waste heat using stirling engine

Different processes that use energy and machines that do work do not have perfect efficiency. So energy is wasted from these processes in the form of heat. Power generating stations, industrial processes, rice mills, brick fields and other human activities are major sources of waste heat. Mud stoves used in rural areas for cooking purpose produce above 85% of waste heat. This wasted heat can be used to generate electrical power using Stirling engine (SE). Stirling engine is a heat engine that is operated at different temperature levels by cyclic operation of compression and expansion of working gas. A DC generator is coupled with the SE to generate electrical energy. In this research amount of waste heat from significant sources has been presented and theoretical analysis has been made to harvest electrical power using a displacer type SE. Utilizing helium as working fluid and a DC generator having 90% efficiency a SE with displacer swept volume of 7.37 ×10^-4 m³ can generate 80 watt of electrical power at 115 rpm engine frequency. In this mathematical approach the phase angle is 90^o and the temperature difference is about 150 ⁰K. The setup discussed is working as a personal power plant for each rural household.